Model Boat Mayhem
Mess Deck: General Section => Chit-Chat => Topic started by: irishcarguy on March 05, 2013, 11:32:18 pm
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About a week ago I posted quite a bit of information on a C/V joint that I got from the local hobby shop in my search for a descent drive joint for boats. I posted it in engineering & to say the least the response has been a bit of a disappointment. I am raising it here because most if not all check into Chit Chat. The joint in question is made in Taiwan & sold in the US by a company called HPI Racing. I am sure that most of you that race or play with model cars have heard of this company. The spec on the package is Universal Joint 9x162 MM and there are a pair in the package. The cost in Canada is about $40.00 + tax, True you do have to make a few changes to it to fit a boat but they are pretty easy to do,if I can do it most anybody can make the mods.I have NO commercial interest in this, I am just trying to pass on what I deem valueable information to my fellow members. This is so superior than anything I have yet seen & used that if you try them you will wonder why you ever used what has passed for drive joints in the past, By all means if you have questions just post here or PM me. Mick B.
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I have been following it, any chance you could post drawings etc for a clearer explanation?
Ta
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Mick
I didn't miss you're write up on your CV joint. I'm building a Joffre at the moment and I'm going to try one out. Anything has to be better than the traditional Huco that most modellers use. I think there is still a reluctance on the part of many modellers to accept that what they have been using is not quite right. Even the Caldercraft drawings on the Joffre show a single Huco being used. Don't get discouraged. I think it'll take a while for the masses to see the light.
John
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I think what upsets me is the way the trade has short changed us & basically sold us junk pretending it was O/K & made no attempt to change. It is obvious to me that they are aware of what has gone on. I will not give up until I see real change. I am going to write to HPI racing hoping to get a better response than I got on the phone. It is obvious that they don't make them theirselves as they come from offshore, the search goes on.Thanks for the encouragement John. I will try to draw it & show how to modify it. Mick B.
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If you go to a model shop that sells HPI parts, the part# is 87239 just in case the bright spark in the store don't know what you are looking for. Mick B. PS =look up their web site (HPI Racing).
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If you go to a model shop that sells HPI parts, the part# is 87239 just in case the bright spark in the store don't know what you are looking for. Mick B. PS =look up their web site (HPI Racing).
Thanks Mick. I'm going to see what our local hobby store can rustle up.
John
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Hi John, if you have trouble finding some PM me & I can send you a set, regards, Mick B.l
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I have been looking for some high quality shaft couplings for use with large brushless motors. I am going to use Emax BL4030 motors which now come with an 8mm shaft so the normal couplings were of no use. I found some "dog and bone" couplings advertised on Propshops website and they made a pair up for me to the sizes I required. They weren't the cheapest of couplings at £25 each but they are large and well made and look to be very strong and far superior to the Huco type coupling. I can't comment on how they perform as I will not be able to try them out for some time.
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wont take mis-alignment
:embarrassed:
vnkiwi
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wont take mis-alignment
:embarrassed:
vnkiwi
Which one?
The type shown in the last posting is similar to the original ones supplied by RipMax back in the late fifties and in another form seems to suffice for fast powerboats. This one :- http://www.puffinmodels.com/product.php?prod=1706 (http://www.puffinmodels.com/product.php?prod=1706) may be a bit cheaper.
They do take out minor misalignments in more than one plane, but let's face it, we all use a rigid sleeve for initial propshaft/motor alignment don't we?
Regards Ian
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While I fully appreciate what Mick is trying to achieve, a true C/V joint has no endfloat capability so any float is transmitted back to the engine/motor, that's the advantage of the Ball joint coupling.
Regards Ian
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I am sure we all use rigid sleeves to set motor positions relative to prop shafts, but inevitably very small misalignments in any of 3 planes are almost inevitable. I tend to use double jointed couplers rather than single as these tend to work for all planes. Disadvantage is they can be noisy at low rpm.
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Huco sell many different types.... http://www.huco.com/products.asp?cat=64
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As has been covered extensively in another thread, a single universal joint only covers in one plane, as was said above. This is the reason for vibration and noise in the motor/shaft drive train many modelers experience. No matter how you look at it a single joint (dog bone, Huco or whatever) only does half the job. All you have to do is look at the drive shaft(s) under you car. If a single universal would look after all planes of misalignment you can be sure the manufacturers would only use one.
I doubt everyone uses a solid tube to align their motor/prop shaft. If they did, why buy the single universal joint? You could just leave the solid shaft in place and save money. In fact you'd have a quieter coupling doing so, although it may tend to be a little tight in places.
John
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O0
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I have been looking for some high quality shaft couplings for use with large brushless motors. I am going to use Emax BL4030 motors which now come with an 8mm shaft so the normal couplings were of no use. I found some "dog and bone" couplings advertised on Propshops website and they made a pair up for me to the sizes I required. They weren't the cheapest of couplings at £25 each but they are large and well made and look to be very strong and far superior to the Huco type coupling. I can't comment on how they perform as I will not be able to try them out for some time.
If you used two of those, back to back, with the dog bone set at 90 deg. to each other, you'd have the ideal set up.
John
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All you have to do is look at the drive shaft(s) under you car. If a single universal would look after all planes of misalignment you can be sure the manufacturers would only use one.
Wonder why Uncle 'enry only put one on my 10 then?
The coupling on a toy boat is precisely that, a coupling, it doesn't have to take up many planes of alignment, the shaft is fixed, the motor is fixed so it joins one to t'other. If the builder is too lazy to line things up, then an increase in wear on the various bits and an increase in current drawn results.
Basic mechanics dictates a ball and socket joint will transmit drive on more than one plane and do it with less stress than a Huco.
Still can't beat lining them up properly.
Regards Ian
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The main reason I bought the expensive couplings from Propshop is that I was unable to find anyone else who could supply a coupling for an 8mm motor shaft. It was only after the motors arrived from HK that I found out they had changed the spec from a 6mm shaft to 8mm.
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Hi guys I have not looked at the whole range of C/V joints made by HPI Racing. There are similar ones made by other companies but in my search these ones I purchased came near to what I was looking for & which I felt with a little bit of work would fit. I feel pretty sure there are others out there that can do the job too it is just that I found one that I knew I could modify to fit most applications that I was using or going to use in my boats, (1/16 Tamar, 1/12 Tamar, Smit Nederland,and the Fairmount Alpine) I have now modified 3 sets of these & had no problems what so ever. Dave (Norseman) has one I sent him to try & photos are on the engineering thread. It would be nice if HPI racing took the time to take my phone call, but I hope my letter will get a better chance to reach the top.This particular joint is very easy to adapt to most setups that we use on our boats, hence the choice I made. There were others of a similar design but would have required more work to adapt. You are correct Martin Huco do make other joints but still in the same design & with the same problems, they were what got me started on the hunt for a better joint in the first place,I feel I have found one. Mick B.
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Irishguy
Am I being confused, but I don't see a constant velocity joint in the HPI catalog?
I do see universal joints of various types but not a true CV.
All UJ s are useless unless used as opposite pairs.
The comments about using proper alignment are true BUT it is near impossible to maintain in a model let alone a real size boat where immersed and dry hull movement is quite large.
Some years ago we built a simple type for a model based on the chinook helicopter as the model had the same prob as the original, a commoning shaft windup, when using UJ s.
The type we made was like this one
http://www.youtube.com/watch?v=yoipuajv8wk
Good thread though.
Boneash
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Hi Mick,
Love your solution to the CV for boats.
The Huco seem to be designed, not for misalignment, but for changes in direction, of properly aligned shafts. (and that in one plane only).
If they'd made the centre link ends of their double at 90 degrees to each other, would have made a more useful joint for use by us model boaties.
These (Huco) joints where never designed for the use we put them to.
Keep up the good work
cheers
vnkiwi
ps Boneash, that's a CV joint designed to carry huge loading, nice piece of design, thanks for the link
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Hi Guys
I am very fortunate in having one of Mick's joints but I am not yet ready for the build it pairs up with. What I can say is it is a solid piece of kit that inspires some confidence. I do agree that one has to make good efforts to align everything ... But for any small errors this really seems to be a good answer, and especially so for the more powerful set ups.
Dave
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It is in the catalogue under part #87239 & it also shows where stock levels are at & availability in different countries. It is a true C/V joint as it will pivot in any direction through 360 degrees, a U/Joint won't do that. I do know the difference between a U/Joint & a C/V joint as I fitted quite a few in my 50 years as an Automotive Tech, just wishing I had a $1 for each one I fitted.Mick B.
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Generally a C/V joint which are fitted these days to all front wheel drive cars (some have different names) show no loss of power when driving through different angles, some turn through an angle of over 30 degrees when you steer your car. This of course means that its alignment is not critical and it will tolerate misalignment without any perceptible power loss or noise, really a win win situation for us model boat builders. Mick B.
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really a win win situation
All win win situations are gratefully accepted Mick :-))
Now if you can sort out my kids I will be impressed O0
Dave
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what you guys are looking for is these:
http://www.litemodz.com/specials.php (http://www.litemodz.com/specials.php)
they are £44 each of course:
http://www.litemodz.com/index.php?cPath=34 (http://www.litemodz.com/index.php?cPath=34)
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what you guys are looking for is these:
http://www.litemodz.com/specials.php (http://www.litemodz.com/specials.php)
they are £44 each of course:
http://www.litemodz.com/index.php?cPath=34 (http://www.litemodz.com/index.php?cPath=34)
Beauty.......nice bit of kit
John
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SHG and Hunter Systems supply a little double end yellow plastic coupling that behaves in the same way as a CV coupling. Very cheap- under a fiver last time I looked. No good for high power, but fine for most scale subjects.
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I like that joint & would like to get one to see if it is possible to adapt to our boats. My own prototype design is similar but I am using 4 ball bearings. I can't curve the Ball slots as they have done on that shaft but it should work well with 4 or 5 balls if you align it within 10 degrees, any more out of alignment & it will probably vibrate, These things take time & a lot of effort & often don't work after all. However the one Made from the HPI racing shaft does work & can fit most of our models, the limiting factor is the motor shaft diameter @ 6MM. There is not enough metal to make the bore larger. The attaching sleeve can be made to fit any propshaft. Mick B.
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Sorry I should have said the joint put up by Mad Mike. Mick B.
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%% here is an idea ,can you ran a 6m/m die over the shaft and then turning a sleave with a hole tapped 6m/m , this can be any diameter
you require to receive shaft, hope this is clear .Ray. %% %% [size=78%] [/size]
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Also, suppose consideration was given to using the unit "as is", that is no cutting down or is the overall length too long?????????????
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I like that joint & would like to get one to see if it is possible to adapt to our boats. My own prototype design is similar but I am using 4 ball bearings. I can't curve the Ball slots as they have done on that shaft but it should work well with 4 or 5 balls if you align it within 10 degrees, any more out of alignment & it will probably vibrate, These things take time & a lot of effort & often don't work after all. However the one Made from the HPI racing shaft does work & can fit most of our models, the limiting factor is the motor shaft diameter @ 6MM. There is not enough metal to make the bore larger. The attaching sleeve can be made to fit any propshaft. Mick B.
I think i have missed the point of the thread are you planning on producing your own cv joints or talking about adapting readily available ones? That supplier of those cv joints make them for both front and rear wheel applications, the front wheels of course having steering need to deviate 30 degrees from the centre line, not including any additional angles provoked by suspension movement. Unless were talking about different cv's of course.
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Mike I don't know how long you have been following this thread & also another thread by John(oldiron). When I tried out the Huco couplings supplied with my motors for my Smit Nederland I was not happy with the racket they made. At that time a lot of discussion took place & John actually did a series of tests & found the Huco sadly lacking compared to other joints, the Dumas dogbone was the best one he tested.Neil expressed the opinion that the Huco was in fact only rated by Huco for around a thousand revs, certainly not up to the revs used by many in their boats. At the time I had an idea that I could make a real C/V joint using an inner ball housing holding 4 3/16 ball bearings in 4 cups 3/32 inch deep drilled in that housing. I would then make an outer housing 3/4 inch diameter & put 4 3/16inch grooves 90 degrees apart for the ball bearings to run in.All this was done free hand. The centre for the outer is bored 3/8 inch for the inner hub carrying the 4 ball bearings to fit & is 5/8 inch deep It worked but was not accurate enough & had vibration. I decided there & then that I needed a mill to get the accuracy I wanted, guess what I bought myself a mill. During the time I tried making my prototypes (3 in fact) & getting my mill I saw in my local model shop Axle shafts made by HPI Racing that I thought I could modify & be able to use on my boats, These are true C/V joints & there were different ones but I finally settled on one type that had enough meat(metal) on it that allowed me to make the mods to fit my boats.I made it & tested it & it worked like a dream. I sent one to Dave (Norseman) to put some photos on the Forum (I can't yet,dumb) & also to use on his upcoming model & I also wanted his opinion on the joint. This is where I am at now. The joint works & is fairly easy to modify to fit most shafts, up to 6MM motor shafts & the connecting sleeve can be large enough in diameter to be threaded 4MM to attach to the shortened axle shaft & the necessary thread or hole to fit a propshaft of just about any size. The sleeve is made of brass in mine & is threaded for a 5mm propshaft. I happen to think it is well within the skills of 80% of the members on the forum. When fitted I doubt you will ever have to replace it, (my opinion).I hope this answers your questions Mike if not send me your phone # & I will call you, Regards, Mick B. = PS I have not given up on the idea of making my own but a stroke has slowed me down a bit for now as the fingers on my left hand don't do what I would like them to do & I am a strong Lefty. Mick B.
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It seems evident then a ball type cv wouldnt be necessary as its intended for extreme angles. The inner cv of a car half shaft has bearings as its only required to move around 10 degrees. I have no doubts they could move more though. They sound similar to what you have allready made. Ive allways wanted to try metal ujs, i currently use tubes and they seem to tick all the right boxes for most of my builds:
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The joint you have displayed Mike is not a true C/V joint. I am not sure what car it came from. Nissan made one like that & called it a tripod joint which was failure . They did it to get around paying royalities on the original design which was a British design, & which most C/V joints are still copied from. Mick B.
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I am no fan Mike of a bit of plastic fuel tubing as part of a drive shaft or polyurethane for that matter. I have solved the problem in my own case. I will just for the fun of it try to perfect the one of my own design just to prove a point to myself & if I fail so what. Mick B.
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Well Mick, if you don't mind I'll just keep faith with your recent engineering efforts.
I can hold your modified joint in one hand and the all the other 'crud' I have in the other. No contest !!!
Dave
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I think its off something like a toyota, i found the picture on the internet. I didnt know they were a failure i thought all cars had these on the inner half shafts. Learn something every day :-))
My boats are not very big so a bit of plastic tube in most cases is quite adequate for what i want to do. I totally understand the neccessaties of a more substancial coupling on a larger model. I think your coupling is a good idea, but im curious to see what you have developed from scratch and i wish you all the best with it for the future.
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Hi Mike thanks for the support & you too Dave. As I said before if you would like to have a chat Mike send me your phone # and a good time to call (you are 7 hours ahead of us in Canada) I have been watching with interest your work on the steam & gas (petrol) engines. Don't give up it is nice to see someone thinking outside the box, Mick B.
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Hi Mick,
Have been following your posts with interest.
Your approach is to be commended, and has resulted in myself having a new look at couplings.
Part of my job is to design mechanical 'things', and have never seriously sat down and looked at couplings in my model boats.
Your coupling allows for miss-alignment in all planes, and with the addition of a sleeve/spline on one of the shafts could also allow forward and aft adjustment.
Will be looking into your ideas, if you don't mind, with a view to replacing joints in all my boats, ranging from 12" to 48".
I generally "steal" from everywhere in building my boats, so to borrow from model car development, if it improves things, is acceptable.
If the old "dog-bone" style coupling had the pins each end at 90degrees end for end, it would have been a step in the right direction, even the 'Huco" double couplings have been designed for only one plane change in direction, not mis-alignment .
Keep up the good work, and keep posting please.
The world needs creative thinkers like yourself
cheers
vnkiwi
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Hi Vinkiwi, I did not do this bit of testing just for me feel free to copy or "steal" anything you feel will help you build a better boat or anything else. When I joined the forum I got massive amounts of help from total strangers on the forum.....90% of what I have picked up came from our members. I am happy to share & today spent more money on a different indexing head for my mill that is very accurate & hope this will help with my own prototype, only time will tell. Thanks for the support, it does help a lot.Mick B.
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Your coupling allows for miss-alignment in all planes, and with the addition of a sleeve/spline on one of the shafts could also allow forward and aft adjustment.
No it doesn't vnkiwi. angular yes, within limits, but not all planes.
Regards Ian.
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Ian,
your quite correct, :-)) But then any one joint can only take angular deflection, 2 together, Which is what I was thinking, and envisage, with a suitably placed spline/sleeve, can take misalignment in any plane, up to considerable out of alignment, and still transmit smooth rotary power.
Something simple UJ's cannot, even when rotated 90 degrees apart, when in pairs as in full size rear drive vehicle drive trains.
The simple joints we use in model boats are there to transmit power through an angle in one plane only, which is why they are noisy.
And the larger any misalignment, the noisier they get. O0
Happy with that %) , rant over, I'm going to bed :}
cheers
vnkiwi
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Hi Mike thanks for the support & you too Dave. As I said before if you would like to have a chat Mike send me your phone # and a good time to call (you are 7 hours ahead of us in Canada) I have been watching with interest your work on the steam & gas (petrol) engines. Don't give up it is nice to see someone thinking outside the box, Mick B.
Dont worry Ive not given up on steam. My engines worked but they were barely usable as functional powerplants. They were inefficient and wasted a lot of steam. Ive got a new larger boiler on the way and im going to experiment with burners to produce more steam. The plant that i had went into building a small river launch. The gas engine was a long shot and not a serious project, it was more to see if i could do it. The compression was bad at the beggining and was the ultimate problem in the end.
No it doesn't vnkiwi. angular yes, within limits, but not all planes.
Regards Ian.
thanks for clearing that up i got all confused for a moment when he said it allows for missalignment on planes
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Firstly, the work that MickB has done is to be applauded and there is no criticism to this, however, due to the cost, we seem to be applying a £40 sledgehammer to crack a £4 nut or even more if you want to add another C/V joint into the equation as in full size drive trains. Don't forget though that in full size systems, invariably one, the other or both shafts they are coupling are subject to in use miss alignment ie. steering/suspension or vibration isolation mounts.
Let's now get back to our toys. The prop tube is rigidly mounted. The power unit is usually rigidly mounted. we can't solidly lock the propshaft in the tube so a bit of end float is allowed. Even the prehistoric bent shaft end couplings of Eze-built (and before) eras allowed more miss alignment and end float tolerance than a Huco or true C/V joint will without extras. It still does the job far more efficiently but it doesn't look as pretty as a bit of red or black plastic at the pondside.
At the end of the day, it's down to personal preference or depth of wallet but in simple ingineering terms there is nothing to beat correct alignment, a bit of endfloat and a sliding coupling that allows minor deviations. Splined drives in our sizes aren't practical (forget those on the end of the Hucos, they're there to allow a basic plastic molding to "Fit" all sizes of shaft, not used as a sliding spline ) so I know who's going to get part of my pension :-))
Regards Ian.
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I hear what you say but you could just think of it along the lines of the lads who like to put a lot of effort into building every single part of their own steam engines. Totally mad, but gloriously so :-)). Plus Mick's particular stock part wasn't anything like £40.
I have a few boats with Hucos that will stay that way, a couple of builds that I have the equipment for already, and one of Mick's for a Tosher I was collecting parts for when Mick sent the coupling across. I don't have any other expensive tastes at all, so the price difference is not very significant to me, especially when taken in with the cost of a full build. So my Boston Typhoon and Kalakala will get Mick's type when I do them.
Hmmn ... The second hand Vliestroom I have been working on has motors that must have been aligned after emptying a bottle of scotch ... More work O0
Dave
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I feel Circlip you have not grasped the full implication of what a TRUE C/J brings to our model drive lines. First both propshaft & motor are fixed so only one joint is required to give true 360 degree free rotation The $40.00 cost gives you two axle kits in the package,therefore you get two joints. If they had a sliding spline they would then work in all planes without the use of a second joint .Cars use two because of the added complication of steering & suspension, we have no such problem with our boat drivelines. I would note here you can by means of the connecting sleeve adjust the distance between the motor & shaft very precisely if care is taken when installed. With the price of most "good" models costing from $600.00 to$800.00 I do not consider it expensive to pay $20.00 for a part as fundmentally necessary as a PROPER Joint,but then as we have seen on many builds on occasion is paint finish is given much more priority than the mechanical's of the boat or ship what ever it may be. Bottom line to all this is that what I see on the market now do not do the job we need & in general the trade has been happy to sell us what I consider sub standard "joints" & show little inclination to improve. Where would we be with Radios,Motors & the many other improvements we have seen over the last 30 years if that had been the same case...Just a thought for the day. Mick B... PS= In my case I have a joint that does what no other joint on the market today will do but I will also never stop trying to find a better answer when I feel I should...
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Perhaps a hydraulic drive coupling would have similar implications Mick? Completely mechanically isolating the input and output shafts. That would be better still, but at what cost? With reference to adding a splined sleeve to a single C/V and having all plane freedom? not on this side of the Atlantic. All plane working was a reply to another post, basic mechanics, and whichever way you look at the problem, a single joint, which I have constantly advocated, is satisfied better by a ball and pin drive I originally linked to. The first eighteen words to my previous reply should have explained my views on your efforts but seem to have been ignored.
The reply from another post shows that the toy car brigade have a manufacturer who has already done this for cars so I'm surprised no one has asked them for a boat variant as they have the "Hard work" tooling.
If the careful setting up was followed, as I stated then considerable savings all round are to be had.
There is always room for a better mousetrap but is the end result worth the multiple of the original cost, to achieve what?
Regards Ian
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Hi Ian, There was/is another thread by oldiron(John) that shows some tests that John done that the huco was actually the worst. I have been looking at the complete kit & the other end of the main shaft is actually a dog bone where it attaches to the diff I think. If that is the case & I am still checking into it, the single kit with the addition of the inner shaft connector which does not come in the kit will give you 2 C/V joints & 2 dogbone type joints,with a little this gives you 4 joints for about $50.00. Granted the dogbones are not anywhere as good as the C/V joint end but in my mind still far superior than a Huco or a piece of plastic tube.I will try to find the inner dogbone part that will fit which I think costs about $10.00. I priced out the parts for one Huco joint from one of your better U/K suppliers & the cost for one complete joint(double)with motor & propshaft connectors is about $18.00, not a lot of difference in the end. If you would like PM me & give me your phone # & I will call & chat on my nickle(cheap from here). Also if you want to hold one in your hand I would be happy to let you try one ,all I need is the motor shaft diameter & the thread size for your propshaft , free...Mick B. PS = Ian I did phone the Company HPI Racing but they refused to connect me to anyone,brushed me off with "send
us a letter and drawings"
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Am I now going to throw a spanner in the works with this.......Yes I applaude you for all the hard work that you have done with this but suerly a CV Joint is designed for things that move in various planes.
What I am getting at is that when an engine or suspension moves a CV joint is designed to allow for that movement either in an up and down plane or side to side.Our Model motors simply do not move they are static.
The way I see it and fully agree that allignement is parramount to smooth running of the shaft to elliminate any wear on the bearings on the shaft let alone the motor.
I use a solid coupling to join my shafts to motor and pack up the motor to give perfect allignment of shaft and Motor.....thus elliminating the use of a coupling.I will only use a solid coupling for high reving motors...ie brushless or silly voltages of a 900 motor.
Also I make sure that the shaft end near the coupling is solidly mounted to eliminate any shaft movement and also the prop end can not whip either.
If I have a small Model I will still set up with a solid coupling then use a huco type coupling.
What are the advantages of using a cv joint if your motor shaft are aligned initially with a solid coupling ?????
Or would it be advantageous to use some sort of rubber mountings under the motor to allow the CV to work properly ??
Dave
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Ian
You’re correct, a hydraulic coupling would certainly be a Cadillac way to drive a prop shaft, however, as you pointed out it would be completely impractical from an expense and engineering standpoint in our models. As to Uncle Henry’s single universal joint, don’t forget that was done with a torque tube arrangement that kept the rear end in constant alignment with the shaft while the differential moved up and down in a fixed arc with the arc’s center at the universal joint at the rear of the transmission. In that case you can get away with one Cardan joint. Not ideal, but it works. On a model boat we are at a disadvantage due to size of equipment and skill of the various builders. It may be true that correct alignment of the prop shaft and motor shaft is easy by using a piece of tubing to do the aligning, I know that not every modeler has the skill, despite his work ethic, to know how to do the job properly. That’s not my judgment, but reasons offered by fellow modelers building their own boats. In that case you are bound to get the motor out of alignment in one or more planes due to poor alignment (and the alignment situation works the same on both sides of the Atlantic). If the motor shaft and prop shaft alignment intersected at exactly the pivot pint on the Cardan joint you would have a point that one U joint would suffice (go back to Uncle Henry). However, since we can’t guarantee alignment in one plane, we are certainly not going to guarantee alignment at a pivot intersection. Any deviation from those parameters is going to cause noise and vibration. The solution is a double (phased) Cardan shaft arrangement or something along the lines that Mick is promoting. Either arrangement falls into the capabilities of all modelers and produces a quiet smooth running vessel. Don’t forget this whole thing started a year ago when some one asked “why does my boat run noisy?”
John
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Hi Stavros,
good to get your two bob's worth.
Our models are usually made from wood, in its various forms, or fibreglass, and as such flex, and move with temperature, and moisture content. I agree that IF our motors and shafts where perfectly aligned, then all will be quiet and smooth.
In real life, this is just not going to happen, with varying degrees of misalignment.
Also, the practice of fixing the motor solidly to the hull, as is the shaft tube/bearings, simply ensures the best sound path from the motor to the sounding box, the hull, so that any vibration/noise is amplified, usually more than somewhat.
Even though I've been guilty of solid fixing, I am now going back to rubber mounting my motors in all my boats.
They do run quieter, but necesitate a coupling to allow for this.
I'm sure Mick is on the right track, and will achieve what he's looking for. Just wish I had access to machine tools, and had the skills to use them
cheers
vnkiwi
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Hi Stavros I too use alignment sleeves to set up my alignment, In a mad moment I made a complete set with just about every combination you could think of. However there are a wide range of skills on here & experience teaches me that we are not all created equal, you only have to look at some builds to see how far out of alignment some shafts & motors are. I still feel happy if I am within 4/5 degrees & really that is not that good. This is not for the experts among us, it is for the guys & girls where skill is limited & it gives them a better set up with no headaches. It is not expensive to do & most us of know someone with a machine that will do it for us if we ask nicely. For me it works well & I am happy with the results. That will not stop me trying to build a better mouse trap however, I am now off the model shop to try & find the other half of the dogbone end. Mick B....
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Firstly yes John, the Enery saga, I used to have a Ford special with that configuration on it, (38 10HP base) and later on a different car, double Hardy Spicers with a sliding spline cos the back end moved in different directions and about forty odd years ago my first "Lemon" sorry, Citroen "G" series with trick gas suspension and C/Vs. So I am fully aware of the coupling systems.
Your picky shows the problem precisely and the top two diagrams can be coupled with Micks C/V or more cheaply a single ball joint. I'm not even adding a Huco cos we know it will couple anyway.
It's the second two pictures that highlight the main grunt. This is where inefficiency abounds for drive loss as there are two couplings needed .
Now with the most basic bits, sixty years ago we could achieve a situation that the top two pictures represent at worst case, the angular line up in both directions was better, then to even think that we can't match this shows how much we have "advanced" to have to consider the second two. In that example a good ole pin and disc would be better and take up far less room.
One advantage of the double carden and miss alignment, - you don't need a separate "Noise" generator to sap your batteries.
Regards Ian
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Thanks for the illustration John - any new lads looking in will find it a great help too.
Dave
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Hi Stavros, yes I think it would be an advantage to put a rubber base under the motor after alignment with a solid coupling & then using the C/V joint.You would have to try different density rubber to test how it deadened the sound, also you should use lock nuts on the mounting bolts if mounted on rubber. I am afraid I did not have any luck finding the outer dogbone matching end,no stock. Mick B.
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Drawing from my old model railroad days, I used to mount motors on a base of silicone sealant. Set down a pad of the sealant, then place the motor in it. There was enough stickability in the sealant to keep the motor in place and provide a sound deadening.....no bolts required. I never bothered on boats, as once they're off the dock I can't hear them anyway.
John
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circlip what are these ball joints or ball and pin your talking about, I googled it and could only find caravam tow bars. Is the same as these dog and bone couplings?
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Don't need to use Goggle Mike, posts #7 and 9 are much closer O0
Regards Ian.
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ah the dog n bone couplings. awesome name that. I use to have an toy rc truck with them on, but only for the propshaft. It being 4 wheel drive the steering couplings however had dog and bone couplings but with 4 pins rather than just 2. They looked like these:
http://www.vac-u-boat.com/images/Catalog/M10456.jpg (http://www.vac-u-boat.com/images/Catalog/M10456.jpg)
It took so long trying to find a pic to show that i forgotten what point i was trying to make
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Similar, but those of fifty years ago are like the ones in 7 and 9, only half what you show :-))
Regards Ian
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{-) {-) {-) Know the feeling (Mad) Mike O0 been there done ....(Do!) that many times, oldtimers setting in for me I think %% Good pic of the coupling though.
Mick - Irishcarguy, admire your integrity and your relentless pursuit of success in your project - as do many others no doubt I wish you well :-)) Kind regards, Tony.
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Similar, but those of fifty years ago are like the ones in 7 and 9, only half what you show :-))
Regards Ian
What i was saying was though that the truck had both, but the angles were most extreme and continuously moving on the front wheels it had 4. If a 4 point type dog and bone coupling was used, then the slots could be opened up to allow for some sideways movement. I dont think this would work very well for 2 a pin type especially at angles because the pins would come out under torque. Also with 4 pins because at least 2 is allways in proper contact i suppose you wouldnt lose the efficieny threw the coupling that you get with UJ type couplings at extreme angles. Ive drawn a picture anyway :embarrassed: The dog is see threw so you can see how the bone would fit inside it.
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As soon as you induce an angle into the joint, efficiency does a nose dive. Most efficient is a straight line.
Regards Ian.
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Most efficient is a straight shaft. Motor with bearing solid one end, prop with bearing solid other end.
As per some brushless installations. O0
That 4 pin dog bone is better than the 2 pin variety, in my humble opinion anyway. %) But would have to try one.
The aim here is to see how near one can get to an efficient, quiet method which takes up misalignment, with minimal power loss.
just my thoughts, should have stayed in bed, think its going to be one of those days >>:-( :o
cheers
vnkiwi %%
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of course you would not have angle such as that in the picture but the coupling would compensate for some angle and misalignment.
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I like that 4 pin joint Mike, it is better I think than the 2 pin one which is on the other end of the shafts that I got. The beauty of C/V joints is that they do exactly as their name employs & that is keep the velocity constant at different angles. Thanks Tony for the vote of confidence, I feel like a pit bull sometimes,I find it hard to let go until I feel I have solved the problem....Cheers, Mick B..
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i dunno what its called that type of coupling. It of course wouldnt suit seriously angles connections but probably still better than a huco. I dont think that the velocity would dip either but it could possibly be still noisy if its slightly baggy to compensate for misalignment. It would need making and testing.
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A friend of mine just brought over an HO 4-4-0 model steam locomotive produced by Rivarossi many years ago. Its tender drive as the loco is so small. What really hit me was the universal set up between the engine and tender. Bear in mind a tender can move in many directions relative to the locomotive so a good smooth universal is vital.
The closest thing I can relate it to is a poor man's constant velocity joint. The "dog bone" (if i may call it that for now) has a hex at each end. This hex fits into a corresponding receiver in the tender (motor end) and the locomotive (driven end). The dog bone can move freely in the receivers in any direction with no hinderance. For us, its very easy to make from hex brass shapes. I dare say a half hours work would have enough made up for a twin prop vessel with no special tools and be very inexpensive.
In fact the parts would appear to be available here:
http://www.bowser-trains.com/Parts/Parts.htm (http://www.bowser-trains.com/Parts/Parts.htm)
John
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I take it the joint is held in place by the position of the locomotive relative to the tender, sort of like the Dumas dogbones?
I have always liked the dogbones as they can take a fair bit of misalignment, can be threaded easily to attach on threaded shafts and they can be extended by cutting the nylon part and fitting a brass/aluminum tube over it (and pinning that in place, of course). I installed a new motor in my tug 'Peninsula' which is significantly larger in diameter than the original, meaning that the motor could not be aligned with the shaft (keel was in the way). Dumas coupling was duly extended, drilled out to fit the huge new motor shaft and it works just as well as it did originally
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i have seen the same system as oldiron has shown using 3/16'' rod with nuts screwed on either end and a 1/4'' drive socket to suit the nut being used as the female part of the connector. i guess that could also be scaled down and the same type of set up used on a boat.
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I take it the joint is held in place by the position of the locomotive relative to the tender, sort of like the Dumas dogbones?
Yes, you're quite right. I like the Dumas dog bones myself too. Mick has been advocating, rightly, a constant velocity joint. When I looked at this yesterday I thought there's a nice cheap way of getting pretty close to the same thing. I've got some telescoping brass hex stock, I'm going to try building one.
That socket/nut idea sounds good for larger vessels.
John
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just a thought and going right back to basics, there already exists a similar pairing in the allen key and allen screw -
(http://s23.postimage.org/vfn4diitz/IMG_3189a.jpg) (http://postimage.org/image/vfn4diitz/)
(http://s22.postimage.org/vmk42bjd9/IMG_3190a.jpg) (http://postimage.org/image/vmk42bjd9/)
(http://s22.postimage.org/ozxg951ot/IMG_3191a.jpg) (http://postimage.org/image/ozxg951ot/)
now while I can feel the setup binding slightly when it gets a long way off alignment, it does seem pretty smooth when its close to alignment, plus it has the advantage of allowing the joint movement within the socket back to front, just thinking here it might be another good start point for a coupling.
Grendel
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I like this hex idea you lot got going on. If you make the coupling oldiron post it on here. The only thing that would concern me about it being brass is that the hex might round off. The allen key/screw idea is brilliant. You would just need to cut the angle off the the end of the allen key and then lock it in one of these chuck type couplings:
http://www.ebay.co.uk/itm/PZ216-1pc-couplings-flex-4mm-motor-to-4mm-Flexible-Aluminum-alloy-Methanol-boat-/111016901019?pt=UK_ToysGames_RadioControlled_JN&hash=item19d91f799b (http://www.ebay.co.uk/itm/PZ216-1pc-couplings-flex-4mm-motor-to-4mm-Flexible-Aluminum-alloy-Methanol-boat-/111016901019?pt=UK_ToysGames_RadioControlled_JN&hash=item19d91f799b)
or even 2 sleaves with grub screws would do it for the motor and propshaft end.
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I like this hex idea you lot got going on. If you make the coupling oldiron post it on here. The only thing that would concern me about it being brass is that the hex might round off.
If the fit between the inner and socket was sloppy, I agree, in time, it would round off. However, I think you'd be fine if you had a proper fit with no slop. Don't forget, there are six surfaces applying pressure during operation.
John
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Too large maybe for you guys but from Ian's Boats (http://www.iansboats.co.uk/), 7 -5mm or M8-5mm
(http://www.iansboats.co.uk/large%20hex.JPG)
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Hi guys
I'm following this thread with interest, and it's great to see people coming up with ideas. I have a question about the last few suggestions .... I think what got Mick started was the noisiness of his original set up - so are the last few suggestions as quiet as you would expect Micks joint to be?
Dave
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I quite like the idea of the Dumas dogbones but having had a trawl around the usual traders no one seems to sell anything like them in the UK
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If the fit between the inner and socket was sloppy, I agree, in time, it would round off. However, I think you'd be fine if you had a proper fit with no slop. Don't forget, there are six surfaces applying pressure during operation.
John
yes that are 6 surfaces, and closer it is to being a circle. the more flats the more round it is. the more round it is the better its good for rounding off. It would be better if it was square or even triangle but then i dont think it would flex. It remind me of torx bits and screws from when i was a garage apprentive. I generally do not agree as whole that the more surfaces there are the better application of pressure. Especially torx bits, all you got to do is get a bit of rust in a torx screw use the bit and next thing you know your drilling the screw out because the teeth have crumbled.
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torx screws and bits - theres your splined drive.
Grendel
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I think there are more ways than any of us can think of for making joints. I would point out here the C/V joint has been around for a long time & since the advent of the Mini in 1959 they have been the go to joint in various forms, & we should ask ourselves why. I like many of tha ideas discussed here, but for $20.00 & about 1/2 an hour of my time I can have a true C/V joint that will adapt to most motors & shafts & I am sure has been well tested in competition by its makers who are one of the leading companies in the model car racing business & are very successful at it. I can see good & bad in the hex drive for instance, you are assuming that the head of a nut or bolt is a true hex. Those of us that use nuts & bolts everyday of our lives are well aware that is not the case. Can you imagine a drive made from an Allen screw turning @ 6000rpm and does not run true. In the case of my own prototype it was only out about 3 degrees and the vibration was bad,putting it mildly. The Dumas dog bone seems like good bet of all the ones you guys have discussed, but until something better than the HPI racing unit comes along, guess what will be fitted to my boats, Mick B.
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One other point I would like to make, as long as we accept the joints that are been sold to us now nothing will change,it is up to us to put pressure on the retailers & the makers of this poor quality stuff to improve what they are selling, if not done let them keep them. Mick B.
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Mick
I totaly agree with your last entries, especially where it behoves us to press manufacturers for better quality universals. however, we have to realize there's a problem first.
Not to steal your argument, but I took one of the ideas/suggestions made by a previous contributor on this thread and made up a U joint using a socket and bolt arrangement. the cost came in at about $12 Cdn. As to the vibration concern. I have yet to try it under load. This is a build and try it exercise. We'll see where it goes. For the minute I'll show where I've gone with it.
I selected two hex head bolts at my local hardware store (Canadian Tire for you Canucks), plus two 1/4" drive sockets to fit the bolts. I turned the square drive end off the sockets. This leaves enough round inside the socket to grip the prop/motor shaft. I drill out the round opening in the socket to an even 1/4". I then turned up a short length of brass that press fit into the 1/4" hole inside the socket. I then drilled and tapped the socket for a 6-32 grub screw to hold the unit to the motor shaft. The brass filer was drilled to be a good fit on the motor shaft.
For the dog bone, I took the two hex head bolts and made a sleeve to connect them back to back (see photo). Each end fits inside each socket. There is tons of end play for those worried about that. These can be made in any size you want. They're not likely to round off under our usage. The only question remains, when the ice is off the water, what they're like for vibration under load.
This was an hours work engineering and building this morning for a very cheap sum.
John
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It will be interesting to see how it works John,glad to see you bought the good Canadian Tire sockets, I use a lot of their bits & pieces, cant beat them for price either. There are other solutions but the quality of the HPI joint & price makes it a no brainer for me. I must learn how to post photos, a picture is worth a thousand words. Mick B...
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nice one - keep up the good work.
inerested in how it reforms
cheers
vnkiwi
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Well lads, I just tried out my U joint described above. As much as I can test it on the bench it passed in flying colours. There was no discernable vibration no matter what angle I placed the motor relative to the prop shaft (within the limits of the dog bone of course.)
The only noise was from the gear box in the Decaperm motor. As i said, this unit can be made to any size desired at minimum cost.
The boat its installed in is the Joffre I'm building for another thread.
The bottom picture shows the motor in operation.
John
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That's cool. Will have a go at one of these, but could be interesting without a lathe.
Mick, we now need to see yours in a boat and trialed.
Will be haunting the hobby shops tomorrow to see if I can find a cv like yours.
cheers
vnkiwi
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That was a brilliant build and trial, most impressed at your speed of manufacture and installation!!
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love it oldiron give yourself a pat on the back :-))
Im sure there are all kinds of solutions to this problem, it seems though so far you need a lathe to do anything about it though.
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Well done John - well impressed, you don't hang about do you! {-) Am following your Joffre build - will you be using your new coupling?
Regards, Tony.
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Hi John I had a sneaking suspicion you are a bit of a genius, I think you just confirmed it. Patent it, if Huco See's this I wonder what they are thinking now. Mick B.
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If you look at the driveshafts of a Tamiya Frog and other cars that used the same chassis from the early to mid eighties, you will see the same dual hexagonal arrangement. The reissues use dogbone driveshafts however, as the original hexagon axels were prone to stripping.
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love it oldiron give yourself a pat on the back :-))
Im sure there are all kinds of solutions to this problem, it seems though so far you need a lathe to do anything about it though.
>:-o <:( >:-o <:(
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Hi,
I have been following this thread with great interest and just did a quick google for rc cv joints and found these:
http://www.wheelspinmodels.co.uk/s/?q=cv+joint&x=0&y=0
Look like sensible prices to me!
Ian
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I've used these before for shaft couplings on production line equipment.
http://ondrivesus.com/pdf/couplings/double%20loop%20coupling_ondrives.pdf (http://ondrivesus.com/pdf/couplings/double%20loop%20coupling_ondrives.pdf)
No moving parts, can cope with both axial and radial misalignment and are strong enough I'm sure for spinning a small boat propeller under the water.
I have a standard plastic universal joint in my boat with the motor mounted on a soft rubber mount. It works fine but I can see improvement could be made especially in high RPM situations.
Craig.
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could work but they limited to 3000 rpm max which is the slowest of model boat prop speeds. props like that are usually around 80mm/3" in diameter. Plus i would have thought that the rubber would have been springy. I would say when ever the coupling was used at an angle, on the inside curve of the joint there would be compressional forces acting upon the rubber, which in turn being springy would fight against the revolution of the coupling, effectively trying to push back the other way. UJ's and cvs dont do this.
On a straight coupling though these would be very very quiet .
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Thanks for the compliments gentlemen. I had thought about production of these, commercially. I don't know if there's some obscure patent on them or what it would take to get some one to produce them.
If made commercially they could be made of Delrin plastic which is very slippery. This would reduce any concerns on friction, although I put a dab of light grease on mine to reduce an friction.
John
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I must say this has been a very satisfying thread for me & the discussion & suggestions & ideas that it has produced shows how much talent is on this forum if only we would use it all the time. This time we did & look what transpired. As I have thought & actually known for as long as I have been on the forum there are a lot of talented people on here, we just need a wake up call now & then, Mick B.
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Well, just to shown that Mick will put his money where his mouth is, a beautiful little CV joint arrived this morning from sunny Calgary. The whole joint is less than 50mm end-to-end and is as smooth as greased weasel-pooh. My profuse thanks go to Mick for his effort and expense. No more crummy Huco's for this guy!
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Congratulations on a magnificent achievement Mick. O0 Such a compliment from the ex Action man himself is praise indeed and I'm really pleased for you to have achieved such a successful out come for all your endeavors - well done to you!! :-))
Right! ---------------- now how much are they including postage to the uk??
Kind regards, to you and Phyllis, Tony.
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Congratulations on a magnificent achievement Mick. O0 Such a compliment from the ex Action man himself is praise indeed and I'm really pleased for you to have achieved such a successful out come for all your endeavors - well done to you!! :-))
Right! ---------------- now how much are they including postage to the uk??
Kind regards, to you and Phyllis, Tony.
2nded only but to sunny Finland (27c today)
When does the order book open?
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Thank you Dave for the kind words. It started life as an axle made by HPI racing but they just did not want to bother with a little guy like me & just brushed me off with my design conversion.I have sent two to England to two friends that I knew would give me an honest opinion warts and all. It is not my intention to produce them for sale, the sole intent was to make something to put that dreaded Huco to shame. Most of you know that the two guys I trusted to test it was Dave Martin ( Norseman) & Dave Milburn ex ACTion guru. However I have gained several good friends on this forum & would be happy to make one for you at dead cost. One axle is $20.00 (two in a packet, $40.00 ) & posting was $10.00, total $30.00 or about 20 pounds each. Tony & Essex I have you on my list & will make one for each of you, but I require measurements as each is custom made to fit your motor & shaft. We can talk later through PM. A final note if you want to make your own it is not hard but you do need the best drills,taps & dies. PM me for details. Mick B.
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Tony I can oversee the job for you in August, but I can't however guarantee Mick's sobriety level as I intend to be a thoroughly bad influence on him. ... CV joint really is a nice piece of kit and is crying out to be manufactured commercially O0
Dave
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Hi All,
I alway's use either the Robbe or Graupner direct coupling,not only does it align your shaft and motor it's simple and keeps the torque.
Destroyer42
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destroyer42 ...I have checked the WEB....could you please post a link to either the Robbe or Graupner direct coupling you mention...I am after 4 mm x 4 mm rigid or fixed coupling ......thanks Derek
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destroyer42 ...I have checked the WEB....could you please post a link to either the Robbe or Graupner direct coupling you mention...I am after 4 mm x 4 mm rigid or fixed coupling ......thanks Derek
Yes please :-)) :-))
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Hi Guys I made a full set of fixed couplings on my lathe which I use to initially align the motor & propshaft. I then enstall my C/V joint. I should point out that even if you use a solid connector to align the shafts, when you tighten the bolts/nuts on the motor mounts it will distort somewhat & you are well advised to install a joint to correct any possibility of misalignment.Mick B.
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Hi All,
I use either the Robbe or Graupner straight rigid couplings, never had any problems and the motor/prop shafts run true and straight. I run some torque motors on my models all geared either Robbe or Graupner, I have never found better motors.
You will soon know if you have misaligned it when fitting you will see it.
http://www.cornwallmodelboats.co.uk/acatalog/couplings.html (http://www.cornwallmodelboats.co.uk/acatalog/couplings.html)
Destroyer42
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Thanks destroyer42........when I searched for Graupner shaft couplings all of the usual Huco style & dog+bone style appear.... but not rigid couplings
When I search for Graupner 3382 couplings.....BINGO......they appear :-)) .....Derek