Model Boat Mayhem
Mess Deck: General Section => Chit-Chat => Topic started by: frogman3 on July 03, 2019, 09:44:42 am
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HI ALL I'm still building my tiger hull but I'm thinking ahead as I would like to have 2 motors driving 4 prop shafts I know this can be done by a pulley and cam belt drive but how do I fit the pulley wheel to the shafts while fitting a universal join on the shafts ? anyone know how an a diagram would be very helpful
chris
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Make sure that there is enough bare shaft where the pulley is wanted. Most shafts need a collar to act as thrust bearing, a pulley can double up on that job.
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Hello,
On my four prop hulls I tend to put larger motors on the inner shafts to provide the main thrust and two smaller motors on the outer shafts just so they turn. I tend to put 550s on the inner and 385s on the outer.
I did build a tiger many years ago and put the larger motors on the outer shafts, the turning circle was horrible. Better to have the power on the inner shafts to push water past the rudder.
I think having pulleys or gears would be more difficult to set up where as motors are easy to install
Bart
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Hi the belt should take up small alignment problems so you wont need to use u/js bill...
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Hi the belt should take up small alignment problems so you wont need to use u/js bill...
HI if I don't use U/J how do I fit the pulley wheel to the threaded end on the prop shafts ?
chris
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Hi frogman3
On my invincible build I used 4mm diameter (non-threaded) shafts and used grub screws to attach everything together. See my picture for my setup (not the best I知 afraid).
(https://i.ibb.co/JjHrXfF/7-F9-D1-A67-A4-A2-4055-957-D-173-AB9-B5-E463.jpg) (https://ibb.co/JjHrXfF)
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Hi frogman3
On my invincible build I used 4mm diameter (non-threaded) shafts and used grub screws to attach everything together. See my picture for my setup (not the best I知 afraid).
(https://i.ibb.co/JjHrXfF/7-F9-D1-A67-A4-A2-4055-957-D-173-AB9-B5-E463.jpg) (https://ibb.co/JjHrXfF)HI Nick cheers for the pic an info but I still need more info as you say pic not great to learn from but cheers all the same
thanks chris
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Hi frogman3
On my invincible build I used 4mm diameter (non-threaded) shafts and used grub screws to attach everything together. See my picture for my setup (not the best I知 afraid).
(https://i.ibb.co/JjHrXfF/7-F9-D1-A67-A4-A2-4055-957-D-173-AB9-B5-E463.jpg) (https://ibb.co/JjHrXfF)
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Hi Chris
When I finish work on Friday morning I値l pay a visit to my invincible in the work shed and take some better pictures. I thought I had some better pictures of the set up but alas not on my iPad in my barrack block.
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Hi Chris
When I finish work on Friday morning I値l pay a visit to my invincible in the work shed and take some better pictures. I thought I had some better pictures of the set up but alas not on my iPad in my barrack block.
OH great Nick thanks that will be most helpful top view and close up if poss :-)) I zoomed in on your pic an I see you have got a cam belt drive on each shaft just what I'm looking for many thanks for your time an effort :-))
chris
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Nice job Nick
Click it to big it
(https://i.ibb.co/m54hQLF/7-F9-D1-A67-A4-A2-4055-957-D-173-AB9-B5-E463.jpg)
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Thanks Andy, didn稚 realise that the picture could do that! :-))
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YES cheers Andy for the big pic and I'm hoping for some more pics from Nick on Friday
chris
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I think you're getting the MFA timing belt reduction drive set-up confused with how to drive 2 shafts from one input. You obviously don't need a U/J with a belt drive unless you opt for these particular types. Hopefully the pics before helps, I believe another member provided parts from MFA's website which showed belts and pulleys. You could also have found the kits on Cornwall Model Boats -but they're pricey. Just be wary though with belts, they should really be very carefully aligned. O-ring type drives take tad bit more misalignment in my experience.
BTW: Struggle to understand your posts but just seen the location -I get it now I read it hearing the accent. LoL! Love Norfolk area.
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I think you're getting the MFA timing belt reduction drive set-up confused with how to drive 2 shafts from one input. You obviously don't need a U/J with a belt drive unless you opt for these particular types. Hopefully the pics before helps, I believe another member provided parts from MFA's website which showed belts and pulleys. You could also have found the kits on Cornwall Model Boats -but they're pricey. Just be wary though with belts, they should really be very carefully aligned. O-ring type drives take tad bit more misalignment in my experience.
BTW: Struggle to understand your posts but just seen the location -I get it now I read it hearing the accent. LoL! Love Norfolk area.
HI RST thank you for the warning of bein wary much appreciated of the belts.But ive used the MFA plastic pulley belt drives motor mounts on all my big models for the last 30 YRS an had no problems with them but I must admit that ive never treid to run 2 sharfts off one motor.Thats the reason im askin for help on this subject
an you say I don't need a U/J well how do I connect the motor sharft to the inner prop sharft ? on both side's ? an what particular types do you mean as you have not said ? .An thank you for telling me about the kits setup from corrnwall M/B an bein pricey an I just got to hope I understand from Nick's pic's how his setup works
as I know in theory but I need to know in practical the parts no.s for the pulley's an the belt drive an prop sharfts an where t get them from an how he fixed the pulley's onto the sharft .But I have a little idea an that's fittin the pulley's with a collett fitted with a alan screw to hold the pulley tight to the sharft so I hope im right on this but will see after ive studied Nick's pics
an im sorry if you have difficulty readin my post but as you say im from Norfolk lol but thanks for your reply an instrest in my post
chris ps I should have called the cams timin pulley's sorry about that but ive never had to buy these on their own before
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Nick did you get your pulley's an belt drive 's from MFA ?
Chris
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For the cost and mechanical complexity, I'd avoid 2 motors/4 shafts and go straight for the 4 motors solution - so much simpler to install and no strange side-pressure wear on shaft bearings designed to have straight loads.
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HI thanks for your good advise but ive already done that in my big USS NIMITZ carrer hull as I had plenty of room
see link for pic https://ibb.co/pKTgXJC But in my tiger hull their is only limted space an be easyier in my opinion to do what this thread is about
chris
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Hi Chris
My pulleys and belts were made by SHG Models (Staffordshire), they have different types and can be made from resin or aluminium (price varies of course and the aluminium ones are more expensive).
I have used both material types and the resin ones are more than okay for warship type models, the aluminium versions are more suited to fast large scale models like 1/12 scale ASRLs/MTBs etc.
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Hi Chris
My pulleys and belts were made by SHG Models (Staffordshire), they have different types and can be made from resin or aluminium (price varies of course and the aluminium ones are more expensive).
I have used both material types and the resin ones are more than okay for warship type models, the aluminium versions are more suited to fast large scale models like 1/12 scale ASRLs/MTBs etc.
HI again Nick thanks for info i'll proberly take your tip an go for resin ones but I can 't order them for a while as im still building hull an I don't know what size I need but lookin forward to your layout pics ps have you had any probs with the prop sharft bearins wearin from the side pressure wear as described by PLASTIC ? an the resin pulley have they got collets fitted with a alan screw to tighen on prop sharfts ?
chris
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Hi Chris
Yes they have moulded in collets with grub/alan screw in each pulley, if I remember correctly they have two screws per pulley opposite each other.
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Hi Chris
Yes they have moulded in collets with grub/alan screw in each pulley, if I remember correctly they have two screws per pulley opposite each other.
Great stuff Nick that's just what im lookin for many thanks for info :-))
chris
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Has anyone actually experienced sideways wear on pulley drive bearings? I rather doubt it. You are more likely to get wear from a slight misalignment of a conventional coupling or an off centre bore in the coupling itself. Both are common and lead to noise and vibration.
See my post #5 here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg668026.html#msg668026 (https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg668026.html#msg668026)
And topic here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg667984.html#msg667984
Colin
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Has anyone actually experienced sideways wear on pulley drive bearings? I rather doubt it. You are more likely to get wear from a slight misalignment of a conventional coupling or an off centre bore in the coupling itself. Both are common and lead to noise and vibration.
See my post #5 here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg668026.html#msg668026 (https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg668026.html#msg668026)
And topic here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg667984.html#msg667984 (https://www.modelboatmayhem.co.uk/forum/index.php/topic,63191.msg667984.html#msg667984)
Colin
HI thanks Colin for the info an yes I read your post in the link will see how I get on when I get that far :-))
chris
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hi there, to answer Mr Bishop's question - the standard O rings that we use in the driving belt situation is in theory outside its specs - an O ring is basically designed to be crushed forming a seal - normally in a machined groove - either in say a piston or a joint between 2 flat surfaces. They are designed to be stretched slightly as the material they are made from isn't given to stretching very far before snapping.
Also for side loading shafts, we should really use ball races/roller races rather than phosphor bronze bearings as roller bearings displace its load throughout the radius of the balls evenly around the inner cage of the bearing
as a footnote - one should be able to get 4 motors in as I did in HMS Exeter and that is only 1:96 scale which should be a slightly narrower hull.
https://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.msg350818.html#msg350818
John
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With regard to 'O' rings I agree they were not designed for the task but they work extremely well regardless. The things to bear in mind are:
Don't use rings that are too thick as they do not like being deformed from the circular and will not stretch much. Thinner ones are more flexible and forgiving and perfectly strong enough.
When fitted, keep the rings as circular as possible, stretching them simply ramps up the friction and makes them inefficient as well as putting stress on the bearings. It is simple to 'tune' them using an ammeter and a low voltage supply to the motor.
It is surprising how little tension is needed to give a strong, non slip drive. Get it right and you are simply twirling the pulley round rather than compressing the belt and this puts very little stress on the bearing.
Almost all the models I have built over the years have used belt drive of one type or another and they have all proved to be reliable and very efficient in power consumption when geared down. What's not to like?
For a multi screw setup pulleys and belts are rather cheaper than purchasing extra motors and couplings and offer significant gearing advantages while direct couplings are inherently inefficient for the reasons described in my other posts and the slightest misalignment in any dimension introduces friction and a tendency to open up the shaft bearings.
As John says, ideally roller bearing shafts should be used, but in the low RPM low power applications of most scale models it simply isn't necessary in practice. And bear in mind that at the other end of the shaft we accept that there is a propellor which is generating sideways thrust against the bottom bearing and nobody worries about that do they?
Colin
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OK Colin an John many thanks for your inputs but I shall not be usein 0 rings but cam belts if possible if it all works out :-))
chris
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I used "O" rings from B&Q on my Iron Duke and they have lasted over two years so far with no issues at all. I machined alloy pulleys and fitted one to the front of the engine before the univrsal joint takes the drive to the inner shaft. The outer shaft uses a matching pulley with widly spaced bearings and again a universal joinyt to the shaft. Basically the engine and pulley system is a complete unit.
The pulley is pinned to one end of the huco universal joint which uses a grub acrew to fit it to the motor shaft so you get motor, pulley, universal joint.
Cut the "O" rings with a very shafp knife and super glue together. As above two years on and its all going strong.
Cheers
Geoff
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HI Geoff thanks for your input an some picces would be nice of your layout if possible :-)) hopefully nick is goin to post some but if you could as well be great as you never can have enough info an pics says it all :-)) all best
chris
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Its not entirely clear but this is probably the best shot of the layout.
Cheers
Geoff
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Hi Chris
As promised, some close ups of the pulley and belt system I have on Invincible. Not the easiest pictures to get as I found out... should have taken plently of pictures before I sealed up the back end!
(https://i.ibb.co/FkTGBpY/IMG-0809.jpg) (https://ibb.co/twrybR2)
(https://i.ibb.co/XV0CtxK/IMG-0810.jpg) (https://ibb.co/LvjZ1dc)
(https://i.ibb.co/6rdZ7BV/IMG-0811.jpg) (https://ibb.co/5G79gFt)
(https://i.ibb.co/KjJBLvM/IMG-0812.jpg) (https://ibb.co/1fkBdWD)
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(https://i.ibb.co/1KK9LHh/IMG-0807.jpg) (https://ibb.co/NppLswQ)
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CHEERS Geoff for the piccey an I can an I can see your o rings a great help :-))
chris
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AN CHEERS Nick some lovely pics an I think this is the way to go for me as with the cam belt 's it cant slip due to teeth on belts an teeth on the pulleys brilliant pics Nick many thanks for takin the time to take picces much appreciatied I will have a good study of them all best
chris :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-))
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Believe it or not but 'O' rings don't slip either! We wouldn't use them if they did.
Colin
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Believe it or not but 'O' rings don't slip either! We wouldn't use them if they did.
Colin
OK Colin point taken :-))
chris