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Author Topic: OTW Vanguard help  (Read 78564 times)

Patrick Henry

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Re: OTW Vanguard help
« Reply #150 on: December 09, 2011, 06:14:36 PM »

Good man Mark, I know we can rely on you for test, test and test again...it does pay.

Have a word with David, I know he'd be happy to help you out with any information that you need. Besides, I'm following this with great interest...I'm on the point of saying 'yes' to a 1/72nd scale Skipjack, which I believe originated from The Scale Shipyard, so I'll be facing the challenges you're having to overcome.

Good luck,


Rich
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Re: OTW Vanguard help
« Reply #151 on: December 09, 2011, 09:06:36 PM »

How are you planning on linking the 6mm gearbox shaft to the 4mm propshaft- will you use a rigid coupling or a flexible one? I would think you're planning on using a coupling external to the module, in order to make it easy to take the cylinder in and out of the boat.

The oil seal could be mounted in the endcap, drill a 12mm bore to press it into. To support the shaft, sometimes the bearings of the motor/gearbox are sufficient, when used with a  rigid coupling- that's how Engel do it in the Lafayette for instance. But if you're using a flexible coupling (e.g. Huco) then you will need an additional bearing. Some people use a ballrace mounted directly behind the seal with a collar soldered on to absorb axial thrust from the prop. That's the optimum solution, but a plain bearing will work too.

As you have very thick endcaps, you may have enough thickness to mount both the seal and the bearing.

Davy1

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Re: OTW Vanguard help
« Reply #152 on: December 10, 2011, 10:43:51 AM »

I'm impressed that you are having a look in the archive at my efforts, Mark!

I take it that is the Simrit "sandwich" hard soldered on to the end of a brass bolt.

Simple and  a bit crude but you may be encouraged to know it's the method I still use.

The only recent mod I have made is to put a ball race behind the Simrit. (I drill into the bolt head to inset the ball race.)

I certainly used to make the pre ball  race versions without a lathe and I think , with care, you could make the ball race version without a lathe too.

A bit of an advantage over drilling into endcaps etc. is that if you make a complete ***** of it you just throw the bolt into the bin and grab another one!

David
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thegrimreaper

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Re: OTW Vanguard help
« Reply #153 on: December 10, 2011, 03:16:15 PM »

The problem I have David is drilling into the bolt without a piller drill or lathe that will possibly be beyond me so I think I will be knocking something up in perspex for the seal and bearing IF I go for a u/j on the shaft might go for just the seal and a rigid joint. got to get my head around drilling a bolt without the proper tools. Was fine spinning the end caps in a drill but holding a bolt in a vice and drilling it square hhhmmm will have to see.

Regards Mark.
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thegrimreaper

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Re: OTW Vanguard help
« Reply #154 on: December 10, 2011, 03:50:05 PM »

David I hope you don't mind I have nicked your picture and reproduced it here I was wondering do the brass plates go either side of the end plate (yes I think) why use a bolt drilled is their any need for the extra length that introduces into the WTC dry side




please don't bite only asking would it be easier for me to make up the two brass plates for the two sides to sandwich the seal into the endplate with a bearing on the dry side of the end plate. Unfortunately on the works computer and no photo editing possible could alter your photo to show what I mean if this seems like gobeldygook.

Regards Mark.
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Davy1

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Re: OTW Vanguard help
« Reply #155 on: December 10, 2011, 05:03:28 PM »

Hi Mark,

I realise that is a very old photograph where I was fitting the ball race at the other end of the bolt.
The following shows an updated one:
http://www.theassociationofmodelsubmariners.com/t266p15-prop-shaft-seals#3001

(Sorry its a link but I had difficulty uploading the photo on this site.)

The ball race now fits in the bolt head just under the Simrit.
The bolt goes through the bulkhead and the nut is tightened. (Silicone rubber makes the seal hence the messy appearance!)
You can see one of the geared MFA motors behind.

David.

PS I find it best to hard (silver) solder the brass plates to the brass bolt. I find it easier to do than soft soldering (you do need a small gas torch) and it is much stronger.

PPS Just reading your post again.You will find that drilling through a bolt without a pillar drill will be difficult. I recall doing it but had to use the best of 6 bolts! (You did want a demanding hobby didn't you!) Drilling the recess for the Simrit will be difficult too.You may just do it not using  a ball race or use one mounted on the other end as in the old photo.
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Re: OTW Vanguard help
« Reply #156 on: December 10, 2011, 05:36:40 PM »

If you want to make it up this way, Mark, send me the bolt and I'll drill it through on the lathe- 5 minute job.

thegrimreaper

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Re: OTW Vanguard help
« Reply #157 on: December 11, 2011, 08:44:42 PM »

David thanks for the info got it worked out in my head now as to how and where your seal works and go`s. Andy thanks for the offer with the bolt will be giving you a shout in a couple of days if the plan I have drawn up dosn`t work for me I will put my little drawing up on Monday for all to see and advise or tweak. I think I am lucky in the fact that my end caps are 12mm thick so I could get the simring seal and a bearing sitting behind one another with two brass plates one in the wet side the other in the dry side. please bare with me untill Monday I think you will see then where I am going.

thanks to all for the advice and info given so far.

Regards Mark
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Re: OTW Vanguard help
« Reply #158 on: December 11, 2011, 09:27:52 PM »

Ha. Found this whilst looking at stuff for another post-

http://www.ebay.co.uk/itm/RC-Submarine-Motor-shaft-seal-set-ID-4-mm-Type-S-/280784397580?pt=Radio_Control_Vehicles&hash=item41600de50c

Very basic, the shaft is running inside brass, a bronze bearing would have been nice. There was an outfit around a few years ago run by Francis Fearn called Subway designs. they used to supply a beautifully CNC machined shaft seal for 4mm shafts, complete with ballrace, all in Stainless steel. It was custom designed for WTC's. Unfortunately no longer available AFAIK.

thegrimreaper

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Re: OTW Vanguard help
« Reply #159 on: December 12, 2011, 01:06:54 PM »

O.k. as promised a couple of drawing of my idea using ideas adapted from other peoples ideas and examples 1st picture shows two endplates adapted from Davids idea for clamping a simring seal I have the room to put my simring seal and a steel bearing behind it in my end cap.




2nd Drawing is of the layout of the tek rack with the motor and servos in position with a universal joint which I think is a double u/j I don't know if I should also fit one on the wet side of the end plate.




Please go easy on my drawing I cant draw to save my life at the best of times but I would like advise  if possible on any better ideas /ways of doing this.


Regards Mark.
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Re: OTW Vanguard help
« Reply #160 on: December 12, 2011, 02:03:26 PM »

That looks fine to me. Ideally the thrust load from the prop would be absorbed by the ballrace, which won't happen with that set-up, instead it will be taken up by the bearings in gearbox, which it should handle easily.

I can't see how you can get away without having an additional coupling of some description external to the module if you want to make it removable.

thegrimreaper

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Re: OTW Vanguard help
« Reply #161 on: December 12, 2011, 02:18:00 PM »

Andy I don't want to put to much load on the gearbox bearing where would you suggest putting the bearing or even changing the layout so that their was as little thrust load on the gearbox bearing ?? .

Regards Mark
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Re: OTW Vanguard help
« Reply #162 on: December 12, 2011, 02:54:09 PM »

You would need to create a small gap between the ballrace and the seal to allow a collar to be either hard soldered or Loctited (bearing grade) onto the shaft. This butts up against the ballrace allowing it to shoulder any axial force from the propeller.

Not sure how you can do that with the layout shown there- you have a 12mm thick end cap, the seal is 6mm thick, so unless you use a very thin ballrace, you're not going to have enough space for a collar.

But as I said, I don't think you have anything to worry about with the original layout.

Andy_k

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Re: OTW Vanguard help
« Reply #163 on: December 12, 2011, 05:01:24 PM »

Why not use a stub shaft just to come through the WTC and have a u/j to connect to the prop shaft would also make life easier when you want to remove the WTC and the  u/j would take up all the thrust from the prop  :-))
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Re: OTW Vanguard help
« Reply #164 on: December 12, 2011, 05:29:52 PM »

You've lost em there, Andy. I'm also unclear how a U/J absorbs an axial load.

Andy_k

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Re: OTW Vanguard help
« Reply #165 on: December 12, 2011, 06:02:30 PM »

WHOOOPS must get my eyes checked I thought I read thrust just ignore me having an off day I am going to go and mutter in the corner :embarrassed:
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Re: OTW Vanguard help
« Reply #166 on: December 12, 2011, 06:08:23 PM »

Right I've had a little thinky (yes I know I should be careful....).

Simply triple the thickness of your endcap at the point where the shaft seal is located. That gives you an extra 6mm of clearance which is plenty to allow a collar to be fitted.

thegrimreaper

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Re: OTW Vanguard help
« Reply #167 on: December 14, 2011, 09:08:16 AM »

O.K. so I triple the thickness of my endcap to 18mm, I know that stainless is tough And you say locktite (bearing grade) a coller to the shaft which I can visualise in my head but bearing grade loctite ??? thought loctite was loctite.
I know I must run a stainless steel shaft through the seal was thinking of altering my plan slightley so that I used a shorter u/j in the WTC enabeling me to go the way Andy_k suggests with a stub axle (stainless) out of the WTC onto a second u/j then the actual prop shaft. with the saved space of using a single u/j in the WTC I could fit a bearing in between the u/j and endcap or as you suggest Andy actually into the endcap. Question is what is bearing grade Loctite and where do`s one aquire some from???

Regards Mark.
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Re: OTW Vanguard help
« Reply #168 on: December 14, 2011, 09:49:05 AM »

The industrial grade stuff is numbered, and comes in different strength formulations. For instance you can get formulations with lower strength used for thread fastening e.g. Loctite 222

Those weaker formulations are sufficient to prevent a thread from loosening but will break if you need to.

For your application you need a high strength retainer specified for holding roller bearings etc. Loctite 638 would be a good choice. Once the collar is glued on with that, you will need heat to remove it.

Try googling for a local supplier, or ebay etc. The stuff isn't cheap, but it lasts for years and you only need a drop, so buy a small bottle e.g. 10ml which will last a long time.

http://www.ebay.co.uk/itm/Loctite-638-high-strength-retainer-10ml-/190595028546?pt=LH_DefaultDomain_3&hash=item2c60595642

batfish

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Re: OTW Vanguard help
« Reply #169 on: December 14, 2011, 12:50:19 PM »

Your fairly getting on with it mark, Good to see it coming together.
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Albion

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Re: OTW Vanguard help
« Reply #170 on: December 14, 2011, 11:29:47 PM »

The industrial grade stuff is numbered, and comes in different strength formulations. For instance you can get formulations with lower strength used for thread fastening e.g. Loctite 222

http://www.ebay.co.uk/itm/Loctite-638-high-strength-retainer-10ml-/190595028546?pt=LH_DefaultDomain_3&hash=item2c60595642
When i was an apprentice we stuck a 50p piece to a marking table. then sat back to watch as people tried to secretly pocket it (50p could buy a pint then).
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Re: OTW Vanguard help
« Reply #171 on: December 15, 2011, 09:56:18 AM »

A somewhat more sadistic variation on that, was sticking a pound coin under a blowlamp and chucking it for someone to catch.

Patrick Henry

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Re: OTW Vanguard help
« Reply #172 on: December 15, 2011, 12:10:28 PM »

Now that is evil, Mr L...   %)
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Re: OTW Vanguard help
« Reply #173 on: December 15, 2011, 01:31:10 PM »

I perhaps should have added that I wasn't the perpetrator- or the victim.

batfish

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Re: OTW Vanguard help
« Reply #174 on: December 15, 2011, 05:18:26 PM »

Hi Mark,

I have a Engel lavayette motor mount 2 compression seals a prop shaft again engel, and 2 4mm solid couplings. if any use give me a shout.

regards

adam
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