Motor Shaft Help,

Afternoon All,

I rebuilding the two WTC as fed up with the old darnel box leaking. two question,
1, what the best tube to use for the cables to go thought to join up the two boxes, was going to PVC waste pipe but didn't bond well.
2, on the last box the prop shaft went though the wall of the box which didn't help the leaking, so I wanting to put the motor directly on the box wall. the motor are MFAcombo gearboxes but the shaft are bit short. whats the best way to extend them and make them water tight.


Thanks

Hi Tim,

You may have a look over at the build log I'm doing on the Darnell type XXI. It may spark some ideas off.

I now have both boxes out but I'm unlikely to reinstate that tube joining the boxes. Too much leak potential! High current wires between the boxes will go via brass nuts and bolts. (See elsewhere on the forum for details) Control circuits - I haven't yet worked out the details but probably a small sealed gland.

The greased prop shafts have gone but I am not using MFA motors on this one. One problem you have with them  is, as you have found , you need to join shafts. That can take up valuable WTC length. Our Chairman Nigel has some neat ideas on letting MFA shafts into end caps incorporating seals. Maybe he will come in on this.

I suggest that whatever you do, you put in decent oil type seals (e.g Simrit) and have any univeral joints outside the WTC (again to save your valuable WTC length.) Don't forget that you put sealed lead acid batteries in the wet.

If you look at the build log you will see that I am testing 2 different flat plate sealing methods. Early testing seems to show that they are both working adequately. Which to choose!? A bit more testing time will tell.

David

thanks david. I check out that build log

Cheers
Tim

Don't know if this will help, Tim, but I made this up this afternoon out of redundant MMB Sub Sonic parts....took me about half an hour to make.

It's basically an MMB end cap with a short length of alloy tube cut to go through it, two of his PTFE bearings and a tiny O ring pushed into the ends, then the whole lot goes through one of his Sub Sonic motor mounts. At the inboard end is a brass wheel collet ( a push fit) to take up any slack. A short stub shaft goes through the whole lot and with a couple of Huco connectors and brass thrush washers at both ends, the job is done.

The motor mount can be trimmed shorter than mine if you need to, but I have plenty of space in the wtc, so I didn't bother doing that. I did run it for a few minutes on 2.4volts, and it ran perfectly freely.

I can do you a drawing of it if you wish?

I'd done the drawing anyway, so here it is...hope it helps.

cheers Richard, I had a look at them online not sure why I didn't go this route. Just order two oil seals from Simply bearing and like on you x type.

Have to admit, I would recommend this company to any one, after 30min of ordering online got a email saying order complete and dispatched to royal mail, plus free delivery.

That's pretty good service, Tim...can't complain at that!

Good luck mate, keep us posted.

Richard

taken some photos, so will post when done. at least very time i rebuild it I'm learning and improving.

What are those 2 Flange for RICHARD?

They are part of the motor mount, Marius...I don't know why they are there really, one would be more than sufficient.

That looks very neat, Richard. (And not a million miles from the method Nigel uses.)

My method for seals has not changed in years and involves a "sandwiched" oil seal on the end of a brass M8 bolt which has been drilled out to 4mm.  But it does require a lathe which not everyone has. Works very reliably for me. Some of those Simrit oil seals have been in my subs for many years.

And yes Simply Bearings offer a great service and they are based in the North!

While I am sharing things, I have found some "magic dimensions" for model submarines:

4mm OD  - for prop shafts, push rods through bellows, air and water connections (using 4mm OD nylon tube)

42 inches - that model length which allows you to place it full length on the back seat of a car!

David

Here you are Tim....the completed mount fixed on the end cap and in position.