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[das boot]

I'm having trouble getting the props for the Mighty Mo....what I need is two x four bladed 25mm diameter brass props with a 1/16"th hole in them, not a 2Ba or a 4BA thread or anything else sized thread, just a 1/16"th hole. I've used 1/16"th diameter brass rod for the propshafts and brass tube of 1/16"th internal diameter for the tubes because it all fitted perfectly in the spaces provided.

I think can get the props without too much problem, but what I need is some ideas as how to get the 1/16"th brass rod to fit them. I had thought of screwing a bolt into the props, cutting it off flush and then trying to drill a central hole through the bolt...any ideas guys?


Rich

[Colin Bishop]

There are several options. Firstly you could just glue the props straight onto the shafts using a series of concentric brass tub inserts to centralise them. Use one of the metal filled epoxy glues. If the props need to be detachable then another possibility would be to glue or solder a small diameter brass nut into the hole at the back of the prop and then put a thread on the shaft so you can screw it on in the usual way. It's a bit fiddly but I have done it successfully in the past. As you will have realised, you need to get the prop on straight!

I'm sure that others will come up with alternative suggestions.

Colin

[tonyH]

Why not just phone/e-mail George Sitek? He's very helpful regarding these sorts of things.

Tony

[das boot]

There are several options. Firstly you could just glue the props straight onto the shafts using a series of concentric brass tub inserts to centralise them. Use one of the metal filled epoxy glues. If the props need to be detachable then another possibility would be to glue or solder a small diameter brass nut into the hole at the back of the prop and then put a thread on the shaft so you can screw it on in the usual way. It's a bit fiddly but I have done it successfully in the past. As you will have realised, you need to get the prop on straight!

I'm sure that others will come up with alternative suggestions.

Colin

Thanks Colin, that's one idea....(is that what they call 'micro-engineering') think I need to go to Specsavers for that 

Why not just phone/e-mail George Sitek? He's very helpful regarding these sorts of things.

Tony

Tony...been there, done that. George can't help me out, he only goes down to 3mm shaft sizes.


Rich

[Shipmate60]

Couldn't you fit graupner 2mm shafts.
prop Shop make 2mm props.
That is what I did on all mine.

Bob

[FullLeatherJacket]

Rich

Try SHG Marine - there ain't much about little models that Jerome and Sue don't know.....or stock!

FLJ

[das boot]

Couldn't you fit graupner 2mm shafts.
prop Shop make 2mm props.
That is what I did on all mine.Bob

With liberal amounts of hindsight Bob, that's what I should have done, but it's far too late now, I'd never get the brass tubes out in a month of Sundays, so I go with what I've got. We live and learn mate....

Rich
Try SHG Marine - there ain't much about little models that Jerome and Sue don't know.....or stock!FLJ

Thanks FLJ, I'll be onto that tonight after work. Report back later...


Rich

[Colin Bishop]

Thanks Colin, that's one idea....(is that what they call 'micro-engineering') think I need to go to Specsavers for that 

I call it bodging, but it worked for me! 

[malcolmfrary]

Have a look here
http://www.towboatjoe.com/
go to Shafts, scale things down to fit
The home-made cut-out flat brass props solder onto the brass shaft easily, and, for removal, un-solder just as easily.

[Shipmate60]

Could you modify the outer shaft to take a 2mm propshaft?

Bob

[das boot]

Could you modify the outer shaft to take a 2mm propshaft?

Bob

err...explain more, can you Bob, please? Not quite with you on that....? 

[tonyH]

Sorry Rich, should have guessed you'd tried the logical routes.

One thing that worked for me that is roughly the same as Collins method was using layers of heat shrink onto the piano wire to build up to the required thickness and then screwed the prop onto it. The prop 'cut' a sort of thread onto the plastic wrap. I then trimmed off the excess and dosed the whole thing with runny superglue. OK for low power but not recommended for nitro!

Tony

[das boot]

Sorry Rich, should have guessed you'd tried the logical routes.

One thing that worked for me that is roughly the same as Collins method was using layers of heat shrink onto the piano wire to build up to the required thickness and then screwed the prop onto it. The prop 'cut' a sort of thread onto the plastic wrap. I then trimmed off the excess and dosed the whole thing with runny superglue. OK for low power but not recommended for nitro!

Tony

hmm...I like that idea Tony. Maybe a couple of layers of insulating tape with a sandwich of superglue, prop screwed on and then as you say, another layer of thin superglue to secure the whole lot? That may just do the trick, I have low power a'plenty....two 280 sized motors on a 6volt battery, don't get much lower than that.

Thanks for that....I'll give it a try.

Rich

[tonyH]

Hi Rich,

The reason for the shrink tube was that there were no loose ends to cause eccentric running/imbalance.

Tony

[das boot]

Yep, got that Tony...ok, shrink tube it will be then. Thanks again for that, much appreciated. 

Rich

[Bee]

Too late maybe but couldn't someone with a lathe drill a 1/16 hole down a 2 BA brass screw for you?

[Shipmate60]

Sorry didnt remember you are using 1/16 ID tube for the propshaft outer tube.

Bob

[das boot]

Too late maybe but couldn't someone with a lathe drill a 1/16 hole down a 2 BA brass screw for you?

Never too late! I tried to chat up our fitters at work to do just that, and got a blank stare in return. Useless bunch of.......   


Rich

[boat captain]

I had the same problem.  I drilled a screw out to suit my shaft, soldered it onto the shaft and then fitted my prop on with a locknut.   

Joe

[das boot]

I had the same problem.  I drilled a screw out to suit my shaft, soldered it onto the shaft and then fitted my prop on with a locknut.   

Joe

I think that's going to be the answer Joe, I have fears of the losing the props if I go down the shrink wrap road (sorry Tony )
I think I'll have a sniff around the engineer shops on the local trading estate tomorrow, one of them must need a tenner in his pocket...

Rich

[Bee]

Are you sure it's only 1/16? That's awfully small.
Anyway I've done a couple of 4BA set screws with a No 52 drill which is a couple of thou oversize. I did one No 53 which would be undersize but the drill broke on the second one. Drop me a pm with your address.

[tonyH]

I'm really hurt Rich!

Well done Bee!

Tony

[das boot]

Are you sure it's only 1/16? That's awfully small.
Anyway I've done a couple of 4BA set screws with a No 52 drill which is a couple of thou oversize. I did one No 53 which would be undersize but the drill broke on the second one. Drop me a pm with your address.

That's what it says on the packet...pic attached. And yes, it is awful small, as is everything on this kit!!

(I've sent you a pm, by the way....)

Rich

[Bee]

I just think it is going to be in danger of bending at the end if the prop is knocked in transit or a collision. Some adaptors will be in the post as soon as it stops raining - I shouldn't have had that extra hour lie in. 
Anyone else need a 4BA bolt drilled before I take the jig out of the chuck.

[malcolmfrary]

I've been using 1.5mm brass rod as prop shafts for a long long time (something like that, anyway - its a sliding fit up the inside of a Q-Tip plastic tube).  Yet to bend one.  The only way would be to drop the model on it, and the shaft would then be the least of your worries.