Strut bearings/bushes?

[jaso]

Hi all. I'm just about to start making my hardware for my new .21 rigger and was trying to decide what was the best method for bushing the strut for the prop shaft to run in.

The last time I used needle rollers but I was interested in trying some teflon.

I was planing to make one long bush to press fit into the strut .

Only thing I'm not sure of is how long this would last and if I would need to machine a slot or hole for the water to get into the bushing for lubrication.

I know that probably the best lube for teflon is water and theres plenty of that under the boat.

Anyone tried this or has any Ideas?

Any input welcome.

 

[Mike Hughes]

I run the teflon bushings from Octura. I don't not have any special grooves or anything. Works fine. They will last a couple of years depending on how much you run.

Mike

 

[jaso]

Thanks Mike the reason I asked was I don't think I've seen anyone locally run teflon in there struts and just wondered why not?

I've got a bit of it (teflon) floating around so I thought it would be a cheap and easy bush to use.

My .90 rigger uses brass tube inside the stuffing tube and I don't really like how it wears even with constant lubricating between runs . It also seems to get excessive clearance between the shaft and the bush pretty quick which has to make vibration I think . Can't be a good thing? :blink:

 

[Joe_Knesek]

This bushing is at least 7 years old and has only.0005 wear on it. Balanced props and good lube is the key.

 

[TimD]

I've got a bit of it (teflon) floating around so I thought it would be a cheap and easy bush to use.

Do you mean you are going to make a bushing from a piece of teflon stock?

The teflon people refer to for strut bushings are the Lead /teflon ones (octura)

Personally I find the brass tubes more durable / easier to change / cheaper.

 

[jaso]

Yep Tim thats what I mean, plain straight teflon.

Years ago when I first got started on the boats, I used to make fixed shaft stuffing tubes out of a piece of alloy tube and machine up a pair of teflon bushes to press fit into each end. Of course that was a bit different in that it was slow elecric motors and I was using and small plastic props. ( Dad wouldn't let me go to glow powered till I was in late teens.) :blink:

So I guess what I wanted to know a bit more specifically was, can you use straight teflon in glow powered high performance applications or doesn't it hold up very well? If you have a strut tube length around say 50mm long and you have a nearly full length teflon bush is it still too soft a material to use?

 

[Preston_Hall]

This bushing is at least 7 years old and has only.0005 wear on it. Balanced props and good lube is the key.

Come on Joe.

 

[Mike T.]

Only .0005 on the OUTSIDE, Preston. Kinda hard to mesure the inside where the shaft runs.

Besides, it's been in the tool box for 6 -1/2 years. Well lubed, or course.

Sorry, Joe, I couldn't resist.

 

[Joe_Knesek]

Only .0005 on the OUTSIDE, Preston. Kinda hard to mesure the inside where the shaft runs.
Besides, it's been in the tool box for 6 -1/2 years. Well lubed, or course.

Sorry, Joe, I couldn't resist.

It's not hard at all to measure when you have guage pins. It fits or it doesn't. I've only made 2 of these bushings and have ran 2 boats for the last 6 years.

 

[TimD]

Jason,

I'd doubt the teflon would be any more durable. We use them in some places in the copiers I work on and they are less durable than the scintered bronze bushings of the same dimensions. Friction is not an isssue in this application tho'.

Tim.

 

[Mike Hughes]

I have reread my post. I should of said lead teflon bushings. I am not sure on just teflon. I use it for push rod seals. Works great. I guess it might do ok. Give it a try. The worst that can happen is that will get out of round.

Mike

 

[jaso]

Sounds like no one has tried what I'm thinking of. The boat is only a .21 ( not huge heavy prop to support). I guess I can try it and if it gives way quick I can make a reducer to go in to the strut and run a conventional brass bush made of K+S tube .

Any one have any other methods they use for strut bearings or bushings? :blink:

 

[apache5056]

Have you considered oilite material over the teflon?

Beemer Precision Inc.

 

[EatMyShortsRacing]

Hmmmm I could take all my oilite bushes out of my slot cars and throw them in my twin!!!! May be a little of a discrepency in the shaft diameters though. :lol:

The old Full Ahead (Australian Manufacturer) straight shafts used what looked like a black plastic bushing that was very tight on initial installation but once you worked it in (Electric Drill on the shaft)they never seemed to wear out at all and the shaft always seemed free yet there was no noticeable movement laterally in the shaft.... Anyone have an idea what that stuff was???

EMS Racing Yes we race Slotcars too

 

[jaso]

Hi Craig, guessing it was some sort of nylon or teflon. In straight shaft use they don't have to put up with the same loads as a flex setup.

Anyone have any other ideas on this?

 

[Preston_Hall]

Why fight it? Most people use the brass tube bushing. Materials are cheap and easily acquired.If you own a Dremel and a soldering iron you are done.

One of the biggest reasons to use the brass tube is to be able to run a smaller/lighter strut. The strut only has to be large enough to accomodate the brass stuffing tube. Your bearing/bushing will have an outside diameter of _________? The strut will have to be machined or larger than typical. Why reinvent the bushing? What would be any advantage?