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GRAPHITE/NYLON BUSHINGS ON ALUMINUM?

23 posts in this topic

Posted (edited)

Anyone know if Graphite has any bad effects on aluminum?

I found Graphite Impregnated round flanged Nylon bushings with 1/8" wall for my flap and aileron tubes and hangers.

I looked for Polyethylene bushings, but only found thin ones so far.

EdMO

Edited by Ed In Missouri

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Posted

Ed how thick does the nylon piece need to be ? Will this work ? It's 1/4 in thick 6 in long 3in wide

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Posted (edited)

Thanks Jbird,

I have the nylon plates for my fuselage and turtledeck bearings, I think it is 1/4 or 3/8" thick.

What I was asking about was the round, flanged bushings to go between my flap and aileron tubes, and also inside the hanger tubes.

If I had my lathe going, I could make them out of nylon, but it is cheaper to buy bushings than to have them made at the local machine shops. I almost had a heart attack when I got the bill for the last job I sent to a shop!

EdMo

Edited by Ed In Missouri

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Posted

Ok I now I know what you are looking for

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Posted (edited)

I found the bushings in one of my catalogs, but I don't know if Graphite will hurt aluminum. I know its OK for steel tubes.

I think it is inert, and non-destructive, like the nylon, but I don't know for sure.

The guy who built a tailwind used PVC pipe as his bushings, but I think this is better, and PVC pipe is not the correct sizes and would have to be machined.

EdMO

Edited by Ed In Missouri

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Posted

My kitfox manual says to NOT use a pencil to mark on aluminum spars because it can cause corrosion.

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Posted (edited)

My kitfox manual says to NOT use a pencil to mark on aluminum spars because it can cause corrosion.

Thanks tcj,

That's what I was worried about. I know you cant use a pencil on exhausts because it can cause cracking.

Is MDS (Molybdenum Disulfide) OK on aluminum? I found Nylon impregnated with that stuff too -

From what I read it sounds harmless, and better than plain nylon?

Guessing unless I get a big "No-No" from someone, that is what I will buy.

EdMO

Edited by Ed In Missouri

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Posted

Ed,

 

I have a small lathe and a small bench mill, if you send me a drawing and the required material I can make your bushings.  It will only cost you the price of the material and postage. 

 

MarkD

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Posted (edited)

Thanks Mark,

I am getting close to the time to start building my hangers. I will keep your offer in mind, and sometime this year I may figure out what I need for bushings. The MDS/Nylon ones I have been looking at are priced at $5 to $9 each. I know I have some round nylon, and can always buy some more. I have some gray nylon, but don't know if it is graphite or MDS impregnated, and afraid to use it.

Polyethylene would probably be the best choice, if I could find bushings thick enough.

Much appreciated,

EdMO

Edited by Ed In Missouri

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Posted

The offer stands as long as I have the machines and ability to perform the machine work.

I agree to not use the material with additives. Raw Nylon or Polyethylene as bearings/bushings for aluminum works well. Graphite on aluminum can cause intergranular (stress) corrosion and or galvanic corrosion depending upon the environmental conditions.

I'm not sure about chemical properties of the Molybdenum-Disulfide lubricant. In grease it is usually used in High Load Bearing applications. I do know that Moly-coat (MDS based grease) does not wash out when you get it on your jeans and really makes the little woman unhappy when it gets into the washing machine and gets all over her stuff. (Another manly way to make her really unhappy, deep sigh. She will not wash shop rags anymore.)

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Posted

How much do you need Ed?  I have a 5" x 4" x 1" piece of what appears to be nylon from all the scraps I got with the machine shop I bought.  If I still lived in Illinois I'd bribe you with it to come show me how to work all that equipment I got!

 

Depending on how big a hurry you are in, I'll be going back sometime late October/Early November to get the Avid - last load on my move to Florida!  Woo Hoo!

 

Mark

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Posted

Here's a picture - the 5x4 is the biggest part, the extra leg I didn't measure

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Posted (edited)

Mark,

I either have, or can buy round Nylon - I need some parts about 2 1/2 OD, and some 1 1/2 OD before machining. I also have some flat nylon if someone needs any, and maybe some round Teflon too, but you can buy it at Spruce or other places. I made new Teflon O-rings for my Cessna 150 steering wheel shafts to replace the rubber ones where it goes thru the IP, and have extras if anyone needs some.

Thanks,

EdMO

Edited by Ed In Missouri

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Posted

Mark,

I either have, or can buy round Nylon - I need some parts about 2 1/2 OD, and some 1 1/2 OD before machining. I also have some flat nylon if someone needs any, and maybe some round Teflon too, but you can buy it at Spruce or other places. I made new Teflon O-rings for my Cessna 150 steering wheel shafts to replace the rubber ones where it goes thru the IP, and have extras if anyone needs some.

Thanks,

EdMO

Ok, sorry, misunderstood what you were looking for.  If I was still in Illinois, you'd be welcome to make a road trip and use one of my lathes.  Coming to Florida would probably cost more than even the exhorbitant machine shop costs!

 

Mark

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Posted (edited)

Mark,

I have a gunsmith lathe and a vertical mill that I brought back from Alaska - If I wasn't so involved in trying to finish this plane while I am still able to fly, I would take time to get them wired up and going. Guess I should have sold them with the rest of the machinery when I moved, but ran out of time to move.

EdMo

Edited by Ed In Missouri

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Posted

Ed,

I would stay away from Nylon. It absorbs water and swells. Polyethelyne would also have a lower coeffient of friction.

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Posted

Ed,

I would stay away from Nylon. It absorbs water and swells. Polyethelyne would also have a lower coeffient of friction.

Sometimes you just have to get what is available - So far, the MDS enriched Nylon are the only ones I have found the right size for mine.

EDMO

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Posted (edited)

Latest on the Nylon MDS bushings - Well, I bought about $300 of them, and they are all about .030" oversized both ID and OD - now got to find steel hanger tubing to match and maybe some stainless tape to put over the aluminum inside flap and aileron tubes to make them a press fit there, or maybe aluminum shim stock. 

They look exactly like the bushing that Kitfox used for the elevator push-pull tube.

EDMO

Edited by EDMO

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Posted

There goes your Beer money  this month ha

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Posted

There goes your Beer money  this month ha

For me, that's about a year's beer money - but I keep beer money in the office supply account, not in the airplane account!

EDMO

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Posted (edited)

Just to update this old post - One member used RULON bearings from McMaster-Carr, and said they were great - about 2x price of MDS.  You can get 50 lbs gas springs from them too.  EDMO

https://www.mcmaster.com/#gas-struts/=18kvqga

Edited by EDMO

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Posted (edited)

I am wondering if instead of nylon we could use teflon (PTFE) instead? Anyone have experience with this?

 

https://dir.indiamart.com/hyderabad/ptfe-bushes.html

 

I used Teflon on my Cessna & Ercoupe steering wheel tube supports to replace the rubber rings - was a little tight, but hit it with a quick shot of WD40 and it was slick as owl shit.  Teflon is slicker, but softer and will wear faster - and is/was more expensive.  EDMO

Edited by EDMO

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