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Teflon Spring buttons


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Alex, I had a friend machine mine. And apparently PTFE isn't the best material for this application, but oil-impregnated nylon. I'm afraid I've forgotten the trade name of the material, sorry.

Cheers, Richard

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20 hours ago, ed.h said:

I used Delrin (Acetal).   It is almost as slippery as PTFE, but has much higher compressive strength.

Ed

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Now that would be brilliant Ed where do you get these from?

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Bought a wad punch and some polyurethane sheet of eBay to make some for my Vitesse spring, used an hydraulic bearing puller to drive the punch to cut them.

Using my biggest lump hammer a waste of time.

Regards

Paul

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Teflon is better certainly than the original rubber but for wear  resistance, ultra high molecular weight  polyethylene (UHMWPE) is probably the first choice according to American and Dutch websites and is probably better than Acetal ( Or Delrin as it is known in the States)

(As a complete aside, this  mirrors orthopedic practice where Sir John Charnley’s first hip replacements using Teflon wore out after year or so but when he changed to UHMWPE they were very much more successful.This material, with slight changes, is still used for its wear resistance is various orthopaedic roles) 

It is cheap, comes in bar, white and waxey- looking .Resistant to pretty much anything( apart from heat) 

It is said to be “easily machinable” Not by me, - I had quite  a little pile of failures  along side the mini lathe, long stringy bits of white swarf, and   all different thicknesses until I had a set that looked reasonable.

(The width of the spring with a 2 mm or so “bump” to fit the recess.

Haven’t tried them yet as body still off chassis.

 

 

 

 

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This is a useful table for comparing plastics properties.  Ignoring the engineering ("designer") plastics, and focusing on some of the more common plastics for this application, Delrin acetal is designated as POM H, Nylons as PA, UHMWPE as UMHW, Teflon as PTFE.

The most important properties would be Compressive Strength (higher is better) and Coefficient of Friction (lower is better).  For example, PTFE (Teflon) is very slippery, but also very weak in compression.

The table doesn't seem to include fortified plastics, like Nylatron, which I believe is just a Nylon infused with Molybdenum disulfide to reduce friction, which would seem to make it a good candidate.

https://precisionpunch.com/wp-content/pdf/PropertyComparisonChart.pdf

 

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