Author Topic: bonding.attaching ptfe bearings  (Read 1760 times)

Offline kev

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bonding.attaching ptfe bearings
« on: February 26, 2017, 07:58:33 PM »
Im wanting to make a propshaft with ptfe bearings for a long endurance voyage.

Anyway to bond them into a brass tube or maybe its best to press fit them and drill after fitting?

any thoughts guys?

Offline Bluechip

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Re: bonding.attaching ptfe bearings
« Reply #1 on: February 26, 2017, 08:19:12 PM »
Im wanting to make a propshaft with ptfe bearings for a long endurance voyage.

Anyway to bond them into a brass tube or maybe its best to press fit them and drill after fitting?

any thoughts guys?

Ah ... Funnily enough ....

I had this thought that it cannot be glued. Then about 2 years ago a friend from  R.R. sez you can by using ordinary Cyano. but with this primer first.

http://uk.farnell.com/permabond/polyolefin-primer/coating-bottle/dp/2564775?ost=permabond+primer&selectedCategoryId=&categoryNameResp=All&searchView=table&iscrfnonsku=false

( Get a good grip on your chair before you see the price ...  ;D )

The PTFE I have/had is white in colour and he put a bush in alloy  for me ...  :cheers:

AFAIK it's still in there  :ThumbsUp:

Seen the price ???

Press and drill/ream it is then eh ??????  :lolb:

Dave




Offline GailinNM

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Re: bonding.attaching ptfe bearings
« Reply #2 on: February 26, 2017, 10:36:35 PM »
Press fits don't work well with PTFE.  It cold flows (crereeps) under pressure so does not make a good mechanical joint.

The best way I came up with was to turn a series of shallow grooves in the PTFE and then cut a few grooves length wise connecting these grooves.  I think I did 0.02 wide grooves spaced about 0.05 apart and about 0.005 or 0.010 deep. This was years ago on some bushings.

I roughed up the inside of the hole and then used epoxy to hold in place.  The epoxy does not stick to the PTFE but flows into the gooves and makes a mechanical joint.  The circular grooves keeps it from pushing out and the length wise grooves keeps it from turning so you can machine it if necessary.

Gail in NM
I would like to be the kind of person my dog thinks I am.

Offline Dave Otto

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Re: bonding.attaching ptfe bearings
« Reply #3 on: February 26, 2017, 10:50:51 PM »
Many years ago when I was an equipment maintenance tech in a PC board shop; we needed to bond some PTFE strips to the stainless steel frame work where the conveyor chain ran inside of a PC board cleaning machine. We used Tetra Etch to prep the strips and Black Max to bond them in place; the Black Max is a toughened CA glue.

http://www.polytetra.de/en/products/special-products/tetra-etch-r-fluorocarbon-etchant.html

Dave

Offline old-and-broken

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A journey of 1000 miles begins with the first step.