Model Engine Maker
Supporting => Engine Ancillaries => Topic started by: kev on February 26, 2017, 07:58:33 PM
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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?
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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
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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
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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
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https://www.amazon.co.uk/Permabond-TA4610-Toughened-Acrylic-Adhesive/dp/B019FCOKFO