Piston packing again…

[David HaynesParticipant @davidhaynes53962]

A lot of folks have already made there thoughts known about preferring O-rings and the need for a nip in the fit. But, if I want to use graphite yarn, poking it in to the gap with a blunt knife etc, does anyone have a favoured technique for doing this? I end up packing it and then shaving some of the bulge off with a knife, as it won't fit in the cylinder otherwise (even though the correct 'nominal' size was used for the groove).

Not much has been expanded on PTFE tape, how successful is this as cylinder packing?

Dave

[David HaynesParticipant @davidhaynes53962]

Choice of material

[julian atkinsParticipant @julianatkins58923]

dave,

soak it in steam oil after cutting a scarf joint. it will compress much easier, and will also form a better fit as a result. ive never used a blunt knife. tip of a screwdriver for me and very gently and slowly. only use square graphite asbestos packing, not string. for pistons, i make the groove fit the packing…which often requires a bit of experimentation with new stock…dont rely on the drawing dimensions to suit the packing. and if you use string for glands make sure there's no brass wire in it.

cheers,

julian

Edited By julian atkins on 24/02/2013 21:47:40

[Ian S CParticipant @iansc]

One suggestion I came across for fitting a piston with packing, leave the edge of the cylinder sharp, and without taper, and force the packed piston into the cylinder, the excess packing is shaved off on its way in. another type of packing worth thinking of is teflon tape. Ian S C

[David HaynesParticipant @davidhaynes53962]

Who has tried teflon tape?

Dave

[Ian S CParticipant @iansc]

Don't know if he looks in these days, but Tel from Austrailia has suggested teflon for one, I use it for gland packing. Ian S C

[nigel jones 5Participant @nigeljones5]

I wurried about using packing on my 5" but it works brilliantly – I know this as I left a bit of water in the cyninder and got hydraulic lock! Plenty of oil/greace on insersion! Dont use yarn, buy square stuff and machine to suite

[Ian S CParticipant @iansc]

fizzy, thats what drain cocks are for. Ian S C

[nigel jones 5Participant @nigeljones5]

I forgot to swap the plugs with the drain cocks before firing!

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