graphite year stuffing

This topic has 17 replies, 7 voices, and was last updated 24 January 2011 at 16:29 by Edward Berthelemy.

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23 September 2009 at 14:34 #4775
mike robinson 2
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@mikerobinson2
Stuart no 9
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23 September 2009 at 14:34 #43750
mike robinson 2
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@mikerobinson2
The No 9 engine is an absorbing engine to start this hobby with. Lots of thinking

How much graphite yarn should be used in the cylinder and value glands respectively ? How many turns or what length?

Appreciate the help

Mike
23 September 2009 at 14:51 #43752
JasonB
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@jasonb
Would depend slightly on the gap and size of your yarn. The yarn will pack down as the gland is tightened, about 3 winds of yarn would be a good starting point. You want to fill the void at the end of the gland plus a bit more ie you don’t want the gland bottoming out.

If the gap on the valve rod is small you can unravel the yarn and just use one strand

Jason
23 September 2009 at 14:55 #43753
Ian S C
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@iansc
Or use Teflon plumbers tape instead,it ain’t so messy.Just a thought.IAN S.C.
23 September 2009 at 17:48 #43756
mgj
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@mgj
This is a bit like stuffing glands on boat propellor shafts. I’m using the dirt cheap hemp yarn and grease on my piston rod because I can’t be bothered with graphited and I can thus argue it’s more prototypical.

Wind some round the rod, so its going to fill the hole reasonably, overlay with grease, tighten gland outer till assembly doesn’t leak, and is not too tight. Victorian technology – not very complex! (They used a lot of tallow – but that smells) If it does leak a bit – see all sorts of steam engines at the steam fair, and:

a Don’t worry.

b Tighten a bit more

c If that creates too much friction, loosen a bit, and if it leaks a smidgen:

d Don’t worry.
23 September 2009 at 19:35 #43757
chris stephens
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@chrisstephens63393
Posted by Ian S C on 23/09/2009 14:55:48:
Or use Teflon plumbers tape instead,it ain’t so messy.Just a thought.IAN S.C.

Hi Ian,

Rather than use PTFE plumbers tape, you can get the same stuff in round a bit like string, it is used in he gland on top of water taps. Should work well in steam engines as long there is not too much super heat.

chris stephens
23 September 2009 at 20:13 #43760
mgj
Participant
@mgj
Chris – where do you get that because thats exactly what I was looking for. But none of the big plumbers in Yeovil stock it.

There is gas type ptfe tape which is quite a bit thicker than the standard, which could well work too, but that string is the stuff.

LSM stock gland packing, but its really a bit thick for this sort of application.
23 September 2009 at 20:34 #43763
JasonB
Moderator
@jasonb
MJ Engineering had some on their stand last week and I think Bruce engineering (polymodel) do it as well

Just as easy to take a length of plumbers tape fold it over in half and in half again then twist the four strands together

Jason
23 September 2009 at 21:04 #43767
mgj
Participant
@mgj
Thanks – I’ll try that

Sometimes, given the simplicity of other peoples ideas, I feel I haven’t considered my options very well .
23 September 2009 at 22:46 #43769
chris stephens
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@chrisstephens63393
Hi Meyrick and you others,

Can’t find my pot of the PTFE string so can’t give a brand name, if I find it I shall post but I’m sure someone will beat to it.

The gas tape is indeed thicker than the plumbers, but I wonder if in these regulated days whether a gas fittings supplier would dare to sell some to a none Corgi(of whatever it’s called now) registered customer. They don’t want to be seen to assist hobby gas fitters, do they? Useful stuff though, even when used for plumbing, if you can get it.

Plumbers tape is very useful on motor vehicles, used on screws that are only undone rarely, it stops them corroding together. Very good for stainless screws in Alloy cases.

chris stephens
23 September 2009 at 23:10 #43770
Niloch
Participant
@niloch
PTFE string: surely, you must mean: Screwfix product no. 42142 Pipe Seal Cord, £2.93/50metres
23 September 2009 at 23:39 #43772
chris stephens
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@chrisstephens63393
See, I told you some kind fellow would come up with the answer.

Sounds like a bargain price, seem to recall paying 7 quid for about ten yards!

chris stephens
24 September 2009 at 03:50 #43779
Ian S C
Participant
@iansc
Haven’t seen the string at this end of the world(NZ),but its proberbly out there.I just take the tape and roll it into a string.I think it comes in 50m rolls for between nz$1 &nz$2 a reel(About $3=£1).IAN S.C
24 September 2009 at 14:36 #43790
Niloch
Participant
@niloch
Ian S C,

You seem to be managing well enough without PTFE String but in case you would like further information it is a Loctite product. Loctite is, in turn, owned by Henkel (Dusseldorf, Germany) but they have an Asia-Pacific arm. Henkel N.Z. Ltd, East Tamaki, 2 Allens Rd, Auckland.

Screwfix is a British company which until a couple of years ago was mail-order only:

http://www.screwfix.com

with very competitive pricing.

Usual disclaimer.
24 September 2009 at 15:55 #43794
mike robinson 2
Participant
@mikerobinson2
My thanks to all for the enlightenment – Stuarts sell graphite yarn at £3 per 6″ – the bit in the kit is 3″ long and the diameter of cotton.

I guess PTFE yarn will pack down ok, I will try it. All your (international) help much appreciated

Mike
24 September 2009 at 18:16 #43799
mgj
Participant
@mgj
Niloch – thank you. I had looked in the Screwfix catalogue, but didn’t realise that the cord was ptfe.

Great help – and cleaner than greasy hemp!
26 September 2009 at 11:07 #43833
Ian S C
Participant
@iansc
Nilock,the stuff I use is made in Taiwan,75m x12mm x .075mm and cheap as.IAN S.C
24 January 2011 at 16:29 #63065
Edward Berthelemy
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@edwardberthelemy87719
Hi

Thanks to everyone for their help. I now also know why these boxes have to be stuffed.

Thanks again.

Ted
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