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Graphite Bushes

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Howard Warehand16/07/2010 20:17:12
6 forum posts
Hi
I need to make some Graphite bushes but (a) can't find a supplier (min 15mm diam rod ) (b) I have'nt machined this material before, what are the does and donts and (c) I have been told that turning Graphite is a very messy affair and smothers the lathe with fine black dust, this I worry about!!!!. If anyone can give me assistance with any of the above, I would be most grateful.
 
Howard.
JasonB16/07/2010 20:24:42
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25215 forum posts
3105 photos
1 articles
Noggin do Graphite, cant help with what it turns like as I've never used it
 
 
Jason
MichaelR16/07/2010 20:41:54
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528 forum posts
79 photos
I worked in a company that had a graphite machine shop and yes it is messy, and looking like a collier without going down a mine springs to mind, don't know what it is like to machine but all the normal metal working machines were used.
NJH16/07/2010 21:08:20
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2314 forum posts
139 photos
Hi Howard
 
I recently milled a small block of this and yes it does make a mess -think rubbing a soft pencil on glasspaper. However it  was very easy to machine and a good finish was produced. Sharp cutter run fairly fast.
 
Norman
chris stephens16/07/2010 22:43:19
1049 forum posts
1 photos
Hi Howard,
Graphite might be messy but should do absolutely no harm to you lathe. It is after all one of natures best lubricants.
christephens 
Steve Garnett17/07/2010 00:46:43
837 forum posts
27 photos
Graphite powder is messy though! But since it's carbon-based you can wipe it up with a rag soaked in methylated spirit, which will soften the powder into a very useful lubricant indeed, especially for making bits of wood slide over each other - ask any organ builder.
Ian S C17/07/2010 10:28:24
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7468 forum posts
230 photos
Had a look on the web;They recomend a dust removal system, the particals go down to 0.0004". They also suggest that carbide tools at least be used, better daimond coated. For your job HSS would be OK I think. Theres info on all aspects of machining on the first site I looked at. One thing that is suggested is chamfering the edge at the start and end of the cut to prevent chipping, also slow the feed at the end of the cut. Ian S C
KWIL17/07/2010 10:38:21
3681 forum posts
70 photos
Out of curiosity, what are the bushes to be used for?
Howard Warehand17/07/2010 20:00:01
6 forum posts
I'm very grateful to you chaps for taking the time to help. The information was just what I was hoping for and has given me the confidence to have a crack at these bushes.
Just to help KWIL sleep at nights; the bushes are for a Low Temp Stirling Engine and the piston is also graphite which runs in a glass cylinder.
Thanks again for the information and advice,
 
Howard.
KWIL18/07/2010 09:10:29
3681 forum posts
70 photos
Thanks Howard, a Sterling Engine, that will really put me to sleep!  Used them in the real world for low temp IR target, that was enough!!
Lawrie Alush-Jaggs18/07/2010 11:06:54
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118 forum posts
32 photos

Hi Howard

I used to machine this stuff all the time when I worked as an EDM operator.  We would engrave slabs of it, burn the job and then clean off the graphite  with a surface grinder.
The advice you have been given thus far is sound.  Use very sharp HSS with a rounded nose run fairly fast. If machineing any substantial length, take light cuts.
 Hook up a vacuum cleaner and hang it over the top of the tool.  Don't make a habit of it though, it will completely root your vacuum cleaner after a while.  A couple of short jobs will be fine.  Not a bad idea to wear a mask if your vacuum cleaner has asthma.

Lawrie

Howard Warehand18/07/2010 18:58:00
6 forum posts
Thanks Lawrie. Your input is most appreciated. I only have a few components to make so I think that my Vac and air extractor will probably cope. Many thanks,
 
Howard
Sam Stones19/07/2010 06:42:50
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922 forum posts
332 photos
Hello Gentlemen,
At the opposite end of the scale to machining graphite, which receives praise as a fine and natural lubricant, may I suggest that the following could serve as a warning for those unprepared as I was.

While looking for a plastic material which offered high creep resistance, I was handed a short length of 50mm dia. glass filled polymer, possibly polyacetal. The glass was in the form of spherical beads less than about 0.1mm in diameter. It machined easily in the lathe with the swarf falling more as a powder than a continuous thread.

Suddenly, the saddle of my Myford ML7 jammed.

Glass beads had found their way past the felt lubricating strip and then between the saddle and the bed. I realised in the nick of time what had happened, and stopped everything rather than try to move the saddle any further.

Clearly, during the machining process, the glass beads had remained intact while the polymer was being shaved away as normal. That part of the machine required a complete strip-down to get rid of all the beads.

Luckily for me and the Myford, the top section of the saddle can be unscrewed and lifted vertically. Even more lucky, the saddle wasn’t traversing under power.

I trust that my experience serves as a warning to ME members and others.

Regards,

Sam

Sam Stones19/07/2010 06:42:51
avatar
922 forum posts
332 photos
Hello Gentlemen,
At the opposite end of the scale to machining graphite, which receives praise as a fine and natural lubricant, may I suggest that the following could serve as a warning for those unprepared as I was.

While looking for a plastic material which offered high creep resistance, I was handed a short length of 50mm dia. glass filled polymer, possibly polyacetal. The glass was in the form of spherical beads less than about 0.1mm in diameter. It machined easily in the lathe with the swarf falling more as a powder than a continuous thread.

Suddenly,  the saddle of my Myford ML7 jammed .

Glass beads had found their way past the felt lubricating strip and then between the saddle and the bed. I realised in the nick of time what had happened, and stopped everything rather than try to move the saddle any further.

Clearly, during the machining process, the glass beads had remained intact while the polymer was being shaved away as normal. That part of the machine required a complete strip-down to get rid of all the beads.

Luckily for me and the Myford, the top section of the saddle can be unscrewed and lifted vertically. Even more lucky, the saddle wasn’t traversing under power.

I trust that my experience serves as a warning to ME members and others.

Regards,

Sam

Edited By Sam Stones on 19/07/2010 06:45:34

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