chrisg
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| posted on 26/10/07 at 06:36 PM |
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Clearance?
Calling all lathe experts!
I'm making two circular parts that fit one inside the other, the inner part is 40mm outside diameter.
How much bigger does the outer part need to be internally so that I get a good sliding fit, without sideways movement.
Millimeters (well fractions of) please, I don't do imperial
Ta.
Chris 
Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the
error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!
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rusty nuts
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| posted on 26/10/07 at 06:38 PM |
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A couple of thou? I don't do metric
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Wadders
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| posted on 26/10/07 at 06:47 PM |
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1 thou = 0.001" = 0.0254 mm
Al 
quote:
Originally posted by rusty nuts
A couple of thou? I don't do metric
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Mansfield
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| posted on 26/10/07 at 06:48 PM |
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You want a 40 H7 hole I think.
Shaft will be 40 g6.
ROYMECH is good for this sort of thing.
40.000 - 40.025 hole
39.991- 39.975 shaft
This on the 'hole' based system of tolerancing, the hole is generally size to plus. Ground bar normally comes size to minus and reamers
will rarely cut less than the nominal size.
[Edited on 26/10/07 by Mansfield]
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rusty nuts
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| posted on 26/10/07 at 06:53 PM |
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quote:
Originally posted by Wadders
1 thou = 0.001" = 0.0254 mm
Al
quote:
Originally posted by rusty nuts
A couple of thou? I don't do metric
Knew that really , just my sense of humour
[Edited on 26/10/07 by rusty nuts]
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Confused but excited.
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| posted on 26/10/07 at 07:28 PM |
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Of course, it all depends on the degree of surface finish of the sliding surfaces. The better the finish the tighter tolerance that you can have, up
to a point.
Tell them about the bent treacle edges!
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daviep
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| posted on 26/10/07 at 09:22 PM |
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Depending on the length of the parts unless you have a very good machine you will struggle to bore the internal parallel. If I was doing this I would
turn the shaft and then ream the hole to suit using an expanding reamer.
What you are describing sounds really easy....until you try to do it. I really struggle to take a 1 thou cut on my lathe at home.
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mark chandler
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| posted on 26/10/07 at 09:28 PM |
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I,ll second that, just about fits, just about fits, a wafer to go.... start again.
doh
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Wadders
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| posted on 26/10/07 at 09:45 PM |
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LOL Iv'e spent hours turning stuff 'somewhere near' and then seconds making it fit like a wizards sleeve.
One day i will treat my lathe to a DRO
Al.
Originally posted by mark chandler
I,ll second that, just about fits, just about fits, a wafer to go.... start again.
doh
[Edited on 26/10/07 by Wadders]
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