Surface grinding needed

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jcfx
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Surface grinding needed

Post by jcfx »

Looking to see if anyone with a surface grinder interested in doing some surface grinding for me ?

I have two sets of 5C collet blocks that I would like to be matched so I would have a pair
of each square and hex that are matched. The hex blocks would be a little more work for them to match.
PM if interested.
James
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GlennW
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Re: Surface grinding needed

Post by GlennW »

Grinding them to match, having the angles equal, and having all flats equal distance from the axis of the collet bore will be a bit of a project!
Glenn

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Bill Shields
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Re: Surface grinding needed

Post by Bill Shields »

Will require an arbor
Too many things going on to bother listing them.
jcfx
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Re: Surface grinding needed

Post by jcfx »

GlennW wrote: Fri Feb 24, 2023 9:10 pm Grinding them to match, having the angles equal, and having all flats equal distance from the axis of the collet bore will be a bit of a project!
The collet blocks I have are a very close match in dimensions, the square ones are 1.749 and 1.748
and the hex blocks measure the same respectively, not knowing much about surface grinding I guessed that the
larger square blocks would be ground .00025 on each side ( after doing the math I'm not sure if a surface grinder can do that ? )
where as the hex ones would be the same except the corners which would take some creative part holding to grind the corner.
I maybe missing something where the axis of the collet bore comes in ?
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GlennW
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Re: Surface grinding needed

Post by GlennW »

jcfx wrote: Sat Feb 25, 2023 11:58 pmI maybe missing something where the axis of the collet bore comes in ?
Another example might be wanting a 5C adapter for a lathe spindle ground and stating that it just needs to be round on the OD, it doesn't need to be concentric with the collet bore.
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Bill Shields
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Re: Surface grinding needed

Post by Bill Shields »

jcfx wrote: Fri Feb 24, 2023 6:12 pm Looking to see if anyone with a surface grinder interested in doing some surface grinding for me ?

I have two sets of 5C collet blocks that I would like to be matched so I would have a pair
of each square and hex that are matched. The hex blocks would be a little more work for them to match.
PM if interested.
James
to me, 'matched' means that the relative sizes and distances from the center of the collet bore are the same for both sets.

any yahoo (which probably includes me) -> can give you a pair of square or hexes...but are the sides in the same position relative to the center of the bore and, in the case of the hex collet - angular position with respect to the zero degree location pin of the 5C collet.???

hence - need an arbor to provide a centerline and angular position reference
Too many things going on to bother listing them.
tetramachine
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Re: Surface grinding needed

Post by tetramachine »

I have a good surface grinder. My question is what are you wanting as end result.
To get each centerline of collet bore equal to each surface (4 sides, 6 sides)but equal to each other will really add to setup and grinding time. And what is your tolerance allowed? And why do you need it??

If you are using the collet blocks in a lathe Chuck, it is useless to spent $$ on grinding, the blocks as the lathe will likely not be repeatable within a .001.

On reading again, I see you want each type to be equal to its mate. To do this, needs 2 new extra tolerance collets, and a hardened shaft to match 1" dia. Then find the shortest flats, grindpairs, and mark so.
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jcfx
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Re: Surface grinding needed

Post by jcfx »

Tetramachine,
Yes you're correct basically a pair of square matched and hex matched.
As I see it, .001 tolerance would be fine.

I don't think I'll ever use the collet blocks in a lathe check, this is mainly for a
a miling vise useage, so that I can have the vise set up with stops and swap out collets
with the work .

I'm not understanding the latter part of your post about the extra tolerance collets, etc.
tetramachine
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Re: Surface grinding needed

Post by tetramachine »

A standard Hardinge collet is concentric within .001". That works for most uses, but for some work that is more precise, they make extra precise that is .00025" max run out.
So you take a std collet to use as a Arbor, and a TGP bar, square them on the grinding Chuck. With both blocks using the TGP together. This would be my idea of cheapest best way. Next more money step is using the extra precision collets. And most money is making a solid shaft to hold the blocks, grinding together.

Then you are back to .001+/- for the collet.

I bought a collet holder that can be gripped in a vise, or bolted to the mill table. Flats both horizontal and vertical.
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jcfx
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Re: Surface grinding needed

Post by jcfx »

Thank you for that explanation.
I'll PM you about details etc.
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ctwo
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Re: Surface grinding needed

Post by ctwo »

This topic inspires me to purchase the 25 piece ER32 collet set, and couple blocks, and might as well toss in the lathe face plate, and practice my grinding...
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Disclaimer: I'm just a guy with a few machines...
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