Surface plate lapping

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Glenn Brooks
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Location: Woodinville, Washington

Surface plate lapping

Post by Glenn Brooks » Sun Nov 04, 2018 1:16 am

Hello All,

Does anybody know of a shop in Bellingham, Seattle, Portland Area that can Lapp and certify granite inspection plates? I have an ok Grade B inspection plate from Grizzly that I would like to have re lapped to a Grade A or better, for use as a reference plate to scrape in machine tool surfaces and a couple of straightedges. Hoping to come up with a couple of leads where I could send this plate to be reworked.

Thanks
Glenn B.
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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SteveM
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Re: Surface plate lapping

Post by SteveM » Sun Nov 04, 2018 9:57 pm

You might try asking calibration shops in your area where they get theirs done.

We found that by having several done at one time, the cost went down, so you might want to get some people together and do a group buy.

The guy who did mine says that he has a customer that buys chinese black granite plates for cheap and has him lap them to better standards.

Steve

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Bill Shields
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Re: Surface plate lapping

Post by Bill Shields » Wed Nov 14, 2018 7:28 am

The last plate that I had reconditioned was done by 'Rock of Ages'.

I know that Starrett also provides (or used to) that service.

In reality, you are most likely going to have to crate it up and ship it off. Places that provide this service are not as plentiful as car dealers.

Glenn Brooks
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Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Surface plate lapping

Post by Glenn Brooks » Thu Nov 15, 2018 1:25 am

FYI, as follow up to Steve’s suggestions, I found two local metrology shops in the Seattle area, and got quotes for my grade B surface plate for around $200 for the initial set up and re calibration. Then $95/hour for lapping - if the plate was within specs. So elected to pass. I can buy a new Grade A plate for around $300 plus shipping, so can’t justify the expense for my limited needs.

Now a production shop with a larger reference surface, say 48x48x6, or larger, I could see spending the money. It would be very cost effective, as these larger plates seem to be running in the many thousands of bucks for the initial purchase price. But, my limited needs - not so much. .0004” high spots I can live with.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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SteveM
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Location: Connecticut

Re: Surface plate lapping

Post by SteveM » Thu Nov 15, 2018 7:28 am

See if they offer a "group" discount and get some friends together on it.

Mine only cost $40 for the 12x18 and $20 for the 9x12.

We had about five plates done at one time - one large one (like 24x36) and the rest 12x18 and under.

Steve

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