# Surface Plate Certification Services



## wcunning (Sep 3, 2018)

I recently picked up a 30" x 60" x 10", 4 ledge Rahn granite plate on a stand for $500 off of a local-ish craigslist. After another $140 in trailer rental (drop deck from Sunbelt) and gas for the truck, I'm not all that much into a decent surface plate. According to the one legible certification sticker, it was a grade A plate in the 90's. Now, since I want to use it for scraping in my mill and straight edges, I need to get it properly certified. Does anyone on this forum know of a surface plate certification and lapping outfit that will travel to a shop in central Michigan? Does anyone know what a sane or good price for that size plate would be?

Thanks!
Will


----------



## TomS (Sep 3, 2018)

Take a look at this thread.  Lot's of good info.  https://www.hobby-machinist.com/threads/surface-plate-calibration-collaboration-or-plate-fest.45514/


----------



## wcunning (Sep 4, 2018)

I have a few friends together, along with a pile of stuff on my own (big plate, smaller plate, angle block, etc.). I'm hoping for a recommendation of someone slightly more local than 2500 miles away...

Thanks,
Will


----------



## T Bredehoft (Sep 4, 2018)

Pick a supplier of large granite plates, inquire of them about resurfacing.


----------



## Bob Korves (Sep 4, 2018)

wcunning said:


> I recently picked up a 30" x 60" x 10", 4 ledge Rahn granite plate on a stand for $500 off of a local-ish craigslist. After another $140 in trailer rental (drop deck from Sunbelt) and gas for the truck, I'm not all that much into a decent surface plate. According to the one legible certification sticker, it was a grade A plate in the 90's. Now, since I want to use it for scraping in my mill and straight edges, I need to get it properly certified. Does anyone on this forum know of a surface plate certification and lapping outfit that will travel to a shop in central Michigan? Does anyone know what a sane or good price for that size plate would be?
> 
> Thanks!
> Will


Whoever calibrates your plate will give you a choice of calibration levels at different prices, probably AA, A, or B.  For scraping purposes, depending on what you will be scraping, it might be worth going for the AA cert, which will be useful for a longer time span without doing it again.  Compare prices and choose.


----------



## wcunning (Sep 4, 2018)

@T Bredehoft : can you give me some suggestion on plate manufacturers? Starrett and Standridge are both a *long* ways away from central Michigan, and I understand Rahn to be out of business these days. 

@Bob Korves : The last time I saw a price sheet, several years ago, it made the difference between A and B totally worth it, but A and AA was a little bit questionable. I'll make some calls to the couple of larger outfits near Detroit and see what their shop visit charge is. I was kinda hoping someone on here would have a recommendation on someone a little more local. 

Thanks,
Will


----------



## Bob Korves (Sep 4, 2018)

https://www.thomasnet.com/michigan/surface-plate-calibration-services-97004418-1.html


----------



## wcunning (Sep 4, 2018)

For some reason the page I ended up on at ThomasNet was less directly helpful. I think it was giving me generic calibration rather than "surface plate services" or something. Also, they more directly linked to the AA Jansson catalog! I couldn't find that when I wanted it, but I had read the prices back in 2016 and wasn't thrilled. I think they're one of the more expensive outfits in the region, at around $470 to get it lapped to grade AA... I hope other places quote me something cheaper. 

Thanks,
Will


----------



## T Bredehoft (Sep 4, 2018)

Here are some I found, I have no connection to, or knoweldge about any of them other than what theyi claim.

https://www.labtesting.com/metrology-calibration-services/on-site-calibration/

http://www.garbermetrology.com/serv...es/surface-plate-calibration-and-resurfacing/

https://www.dimensionalgauge.com/2017/granite-surface-plate-calibration/

https://www.capstonecalibration.com/

https://www.certifiedservicecompany.com/

Google is ouir friend, you can probably find a dozen more. Just google "Surface plate restoration."


----------



## astjp2 (Sep 6, 2018)

Just have it checked with a autocollimator , if it checks good, run with it, that is what I did.  There is no reason to have it lapped unless it needs it.  Tim


----------



## gi_984 (Oct 4, 2018)

Precision gage company, Chicago area.  They did mine.  Was done by the guy who originally made my plates.  Lapped and NIST certified AA.  Very reasonable price.  I brought them directly to the shop. 

http://www.precisiongageco.com/product/astral-granite/


----------

