Thread: surface plate reconditioning

Originally Posted by AdamC

Did you watch the video? Is that how grave stones are made near you? Same tools? Really? Autocollimator? Stones in the video could be flatter than 75microns. That’s .000075”

Please.

If you're building Jet Engines or the Mars Lander perhaps you need some amazing Surface Plate.

If so you're likely not pinching pennies resurfacing some old chipped one.

For a lot of us that kind of accuracy is overkill in a big way.

Btw, in the 1970's time I did work as an Inspector for Satellite Components.

At least then, it was rare to hold any component tighter than within a .005" window.

I expect even now, Surface Plates are more the tool of the Inspector than of the Machinist.

Originally Posted by roll maker

Grade B would be adequate. I would just like to know we have a good larger surface when needed.

As I read it the OP just wants a fairly flat and smooth plate for non-critical usage.

That's why I recommend at least approaching monument companies.

Every city has a few, so transportation should be minimal.

Whether they'd be open to the work, and at what cost, is anyone's guess.

OP said he was looking for grade B. He didn’t mention the size of his plate(s). Grade B for a 24x36 would be flatter than .0004”. Smaller grade B plates would have to be flatter than that.

I agree that it doesn’t appear difficult to resurface/polish granite and that gravestone people or kitchen counter guys do it every day. The difference lies in obtaining the level of flatness required to make a hunk of stone into a surface plate.

Not to be rude, but the OP didn’t ask if we felt he needed the grade B surface plate he asked about. I respectfully suggest you start a new thread to discuss/question the use and merits of surface plates in a machine shop. You’d probably get a lot of strong thoughts on the subject. For example: I use mine frequently, and wouldn’t/couldn’t work without it. I can explain why. But that’s not the subject here.

Originally Posted by AdamC

OP said he was looking for grade B. He didn’t mention the size of his plate(s). Grade B for a 24x36 would be flatter than .0004”. Smaller grade B plates would have to be flatter than that.

I agree that it doesn’t appear difficult to resurface/polish granite and that gravestone people or kitchen counter guys do it every day. The difference lies in obtaining the level of flatness required to make a hunk of stone into a surface plate.

Not to be rude, but the OP didn’t ask if we felt he needed the grade B surface plate he asked about. I respectfully suggest you start a new thread to discuss/question the use and merits of surface plates in a machine shop. You’d probably get a lot of strong thoughts on the subject. For example: I use mine frequently, and wouldn’t/couldn’t work without it. I can explain why. But that’s not the subject here.

"i have a 3' by 4' plate that needs at least a sixteenth removed. Local metrology companies do not have the equipment to do this. I was thinking of approaching a granite counter top mfg to do the initial removal of material then have the finishing done by a service."

That was the first line of this thread.

When a guy is considering a Kitchen Counter Top Company for his Surface Plate, a Monument Company is certainly an alternative for him.

Sorry, I thought you were saying that a grave stone manufacturer could machine a stone flat enough to be used as a surface plate.

Originally Posted by AdamC

Sorry, I thought you were saying that a grave stone manufacturer could machine a stone flat enough to be used as a surface plate.

That's ok. Thanks.

Originally Posted by AdamC

There is a company in Lititz called Garber Metrology whose website says they recondition surface plates. I have no experience with them, but I'm looking for a similar service.

If you contact them, will you PM me and tell me what they say? My biggest plate is 2X3. I can lift it into my pick up with one of my kids and take it. I also have a Starrett pink 12X18" I'd like recal'd.

I've seen youtube videos from the west coast of calibration teams going to guys shops and reconditioning a bunch of plates in one day. If that service were available, maybe a bunch of us could travel to bring down the cost per plate of a house call.

I agree with others here - no reason to remove a 1/16 from any surface plate. They fill deep nicks with epoxy, I think. You really just need all the high spots to lie in a plane. Nicks don't really matter to the calibration, I don't think.

Fazzio's and Cook's machine, both in south jersey, have large stones pretty cheap just sitting outside. If you can transport them, I'm sure you could find a decent stone at either location. The trick is the reconditioning/calibration. I think there is also a place in north jersey that does calibration that might be closer to you.

from Kerry Garber:

this is what they told me when I inquired about my 2'x3' Starrett pink

Hi Dezso,

Thanks for contacting us today.

It would be best to leave it here, as our techs are on the road very often and even with coordination, emergency service calls arise and they have to leave.

We charge $95 to calibrate/validate the plate and $190 if the plate needs lapped.

Keep in mind, we also provide on-site calibration services.

Regards,

Kerry Garber
Business Development Manager/Sales

Originally Posted by dcsipo

from Kerry Garber:

this is what they told me when I inquired about my 2'x3' Starrett pink

Hi Dezso,

Thanks for contacting us today.

It would be best to leave it here, as our techs are on the road very often and even with coordination, emergency service calls arise and they have to leave.

We charge $95 to calibrate/validate the plate and $190 if the plate needs lapped.

Keep in mind, we also provide on-site calibration services.

Regards,

Kerry Garber
Business Development Manager/Sales

That sounds very inexpensive !

GOOD.

Originally Posted by SalemRule

That sounds very inexpensive !

GOOD.

Ah shucks.....I guess you just made the price go up.

dee
;-D

I had a quote a while ago to lap my 2x3 from b to a it was about 800$ IIRC they were 175$ an hour

Silly question, has anyone ever tried patching a granite surface plate with the epoxy granite and lapping it flat? I know people like to build machines out of the stuff, but does it behave anything like granite?

Found it

So they are estimating two hours work to re-lap it. I guess that they know what they're doing before they start the job (unlike some of us )

I'm shure for a real shop 785$ is small money

But this was for my plate at home
no way can I justify that

So I figured out a way to do it myself talk about not knowing what you're doing before you start a job!

But it ended up ok I've worked it down to the point where I can't get it any better without some different tools

I can't get it better than .00008 repeat reading

I'm shure I need a better lap

Didn't realize this got additional response. I did talk to Garber didn't feel it fit their service model. With all the additional responses I might just go for having it lapped.

roll maker
I'm a little late in responding to this post but I'm curious to your determination that 1/16" needs to be removed from the plate. It sounds like you are trying to remove chip holes. Nemours responders have stated that small chips should not affect the accuracy or use of the plate, and I fully agree. One method that could be used to determine the flatness, not down to the .0001", but would give you a better idea of the flatness condition is by using the tight wire method. See the following site for explanation of the procedures and associated Tight Wire Sag Charts.
Tight Wire Sag Chart - 1

Originally Posted by roll maker

Didn't realize this got additional response. I did talk to Garber didn't feel it fit their service model. With all the additional responses I might just go for having it lapped.

Ive messed around lapping plates, an 8" by 12" cast iron lap charged with 400 mesh diamond used dry rips through granite pretty quick, but youd want a bit more to take out a 1/16th
If its only dinged just get lapped, dings dont matter in terms of flatness and some granites have natural pores anyways. If it was dished or domed some huge amount you could rough it close with one of those cheap 6" chinese lap discs stuck to a DA sander, going slow and dry being careful not roll the edges.