Tolerence on slab thickness difference

[glparrish078]

I was wondering what the thickness difference from slab to slab that is tolerable or acceptable? Is there an industry standard?

I had a fabricator irate over a 1/8" difference from one slab to the next. I assumed that 1/8" difference from slab to slab is acceptable, but started to wonder what is too much?

I know with a CNC you can run the finger bit and even the slabs out, but by hand it is a pain in the caboose.

Opinions???

-Geramie Parrish
Levantina USA

[Joshua Hopkins]

To each his own I guess. I work occasionally with an 1/8" difference. I would rather the slabs be the same thickness for obvious reasons but this is not a perfect world.

[Matt Lansing]

An 1/8" sucks and is a pain to deal with, even with automated equipment. If the whole slab is an 1/8" thinner than it can be trouble if the profile is double ogee or similar as the edge profile won't finish correctly at the bottom. Can also be real trouble if two pieces have to seam together as you have to back grind the thicker one to match the thinner one.

We had an engineer once that went around the kitchen with a micrometer measuring all of this pieces. Luckly for me I am also an engineer so I changed my verbage and gave him the Vulcan salute. I told him he can be anal at work, just don't bring your work home. That got his wife laughing and that was the end of it.

[Ken Lago]

1/8" sucks but luckily I don't see it too often. I don't know but I guess you could call it a quality issue that buyers overseas are aware of and probably get discounts for.

[Dan R.]

A finger bit is used on the edge of the slab. A different tool is required to gauge the back side of the slab. !/8" can be huge and can be manageable. It would be nice if the sawyers would slow done and get them gauged properly.

Vulcan? Did someone say Vulcan? Live long and prosper!

[Earth Stone]

We've been on a run of Black Impala with that very issue. An 1/8 diff was within one slab. The others were back and forth 1", 1"1/8, some 1"1/4. All same lot. Had some E quartz with same issue.

[ash20ash]

Hah. We just did a job the one slab was 1 1x4. The other was the same on the outside and then went down to 15/16 in the middle.
Luckly we showed the homeowner and she was fine with it. Were talkin 25 stone. And it was dyed out the arse.

Just signs of the times id say.

I really don't understand why they can't keep it under an 1/8. Just come down to everybody trying to save a buck where they can.

[pkomorowski]

I think the MIA standard was 3CM +/- 3mm. So technically you could have a 27mm slab and a 33mm slab on the same job and both be acceptable. 6mm is almost 1/4".

1/8" different isn't major enough to cause a problem. The fabricator will just have to feather/blend the transition at the seam.

That said, if he hasn't cut the slabs and wants to return them then I don't think he's being unreasonable. A lot of customers expect perfection, but in the end we're working with a rock and the tolerances have to be reasonable.

I wish customers were half as picky with their drywall and carpentry as they are with the stone!

[Carmine Pantano]

agreed 1/8" sucks, but I've seen worse. Especially in Black Galaxy.

IMO - tell the suppliers around the world to slow down in cutting. In these days of price...that extra CNC time on the CNC to calibrate is $$ we're losing. If someone is doing by hand, they are losing their Ar$e.

I've only returned Black Galaxy when we saw the slabs were 3/8" difference from outer edge to center of slab...too bad we didn't see it till the first slab was cut

[Qualey Granite]

I wish customers were half as picky with their drywall and carpentry as they are with the stone!


I say this everyday. Why is 1/4" OK if your a carpenter, but we're held accountable to .001"?

[glparrish078]

Thanks for the info everyone!
I thought that 1/8" was withing the tolerance that the MIA established, but we are dealing with people, and not a spec sheet. I wish they would slow down on cutting and get them a little more accurately cut in the gang saws.

I had the customer return the slabs and gave him full credit (even on the one slab he already cut).

At the end of the day, my customer is worth more than a cut slab of Crema Bordeaux.

Now how about warped 2cm slabs???

[Jason R]

We ran into the same thing on a batch of Crema Bordeaux. The edges were 1 1/8" and the middle of the slab was 3/4" at best. We caught it after starting to cut the 2nd slab, so we put the job on hold until the customer could be brought in to approve. She rejected the slabs and we called our distributor and they told us that we should have caught it before we started cutting.

The next day my boss asked if there was a way to gauge the slabs in the middle (if we had a 3' dial caliper maybe) before we cut them. Long story short, we had to eat the 2 cut slabs, sent the other 3 back and ordered 5 more from a different vendor.

We still do most of our business with our original distributor with the understanding that we have certain standards that we hold their product to. They have a certain responsibility for the consistency of their product. They can't have the used car salesman attitude of the stone being sold "as is".

[glparrish078]

Jason,
I have had this happen numerous times, and every time I have given full credit back to the fabricator. The last thing I want is people walking around our warehouse with calipers and 8' levels!

No one can reasonably expect someone to check the middle of the slab for thickness before cutting! I know that just about every supplier has the mentality of "you cut it, you bought it"! That works if you are trying to make A SALE, but not if you are trying to make A CUSTOMER!

Sorry to hear and your supplier is lucky you are tolerant of this treatment, as my customers usually are not!

[Ken Lago]

You can check the middle with a 10' straight edge.

[Dan R.]

How would you account for bowing?

[Ken Lago]

How would you account for bowing?

Put the edge on both sides of the slab, the difference should be the same,or put it by the edge of the slab first to see if it actually bows and then move it to the middle.