HHIP 4401-1597 6" X 8" X 2" Granite Surface Plate, Grade B, 0 Ledge

Initially I was very skeptical of this surface plate, the low price coupled with mixed reviews on other sizes from the same manufacturer placed it solidly in the "too good to be true" zone but I figured I'd give it a shot and if it didn't meet the advertised tolerances I'd just return it. I'm glad I took the gamble because it ended up not only meeting but surpassing my expectations despite a major hiccup in delivery.I knew it was heavy so when I saw it was out for delivery and my dog started barking at the door I opened it to take it directly from the UPS guy so he didn't have to awkwardly set it down. As I opened the door he stumbled a bit coming up my front steps and dropped it from chest height onto my concrete front porch and it landed right on the corner.When I was unpacking it to inspect it for damage I initially wasn't very impressed. It came packaged in a cardboard box that contained a wooden box with the surface plate inside of it wrapped in a thin foam sheet, maybe 1/8" thick at most. I'd seen some reviews say it came in a wooden box and for some reason I had it in my mind that it would have a nice storage/protection box like gauge blocks do, this is not the case. The wooden box is made from the worst quality OSB you could imagine and sloppily put together, it is only there to protect the surface plate in transit and nothing more. I sliced my hand pretty good on some of the staples that had been holding the wooden box together before the drop as they were sticking out into the cardboard but I don't think that's entirely from the drop as they were sticking out similarly in other places so be careful when opening it. As unimpressed with the packaging as I was it did do its job, the OSB in the corner it landed on had basically disintegrated so there were a ton of splinters and chunks of OSB as well as a fair bit of granite chips, gravel, and grit which had me worried. After very careful examination though the surface plate came out undamaged, no chips, cracks, or any indication it had ever been dropped aside from the mess of a box it had came in so I have no clue why there was granite debris in the package with it.After inspecting it for damage and sending the UPS guy on his way I inspected the surface plate with both a Mitutoyo 543-793 digital indicator (0.0001"/1um resolution, +/- 0.0001" accuracy) and a Mitutoyo 513-409 dial test indicator (0.0002"/2um resolution, +/- 3um accuracy) mounted to a Starrett surface gauge and boy was I impressed. The listing for the "Grade A" plate I purchased claimed +/-0.0005" and the maximum deviation I was able to measure across the plate was ~4um or ~0.00016" with the majority of the plate being dead on flat not even a wiggle on the needle. On the plate I received two of the corners and one spot near the edge are high by 1-2um and a third corner is low by 2um. All of the high or low sections are very small, a single to a few square centimeters at most.For the price tag of $120 I went in with basically zero expectations and honestly would have been happy if it was within 0.001" and maybe I'm just a lucky winner of the cheap Chinese surface plate lottery but I'm extremely impressed. That said though, this is not a Grade A plate per ASME standards, even calling it Grade B in its current state is generous and the example I received is much better than advertised, I'm sure that won't be the case for everyone. I'm certain that if I put a little bit of work into cleaning up the high spots I could have it calibrated and certified as Grade B, anything beyond that would require equipment that I don't have.Overall, for the price, I'd say this plate is definitely worth it if you're just getting into machining as a hobby or looking for a small plate for inspection of smaller parts that don't require crazy tight tolerances. I think the biggest value, at least in the example I got, is how little work is needed to clean it up into a higher grade plate than it is out of the box.

I was a little skeptical when ordering this at first. I was afraid that it might not be perfectly square and smooth. Very well profiled. Perfect for what I use it for hand sanding knives. Awesome quality awesome value.

So smooth, so flat, so heavy. This is a perfect size and a must have for the serious knife maker or small scale machinist. When flat matters, a surface plate is a must! This will outlast me if I take care of it. Great price.

Very flat. Cleaned the granite and floated a known flat lapped part across its surface. Measurements show it to be definitely better than +/- .0005" .Additionally, some of these photo/video reviews are a real hoot! Remember, this is a classB / toolroom grade rock...Most of the complainers are actually revealing the flaws in thier own set-up.... Seller should probably do themselves a favor and include a geometry book free with purchase!

Received in one day. Looks fine. Best deal I found without looking too hard. The one thing people should know (and the pictures clearly show this) is that all edges are beveled with some of the corners being deeper or a bit inconsistently done. On mine it's very slight. Most likely done so they don't have to worry about chips on the edges. For a sanding surface this will make no difference but for me, square edges woud be preferable.For the price it would be hard to do better if you don't need it for the straight edge.It's well packaged in all-natural wood, paper and cardboard. : )I find no nicks scrapes or flaws of any kind. I have no way to test for flatness.I am satisfied with my purchase.

This surface plate is more than sufficiently calibrated for a hobbyist or shop, and is absurd value at $20.

I knew these would be cheap, but oh man I wasn't prepared for how much. They were *technically* in spec, but just barely, right up to the edge of the spec.I needed extreme quality, so I bought 3 to do the 3 surface method and I wanted 6 surfaces so I was going to do 2 sets of 3 surfaces to get pristine flats. Unfortunately the backs were rough saw cut, 2 of them weren't too bad, only varying by about .04" but the third was where cuts from 2 directions met and had a total variance of more than 1/8" which would've made it useless to set on something and get a flat measurement from in any case.In any case it took a few months of working them in my space time but eventually I got all 6 surfaces to flat within .00001" (my finest guage) but kept going with the process beyond that down to .0000001" grit worked with distilled water so they might be flatter. It's gorgeous rock. As I started, it became clear that the original surfaces were simply ground, not lapped, and polished to look flat, the grinding marks popped out very quickly in the process and took a while to work out, about 15 process steps, and to get where I was going took about 75 steps on the pre-finished sides and about 500 steps on the unfinished sides (a fair bit of which I did using sandpapers and even brought out sanders to just get into the ballpark).

My set up has a base of solid 3/4" thick steel milled to .001" , then a 1/8" corrugated cardboard sheet with the A grade granite sitting on top of it. My test system is a ultra-precision block 3x4x1" accurate to .000003" in all directions with a Starrett surface gauge corrected and machined to same tolerance bolted to it. A Brown and Sharp .00005" indicator is attached to the set up. This unit can detect .000005" inch variations and easily measure accurately to .0001". The results were conclusive that there was less than 50 millionth inch variation and probably consistently measured within 10 millionth in the center.... With minor touch ups it is near perfect for me. Great piece