Shars Grade 0 Rectangular Gage Block Set with NIST traceable Certificate 81 PCS 303-5307C M)

I read about Jo-blocks in Simon Winchester's recent book, "The Perfectionists." He writes about them in the prologue. I just had to have them. I think mostly I purchased them because 15-20 years ago a set not as good as these would cost north of a few thousand dollars and maybe more. Today - they cost less than $100, all because of the things outlined in Winchester's book.However, the embarrassing thing is, other than ensuring my digital calipers are spot on, I can think of no other uses for these as yet. I'm not a machinist and don't have tools (other than my digital calipers), that need anywhere near this level of calibration. But they are just so wonderful and perfect, I can't help taking them out and just looking at them. If you know of any other good uses for them, I'd love to hear about it.

I don't have the precision equipment to measure these accurately but they seem pretty dam accurate.They can wring so at least they are accurate enough for that. That includes the 1"-4" inch blocks with higher tolerance.The box that holds them is pretty pretty cheap but for the price as long as they get to you without any issues it's not a big deal. To be fair it doesn't look bad at first glance.There really isn't much else to say.

All of that can be overlooked since I can clean them and oil them properly, but the one thing that I wish I had realized before purchasing these was the fact not all of them were the same dimension when stacking/wringing. If you are trying to measure an accurate cutout hole or slot on something, if you are using a thinner block in your stack it will get pushed. If all the blocks had the same dimension on the mirrored side, I would be extremely grateful. I took a chance on a company I wasn't too familiar with and for its price, I'm willing to take some issues. I hope they have an updated set that will have the same dimension going forward. precision 1-2-3 blocks are next!

Good for what I need them for, usually just in a sine vise/chuck.

The case for my set was damaged in shipping but Shars / Discount Machine Shop sent me a replacement case as soon as I contacted them about it.I'm confident that I'll be buying from Shars again - and probably sooner rather than later!As to the accuracy/precision of the gauge blocks, all I can say is that I'd need a climate-controlled labratory clean room full of very expensive equipment with which to test them.LOL, even the least of these "economy" gauge blocks are only a few millionths off of specified thickness. According to the deviation sheet that came with the set, they average less than 20 millionths of an inch from specified thickness - ~50× more precise than my next best instrument - a Mitotuyo .0001" dial indicator. I plan to use these blocks to check all the other instruments in my home shop for the rest of my life. Barring accidents or neglect, they'll be just as good for some future owner a hundred years from now.

Starting with the box; it is well made and does not cause aggravation. The outside is a durable laminated wood. Inside where the gauge blocks rest is a hard plastic tray that will outlast a wooden one that some sets come in. Each block is clearly and neatly separated by size. The blocks came with an oil paper resting over the top rather than each one being individually wrapped, so they are ready to use. Included is an NIST test report. The blocks fall within grade, so you are certainly getting what you pay for.

I want to start off by saying that I am not a machinist. I'm a retired Electronics Technician. Having said that, I AM a nerd for accuracy. I bought this set and a needle gauge, for WOODWORKING. Setting the height of a saw blade, Dado stack, depth of cut on a router fence, calibration of my Incra LS fence, which is accurate to 1000th of an inch, still needs to be set to (0) absolute zero.

Cheap case. Blocks were ok