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Ken_Shea
08-02-2008, 10:46 PM
Precision can be relative I guess, but with a Hermann Schmidt indexer it means square and parallel to less then .0001 in 8".
At over $17K I likely would not expect less but still have no clue how and what it takes to bet and maintain that kind of precision.

Any one here work in those precisions that can add some in-site as to how that is accomplished?

Oh, here's a link if you want to buy one :D
https://www.hermannschmidt.com/productcart/pc/viewPrd.asp?idcategory=40&idproduct=281


Ken

George Bulliss
08-02-2008, 11:27 PM
The first shop I worked at had the best outfitted grinding room I have ever seen, full of Hermann Schmidt products. We had three magnetic squaring blocks, two for use, and one that was kept locked up for cleaning up the others when needed. Those blocks were the quickest, easiest way to square a work piece on the surface grinder that I have ever used. Rather pricey, but they can save a shop quite a few hours, compared to multiple setups with angle plates and C-clamps.

All the old time mold makers also had Hermann Schmidt grinding vises. I never could bring myself to spring for one; I made due with a homemade vise I picked up at a garage sale. I was able to grind it in just as square as the Hermann Schmidt’s, so it worked just fine for me. Sure took a lot of crap for it though.

George

Evan
08-03-2008, 01:57 AM
Just a note on the difference between precision and accuracy. Accuracy is how true the story is and precision is how many details it contains. A device can be precise without being accurate.

J Tiers
08-03-2008, 11:00 AM
All the bullets in a 2 cm group........ 250 mm off the bullseye.......

Or a 500mm group, averaged group center within 1 cm of target center :D

SGW
08-03-2008, 11:48 AM
You might enjoy the book "Foundations of Mechanical Accuracy" by Wayne Moore of Moore Special Tool Co. See if your library can locate a copy for you.