# Setup Blocks ("1-2-3 Blocks")



## Uglydog (Jul 10, 2017)

I've been casually thinking about how many holes (if any) I want to put in my shop made 123 blocks, and stumbled on this free online article. Perhaps someone here might enjoy it as much as I have. 

https://circuitousroot.com/artifice...y-tools/setup-blocks/index.html#mcmaster-carr

Daryl
MN


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## Bob Korves (Jul 10, 2017)

Multiples of each!  123 blocks with multiple holes can be versatile, but in practice, the holes collect swarf that gets into the setup and ruins the accuracy and rigidity, and on many of the store bought ones the threads are distorted from the heat treating process (or just poor work) so bolts do not screw into the threads.  For many uses I like the ones with no holes, but for some unknown silliness, they actually cost more!  Huh?  How do they justify that?  Proper 123 blocks need to be hardened and ground to within a few tenths or better for accurate setups and metrology use, with all faces precisely 90 degrees to each other, and that is not particularly easy to do.  Matched sets also need to be truly matched.

For ordinary work with setups on the mill, the imports are a bargain.  They are usually amazingly accurate for the prices, but do need to be vetted, always.  Stan Zinkosky is really good at testing them and truing them up for service in his shop:
https://www.youtube.com/user/shadonhkw/search?query=123+blocks

I want to find a decent deal on some good 246 blocks...


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## Mark_f (Jul 10, 2017)

That is a very interesting article. I get the impression from the article that the 1 2 3 blocks are a recent invention to the machine shop industry. The first time I remember being exposed to the 1 2 3 block was while working in a Texas machine shop where every machinist had a set in his tool box. We used them routinely in setups on machines like the Bridgeport. This was in the late 1970's and early 1980's. That was my introduction to them. They were common earlier than that.  I know most were made by Mitutoyo and readily available from the tool supply houses that supplied the shops. There was also a set that was 2 4 6 blocks.


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## Buffalo20 (Jul 10, 2017)

I have 3 cheap sets, a Fowler set and a B&S set, Bob's comment make made me think, the B&S set is the only one, when the threaded holes are messed up


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## rgray (Jul 10, 2017)

Interesting write up. I liked it. Especially the Moore influence to those blocks.
On mine I never seem to need holes.
 If left without holes they aren't as recognizable as a tool and you'd have to guard them to keep someone from using them as a nice piece of scrap iron, or anvil or ???


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## Dave Paine (Jul 10, 2017)

Interesting article.  Thanks for sharing.

I would not have expected to find so much details and options on such a simple tool.

I have a cheap 1-2-3 set from perhaps CDCO.  So far I have not needed to use the holes mostly due to the holes and threads being smaller than the diameter and threads on my clamping set for the mill. If you do add holes, make the size and thread to be the same as your clamping studs.


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## Bob Korves (Jul 10, 2017)

Dave Paine said:


> If you do add holes, make the size and thread to be the same as your clamping studs.


If you add threaded holes, make the threads oversized (loose fit.)  If the blocks are properly heat treated, there is a good chance of the threads (and the blocks) distorting during the hardening process.  After the blocks are hardened, the only real way to repair the threads is to thread grind them, not something many hobby machinists are set up for.


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