123 Block question

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Suwannee Tim

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Most shops have at least one set of 123 blocks, I bought two pair not long ago, seemingly they are standard equipment. The pairs I bought have tapped holes and through holes and were shipped with socket head cap screws fitting the threads in the blocks. The through holes in the blocks are not clearance holes for the SHCS though as I would expect them to be, they are too small to accept the SHCS. My question, what is the purpose of these tapped holes and through holes if not to screw the 123 blocks together to make a 223 block or a 143 block? It seems to me the unthreaded holes should be clearance holes with counterbores for the SHCS. Does anyone actually use these threaded and through holes and for what? Other than standing a workpiece off machine table what are 123 blocks good for?
 
Chinese have been making these "wrong" for decades. Search for Suburban Tool for their story on the subject, or go here:
 
This is a well know <cough> design flaw. You should be able to find lots of background discussion searching the forum.
Dang, machPete99 beat me to it with Don Bailey vid. Here is another.

 
Yes, this has been discussed here but I can't find the thread right now.

Essentially what happened is someone way back made some of these blocks and messed up. The part was then sent to China where that mistake has been reproduced a million times.

If you want ones that are made right you can get them here.


Don't bother trying to bore yours out, they are hardened and will just destroy your drill bits.


John
 
Video posted by petertha is informative, thank you for that. A question, at 8:30 Renzetti knocks on the SHCS with a knocker, what is he doing there? I had a question, I have seen machinists bang on a workpiece with a dead blow hammer seemingly to seat workpiece onto parallels into vise. It always seemed unnecessary to me, I now see it is indeed unnecessary.
 
Suwannee Tim said:
Video posted by petertha is informative, thank you for that. A question, at 8:30 Renzetti knocks on the SHCS with a knocker, what is he doing there?.....
Click to expand...
He's knocking it as close to zero runout as he can by eyeball. When he first snugs up the nut, notice how the screw head wobbles when he starts the lathe, then watch how it doesn't wobble when he restarts the lathe after knocking it and tightening the nut.

Tom
 
matthewsx said:
Essentially what happened is someone way back made some of these blocks and messed up. The part was then sent to China where that mistake has been reproduced a million times.
Click to expand...

I would love to know what really went down. I've heard a few theories:
1) sent them (or they decided to make) legitimate blocks to reproduce. But they failed to see the significance of an alternating tap hole, clearance holes, applied their own 'cost reduction' measure by drilling all tap holes but threading alternating holes. Which is the current model in all its useless glory.
2) (for conspiracy buffs) sent them a known dud which was faithfully reproduced. Hmm... not sure there. Engineer humor? Marketing booby trap? They seem to be doing a brisk business selling duds to all us hobbyist newbs so its not like they got caught with their pants down holding 5 years of 'now what' inventory LOL.

The real question is, particularly because its so painfully obvious the blocks could be so much more USEFUL with just a small change. Why not just swap out the bit & drill the fricken holes correctly? I mean it has to be cnc, they do a decent job of heat treating, grinding, holding tolerance, reasonable price... But once hardened that pretty much limits the remedial options. I said this before on another related post. Someone should file a bait patent application for the RR blocks. Then I bet we'd see them pop up in tooling catalogs within a few months LOL.
 
Found one of the prior posts & contains some remediation ideas
www.hobby-machinist.com

Leggos for Machinists

Well, not quite. About a year ago, I purchased five pairs of 1-2-3 blocks to go with the pair I already had. My intent was to use them for machining setups, etc. As mny of us already knew, although the Asian blocks have 3/8"-16 threaded holes on the 2 x 3 face, all the through holes are bored...
www.hobby-machinist.com www.hobby-machinist.com
 
In my ignorance I can't conceive of a use for screwed together blocks. I think I will be happy with my nine dollar ones.
 
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