123 blocks

[mwooten]

Hey guys. I'm a bit of a rookie and bought some 123 blocks. The threaded holes are 3/8-16. The non-threaded holes are stated as 5/16. They measure .351??
My question is how is one suppose to bolt them together in various configurations? If the answer is not suppose to then what are the holes for?

Thanks in advance for your help
--Mike



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[TOOLMASTER]

STUDS

 

[jamie76x]

1-2-3 blocks are one of the first projects we made in 11th grade machine shop class... And I have used that pair ever since.
The ones we made to print called for .500 holes all the way through for sliding over a stud. Looking back I really wish I had made that set with the holes and some threaded holes to bolt them together. Guys make their own all different ways... I have even seen guys put small T slots in them for certain jobs.
You can make them for more functions that just blocks. The sad part is that once you harden them and finish grind, There is only so many modifications you can make to them.

 

[arvidj]

Hey guys. I'm a bit of a rookie and bought some 123 blocks. The threaded holes are 3/8-16. The non-threaded holes are stated as 5/16. They measure .351??
My question is how is one suppose to bolt them together in various configurations? If the answer is not suppose to then what are the holes for?

Thanks in advance for your help
--Mike

Mike,

Give this thread a try ... http://www.hobby-machinist.com/showthread.php?t=4811&highlight=Blocks and this one
http://www.hobby-machinist.com/showthread.php?t=6173&highlight=Blocks

Arvid

 

[darkzero]

Mike,

Give this thread a try ... http://www.hobby-machinist.com/showthread.php?t=4811&highlight=Blocks and this one
http://www.hobby-machinist.com/showthread.php?t=6173&highlight=Blocks

Arvid

I don't have any studs smaller than 1/2" so I never bothered to check. I currently only have one set of 123 blocks, unknown make & COO but I'm pretty sure they're China.


Quoting some content from the threads you linked....

I discovered that the 18 holes are drilled at the 3/8ths by 16 tap size and not the 3.8ths clearance size … effectively rendering the holes useless unless as a 3/8ths bolt would not fit thru the holes. Note that I understand why the manufacturing shortcut was taken … it costs more to drill two different size holes …

the upscale Ultra Precision version is the unusable “all 3/8ths tap size” pattern.

The two terms that I have see used is "clearance drilled" where the hole is large enough to pass a 3/8 bolt thru and "tap drilled" where the hole is the correct size for tapping a 3/8 x 16 thread.

Just checked mine
Tapped holes are 3/8 16, no question on that!
The non tapped holes measure 0.355

So mine are pretty much the same as the ones 8ntsane measured. The tapped holes are definitely 3/8-16 on mine & not a common metric thread.

So from what I gather they are drilled with 2 different hole sizes so it's not keeping the costs down as the reason for this. Tap drill size for 3/8-16 is 5/16 (.3125) & my threaded holes measure roughly .32. My unthreaded holes are about .354 - .355.

Not sure if it's just a coincidence or intentional but .354 is pretty much the same size as 9mm & the same size hole required to tap M10x1 threads.

 

[RandyM]

STUDS

:think1:

 

[johnh57]

If a person wanted to make a set of 1 2 3 blocks - would grey cast iron be an appropriate material?

 

[arvidj]

I don't have any studs smaller than 1/2" so I never bothered to check. I currently only have one set of 123 blocks, unknown make & COO but I'm pretty sure they're China.


Quoting some content from the threads you linked....




So mine are pretty much the same as the ones 8ntsane measured. The tapped holes are definitely 3/8-16 on mine & not a common metric thread.

So from what I gather they are drilled with 2 different hole sizes so it's not keeping the costs down as the reason for this. Tap drill size for 3/8-16 is 5/16 (.3125) & my threaded holes measure roughly .32. My unthreaded holes are about .354 - .355.

Not sure if it's just a coincidence or intentional but .354 is pretty much the same size as 9mm & the same size hole required to tap M10x1 threads.

I agree with your tap drill size calculation but if I am reading this chart for forming taps ... not cutting taps ... http://www.hobby-machinist.com/showthread.php?t=6173&highlight=Blocks ... a 3/8-16 with 55% and 50% thread seems to fall into the values that you have measured for the unthreaded holes.

I am not claiming that I 'know' how they are made ... just speculating.

 

[mwooten]

Thanks guys. Interesting conversation. Makes a man wonder why someone would cut an array of seemingly useless holes?.....every time


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[flutedchamber]

If you wanted to take the time, you could use a 3/8 carbide endmill, locate the center of each non tapped hole, plunge the endmill in and enlarge them. It worked on my set.