Correct size QCTP for Craftsman 6” Lathe

wa5cab said:
Was the 6" Craftsman made by Atlas or by AA or by someone else?

Also, if all of the cutters are going to be too low, the proper solution is a riser block between the tool post and the top of the compound slide.

The AXA is designed for 3/8" cutters and will just hold 1/2" ones. The 0XA should take I think 1/4" cutters. And just barely hold 3/8" ones.

The AXA,, BXA and CXA dimensions were set years ago by AFAIK Aloris. But I don't think that they ever made a 0XA. Which would mean that there may be no recognized standard for 0XA.
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Aloris did make a tool post years ago that was smaller than the AXA, I had one bought new for a 9" south Bend lathe, they only had one dovetail on the side and L shaped holders to hold tools on the other side, I'd guess that they were about 1 3/4" square.
 
RJSakowski said:
My 6" Atlas/Craftsman measures .773" from the top of the compound to the spindle centerline. From Shars dimensions, I would need a 1/8" shim washer under the OXA tool [post to allow a full 360º rotation of the tool post. The 001 and 002 OXA tool holders would allow 1/8" to 1/2" tools on my lathe.
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The 1/8" shim is to clear the raised portion of the casting, no? I notched a tiny bit out of one corner of the tool post to give clearance:

0XA toolpost mod.jpg

Craig
 
OK. Then Shars or whomever set the 0XA dimensions didn't follow the AXA/BXA/CXA progression, at least on the slot height, but instead used the same dimension as for the AXA,

But what is the slot depth? I can honestly say that this is the first time in 75 years that I have seen anyone use 24th's of an inch!!! I just don't think in 12ths or 24ths or 48ths.
 
With regard to being able to rotate the tool post through 360 degrees, that is also a problem on the Atlas 10" compounds, too. The common solution is to either fly cut or mill the raw casting back out of the way. When the things were originally designed, there was no need for more clearance as everyone just used the lantern type tool holders. At least on the 10" there is enough meat in the casting to allow you to do that without cutting through the top of the casting. It is high time that we learn whether or not that is true of the 6" compound slides, too.
 
According to LMS the OXA tool post size was created by Tormach & LMS. :dunno:
 
wa5cab said:
OK. Then Shars or whomever set the 0XA dimensions didn't follow the AXA/BXA/CXA progression, at least on the slot height, but instead used the same dimension as for the AXA,

But what is the slot depth? I can honestly say that this is the first time in 75 years that I have seen anyone use 24th's of an inch!!! I just don't think in 12ths or 24ths or 48ths.
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I grabbed a 0XA-size toolholder at random--I think it came from All Industrial. Using the diagram above, my measurements compared to the diagram:

B: diagram: 0.516 (33/64") mine: 0.520"
C: diagram: 0.292 (7/24") mine: 0.3-ish" [1]
D: diagram: 1" mine: 1.100"

[1] The surface is rather roughly machined and I get different measurements in different spots. May also be a little swarf in the way.

I should mention that I don't use any 1/2" tool bits. I use mostly 3/8" with a few 1/4" and 5/16" here and there. All HSS so the grind often lowers the cutting lip a little from the nominal tool height.

Using 1/2" size tooling in a 0XA system on a 6 inch lathe reminds me of stuffing a big block V8 motor in a classic VW Beetle. You might be able to do it but there is no good reason. Based on the measurements, around 0.200" of the tool shank (40%) is going to be protruding out the side of the tool holder. The retaining screws are not going to near the centre line of the shank.

Craig
PS I would guess that the 24th-of-an-inch measurement came from someone who works mostly in metric. To them, any denominator in the fraction may make as much sense as any other! My kids learned metric exclusively in school. When I first did little projects with them they looked at me like I had rocks in my head when trying to measure in sixteenths of an inch. "Daddy, why not just use millimetres?" Honestly, they're right!
 
The RMKS has produced the poorest threaded fastener system ever seen on this planet. It only works OK in a Clean Room. And even there, not very well or for very long. And many of the basic units are of an inconvenient size for the real world. In order to use them, you have to multiply or divide by a thousand or a million.
 
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