Lathe Dimensions And Compatible QCTP's

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I'm starting this post at the suggestion of another member of the forum in order to compile information
about compatibility of different QCTP's and their holders with different models of lathe. This question
if often raised, particularly by new members or owners of new lathes. The idea here is for members to post
information about their lathes and which tool posts and holders are (or are not) compatible with their machines.

Here is a link to the original post: http://www.hobby-machinist.com/threads/dorian-first-time-buyer-qctp-and-holder-set-beware.59394/

As was pointed out, a useful dimension to know when trying to determine tool post compatibility is the
distance from the top of the compound to the spindle centerline. With this dimension, the height
of the bottom "shelf" of the tool holder and tool dimensions, it can be quickly determined whether a tool
holder will work on a given lathe. Tool holder dimensions are often published by QCTP manufacturers,
and are also available in the QCTP Holder Reviews stickied above.

My lathes:

Logan 200 equipped with Phase II AXA QCTP
Distance from top of compound to spindle centerline = .897"
Thickness of lower "shelf", or base of Phase II toolholder (p/n 250-102) = .439"
I also measured another toolholder p/n 250-101 and it measured a few thousands
thicker.

Notice that a 1/2 tool won't work with this setup: .500 + .439 = .939, which taller than the distance
from the spindle to the top of the compound. However a Dorian D1 or D2 toolholder, with a lower shelf
thickness of .375 should work, just. (.500 + .375 = .875.). Per the information provided by
RJ, Aloris and Shars.
make toolholders that should work as well.

Edit: Also bought a Dorian partoff blade holder, p/n D25AXA-7-71C which I found does
not work with the Logan compound: it's too tall. A different QCTP wouldn't help.


Atlas 618 equipped with A2Z QCTP.
Distance from compound to spindle centerline = .773".
Toolholder shelf thickness: I measured two tool holders. One measured .170" and
the other .165".
I use 3/8 tools in this lathe with no trouble.
 
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I started a drawing of a typical QCTP and type 1 tool holder and filled in a table for various manufacturers and sizes based on catalog specs.. The dimensions should be verified where possible. I see that I missed the Shars XL holders. I'll fill them in. The Table is in an Excel spreadsheet but can be converted to whatever format is convenient.
QCTP1.JPG QCTP3.JPG

Bob

Edited 5/31/17 to add additional information to chart
 
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My lathe is a PM-1440GT. Spindle to top of compound is 1.582"

I have used both an Aloris BXA and Bostar CXA tool post.

There is a bit of variation in dimensions between the different brands of holders.

I have used up to 3/4" tools on the BXA and 1" tools on the CXA.
 
South Bend 14 1/2. 2.015" from the top of the compound rest to the point of a live center in the tail stock. But that dimension may not be true to all, as my carriage ways were reground. Shars 201, aka a BXA. I can use 5/8" tooling with no problems, but it's near the limit. 1/2" tooling would likely work, also, but it would be close. I have a collection of 5/16 and 3/8 HSS blanks from my mini-lathe. Rather than shimming each one up, I made a 7/16 spacer for under the QCTP. No magic in the 7/16, it's what jumped out of the scraps bucket first. I can now make any tool bit reach, and if I need a really heavy cut, enough to worry about flex or shifting in the stack, I can remove the spacer easily enough.
 
I have a Grizzly G4000 (all white paint job, China, 2008). Distance from centerline of spindle to top surface of the compound is 0.933" (probably ±.002" due to chuck runout).

Phase II AXA tool holders (250-101 & -102) just barely allow the use of 12mm carbide insert lathe tools, but not ½".

PS - The "E" dimension of a Phase II 250-101 tool holder is 1.503"

PS - Just checked the "B" dimension of some no-name 250-101 tool holders. They vary all over the place, from a low of 0.438" to a high of 0.457".
 
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hman said:
I have a Grizzly G4000 (all white paint job, China, 2008). Distance from centerline of spindle to top surface of the compound is 0.933" (probably ±.002" due to chuck runout).

Phase II AXA tool holders (250-101 & -102) just barely allow the use of 12mm carbide insert lathe tools, but not ½".

PS - The "E" dimension of a Phase II 250-101 tool holder is 1.503"

PS - Just checked the "B" dimension of some no-name 250-101 tool holders. They vary all over the place, from a low of 0.438" to a high of 0.457".
Click to expand...
Thanks for the info John.

When you say The "E dimension", are you referring to the "D" dimension in the drawing? The "E" dimension refers to the height of the tool post. I have also experienced a fairly wide range of variability in the "B" dimension.

I will update the chart with your info.

Bob
ps John, take a look at the Shars 250-101-XL holders. They were intended to provide for 5/8" tooling. They won't accomplish that, at least on the G4000 but the smaller "B" dimension should buy you enough to use full 1/2" tooling.
 
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RJSakowski said:
When you say The "E dimension", are you referring to the "D" dimension in the drawing?
Click to expand...
OOPS! Yes, it was "D".
RJSakowski said:
ps John, take a look at the Shars 250-101-XL holders. They were intended to provide for 5/8" tooling. They won't accomplish that, at least on the G4000 but the smaller "B" dimension should buy you enough to use full 1/2" tooling.
Click to expand...
Thanks! And thanks for putting the table together!
 
Nogoingback said:
I'm starting this post at the suggestion of another member of the forum in order to compile information
about compatibility of different QCTP's and their holders with different models of lathe.
Click to expand...
Good idea for a thread...

I have a PM1236T on the way, I bought a BXA set from Precision Mathews and an AXA set from Accusize since I got conflicting info on what to get for the lathe, I have lots of AXA tooling so I'm hoping the Accusize fits perfect - If not, Ill probably buy an AXA or BXA Dorian tool post, and use Accusze tool holders since the consensus around here seems to be the tool post dimensions matter more than holders.

Ill post results when I get the Info...
 
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It's been said before but it bears reiterating. The critical dimension when deciding on a QCTP is not the swing of the lathe but the distance from the top of the compound to the spindle centerline. This is the minimum height that a tool mounted in a tool holder can be and still hit the centerline. I measure this height by mounting a pin of known diameter in the chuck and either measure the separation between the pin and the compound and adding half the diameter of the pin. For my Grizzly G0602, that distance is .924". Unfortunately, this information is not provided in machine specs so when buying a new lathe, one must either go on other's experience or wait until you have access to the lathe for an actual measurement before purchasing a QCTP.

One can always use smaller tools than the tool holder will accept. I prefer to use 3/8" brazed carbide or HSS tooling in my AXA tool holders so I don't have a problem with the minimum height restriction. How3ever, if your choice is insert tooling, you have to be able to accommodate the tool shank. 1/2" insert tools won't work with my lathe and most AXA tool holders, the exception being the AXA-XL holders. However, 12mm insert tooling will.

On a final note, the B dimension in post #2 above varies even in tool holders from the same manufacturer. The clue is that the specified dimensions are given in fractional inches rather than decimal inches. There has also been some indication that the spindle centerline to compound distance can vary for lathes of the same brand and model depending upon year of manufacture.
 
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