View Full Version : tool post terminology

The wrench
01-31-2010, 05:12 PM
Hi guys.I have been doing lots of reading here and the amount of info is terrific! What I need to know is what quick change tool post should I get for my 12x36 inch lathe? also, what does CA,CXA, etc. translate to? Between piston and wedge type, is one better than the other? If anyone can point me to the info, or just explain it to me I'd sure be grateful! Thanks in advance.

01-31-2010, 05:59 PM
Wedge is considered the best, piston is 'OK' but wedge is considered better.
Phase II (usally on sale for like $150~ or something at enco) wedge type is usally considered the best 'value' for the money, with only the $500+ aloris and such considered any better really IMO (And the phase II is more then good enough for any kinda HSM work)

BXA/CXA etc are the 'size' of the holder and toolpost, mainly relating to how high it is and how much adjustment range and tool size you can hold

Basicly only a BXA fits a 12x36 however. that lets you use 5/8" tall tools and 1/2" boring bars in the standard holder, and 1" and smaller boring bars in the heavy duty 'boring' holder, and also you can get a nifty holder for a MT2 shank (for power feed drilling via carriage)

Technicaly you could remachine the holders to hold much bigger tools, maybe up to 1", but generaly people just deal with the capacity limit unless they have a good reason to do otherwise (like getting a hold of some REALLY cheap 3/4" or 1" tools.. but even then, usally you just mill the shanks to size, 5/8" is lots of rigidity for a 12x36" lathe)

You can buy reasonable quality additional holders from many places (ebay, a few dozen 'ubercheap' tool retailers online, etc) and they are all reportadly the same more or less: They are good holders (I mean they are just a chunk of metal), some may need a fine adjustment on the front face (easy) to fit your toolpost just right, but usally with a good phase II or better toolpost they fit as is. You will want to buy new set screws for them, it seems the biggest diffrence beween a $10 toolholder and a $50 tool holder is the 4 $0.20 set screws used. the cheap toolholders allmost allways have near unusable set screws. heads not in the center of the screw, heads oversized so they get striped by the CORRECT hex key, etc. just poor screws.

01-31-2010, 06:29 PM
I have a 12 X 30 lathe and use the Dorian SD25AXA tool post. This is a wedge type. I only have experience with the wedge, but my understanding is that it is supposidly better than the piston type. The pertinent dimension is the cutterheight above the cross slide surface. For my Nardini 1230 the cutter height is 1.063. The different size posts will work over a range of cutter height. The AXA will go from 7/8" to 1-5/8". The BXA will go from 1- 1/16" to 2-1/8. This information is avaliable on the different tool websites. Being in the middle of the cutter height range is better than right on the end. The Question of cost allways comes up. I don't have any experience with any others but I believe you should buy the best tool post you can get. Dorian or Aloris are both good. Most of my tool holders are also Dorian. I have some from CDCO which are a step down in Quality but they are much cheaper and will last longer than I will. You can never have too many tool holders. They are adictive because once they are set up they are so easy and quick to use.

01-31-2010, 06:43 PM
I have a 12 x 40 lathe and find the AXA is probably the best for a 12 inch. Also,
there are other ones numbered 100,200,300 etc. The 100 series toolpost and holders are the same as the AXA, 200 the same as BXA, etc. I have a Phase II
toolpost and some holders and several other brands of holders. They all fit. I have several Phase II tools, and they seem to be the best quality of the cheap stuff. MY toolpost is 15 years old and shows no signs of wearing out. I use my equipment every day as a business.

01-31-2010, 06:56 PM
I have a BXA size on my 12x36 Enco lathe and it is maybe a bit on the big side. Yes the slots in the holders are 5/8", but I have the holders bottomed out with 1/2" tools. There's no way I can get a 5/8" tool down to center without milling a bit off the bottom of the holders.

I have the wedge style, which is more repeatable. When it clamps the dovetail, the wedge draws the stop on the tool holder down against the post. The piston just pushes out to tighten the dovetail.

01-31-2010, 07:35 PM
I do wish the purveyors of these quick-change toolholders would start specifying the size of the machine it's recommended for based upon distance of the lathe's spindle center to the top of the compound slide. That would solve a few problems that occur when trying to match the choice of system to the machine one has.

A friend of mine has a 15" Clausing, and the CXA/300-size is the right one for his machine. My dad's 1640 Victor lathe is just a tiny bit bigger, but can (and does) use the CA/400-size set. When you get into the smaller lathes it seems there's a lot more variation in that distance, so there are some 12" lathes that can successfully employ the BXA/200, while others are best fitted with the AXA/100 size.

There's also some variation in the height of the blocks from each maker for a given toolpost size. I've seen some BXA holders such as what "hornluv" describes that can't put a 5/8" tool shank low enough to use, but other make blocks that will. Mill some metal off the bottom of yours so you can get bigger tools in there.

The wrench
01-31-2010, 07:37 PM
Thanks a lot guys, those replies really help!

Rich Carlstedt
01-31-2010, 10:34 PM
The problem with specifying the Tool post to a lathe size, is the lathe manufacturers differences.
Not all lathes have the same distance from the top of the tool-slide to spindle centerline.
Once you know that dimension, you can select the proper size


If the dimension is 15/16 use a A
If the dimension is 1 1/8 or more, use a B

I use a A on my 12 inch lathe, by putting a 5/8 spacer under the Aloris post
That way, my 10 inch and 12 inch Lathes use the same tool holders without
any adjustment having to be made.