Tool holder dimensions

[Dan Coleman]

I'm making a few blank tool holders for dial indicators and modifying some larger tool holders for direct fit on AXA. The measurements for the fit of the dovetail are pretty critical for a good fit. I have foud a couple drawiings calling out the depth and the dimension between two .250" diameter pins for the AXA, but they differ. I also have BXA and CXA posts, so I would like those two dimensions for those sizes as well. I can measure the ones I have and individually fit the new ones, but I'm thinking the community already has all this info perfected and posted somewhere.

 

[T Bredehoft]

Do you have a commercial AXA Toolholder? Put a pair of 1/4 in dowel pins in the dovetail cavity and measure between them with an adjustable parallel and a mike. Measure the depth of the cavity with a depth mike. Duplicate that with (first) a two flute end mill, (then) with a 60º dovetail cutter. That's how I did it, but you gotta be careful, a couple of thou either way and it won't fit.

I usded some 4140 1 1/8 rod I had, they worked well.

 

[T Bredehoft]

duplicate post

 

[whitmore]

Do you have a commercial AXA Toolholder? Put a pair of 1/4 in dowel pins in the dovetail cavity and measure between them with an adjustable parallel and a mike.

That measures the broad flare of the dovetail, but not the opening at the throat. When clamped, though, the flare base is
NOT in tight contact, only the throat (face and sidewalls). So, if you measure that way, the DEPTH of the
dovetail is critical as well as the breadth. Sometimes the depth is relieved in the center, so it might be hard to
measure.

The opening at the throat is not easy to measure, either (because the sharp feature is blunted for safety).
A go/no-go gage might be easy to fabricate, though.

 

[ddickey]

In case you want to see the actual math. Scroll to the bottom of the page.

Volume 7, No 12 - December, 2002

Home Metal Shop Club Newsletter for December 2002

www.homemetalshopclub.org

For BXA

 

[nnam]

Quick Change Tool Post Set Wedge Type #333 CXA

www.shars.com

Dovetail Dimensions

• H: 0.555"
• L1: 2.202"
• L2: 1.681"

 

[Grandpop]

Yes, you will find different dimensions for the various sizes. I just researched this, as just finished making 6 more BXA tool holders. I saw two main sets of numbers for BXA. One was .412 deep and 1.081 between two .250 dowels; other was .417 deep and 1.087 between the dowels. I measured the 7 tool holders I already had and found they matched the first set.

But both sets of numbers are correct after doing the trig. The 2nd set has the same L2 width as first set, it is just deeper and therefore wider at the bottom. It will just have a slight amount of extra depth clearance. Both will fit the same tool post and tighten correctly. Would not worry too much which set of numbers you choose to use.