Aloris holders don't fit import AXA-style QCTP

[series8217]

I bought a new "AXA-style" (import) toolpost and holders last week from LMS, and some real Aloris AXA1 tool holders from eBay. The tool holders that came with the post fit it fine, but the Aloris AXA1 don't.

Anyone seen this issue before? I don't have a second tool post to compare to.

Is grinding the end of the dovetail on the post for fitment going to affect accuracy?

The attached photos show the interference and clearance at both ends of the dovetail when trying to fit the Aloris holders on the import QCTP.

 

[WobblyHand]

I've had the Aloris AXA be too tall, but it did fit my tool post. I don't understand the photo, are you saying that the tool post doesn't lock the holder? Or the corner of the tool post dovetail is hitting the inside of the Aloris dovetail?

 

[series8217]

Oops, sorry, I should have annotated the images! The corner of the tool post dovetail hits the inside of the Aloris holders dovetail.

 

[WobblyHand]

Perhaps the Aloris holder is out of spec? If you have some dowel pins you could measure the dovetail dimension of your import holder and the Aloris.

 

[WobblyHand]

Hate to ask this, but is the handle all the way in the unlocked position? Could just be a tight fit.

 

[series8217]

Yeah it's definitely all the way. I put some force on it.

Good call on the pins. I found some 6mm dia precision ground pins leftover from a project. With these, I measured a gap of 1.050" for the Aloris and 1.056" for the import. Converting the measurements to the equivalent for an 0.25" pin (assuming a 60 degree dovetail), the Aloris measures out to 1.007 and the import 1.014. I found an AXA holder drawing on another forum that shows a dimension of 1.005" between 0.25" pins.

 

[KyleG]

Shars tool holders just barely fit my Aloris toolpost. You don’t necessarily have to grind the inside of the dovetail wider, grinding the back face of the toolholder will have the same effect. I don’t know if you accounted for it in your measurements, but the depth of the dovetail may vary, which will affect the pin to pin distance, even if the dovetails are the same width.

 

[MrWhoopee]

I've been cutting some AXA dovetails recently. I cut them to 1.005 between .25 pins with .382 depth. They seem to be a perfect fit, with lockup at 4-5 o'clock on my Bostar TP. Check the depth (.382), if too deep it will cause what you are seeing. Be sure to measure that depth right at the edge of the opening, the center is frequently undercut. As @KyleG mentioned, you can grind the back face of the holder to correct this. Also check the narrowest width (the mouth of the dovetail). It's not supposed to be a critical dimension, but if too small will prevent the holder from going on.

 

[whitmore]

Shars tool holders just barely fit my Aloris toolpost. You don’t necessarily have to grind the inside of the dovetail wider, grinding the back face of the toolholder will have the same effect.

This is the key element: the facets of the toolholder that are supposed to be
tightly in contact are the inner dovetail surfaces, NOT the opposite face
to the tool;
***see KyleG's later post; I got this bit wrong

 

[series8217]

This is the key element: the facets of the toolholder that are supposed to be
tightly in contact are the inner dovetail surfaces, NOT the opposite face
to the tool; that opposite face is making contact in the depicted misfit.

The dowel-assisted measurement doesn't touch that face, so doesn't indicate
the problem.

Fixing it requires removing metal from the Aloris part, removing some of the opposite
face to give clearance even after the holder is tightened in place.

Ahh, so the the inner face of the dovetail is the critical dimension and the mating face. That helps clear things up.

As it turns out, the dowel-assisted measurement also doesn't confirm the angle.. and a mismatched dovetail angle would make it look like the outer face is the problem, since the point of the tool post dovetail will push the flat face of the tool holder towards the center of the tool post.

So I took some more measurements, this time of the angles on the tool holders and the post. Unfortunately upon further inspection the "Aloris AXA1" tool holders I got from the ebay seller do NOT have 60 degree dovetails! They are ~62 degrees. Seems someone is selling factory rejects on ebay...

The made in China tool post and tool holders do in fact measure out to 60 degrees.