Dorian Quick Change Tool Post - making it repeat better...

Chris Harris · Dec 29, 2013

I have a Dorian AXA quick change tool-post holder for my CNC machine. It is on a Hardinge HLV lathe retrofitted with CNC.

I have noticed that removing and reclaiming a tool can change the X position by as much as 0.0005" at times. This seems to depend mostly on the pressure used to clamp the tool in place.

Has anyone else had this experience? Is there something one can do to make these holders more repeatable? I want to get it down to 0.0001" if possible. Is Aloris any better?

Regards

Chris

Chris Harris · Dec 29, 2013

I just found this on the Dorian site. They guarantee 0.0001" so my expectations are not out of whack.

athack · Dec 29, 2013

We use one and repeat to .0002-4 on a Haas TL-1. I think there just too many variables to ask the machine to repeat to .0001....probably not necessarily the QCTP.

alphonso · Dec 29, 2013

That is such a small post that it is very easy to twist it when pulling the lever. You could bolt some blocks on the cross slide to brace the post to minimize the twisting. I've done that with a CA post.

Chris Harris · Dec 29, 2013

alphonso said:
That is such a small post that it is very easy to twist it when pulling the lever. You could bolt some blocks on the cross slide to brace the post to minimize the twisting. I've done that with a CA post.

Alphonso, you raise a good point but I have checked everything with an indicator. I have the quick-change-holder locked down tight and it is not rotating. I started with blocks to stop any potential rotation (which I had) but when I put the indicator on the tool itself I can see clearly how the tool holder itself is shifting as one tightens up. I will call Dorian tomorrow and see if there is something one can do to the internals to help it repeat. I was hoping there was some quick machine-shop-practise fix that would cure it. 0.0005" is way too much for what I am doing. I may need to be forced to go with a gang-tool holder.

MyrtleLake · Dec 29, 2013

Two thoughts...
1) the most miniscule of tiny, tiny, tiny swarf will offset a toolholder one tenth. Think about it -- it could be off 50 millionths to offset the seating angle enough to move a tenth when projected out to your tool's cutting edge. In addition to wiping down between each change, you might engage the dovetail so it makes contact as you slide the tolholder onto the toolpost dovetail? (I'm just musing here; no experience with that method) It just seems a lot to ask for a tool in the field. I have no doubt the tools can be made to repeat to that level when first removed from the factory in a controlled, clean-room environment. I'm not sure even Dorian will guarantee that level in the field? (Although I would be curious of their answer to the question)
2) Remove the engagement lever and fit with a shop made, square socket coupling. There are torque wrenches that have the engagement in line with the handle rather than the more common 90-deg. to it. Look, for example, at the torque wrenches used for Rego-Fix's ER nut sockets for a visual example. Use a repeatable torque setting to lock the tolholder.

...all in all, it begins to sound less and less like a "quick" change system given both of the above

I expect you're on the right track with a gang tool setup or some other arrangement if you truly require one tenth repeatability. I'll be curious to hear what your solution is in the end.

[EDIT:] Here is the torque wrench type I was referring to: Torco-Fix. I'm not saying those are suitable or have tue right torque range. The in-line configuration is perfect, though, for retrofitting a toolpost handle. There must be similarly configured wrench options available.

bjorn toulouse · Dec 29, 2013

Chris Harris said:
I have noticed that removing and reclaiming a tool can change the X position by as much as 0.0005" at times.
This seems to depend mostly on the pressure used to clamp the tool in place.

If the clamping torque is the culprit, perhaps you should devise a way to torque the tool holders consistantly.
Maybe a large nut TIG welded to the clamping collar, or machine a hex on the collar itself (just thinkin' out loud).

Rex

Chris Harris · Dec 29, 2013

Arthur.Marks said:
Two thoughts...
1) the most miniscule of tiny, tiny, tiny swarf will offset a toolholder one tenth. Think about it -- it could be off 50 millionths to offset the seating angle enough to move a tenth when projected out to your tool's cutting edge. In addition to wiping down between each change, you might engage the dovetail so it makes contact as you slide the tolholder onto the toolpost dovetail? (I'm just musing here; no experience with that method) It just seems a lot to ask for a tool in the field. I have no doubt the tools can be made to repeat to that level when first removed from the factory in a controlled, clean-room environment. I'm not sure even Dorian will guarantee that level in the field? (Although I would be curious of their answer to the question)
2) Remove the engagement lever and fit with a shop made, square socket coupling. There are torque wrenches that have the engagement in line with the handle rather than the more common 90-deg. to it. Look, for example, at the torque wrenches used for Rego-Fix's ER nut sockets for a visual example. Use a repeatable torque setting to lock the tolholder.

...all in all, it begins to sound less and less like a "quick" change system given both of the above I expect you're on the right track with a gang tool setup or some other arrangement if you truly require one tenth repeatability. I'll be curious to hear what your solution is in the end.

[EDIT:] Here is the torque wrench type I was referring to: Torco-Fix. I'm not saying those are suitable or have tue right torque range. The in-line configuration is perfect, though, for retrofitting a toolpost handle. There must be similarly configured wrench options available.

Thanks Arthur. I do require 0.0001" (on radius) repeatability for this task. Anything much more and I am looking at problems with the finished product.

I have cleaned all the surfaces meticulously. The problem is quite evident when all one does is release the handle that tightens the tool holder and re-tightens WITHOUT removing the tool holder. It is tough to repeat.

I have played with making a mark on the nut and base to tighten up to and that does help but not perfect. I do like the idea of the torque wrench adapted to fit the lever. I like the look of the Rego-Fix torque wrench. That could be perfect. Thanks.

As I stated above, Dorian do guarantee the 0.0001" but you maybe correct, they could be assuming a clean room. But I would argue that their equipment is not intended to be used in a clean room. We will see what they say.

MyrtleLake · Dec 29, 2013

One last thought... trying approaching it from the weakest link. I know I've seen many toolholders from various systems with a bent vertical height adjustment screw. What size stud is on the Dorian AXA? A trial test might be done to see if variation is originating from flex in that height adjustment screw. For the test, a solid L piece might be attached with a SHCS bolting it to the top of the toolholder. If it improves repeatability, maybe try making a dual-diameter stud. The smaller thread screws into the toolholder amd bottoms out on the flat of the larger diameter stud. Just thinking out loud here...

drewboyer · Dec 29, 2013

Boring bars will give you the most trouble, a spec caught on either side will throw the point location out of whack much more than .0001

John Welden · Dec 29, 2013

Gang tool it….

moonlight machine · Dec 29, 2013

John is right, gang tool is the only way you will get the sort of accuracy you are looking for. I have 3 lathes with cxa tool posts and one with a ca, I have never been able to hold the sort of tol. that aloris claims. In a perfect world maby but not with swarf flying around, the tiniest chip throws it all off.

athack · Dec 29, 2013

Maybe more detail on the Hardinge HLV lathe. I know the 3 we have we would never think of repeating within .0001 even with gang set ups.

Athack

MyrtleLake · Dec 29, 2013

Hopefully you will forgive a short, pedantic aside... Dorian claim "Quick Change Repeatability" of +/- 0.0001; furthermore, the technical definition is nowhere spelled out. It is listed as a tolerance for each of the toolholder and toolpost, which leads me to question if it refers to only each in their own right. For example, "Quick Change Repeatability" may refer to the repeatability of the toolholder wedge movement / positioning. Likewise, the definition regarding the toolholder may only specifically refer to the dovetail accuracy among holders. I don't know. In such a case, though, tolerance stacking could lead to the two items together having an acceptable, combined tolerance range of 0.0004".

Joseph61189 · Dec 29, 2013

For what its worth.. we were having repeatability issues with ours as well, most especially our drill chuck blocks. It was as bad as between .003-.007 at some points. Turning tool blocks weren't nearly as bad, best we got was .0003 in some cases. A lot has to do with the same amount of force applied when changing out the blocks, that was Dorian's answer to us. Our solution? Deal with it. Critical tolerance parts I just touch off just for the sake of it, but I can do that because I don't normally turn more than 10-15 of the same part. Another thing is I try and program with the minimum amount of tools and try to get the most out of each one with the appropriate insert. Now if your constantly running 50+ parts, gang tool it like some suggested. That's your best option in my honest opinion.

Chris Harris · Dec 29, 2013

Arthur.Marks said:
Hopefully you will forgive a short, pedantic aside... Dorian claim "Quick Change Repeatability" of +/- 0.0001; furthermore, the technical definition is nowhere spelled out. It is listed as a tolerance for each of the toolholder and toolpost, which leads me to question if it refers to only each in their own right. For example, "Quick Change Repeatability" may refer to the repeatability of the toolholder wedge movement / positioning. Likewise, the definition regarding the toolholder may only specifically refer to the dovetail accuracy among holders. I don't know. In such a case, though, tolerance stacking could lead to the two items together having an acceptable, combined tolerance range of 0.0004".

They specifically refer to "positioning" in some of their documentation and frankly that is what I would assume. I would imagine that 99/100 customers would assume the same.

Chris Harris · Dec 29, 2013

Joseph61189 said:
For what its worth.. we were having repeatability issues with ours as well, most especially our drill chuck blocks. It was as bad as between .003-.007 at some points. Turning tool blocks weren't nearly as bad, best we got was .0003 in some cases. A lot has to do with the same amount of force applied when changing out the blocks, that was Dorian's answer to us. Our solution? Deal with it. Critical tolerance parts I just touch off just for the sake of it, but I can do that because I don't normally turn more than 10-15 of the same part. Another thing is I try and program with the minimum amount of tools and try to get the most out of each one with the appropriate insert. Now if your constantly running 50+ parts, gang tool it like some suggested. That's your best option in my honest opinion.

View attachment 95268

This is my finding and I am going to ask them tomorrow if they provide a way of measuring the torque. It is senseless to expect repeatability to the extent they claim and not have an easy means of attaining that.

MyrtleLake · Dec 29, 2013

I agree, but I'm a constant skeptic of ad copy when not spelled out 100% in technical terms. The fact that that specific tolerance is nowhere mentioned while all the others on that chart are explained in standard, specific datum features makes it a prime target for skeptisism. This is not to imply I have any negative leanings toward Dorian or the quality of their toolposts. Such assumptions as you mention, though, are ripe picking for ad copymen. Ever note the intentional misimplication by Jacobs stamping their chucks "Jacobs U.S.A." the minute they off-shored? Or in a similar vein "llambrich USA" by the Spanish?

Joseph61189 · Dec 29, 2013

Chris Harris said:
This is my finding and I am going to ask them tomorrow if they provide a way of measuring the torque. It is senseless to expect repeatability to the extent they claim and not have an easy means of attaining that.

One way we came up with to get the general idea was set up a travel dial with the tip some where on the handle and try to hit the same number each time. Not exactly ideal and you have to tap it into place once you get close. Needless to say that didn't last long.

Chris Harris · Dec 29, 2013

Joseph61189 said:
One way we came up with to get the general idea was set up a travel dial with the tip some where on the handle and try to hit the same number each time. Not exactly ideal and you have to tap it into place once you get close. Needless to say that didn't last long.

That is exactly what I was doing! As I said before, I want Dorian to come up with a suggestion. I can hardly imagine that they have produced these holders for so long without knowing exactly what affects consistency.

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