repeatability of toolposts/toolholders

[dian]

pinstripe, you make two collars and cut them separately.

btw, the video is a joke. the guy moves the cross slide around. you use an indicator with a cable. also both toolposts shown are fukced up. you cant go over center with a multifix (unless you take out the toolholder). when he called the enco contraption "true", "original" and" swiss" i almost fell off the chair. (stopped watching there.)

[pinstripe]

before you get too excited check out the prices of their holders - E70-100 ('bout the same in $ give or take). Not dissimilar to Aloris, but there's no way you're making your own copies of these.

They are not cheap, but the web site prices include VAT. They take 20% off the prices if you are outside the EU. Making the holders is very difficult. I've seen it done, but I'm not sure I would try. The original holders are ground as well, making it even more work.

I think there's a Chinese Multifix supplier that's decent, but I can't remember any details. Several people have reviewed them and the price per holder is much more manageable.

The Chinese brand is Create Tool. The guy in the video that I linked to earlier has a video on those as well. He said they were pretty good, but not as good as the AXA. The original Multifix appears to be the best.

pinstripe, you make two collars and cut them separately.

Ok, but I still don't see how it would be more accurate then measuring the insert position. It's 4:00 AM here, and I'm "working" so I'm not firing up the lathe

btw, the video is a joke. the guy moves the cross slide around.

I didn't like his technique. I left the lathe controls alone and just removed and inserted the holder. After a while, I just locked and unlocked the handle. I was getting the same results either way.

also both toolposts shown are fukced up. you cant go over center with a multifix (unless you take out the toolholder).

Not sure what you mean. They were both new. The enco was NOS.

when he called the enco contraption "true", "original" and" swiss" i almost fell off the chair. (stopped watching there.)

AFAIK, he is correct. Enco rebadged the original Swiss Multifix which is no longer made. There is a Swiss company that makes them still, but they are not the original.

[tomato coupe]

edit: experience with other types of toolholders

Dorian CXA series: no worse than .0001" (.0025 mm) repeatability.

[garyhlucas]

Making multiple identical parts swapping multiple tool holders in and out of an Aloris toolpost using the same dial position for the cross slide all the parts were easily repeatable to 0.001” diameter. Aloris claims 0.0001” repeatable.

[dian]

keep the comparisons coming.

btw, there is no swiss company producing the multifix. swiss production stopped 20 years ago and the last original "j.f.minder" multifix was made 50 years ago. but this thread was not about the multifix but rather about the other systems.

[Glug]

What is an appropriate method for measuring this? As asked, the question was "repeatability".

I think there needs to be some machining with a different tool holder, between the two comparisons.

[danlb]

I have lathes with Aloris style QCTPs. One has a 0xa piston style toolpost and another with an AXA wedge style. I used a dial indictor on magnetic base with articulated arm to measure the location of the tool's point in the X axis after remounting the tool holder multiple times. I expected the wedge style to perform better. What I got was that both repeated within +- .001 normally. If I used the exact same technique every time it did much better. I got less than one half of a division consistently and, in many cases the needle was back on the zero mark 5 times out of 10.

I suspect that part of what I was seeing was the movement of the compound as I tugged on the handle to cinch it down firmly. The magnet base was on the cross-slide and that left some leadscrew / gib play in the compound.

Dan

[garyhlucas]

The piston style might repeat well, but they are not nearly as stiff because the piston pushes the toolholder out against the dovetail so high cutting forces can cause it to twist. The wedge style pushes the flat side of the toolholder against the flat surfaces on the toolpost and against the fixed dovetail and the wedge. Damn near a solid block of metal at that point. I got rid of a piston style when I realized where the errors were coming from on heavy cuts.

[johansen]

The piston style might repeat well, but they are not nearly as stiff because the piston pushes the toolholder out against the dovetail so high cutting forces can cause it to twist. The wedge style pushes the flat side of the toolholder against the flat surfaces on the toolpost and against the fixed dovetail and the wedge. Damn near a solid block of metal at that point. I got rid of a piston style when I realized where the errors were coming from on heavy cuts.

what i'm concerned about is the wedge type pulls the back side of the tool holder down while its tightening.

i don't know what the math is on the friction coefficients but it might not self square.

if you hold the tool holder intentionally tilted at an angle, with the tool above center.. when you tighten it, there is no guarantee it pulls the entire tool holder down against the height adjust stop screw, and squares it before it tightens and locks into position.

this however is only a problem for tool height, not lateral location.

also it gets worse with thinner tool holders, if the tool holder is longer or deeper than the dovetail is wide then it will self square even with a high friction coefficient.

[tomato coupe]

if you hold the tool holder intentionally tilted at an angle, with the tool above center.. when you tighten it, there is no guarantee it pulls the entire tool holder down against the height adjust stop screw, and squares it before it tightens and locks into position.

It seems like there must be a solution to that problem.