Learned a valuable lesson, Without breaking anything or hurting myself

[Sleazey]

I bought one of Haimer's 3D Taster early last year.

Now, the dial on mine is graduated in inches, but the instruction manual that comes with it describes the shank as a 20mm shank. It also describes the probe ball tip as 2mm diameter.

I bought a dedicated 20mm R-8 collet to use with the Taster, and marked the shank and the collet so I could get a little bit more repeatability and not have to calibrate the concentricity every time I used the taster.

Well, that didn't work so well, plus trying to hold the Taster in the collet, and tighten the drawbar with just 2 hands, always offered the possibility of dropping the Taster onto the milling table. 3 hands were needed, one for the spindle brake lever, one to hold the Taster and the collet in the spindle, and one more hand to turn the drawbar wrench.

Plus, I had noticed that the 20mm collet always got sucked way up into the spindle.

So, I bought, from an eBay seller in the UK, an R-8 end mill holder for a 20mm shank end mill, and 7/16-20 UNF threads. Impossible to find here in the US, and most of the true metric ones were something like an M10 (12?) thread for the drawbar. What with shipping and the cost of the end mill holder, it was like $86 USD.

It finally arrived in the mail today, so I spent a couple of hours trying to calibrate the Taster in its new dedicated holder. I could not get enough travel in 2 of the 4 centering screws to get the Taster concentric to the spindle rotation. I tested the 20mm end mill holder with an indicator and it was very true, the indicator didn't wiggle a bit.

So I put the Taster back into the end mill holder and finally twigged to the fact that the 20mm bore was a bit too big for the Taster shank. ?What the Hell????

So i miked the Taster shank. It was not 20mm, it was 0.75000". Jesus H. Christ on a crutch! I got a 3/4" end mill holder, and popped the Taster shank into it. Slipped in as perfect as could be. Mounted the endmill into the mill spindle, and then it took about 20 minutes to get the Taster concentric within less than 0.0001".

So I wasted 2 hours tonight trying to calibrate the Taster, $86 on a 20mm end mill holder, and about $30 last year on a dedicated 20mm R-8 collet for the Taster.

This also explains why the 20mm R-8 collet would suck up so deep into the mill spindle. Fortunately, I never felt the need to torque it really tight, since it's just a measuring instrument, not a cutter.

Lesson learned, don't trust anything you haven't measured and verified yourself.

Now it occurs to me, I better measure the diameter of that probe ball on the end. It may be a 1/4" for all I know.

Oh well, no damage done, and I learned a lesson without breaking anything or getting hurt, so it was a cheap but effective learning experience.

[loose nut]

Is this just a collet or is it a tool holder. For a 3D taster to work right you have to keep it in a dedicated tool holder that has set screws to mount the shank permanently to it and then adjust it. If you are just using a collet then it has to be adjusted every time you mount it in the spindle.

Once you get it all set up and true it's a blast to use one. I have had mine for a year now too.

[rode2rouen]

Lucky it only took a year and a half to figure things out.


Rex

[Sleazey]

Loose Nut:
Yes that was why I bought the 20mm end mill holder, to use it as a dedicated mount for the Taster. So now I will get an extra 3/4" end mill holder for use as the Taster's permanently dedicated mount.

Rode2rouen:
Using a bare r8 collet kind of disguised the problem. I always inserted the collet in the spindle first and ran the drawbar in as far as possible hand tight. Then I would insert the Taster and using all 3 of my hands , tighten it up with the wrench. I was always focused on not dropping the Taster, while tightening the drawbar.

In a bare collet, it centered just fine, usually PDQ. So I am not too embarrassed about that. I am slightly embarrassed taking two hours to figure it out last night.

[Toolguy]

One thing I have never figured out and no one has been able to explain is how to use the Z axis part of one of those. If you don't use the Z axis, then you may as well use a co-ax or dial test indicator. I have never bought a 3D indicator because I can't see any advantage over what I already have. Can someone who has one explain it?

[danlb]

It seems that a lot of tooling is made in factories where the markings go on last. I suspec that lets the same line make expensive high quality tools and cheap crap from the same batch. It depends on how close they match the specs.


Dan

[loose nut]

One thing I have never figured out and no one has been able to explain is how to use the Z axis part of one of those. If you don't use the Z axis, then you may as well use a co-ax or dial test indicator. I have never bought a 3D indicator because I can't see any advantage over what I already have. Can someone who has one explain it?

If you go to their web site they explain how to us it in all axis.

One interesting use in the Z axis is to measure the depth between to steps. Also these devises are very accurate (you can pick up an edge to 0.0002 if you have it adjusted properly and if your equipment is good enough), very quick and there is no calculating offset of the indicator ball to pick up an edge with no overrun . Are they really necessary, not really for most of us, you can do the same things with other means but once you have used them you probably won't go back.

You need to shop around because the price can very greatly, by as much as 100%.

[loose nut]

It seems that a lot of tooling is made in factories where the markings go on last. I suspec that lets the same line make expensive high quality tools and cheap crap from the same batch. It depends on how close they match the specs.
Dan

The genuine 3D Tasters are made in Germany and are first class quality. There are off shore copies (China) that run from not as good to down right crappy and are not even that much cheaper.

[Toolguy]

If I get one, it will only be the high end German one. Some things you just don't skimp on. However, I will keep an eye out for one like loose nut is talking about that is 100% off.

[Carld]

I want to offer a little third hand help. If you have a Bridgeport type mill with a V belt drive and high/low levers you can lock the spindle and not use the spindle brake with your non existent third hand

What you do is move one lever as if your changing ranges and that will depend on which range you have it in. That will lock the spindle between the high/low range and you can insert the collet and whatever with one hand and screw in and tighten the draw bar with the other hand.

That's an old Indian trick I learned years ago when I needed three hands and didn't have a third hand.

Most the time I am in high range and I use the handle on the side of the head. When I am in low range I have to use the lever on top to lock the spindle. Sometimes when in low range I don't even lock the spindle since the spindle is hard to turn anyway.

Always give the spindle a quick turn to snap the dogs into gear. I hate to hear the GRRRRRRRRRRCHUNK when I turn the motor on and the dogs are not engaged.