Control and measurement of cones 7:24

[Milling man]

Hello dear colleagues.
Tell me - how do they measure tapers in machine tool spindles and on tool holders in the US and EU? I mean cones like BT, SK, CAT and the like - with a taper of 7:24.
I used to measure them using these gauges:



These are precision parts with precisely made cones and base ends located in precisely defined places relative to the cone. By inserting a plug gauge into the spindle and measuring the distance between the end of the spindle and the end of the gauge, you can understand how correctly the spindle taper is located. Similarly with the sleeve gauge, I insert a collet chuck into it and check that its back end and front end are in the right place.
Lately I've been trying to find similar calibers in the US, EU and China - and failed. There is something with ends that are not processed at all after hardening - it is obvious that it is impossible to measure something relative to such ends.
Maybe I don’t understand something, the world has gone far ahead, and I use the technology of the century before last?

 

[jccaclimber]

I've measured internal cones by dropping in two different diameter ball bearings and noting the distance both between them and relative to any end flange. I'm curious about a good solution for external ones that does not involve a sine table.

 

[???]

I've measured internal cones by dropping in two different diameter ball bearings and noting the distance both between them and relative to any end flange. I'm curious about a good solution for external ones that does not involve a sine table.

Remove pull stud and place upside down on surface table, using 2 rollers measure across outside..
Place rollers on 2 parallels or slip gauges measure across. Basic trig after that.

 

[???]

Excuse the crappy sketch

 

[TGTool]

Or get a taper micrometer

https://www.ebay.com/itm/1546236104...oc:2&msclkid=8d875194488c10c5160d3510bd4ff589

 

[sfriedberg]

I'd love to have a taper micrometer, but 1) they are very, very scarce, and 2) there probably aren't very many taper micrometers that can accomodate the diameter of an NMTB40 (much less 50) taper. If I were inspecting 7:24 tapers, I'd build a mild fixture around a 6" or larger sine plate.

 

[TGTool]

I'd love to have a taper micrometer, but 1) they are very, very scarce, and 2) there probably aren't very many taper micrometers that can accomodate the diameter of an NMTB40 (much less 50) taper. If I were inspecting 7:24 tapers, I'd build a mild fixture around a 6" or larger sine plate.

Yes, expensive and I would expect a little touchy since they have a fairly short sine and one could introduce flexing if not done with sensitivity.

If the part can be manipulated separately, as distinct from having to measure a taper on a machine, the sine bar check sounds pretty easy. Put an adjustable parallel under one end of the sine bar to make the indicated side of the part close to horizontal. Adjust the parallel until you can get zero indicator movement sweeping the part. Then just measure the adjustable parallel. If you want to verify you could swap a gauge block stack for the parallel and do a cross check. But given the variability possible with the taper mic, the measurement of an adjustable parallel is probably as accurate.

 

[Milling man]

It seems to me that a cone micrometer will not provide the accuracy of measurement that a cone gauge achieves. And "does not provide" - in several times.
And the main problem is the shape of the cone (deviation from roundness, straightness of the generatrix of the cone, deviation of the angle of the cone) I can check with paint and a Chinese gauge with unfinished ends. But how to understand the axial position of the cone relative to the end of the spindle? Or in the case of tool holders, relative to the rear or front end of the holder.

 

[CarbideBob]

On the holder side it is done with "golden" masters and special air gauge or LVDT bases. Also known as hard gauging.
Face contact ones are the really hard ones.
When I shop I know jumped into making early HSK they spent close to 150K on special gauging just for this one family of tapers.
Fast forward 15 years and another shop wants in. Bought a few 1/4 million dollar grinders and making bad parts. They then spent 70K+ on gauges and masters.

Most CMMs and optical compartors can not do this measuring correctly or repeatably. Cone or taper mics worthless.
T'is much harder than it first looks. There are so many was to make a bad part.
It would seem that you can use rolls or other and 50 millionths indicators. That does not work.

Maybe Frank Mari can speak up about how it is done and the trials and tribulations of production grinding/measuring these things.
Interesting to note is that even the old B/S taper over the sizes is not to what the math says it should be.
....You are walking where angels fear to tread.

 

[Milling man]

Most CMMs and optical compartors can not do this measuring correctly or repeatably

You are right, measuring taper gauge diameters is not an easy task. But in serial production, they are measured by a reference caliber with known sizes up to 0.1 μm, and reference calibers can be measured on an instrumental microscope.
The accuracy of the diameters of these calibers according to the Soviet standard is + -5.5 microns. Such a tolerance is quite possible to reliably measure with an instrumental microscope.

 

[CarbideBob]

Seems you know how so why ask here? You seem to have it nailed and that is all good.

Rule of ten on your measuring?
Under 1 micron R&R on your "instrumental microscope". That is a big problem on a round part with white light no matter how well collimated.
Deep UV like the semiconductor guys use in that range but that is big dollars.
+/- 5.5 microns is part limit plus on well made tapers now. In the 1970's you had ten times this as usable.
The world has so changed.
We now hold this tolerance on brake rotors and this number would be scrap on a cylinder bore or piston.
Why do car engines, drivetrains now go 250,000, 500,000 miles but as a kid 100,000 was used up and dead?
Older engines had a stamp on the base or pan rail of the sizes to put in during assembly. That is also long gone. Tonytn36 could speak to that.

 

[Milling man]

Seems you know how so why ask here? You seem to have it nailed and that is all good.

I'm sorry, maybe I didn't express myself very clearly.
My question is, what instruments are used to measure the position of cones in the US or the EU? Maybe I just don't know the name of the required device/tool, or the calibers have gone out of fashion altogether, and now some magical thing with lasers is inserted into the cone, which measures everything
Some time ago, for the sake of interest, I tried to find suitable calibers in the USA, Germany or the UK - and I could not, which surprised me very much.
Let's say you are standing in front of a machine with a BT40 cone and you need to measure how far from the front end of the spindle the base diameter of the cone is located (for BT40 it is 44.45 if I'm not mistaken). What tool will you use?

That is a big problem on a round part with white light no matter how well collimated.

Absolutely agree. Measuring knives help a lot with this problem. I'm not sure how these things are properly called in English.

 

[4GSR]

We use an Cameron Ball Gage for establishing the cone diameter at face on parts followed by checking the taper on a comparator. I suppose if you have a CMM, that could be used for checking the taper angle. The Cameron Ball gage can get you within a couple tenths in the imperial world. Not sure how that equates in the metric world. Regardless, I don't believe there is one single measuring instrument out there that can do both measurements needed to qualify a cone to a high degree of accuracy IMO.

Ball Gages

Cameron Ball Gauges Archives - Deterco

Cameron Ball Gauge | Deterco, Inc.

detercoonline.com

 

[Milling man]

The Cameron Ball gage can get you within a couple tenths in the imperial world.

You mean 0,1 inch or 0,0001 inch?

 

[4GSR]

You mean 0,1 inch or 0,0001 inch?

0,0001 inch.

 

[Milling man]

0,0001 inch.

+- 2,5um - very good! I haven't worked with ball gauges before, but this looks like a simple and reliable cone gauge. Thank you!

 

[Milling man]

My friend from Canada helped me a little with the search for calibers, showing at least one manufacturer https://www.kuroda-precision.com/products/data/cat_gauges_morse-taper.pdf

 

[SeikiCorp]

We were making a large batch of 'certified' tooling for a customer and ended up buying a STOTZ Taper Air Gage for the factory in Japan. The old tried-n-true bluing transfer from a master gage was not going to cut it for them.

CAT Toolholders & Spindles | Air Gaging LLC - A Stotz Air Gage Distributor

The Stotz taper gages for CAT (SK) toolholder and spindle tapers checks the diameter at 3 levels and reports the…

www.stotz-usa.com