# Short Taper Gauge (to measure lathe chuck back plate tapers)



## RobinHood (Dec 26, 2021)

Alex just posted a video on how to measure short (internal) tapers - like the ones we have on a D1-X lathe chuck back plate for example. Quite ingenious design (as usual when he solves problems…).

It basically consists of 5 ball bearing balls arranged such that 4 are tangent to both reference surfaces at the same time and the 5th one is tangent to one reference surface 180* from the 2 “base pairs”. A DTI is then used to measure the second reference surface at the 180* location. It is not an absolute measuring tool, but rather a comparative one. Therefore one needs to have a good fitting back plate to begin with. But it does allow the machining of a duplicate plate to very close tolerances. I also think the taper angle needs to be known and set precisely - should be possible as D1-X specifications (or other spindle nose designs) are universal / well defined and the angle can be set accurately with a sine bar.

As a bonus, he also shows his version of a tapping head and a chamfering tool.

Here is the video link:


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## Darren (Dec 26, 2021)

Love his videos, he also has the same lathe as me.


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## RobinHood (Dec 27, 2021)

Yes, he is quite the character. Just an incredible mind as well.


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## PeterT (Dec 27, 2021)

Yes lots of innovative ideas there. The chamfering tool is quite trick. I like how he adjusts the guide pin & that then increases/decreases the chamfer distance. Another good idea is a completely sealed spindle cartridge as opposed to an electric motors like a die grinder which typically has vents. Chamfering makes a lot of little swarf chips & they don't play nice with motor windings. My homebrew chamfering machine is reasonably well sealed but I still have to keep an eye on it. Here is the Biax, I bet its spendy. And then you also have a compressor running so choose your poison.




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						Straight Spindles - R 3040 - 40.000 1/min - BIAX
					






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His self feed tapping method is exactly the principle what I was envisioning for my lathe tailstock. It relies on some variation of reasonably close fitting spline/socket geometry so it can slide but resist torque. My plan was to 'build' a nicely fitting square socket from 4 pieces of rectangular steel material & use something like O1 square stock for the tap carrier slide. I think its project ID# is in the 200 series lol


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## Dabbler (Dec 27, 2021)

one of the smarter youtubers out there.  He helped me fall in love with Mikron mills.


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