Matching a Taper?

[warmstrong1955]

That's a neat little gitchie you have earlgo!
Works the same as the ball bearing method, only easier.

I didn't know if I should post a page out of the Machinery's Handbook, so I scrounged this off the webernet:

tapers.pdf

(315.82 KiB) Downloaded 180 times

Bill

[ccfl]

Measuring a taper (in this case, it's the internal taper in the spindle but will work the same way for a part held in the chuck) and then cutting a part to match it: https://www.youtube.com/watch?v=Zz6TqK7fq2g
Measuring starts at 03:00 if you're really impatient.

No math, just measuring amount of taper over a known distance, then setting the compound to mimic that same taper over the same distance. Requires two indicators.

[johnfreese]

Just a hunch: 1 1/2" per foot is a common taper on automotive and industrial equipment. If that is your taper, reamers are readily available. Actually, I could loan you one. It is an old Craftsman repairman's reamer I have had for 40+ years.

[mcman56]

That is great information on measuring tapers. Unfortunately I had no readily available balls or discs of an appropriate size. Since I was already set up and close, I used the Prussian blue method ...really black marker. Using a jewelers head set to watch, I loosened the compound rest and tapped it in very small increments to adjust the angle to cut and try. The tapers matched after a few tries but rereading this, I should have used an indicator to get a rotation measurement. It would have been easier. Thanks

[warmstrong1955]

Well....ya got 'er done.
Kinda skipped over the more regular methods, and right to the Prussian blue & test, but hey....you do with what you have at hand...and as long as ya get there....good!
And...it gives you a reason to go full Steve Graham, and buy some stuff later!!

Thanks for lettin' us know!
Sometimes, results from folks endeavors remains a mystery!!


Bill

[joshuaj97]

If its a light duty situation just for checking ignitions or similar you can get your taper as close as you can without driving yourself crazy and then bore a significant amount out of the center of the taper leaving the ends alone. Example would be if your taper length is two inches long and you'd bore the center 1'' out of it and leave .500 on each end of the taper as you originally cut it, these numbers are just for example, sounds like this would probably be fine for your test bench situation, I've come across this on morse tapers on drill bits and such

[Harold_V]

I'm not sure what that would do for making a proper fit. Whether the center bears, or not, if the taper isn't proper, one end is not going to make contact. That offers the opportunity for the item to oscillate, and it likely will, depending on the load.

H

[Hopefuldave]

If you can mount the flywheel, e.g. on a faceplate or in a 4-jaw and get it running true, you can run a DTI mounted to the toolpost against the taper and adjust the topslide (compound) for no movement on the DTI - to get it on centre height adjust it up and down while in contact with the flywheel taper and look for a minimum deflection, or (less precise) bring the tailstock up to meet it and check it's on centre height - you need the lever / plunger to be horizontal so you're measuring the deflection that matches the taper angle.

Dave H. (the other one)

[AllenH59]

Measuring a taper and setting a lathe by that measurement, and getting a matching taper would be kind of like winning the lottery for me. I have matched a taper, cutting with the compound and careful tool height setting. If that is not perfect you do not stand a chance. After a cut try the taper, and see which end is loose, and correct a small amount for that. When I say a small amount, I mean measuring the rotation of your compound with your indicator at some point, and going the least you can go. maybe .002". Then take another cut and repeat. It will only take a few of these to get the angle correct, then it is just cutting it to depth.