First taper

[DAHoyle]

Probably not a big deal to some of the more seasoned veterans, but I have been wanting to try my hand at turning a precision taper between centers. I needed a 3MT center spindle for my rotary table for a 1911 checkering fixture I have been working on, so I looked up the specs. The biggest hurdle I had to overcome was figuring out how to offset the tailstock the correct amount. I have watched a couple of videos on the process, but all of them required one item or another that I didn't have, so I had to come up with something that would work for me. Ultimately, I cut a bar 10.25" long, and then took the taper per inch and multiplied that by 10. I kind of swagged the numbers because I had no way to accurately measure how far my centers protruded into the center drilled holes, or maybe I was just too lazy to try. In the end, I just called it 1/8" on each end, effectively shortening the distance between centers to 10". That made for some easy math, so I set up a dial indicator and offset the tailstock 0.250 inches, and started turning. I stopped about half way thru, and did a test fit, and it dropped in with a nice plunk, and locked up tight. I managed to knock it back out, hit it with some color and spun it in the bore, and if the contact pattern wasn't perfect, it wasn't far from it. Went ahead and set it back between centers and cut it to the final dimension, re-checked the fit, and called it good.

All things considered, I learned a lot in the process, probably the most important is that it isn't some black magic, but a systematic approach to designing a process that gets you where you need to be. I could have run out and bought some more insturmentation, and I am sure I will in the future, but there was a certain satisfaction from coming up with a plan that made due with what I had.

 

[markba633csi]

Very nice- that is one operation I have yet to do- someday soon
-M

 

[benmychree]

The best thing to have when doing standard tapers is to have a ring gage, I found several of them on E Bay over the years, if you buy a finishing reamer, you can easily make a ring gage to match it, rough bore the gage and finish it with the reamer.

 

[DAHoyle]

The best thing to have when doing standard tapers is to have a ring gage, I found several of them on E Bay over the years, if you buy a finishing reamer, you can easily make a ring gage to match it, rough bore the gage and finish it with the reamer.

I suppose I can add that to the list of other things that would have come in handy today. In truth, it was pretty easy to just do a test fit in the tailstock. I had fully expected that I would have to make an adjustment or two after the test fits, but I got lucky.