math and lathe compound Q

[Bob Korves]

Whitmore: that could make a difference!

Bob: interesting, must be a video somewhere on this as hard to envision.

Just three of the many out there, this is nothing new...
http://www.hobby-machinist.com/threads/sine-bar-holder-for-setting-compound-angle.32797/
http://www.frets.com/HomeShopTech/Tooling/LatheSineFixture/sinefixture.html

 

[Jimsehr]

Hi all, I have a bunch of railroad wheels I need to fit axles to. The problem, I just discovered, is the holes are tapered!

So here are the dimensions:

Hole dia. on side facing outboard: 1"
Hole dia. on side facing inboard (where the flange is located) 1 3/16" or 1.1875
Hole depth 1 7/16" or 1.4375

I found an online taper calculator and it said my taper is 1.5652" per foot.

I've got a South Bend 9A lathe but wasn't sure what to set the compound angle to.

After cutting a taper, I'll then need to mill a small keyway, tilting the axle, so I've got some work ahead of me!!

Thanks!

One thing if you are new at this is to get center of tool dead on. Or your taper will not be true. You should also get your indicator point dead on center.

 

[Asm109]

Another trick to set the compound to an exact angle.
Compute the sine of the 1/2 angle of the taper you want to cut. (Details explained by others above)
Multiply by a convenient travel distance of your compound. Say 2 inches.
Example. say I want a 3 degree 1/2 angle.
sine 3 degrees= .0523
2*.0523 = .1046 inches.
Extend the tailstock ram out fully.
Mount a dial indicator on your tool post and place the tip on the side of the ram.
Move the compound slide exactly 2 inches. The dial indicator should move .1046 inches.
Retract the slide, slightly rotate the compound and repeat.
Its just like tramming in a vise on the mill.
Repeat until you are as close as you desire.