turning a TRIANGLE rod from a round rod on the lathe ???

M

Mutt

Registered
Registered
Joined
Aug 16, 2014
Messages
366
Has anyone ever seen this? A few years ago, I made a handful of these little parts.
C360 brass rod, 3/16" major, o.d. .112" minor o.d., the .112" was about 7/8" long. It's a primer pin for a 50's Harley carb. I had no problems making them on an old worn out Empire turret lathe.

This time I was using my Grizzly 4003. Ran a couple of shallow passes on the first one, got to looking and the part is TRIANGLE shaped !!!!!!!!!!!!!!!!!. Tried another and got the same thing. even tried using a live center. Still not round. What causes this? I need to make these parts so they can go out to the plater with the rest of my stuff. Ideas?
 
Is it in sync with your chuck jaws?

Sounds like a case of sprung chuck jaws. May try a bushing say 3/8" OD with 3/16" ID by say 1/2" long and chuck the material in this. Will reduce the issue of the material "bouncing" or "flexing" in the chuck jaws.

Ken
 
Nope, everything else I have turned is round, only this brass is doing it..
 
What size chuck? 3/16" might be near the minimum for the chuck.
 
Your jaws are sprung. Look real close at the jaws when clamped on the rod. I used to have a old worn out 3-jaw chuck that would do the same exact thing on small work. Chuck was replaced and the problem went away.
Problem usually does not show up on larger OD material. Also have remember, some brazing rod brass is almost full hard and is hard to get it to cut, especially if you are using insert tooling.
 
the problem with that is, the chuck on the Empire lathe was old as the hills and it worked fine and I just replaced the original 18 year old Grizzly chuck with a brand new 8" chuck with hardened reversible jaws less than 6 months ago. So what does "jaws are sprung" mean. Are ya saying I need to buy new jaws ?
 
With more clarification that it was a reasonably new chuck that did this, still believe the jaws are not holding the stock squarely and evenly. Try making a short sleeve as I mentioned above to hold the stock while machining. Another thought is get a hex collet block with a 3/16 collet to hold material with. Last would be use a collet attachment on you lathe if one is available.
 
Is it possible that one jaw is not parallel to the others?
 
You must log in or register to reply here.
Back
Top