mini lathe producing taper when turning. what could be wrong?

[rkovvur]

Hi all:

I have a 7x10 mini lathe.

I am trying to use it to turn down a 6mm diameter drill rod to 5mm.

So i chucked in the drill rod in the 3 jaw chuck and used the tail stock at the other end to prevent rod deflection.

However when i turn down the rod, the end closer to the tailstock has a diameter greater than that at the chuck end.

That means that the rod has been tapered.
I am still a newbie at the mini lathe and right now am clueless as to what might be causing this tapering. i dont see any play in the carriage or cross slide.

Help!!!

raj

[WaveDude]

Align the tailstock--PITA. Search the web for Rollies Dad's Method. The Yahoo 7x10 and 7x12 mini-lathe groups have a wealth of info. Also look at http://www.gadgetbuilder.com/ for a good write up.

[rkovvur]

Thanks!. will read up on the tuning

[diecutter]

A quick way to get it adjusted close (til you can tune it up properly) is to adjust the tail stock towards the operator one half the difference in diameters.
Or you can cut and adjust the tail stock set over till the front and back diameters of the rod are the same.

[rkovvur]

yea, looks like i am not the only one running into this problem

http://www.cnczone.com/forums/archiv...p/t-43400.html

[blades]

I believe any on-the-fly adjustments done to the tailstock would best be done with a slightly larger diameter and softer material, so as to minimize any tool deflection.

[neutronics]

The 7x10 was my first lathe and mine turned taper out-of-the-box as well. The tailstock on mine was WAY out. It does have adjustment screws but they are hard to find (covered up by that thick globbered-on paint).

The lathe is also relatively flexible so when turning without the tailstock you'll have to compensate for workpiece flex as well as machine flex.

It's a good machine to learn on because you'll have to focus on setup, setup, setup!! I suggest getting the follow and steady rests. They only fit 1" workpieces but you can go much larger if you are creative. I turned 3" by C-clamping a 1-2-3 block to the bed and putting the steady rest on top of it. Not pretty but worked great!