Why is my 7 x 12 lathe off from left to right?

[Neblinc]

I am turning this 7" piece of .75 12L14 steel down to .687 and it is off by +.015 on the right side.
What would cause this? I am taking off around .005 every pass.
This is not a critical part, just a bushing for a tractor seat.
Any ideas on adjustments I need to make?

Randy

 

[schor]

You need to adjust your tailstock.

 

[KMoffett]

Google: "Two Collar Lathe Alignment"

Ken

 

[Neblinc]

Thanks guys!!
Going to watch some videos now.

Randy

 

[pdentrem]

Since the right side is + .015 move/pull the tailstock towards you by half the error. That will get you close, after that do the two collar test bar to get things right. Make new marks for when the tailstock is properly lined up. This happens to everybody at some point!
Pierre

 

[David Kirtley]

I just did mine the other day. If it is too big, the tailstock is too far back (away from the cutter).

If it is too small on the end, it is too far forward.

Before you get too much into it, put a dead center in headstock and tailstock and bring them tip to tip and see where you end up. Also check with the quill both retracted and extended.

To adjust, there is a set screw on the outboard end of the tailstock and a socket head screw on the bottom. The general idea is you take the set screw mostly out, loosen the cap screw on the bottom a little and gently move the tailstock until it aligns with the spindle. (I used a small brass hammer with light taps) Match up the points and tighten the set screw to hold it until you can snug up the cap screw below. I got lucky and set it close enough for me just aligning the centers. To get it perfect (as much as possible) you turn on both ends of the bed and keep moving and testing a little at a time until it is as close as you can measure or have the patience for.

 

[12bolts]

Put a centre in your lathe spindle, and then run the centre in your tailstock up against it. Do the 2 points meet together? If it looks ok, then pinch a ruler or similar between the 2 points. If they are off the ruler will not sit perpendicular.
If that test shows they are on centre it may be necessary to run a bed alignment test. Try the simple check 1st.

Cheers Phil

 

[Neblinc]

Sheesh!! I pulled off the tail stock off to take a look at what was going on and the alignment screw was loose!
Dang operator error. I hate it when that happens!
I know I had put 2 centers together when I first got the lathe to make sure they lined up and probably forgot to tighten things up.

Thanks everyone for helping me out! Gotta love those simple fixes!

Randy

 

[schor]

I always check my alignment when turning something long. Get a full clean cut then measure, use a dial indicator to adjust the tailstock. Take another cut and see if your close enough for the job at hand.

ie; I did a drawbar for my mill and was .0035 out over 18", but that was close enough as I was only threading maybe 2" of it at the end. Sometimes even if I don't need to I will make the alignment.

Checkout my youtube if you want to see the drawbar build.