Logan 11 threading what am I doing wrong.

[danlb]

Yay! That seems to be a common mistake. There was a similar problem last year where the person had a HF 9x20 and was using the apron feed lever instead of the halfnuts. I'm tempted to label all the levers and knobs on mine just to be sure that I remember after a month or two away from the shop.

Dan

[Paul Alciatore]

Using an indicator in this manner may be a good way to verify the thread lead, but you must be sure to take up any slack/backlash in the gear train before you zero that indicator. And also be very sure to take exactly one revolution, not more or less.

I would prefer using a scratch test. Coat the work piece to be threaded with some blue marking die or with a Sharpie marker. Then run the threading as normal, but with the tool set to just barely scratch that die or ink. You can then hold a thread pitch gauge against the scratch marks to verify the pitch. This method will almost automatically take up any slack/backlash in the gears because you start the spindle rotation a turn or three from the beginning of the scratch and it will be more accurate because you will be checking across several threads instead of just one.

A bit of advice.
If you are a home hobbyist with a small machine and rarely single point threads, verify the lead before threading, you have all of the time in the world to do 1 job.

Place a dial indicator in such a way that it will measure carriage travel, place the spindle in gear and engage the 1/2 nuts and rotate the chuck by hand measuring the Lead per Revolution.
In this case .091 per rev.
If the machine will not allow rotating the chuck by hand whilst in gear either because it is to large to rotate by hand or has a spindle brake take a skim cut first and measure the lead.

[Bented]

I have taken for granted that anyone using a manual lathe understands backlash and will remove it accordingly.

One of last weeks jobs, all dimensions on part #1 were spot on, the thread is supposed to be left handed however. Turned it RH out of habit (-:

[boats]

Jobs finished. Probably easier new rod new thread but junk axle on hand already threaded 5/8 11 rusty. Run the lathe properly cleaning up rusty thread easy, but must take the backlash out & make sure you set the tool right.

Boats