Lathe Spindle encoder with cheap (max. 50$) LPT Breakeout board

Yes. All the input pins are read at the same time regardless of how many are actually active / used

That are good news! Thanks

You mentioned linear slides. I am not sure that's a good idea. I think most CNC lathes still use normal ways. I think they are stiffer.

Yes, you are right. It will not anymore be that stiff as the normal ways, but i talked with someone here from Poland and he has done it . He has first convert the same machine to cnc on the original ways after they got grinded, but then because of time and costs he decided to rebuild it on linear rails which he has laying around. That are only 25mm rails, but he said even they are not that stiff he is very satisfied. There are a lot of pictures in Polish cnc forum and just after he finished the lathe on linear rails, he took the next (same lathe) and did exactly the same. I think if it would be that bad, then he wouldnt do it again.
Here 2 pictures (if you are interested i can send the forum thread link):
Here is one video where he did an light cut, but he was checking the geometry, so i am pretty sure it not the maximum:

As i saw on google pictures, HAAS use linear rails and they are not the only one. I think they dont use the standard ball bearings linear guide ways, but "roller guide ways" with cylindrical bearing rollers as the Hiwin RG-Series, but i think for an the 30size linear rails are fine, especially if i use 3 carriages instead of 2 per site. Also i think there is no need if making havy cuts on an cnc lathe.

I'm using a home grown 60ppr encoder disc on a sherline tabletop lathe straight into the parallel port, and that has no problems up to the sherline max RPM of 3000. The white stripe is the 1ppr index which uses the standard sherline optical tacho sensor. The black/white sticker on the pulley is the original sherline "encoder" and is not used now.
The sensor is a Honeywell HOA2001 which can be purchased from RS Components and probably many others.
Total cost should be less than $15

Does CNC Threading fine within the limitations of the machine itself - primarily not enough torque at low speeds, which limits both the diameter and pitch of the thread being cut.

verticalperformance wrote: Does CNC Threading fine within the limitations of the machine itself - primarily not enough torque at low speeds, which limits both the diameter and pitch of the thread being cut.

You can crank the spindle by hand. LinuxCNC threading should be compatible with the Sherline hand-crank for threading.

FWIW this video (hexagonal boring) was done with me hand-cranking the spindle for very similar reasons.

Yes, except my spindle encoder gets in the way of the hand crank as they are both mounted on the spindle extension past the pulley

verticalperformance wrote: Yes, except my spindle encoder gets in the way of the hand crank as they are both mounted on the spindle extension past the pulley

Funny you say that. I've got a TCRT500 Infra Red sensor I was going to see if I could use as an encoder on the spindle nut for exactly that reason. It just needs a white line on the rotating shaft. My lathe is a bit bigger than a Sherline though. The spindle nut has grooves in it for a C spanner so I was going to start by painting each groove. One Day....

rodw wrote: The spindle nut has grooves in it for a C spanner so I was going to start by painting each groove. One Day....

Maybe using a tooth detector on the nut would be better.

www.pico-systems.com/bridge_spindle.html