How to setup stepper motor as spindle?

[bebob1]

I am completely new to EMC2 so I have no clue what I am doing yet.

I understand so far that steoconf, the simplfied wizard, cannot setup stepper spindles?

How do I go about doing this? I read something about changing hal, but its not very precise and I am not sure where to start.

Essentially I want to occasionally mount a stepper to drive the spindle of the lathe instead of a DC motor from time to time, so as to allow me to do threads correctly without retrofitting an encoder since I have no parport pins to input that data for EMC2 to read the actual spindle speed.

[svenakela]

Hmm... How come your parport is full, on a lathe?
A stepper conversion sounds way more time consuming than an indexing encoder setup.

[cyclestart]

Have you ruled out single pulse threading ? Adding a stepper also takes up pins ?

I haven't tried this myself so can't offer a how-to but it is the next mod for my 4th axis (currently only a spinner)

[bebob1]

I dont mean to say it is full technically. But I have no other way of accessing the unused pins since I dont have a breakout board and the parallel port cable connects direct from computer to commercial driver. No breakout board in between. The drive takes up 4 axis driving but there is technically some unused pins.

Short of this, I thought an easy way for me is to just swap steppers from mill to lathe. However I since lathe motion only requires 2 steppers and I have a spare, so might as well pop that into the mix as a spindle from time to time to allow for threading.

Question is how to set up HAL to do it? complete noob at it.

[cyclestart]

This could be done by using a 3 axis configuration and some G01 moves. Think of the spindle stepper as another linear axis and proceed as if cutting an angle in a 2D plane. A thread is really a ramp that happens to go around a cylinder. It's not an elegant solution but it's probably the caveman way I'd approach it. (also because I don't have a clue how else to do it )

Look near the bottom of the page in this link:
Projects 5
if my memory is working properly that's the method used to cut those threads

just tossing out a possible, and possibly ugly, alternative.

[cyclestart]

Faulty memory, he did program as A axis.
Gcode can be found in this post:
http://www.cnczone.com/forums/307081-post173.html

Treating as linear moves would also work, pretty sure.
The hot set-up would be a servo motor but more $$$$ and complexity.

Hope you find the answer to the original question.

[chester88]

Here is a thread on the subject in the linuxcnc forum:

Configuring a stepper as spindle motor - LinuxCNC Support Forum

you will need to hand edit the config files.
it involves connecting a step generator component which is in _velocity_ mode to the parport and to linuxcnc's spindle speed control.