Standalone electronic leadscrew (gearbox) mode for lathe

This is an example of how to configure LinuxCNC to operate as a pure electronic leadscrew (or gearbox) for a lathe, without any CNC function.

Background: While I do some CNC machining with my converted lathe it turns out that in 95% of my uses cases I prefer using my lathe in classic manual mode, especially for quick projects. Until recently I used a custom solution to use my Z-axis stepper and spindle encoder to behave like an electronic leadscrew. While there have been requests to supply examples on how to do this in LinuxCNC I have never seen a working example.

The example consists of a standalone .hal file with a QtVcp based panel and supporting python code and is available here:

github.com/tinic/ElectronicLeadscrew

Hardware used:

- 7i96 Mesa board
- Clone/fake E6B2-CWZ6C Omron encoder
- Two generic DM680T stepper drivers for Z and X axis
- Two Nema 23 stepper to drive Z and X axis

Not sure how interesting this is for anyone here, but I thought I should at least post about it in case someone searches for a solution/hints. Questions are welcome.

Hi ttt
A very big thank you for sharing all of your efforts an the results.
Cheers
Bob

Hi just found your ELS Project. Exactly what i am looking for unfortunately i use the paralelport instead of an Mesa Card.
Will this work with the parallel Port too?
Thanks Michael

It should, You can do almost anything with a simple parallel port system
as you can with fancier hardware, there just will be some limitations
on step rates, PWM rates, and encoder resolution.

i tried to change to parallel poert but getting some errors on startup.
There is a window with this message:Traceback (most recent call last):File "/usr/bin/qtvcp", line 377, in <module>APP = QTVCP()File "/usr/bin/qtvcp", line 211, in __init__window.instance()File "/usr/lib/python2.7/dist-packages/qtvcp/qt_makegui.py", line 178, in instanceinstance = uic.loadUi(self.filename, self)File "/usr/lib/python2.7/dist-packages/PyQt5/uic/__init__.py", line 226, in loadUireturn DynamicUILoader(package).loadUi(uifile, baseinstance, resource_suffix)File "/usr/lib/python2.7/dist-packages/PyQt5/uic/Loader/loader.py", line 72, in loadUireturn self.parse(filename, resource_suffix, basedir)File "/usr/lib/python2.7/dist-packages/PyQt5/uic/uiparser.py", line 1013, in parsedocument = parse(filename)File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1182, in parsetree.parse(source, parser)File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 657, in parseself._root = parser.close()File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1671, in closeself._raiseerror(v)File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1523, in _raiseerrorraise errParseError: no element found: line 692, column 6 

iam not good in programming so can someone help out, please?

Here is whats the Terminal is showing:

Cant post the terminal message. Says: to many links in your Message
What am i doing wrong?

Regards

Hi,
at leats i got i running with my parallel Port setup.
One problem left: 
in the HAL are those  sections one for x and one for z

net x-control-type <= lathe_ui.control_x_type
net x-control-type => hm2_7i96.0.stepgen.01.control-type
net x-velocity-cmd <= lathe_ui.velocity_x_cmd
net x-velocity-cmd => hm2_7i96.0.stepgen.01.velocity-cmd

The problemis in the second and the fourth line
I don´t know how to switch this to the parport stepgen commands.
As far as i understand the Hal those are used for jogging with the cursor buttons, but maybe i am wrong.
Any ideas??

Thanks in advance
 

Will this work with only one stepper (on the main leadscrew)?

Yes but then the facing and taper function won`t work