HAL code for hobbing

I have been working on a hobbing setup for my vertical mill based on:

wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing
by Andy Pugh.

I asked Andy for some help on his Youtube channel. In his reply, he suggested I post here. So let me re-start the thread with my questions, his answer, and my response:

Dear Andy:
Greetings from an apologetic admirer. You posted your LinuxCNC hobber 7 years ago and I am afraid it has caused you much inconvenience from people like me ever since. I have been struggling with wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing for about a day now and am pretty stuck. You are pretty much the only resource I can find on the net for hobbing with LinuxCNC so like my occasional predecessors in the last 7 years I am turning to you for help.

I thought maybe I could be more helpful and less of a burden if I could suggest a couple of clarifying questions about this entry so that you might be able to make a few small changes to the wiki that would make cries for help like mine a little less frequent:

1) your original post of hal commands was for integration with a Pyvcp panel. It is not clear whether some or all of the hal code is still relevant to your new Glade panel or whether, when you say: "You would need to hand-craft the HAL to suit your machine." that means modifying this code or starting from scratch.

2) hobbing.hal from your zip file seems like and addition to, rather than a replacement for the hal code in the wiki. Whether I put it in my hobbing.hal or custom_postgui.hal I get an error. EMC does not recognize hobbing.teeth which I assume is a variable passed from the python script.

3) at the top of the wiki you say that posgui.hal [sp?] should link the selected tooth count to invert.0.in. Later you say that postgui.hal should link invratio to invert.0.in. I have written a one line custom_postgui.hal file that says: linksp invratio => invert.0.in. Is that correct? are other lines required? would you be willing to add a postgui.hal file to your zip of the other four files?

I am not expecting a lengthy reply to this rather wordy message. Just hoping that if you could clarify these points in your original posts, I might be able to muddle through and you might be less troubled by those seeking help with hobbing.

Many thanks,
Jonathan Herz
herzmusicbox.com

Andy's reply:
The zip file is the extra bits you would need to add to an existing config to make things work. The problem is that with so much hardware out there nothing is universal. My own machine is using a 5i23 and a 7i49 with resolvers. I know that at least one other person is using the same setup, but it's not common. Can I suggest asking the questions at forum.linuxcnc.org ? That's a much better place for this sort of discussion (and I do read every post, I won't miss it) .

my reply:
Andy:
Thank you so much for your very speedy reply!

I do realize that there is no universal solution. I have tried to keep my questions away from the specifics of my encoder and driver. My spindle encoder is already working for G33 tapping and all four axes work. I think my questions relate to how the HAL communicates with the python script and the VCP.

When you say that the zip is "the extra bits you would need to add to an existing config to make things work", do you mean that I can ignore the code on the above wiki page and replace it all with just 5 lines of HAL code from your zip file?:

net ratioinput hobbing.teeth
net hob-direction hobbing.right
net cool hobbing.cool-on => halui.flood.on
net cool2 hobbing.cool-off => halui.flood.off
net saturated pid.3.saturated hobbing.saturated

where the existing config is the HAL and ini files for a working 4 axis machine with spindle encoder??

thanks to all for your time and attention.
Jonathan

Hi Andy,
Do You remember any updates regarding helical cutting? That seems to be integrated in the gui but not further.
Thanks