I have a new board running GRBL 1.1f . It has 5 driver boards - X, Y1, Y2, Z and A. All works fine.
I want to use A as my 4th axis. It is set up in GRBL ($103 etc. etc.) and I can enter G0 A10 F100 and the stepper on the A driver rotates.
When I go to gSender, searches on Google say I can select between Y axis and 4th axis but I don’t get that choice. It just wants to use the Y axis. Google search tends to indicate this selection came out on V1.4 but it’s not there. I even downloaded the latest version (1.5.7) on my second laptop but the choice is not there.
@iuliancalin That may not be the case. @Lappa says that his board has a motor driver for A. That would equate to the architecture of the SLB. Using the SLB, you don’t select “rotary” in gSender. You select “4th axis”.
However, the SLB is using grblHal and that’s why I asked my initial question. To me, it is contradictory to say “grbl” and 4th axis. However, that could simply be my ignorance. Everything that I have read to date indicates that grbl cannot run 4 axes. That’s why Sienci’s initial setup for the Vortex included a Y/A switch. The grbl Y output was switched to the vortex/A motor, and the necessary firmware settings were changed by setting gSender to “rotary”. The SLB changed all that.
@Lappa Interesting and educational. Thank you.
As I am now runnning the SLB with grblHal, my observations and experience may well not be relevant to you. For me, in gSender 1.4.12, there is a slider choice between rotary and 4th axis. The LB setting was rotary, which transferred Y movement to the A axis. With the SLB, the setting is 4th axis, since the SLB has a motor driver dedicated to rotary.
With the 1.5 series of gSender, it’s my understanding the the default is 4th axis so the slider is simply to change that to rotary.
Thanks again for proving me wrong.
All kidding aside, I learned something new about grbl and UGS. (I started with UGS, but have not used it since the first iteration of gSender.)
I had an interesting 30 or so minutes with ChatGPT this afternoon regarding this problem. Lots of tests of GRBL, entering instructions into the console, some electrical measurements, jumpers on and off, reset buttons pressed and watching Device Manager. Also used UGS, bCNC, CNCjs, Candle as well as gSender,
The conclusion is as follows. The version of GRBL I have is a fork somewhat similar to GRBLmega which Is why I can have a 4th axis. GSender will not work with forks of GRBL - it will only work with “ pure GRBL” re its appearance which is why it won’t display choices for a 4th axis but I can enter commands such as G0 A10 F100 and get the 4th axis - even though it won’t display, it still accepts the commands.
UGS isn’t as fussy so it will happily process and displace a 4th axis if it sees the relevant entries in GRBL settings. It will work happily with GRBL forks.
So the conclusion was that gSender, current,y, will never display any deviations from “pure GRBL” although it may “obey” certain commands. It is not a monumental task to fix this but it appears ( from ChatGPT) that the direction is more towards GRBLHal than making changes to accept GRBL forks.
@Lappa thanks for posting this, Peter. I’ve learned a lot. Before I read your last post, I was about to reply that it appeared the gSender only offered up the 4th axis option to Hal users. It looks like I was right for a change. I did not appreciate why, though. Your explanation shows why I was under the impression that grbl could not operate 4 axes. It seems that, in its “pure” form, it cannot. As I am not a grbl afficianato, I was not aware of “forks”.
In the same vein, I believe that the Hal that Sienci has adopted is not a “pure Hal” either. I think that I’ve read that they are working on moving to a more generic grblHal in the future.
I’ll close this thread, as you have found the reason for your issue and a possible solution.
Thanks again for posting this.
