Ask Grbl CNC questions here.

Possibly, but I don't think so. I'm the only person that operates the mill and my standard offset for Y-Axis is -1270 and now I use -1170. *Shrug*

 

You guys aren't going to believe what my issue was. My vacuum hose came slightly off of its bungie-cord hook and was in front of where the Y-Axis limit switch is used to hitting...

 

Hi Sonny, thanks for this thread. Do you know if an Arduino Nano (CNC shield v4) is fast enough to run 3 axes at 64x overstepping? (TMC2209 drivers)
If that's more steps per second than it can handle without skipping steps, could someone suggest what a reasonable number would be, please?

I realise steps/second is reliant upon how many mm/second you're trying to achieve, but it would be great to know if anyone's run into limitations. This will be my first CNC machine build, so it's all completely new to me.

Thanks for reading this far!

All the best,
Dax.

 

Thanks David, that tool looks excellent. Cheers for putting it on my radar!
And good to know about the 33kHz step rate. It seems fairly low, but these Arduino shields are so darn cheap, so that's fair enough. I have a DLC32 (ESP32-powered) board on its way to me that can do about 88kHz.

 

Hey Gary,
Thanks for your reply. Good question. I assumed that since the Trinamic drivers boast being able to perform up to 64x, higher must be better, though I can now see it's highly dependant on the controller you're using and the speeds you've planning to hit.
I've configured my setup for 16x now and will see how it all runs when the spindle arrives.

All the best!
Dax.

 

If I've read the datasheet right, at 16x microstepping you will benefit from the drivers ability to use interpolated microstepping, meaning you will actually get up to 256 x microstepping. This is not limited by the step rate limitations of the Arduino, as it is implemented within the driver circuitry.
The TMC2209's limitiations are probably the current handling at 2.8A (peak current) max, but I have the TMC2660 drivers in my Duet2 controller, and I can assure you they do not lack torque at 16x microstepping with peak current limiting set at 2.4A.
Alex.

 

Hey Alex, thanks for taking the time to look through the datasheet.

I've picked up 3x TMC2160-OC drivers on AliExpress for £30 delivered and they're rated to 4.33A, so I'll swap out the TMC2209's when the new DLC32 controller board arrives.


That's interesting about the 2.4A steppers you're running. Do you know what torque they are and do you do much aluminium? That's what I want my machine for and I was thinking I'd have to upgrade to 115mm long 4.2A NEMA23 steppers to be able to handle it, though I'd love to save some cash (and space!) by using a smaller stepper. The ones that came with the CNC3040 are babies (57x41mm)

All the best,
Dax.

 

If you have the option/space to put NEMA 34 motors rather than the longer NEMA 24 use the 34. I did and I'm happy with it. Lower amps than the 24 and lower inductance but way more torque.

 

Hey Justin, thanks. I think 86x86mm wouldn't be possible. NEMA 24 (60x60mm) seems doable, but I can't find anything that compares price-wise with NEMA 23 motors.

 

Hey Giarc, thanks for that information. I think I won't need to go for the massive ones I was looking at. Cheers!
Dax.

 

Sorry about the delay in getting back to you - had to check what size my steppers are - they are 175oz/in. I do a fair bit with aluminium, mostly things like plates for upgrading my machine. When I first got my machine I stupidly left a G cramp attached to the spoilboard, and jogged the machine straight through it. It didn't even hesitate - just ripped part of the 18 mm thick spoilboard apart, so I've never had any doubts about the torque available with them. An example of a milling job in aluminium in the pic.

 

Wow, Alex, that's exactly the sort of thing I'd be hoping to do with my CNC. That's insane that it was able to rip through it!
This is invaluable input, thank you so much for taking the time!

All the best,
Dax.

 

Hey Peter. Thanks for that very interesting information. I wasn't aware that I needed to be looking at more than just torque ratings.
I won't ask more since it's probably outside of the scope of this forum (and certainly this thread, so thank you for enduring my tangental wanderings), plus I'm working on a hobby CNC3040Z that I was given. Well, I've beefed it up like crazy (1.5kW spindle, soon adding a 15mm mild steel bed, etc), but it's still my first CNC.

Thanks again for the GRBL support, too!

All the best,
Dax.

 

Hello,
I have a 4 axis grbl version running on my arduino uno.
I would like to rewrite the program so that I can also perform a homing cycle on the 4th axis.
My problem is that I don't understand the pin numbering of Grbl.

For example at "#define Z Limit Bit 4 // uno digital pin 12" the z limit bit is at my arduino the pin input 12 but written is 4.
Now how can i change for example the input to digital pin 13 ?

I am a complete beginner in programming and would appreciate any help.

With kind regards
Tim

 

Hey guys,

I'm having a new issue where my machine is hitting its limit switches when homing but in its "head," it is still moving past them up until it reaches an outer limit and I am stopped by an Alarm 9 (Check Limits). This only occurs for the X and Y axes. I've made sure there are no obstructions on switches, physically, and that everything is clean (I've had an obstruction issue in the past).

Soft and hard limits are enabled and my pulloff distance is 4mm, but I don't think these should affect anything with respect to this issue, right? Normally, the X and Y axes are at 1290mm and 1270mm respectively but the machine "keeps going" (at least it thinks it does) until beyond 3000mm on each before the alarm triggers.

Thanks,
Zach

EDIT: Well, now it appears the Y-Axis is not moving at all so I'll be trying to fix that first haha

 

Alright, so I fixed the Y-Axis not moving. The piece which connects the cork-screw looking rod (which moves the axis) to stepper motor #2 (unsure what this part is called if anyone could help) was detached. Now, it all moves, but the Y-Axis doesn't want to stop despite hitting the limit switch and hard limits being set to ON. Going to sleep on it over night and come back to it tomorrow.

 

They are definitely wired correctly as this is only a new issue after a month of uninterrupted heavy milling. I didn't know about the troubleshooting tab, though, and will check that out first thing in the morning. Thanks!

 

My Y limit switch is just broken it appears. I don't know how to use the console and the people who set this up (who no longer are a part of this company) made so many modifications to the rig that default commands and the like don't play well. I figured it out by simply pressing the limit switches of all the axes during homing and, lo and behold, the Y switch does nothing. Thanks!

 

i get a no firmware found when I try to connect tothe port. I have tried disconnecting all the wiring but get the same thing. This is a new setup and I have been able run the Hello World several times but get same thing when trying to run it. I re connected the wiring one connection t a time but no change. What can I do?
bhemp

 

I am using a new lap top with a black box with 4 nema 23 motors using 2 motors on y axis one connected to y2. I think this started after hooking up a limit switch on x and one on one of the y motors. I have them unplugged but get same no firmware found or no supported firmware found. Both limit switches indicator lights came on when tripped. I have tried several usb cables with no change. I do appreciate the fast reply. I am more of a woodwork person than electronics. I have built store displays out of wood and acrylic for years and can usally follow directions on the electronics without much problem, but can't resolve this problem so I appreciate all the help.
bhemp