ERC TimSav - Cheap DIY CNC Foamboard Cutter

With the Z axis stepper instead of the servo, does this allow you to use standard GRBL firmware if you wanted?
Almost sure the answer is yes. However I don't have this cutter anymore - I built it for someone and sent it off. I know it wasn't anything custom, cuz I'm not that talented!
 

Foamforce

Elite member
Almost sure the answer is yes. However I don't have this cutter anymore - I built it for someone and sent it off. I know it wasn't anything custom, cuz I'm not that talented!
Cool! I’d like to have get an offline grbl controller for mine. Something like this.


But that runs on ESP32, so I can’t run the TimSav’s custom GRBL firmware on it. I was thinking that if the Z axis acted like a normal CNC machine, then we could use a standard controller like this. What do you think?
 

Dudley1001

Member
you would have to use standard grbl but would also have to use an alternate gcode generator as the servo is actually controlled by the spindle speed command rather than the z axis control. Something like estlcam software
 

Foamforce

Elite member
you would have to use standard grbl but would also have to use an alternate gcode generator as the servo is actually controlled by the spindle speed command rather than the z axis control. Something like estlcam software

Are you sure about that? I know that some people use LaserWeb to generate the gcode and I assume that it generates standard gcode. I thought the change to use spindle speed to control the servo was the custom modification to GRBL that TimSav uses?

I know just enough to tinker, but I don’t understand all the moving parts. 🙂
 

Dudley1001

Member
There is also Fluidnc firmware for esp32 control boards and there is a offline controller called Fluiddial. I am using a MKS tinybee on my erctimsav with needle cutter and laser. I am building the offline unit fluiddial on the "cheap yellow display" fluiddial
 

Dudley1001

Member
Are you sure about that? I know that some people use LaserWeb to generate the gcode and I assume that it generates standard gcode. I thought the change to use spindle speed to control the servo was the custom modification to GRBL that TimSav uses?

I know just enough to tinker, but I don’t understand all the moving parts. 🙂
Forgot that yes laserweb4 has an option for z axis but the inkscape plugins for erc timsav will not work.
 

Dudley1001

Member
the use of arduino uno's for grbl powered cnc machines is quickly running up against the available memory on the 8 bit processor. The stm32 and esp32 are quickly taking over and even the new Arduino uno r4 is switching to a 32 bit processor with much more memory and faster processor. There are also new boards that use the cheap raspberry pi pico as the heart of the board and cnc software is being ported to run on them
 

Dudley1001

Member
Fluidnc supports servo as z as one of the standard selections and has a built in webpage ui that you can control from a laptop or phone. The MKS tinybee can be had for about $20US Fluidnc wiki
 

Merv

Moderator
Moderator
...I’d like to have get an offline grbl controller for mine....
Here is the one I use.
Now I generate the Gcode file, stick it in the controller & hit start.


Here is how to hook it up.
 

Foamforce

Elite member
Here is the one I use.
Now I generate the Gcode file, stick it in the controller & hit start.


Here is how to hook it up.

Sweet, that’s EXACTLY what I needed! One question, with this, can I continue to generate my gcode the same as before, using the Inkscape plugin? That sender just takes the commands from the gcode and sends them as GRBL instructions, but it doesn’t really care what they say?
 

Merv

Moderator
Moderator
Sweet, that’s EXACTLY what I needed! One question, with this, can I continue to generate my gcode the same as before, using the Inkscape plugin? That sender just takes the commands from the gcode and sends them as GRBL instructions, but it doesn’t really care what they say?
As far as I know, yes.
The sender reads the gcode from a sd card & sends it on.
 

Foamforce

Elite member
I got one of those GRBL control boards ($15!) and hooked it up. Initial impression was very good. It worked right out of the box.

Now I’ve run into an issue that I’m hoping someone has seen. I was cutting some Chinese lanterns yesterday to test it, and on two of the complex shapes, it omitted several of the points. For example, one shape is a snake. I think it has about 30 points. After it got through about half the snake and was about to go around and do the other side, it just went straight back to the initial point, as is if just skipped the rest of the steps in the cut. It did the same thing in another complex shape. Everything else seems to work fine.

When I look at the gcode find in GRBL sender, the preview correctly shows the entire snake, so I believe the gcode is correct. Tonight I’m going to try to cut the same thing from the computer and see if the issue happens to be in the GRBL Arduino firmware. My only guess at this point is a memory size limitation or something, although I’d think that I’ve cut things this complex before.

Any thoughts?
 

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Dudley1001

Member
I got one of those GRBL control boards ($15!) and hooked it up. Initial impression was very good. It worked right out of the box.

Now I’ve run into an issue that I’m hoping someone has seen. I was cutting some Chinese lanterns yesterday to test it, and on two of the complex shapes, it omitted several of the points. For example, one shape is a snake. I think it has about 30 points. After it got through about half the snake and was about to go around and do the other side, it just went straight back to the initial point, as is if just skipped the rest of the steps in the cut. It did the same thing in another complex shape. Everything else seems to work fine.

When I look at the gcode find in GRBL sender, the preview correctly shows the entire snake, so I believe the gcode is correct. Tonight I’m going to try to cut the same thing from the computer and see if the issue happens to be in the GRBL Arduino firmware. My only guess at this point is a memory size limitation or something, although I’d think that I’ve cut things this complex before.

Any thoughts?
post up your gcode and maybe someone can try it. Mine is in the garage and its -28C here right now so it will not be me :(
 

Foamforce

Elite member
post up your gcode and maybe someone can try it. Mine is in the garage and its -28C here right now so it will not be me :(
Well, I don’t think it’s the gcode now. I tried the same cut three times in a row tonight. The first time, it failed early in an entirely different cut. The second time it it stopped completely about a minute in. It was starting to seem like data errors. It was in the same cord as a fluorescent light, so I turned that off. Then it made it through most of a large sheet, but still with two small errors.

Tomorrow I think I’ll try a different power supply. I have a good power supply for the shield, but I have a super cheap 12v brick for the Arduino right now. Maybe that’s causing issues.

I do love not having to hook my computer up to it! It will be wonderful if I get this part nailed down.
 

Dudley1001

Member
You should not need a power supply for the arduino if you have 12v going to the blue connector on the shield. It will power both boards. Are you powering the servo from the shield? I would run the servo power from the servo tester and just run the signal wire to the shield. If you get any servo binding it can brown out the arduino and cause a reboot. Ignore the green arrows in the picture.
 

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Foamforce

Elite member
You should not need a power supply for the arduino if you have 12v going to the blue connector on the shield. It will power both boards. Are you powering the servo from the shield? I would run the servo power from the servo tester and just run the signal wire to the shield. If you get any servo binding it can brown out the arduino and cause a reboot. Ignore the green arrows in the picture.
That’s what I thought it would do, but when I powered up the shield with 12v, it didn’t power up the Arduino. No light on the Arduino and no voltage on the 3.3 or 5v pins on the Arduino. So then I figured that the Arduino must have been getting powered by USB previously.

I originally had this wired according to the original schematics, which the power coming through the Arduino to the shield. Later, I did the mod to power it via the shield instead. The servo is already directly powered from the ESC.

Hm, so the shield was supposed to power the Arduino huh? I wonder if maybe one of my components went out. It had been working flawlessly for a year and then started having intermitted issues recently. Is the shield supposed to send 12v to the Arduino and the Arduino steps that down to 3.3 and 5v?
 

Dudley1001

Member
Yes just 12v will be supplied from the shield to the uno and its 5v and 3.3v regulators take over from there. If you look at the shield its just a pass-through board with almost no components on it so if you are not getting the 5v on the shield pins then you probably have a bad uno. The uno voltage regulators are pretty small and may even have thermal protection built in which can cause reboots. The big problem of powering through the uno is the diode on the power connection is only rated at 1 amp and can burn up under load so your servo and steppers can put a pretty high load on it. Also if you are buying a new uno, look for one that has the 16u2 chip for the usb rather than the ch340 as they seem to have less dropout problems. If you look at the picture the chip circled is the ch340 while the 16u2 will be a smaller square chip. Also be aware that moving the gantries by hand can destroy the stepper drivers and even the uno so if you are moving them do it very slowly or use the jog commands in the grbl control software ( the stepper motors act like generators and the back voltage is what fries the drivers)
 

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Foamforce

Elite member
To be clear, I’m powering through the shield with a good power supply, so I was under the impression that should save the diode. It’s possible that moving the motors may have burned it out though, although I was aware of that issue and moved them slowly. I wish it had some sort of return home function so I wouldn’t have to move them by hand. I previously would unplug both motors to move it, but that was a pain.

Well, I have another off-brand Arduino that I can try. I’ll give that a shot and report back. Thanks for the tips!
 

Dudley1001

Member
I added endstop switches to mine so I do have the option to do a homing cycle if I have a problem but that only works if you have a worktable set out where the 0,0 position doesn't change. The diode should only have a problem when powering through the uno so probably not your trouble. I would guess its the regulators. My timsav is double duty with a laser and I have gone to a MKS tinybee 3d printer board and fluidnc which is a grbl for esp32 processors. There has been more than a few that have had weird dropouts with the uno's especially the cheaper clones. Some work great and others are duds. The true Arduino uno's seem to be close to bulletproof