DIY CNC Machines

[BalsaMichel]

Hi,

looks good to me, I think this will work.

It´s no problem to use PLA for the 3D printed parts. I have some really old parts here in use, never had issues here with brittleness. Found out if you are using PLA for motor mounts you will need kind of a thermal isolation plate in between, otherwise the PLA transforms into "something a bit liquid"

PETG and ABS will also work of course.

Micha

[Schietwedder]

Yes I have access to print in most materials and they are not to be used in any special environment so I'm quite confident it will work.

Another question:
I have two options with the two stepper motors that both control the X-Axis. I could solver both cables together to make them parallel to one driver on the CNC shield or put the jumpers on the CNC shield to use the "4th A Driver" to clone the X-Axis.
I have instructions for both, which is more clever?

Also I came across microstepping the drivers/motors with jumpers.
How does it work and what setting fits most likely to my machine?
Is it a trade-off between accuracy and speed or what exactly does it affect?
For me being fast is more important than the accuracy as long as it's in a range +-0.6-8mm I'm fine.

Any experience here?
BR Niklas

[BalsaMichel]

Yes I have access to print in most materials and they are not to be used in any special environment so I'm quite confident it will work.

Another question:
I have two options with the two stepper motors that both control the X-Axis. I could solver both cables together to make them parallel to one driver on the CNC shield or put the jumpers on the CNC shield to use the "4th A Driver" to clone the X-Axis.
I have instructions for both, which is more clever?

Also I came across microstepping the drivers/motors with jumpers.
How does it work and what setting fits most likely to my machine?
Is it a trade-off between accuracy and speed or what exactly does it affect?
For me being fast is more important than the accuracy as long as it's in a range +-0.6-8mm I'm fine.

Any experience here?
BR Niklas

Hi Niklas,

the MPCNC (Mostly Printed CNC) guys are recommending serial stepper wiring:

https://docs.v1engineering.com/electronics/steppers/

A seperate stepper controller for each motor will of course also work and if you have it anyway I would do so. Just connect both controllers to the same flange/enable/direction output-pins of your steering (Arduino in most cases). EDIT: Or use the function of your breakout-board.

Choosing steps per rev. is a bit of trial and error and optimization. Don´t forget to switch off the power after a change otherwise the controller might ignore it. I would start with 1.200 steps/revolution for example. You can calculate accuracy with this:

acc = diameter pulley * Pi * / steps per rev
acc = 10mm * 3,14 / 1.200 = 0,026mm per step (for example) ...should be good enough and the limitation of accuracy will come more from your mechanical hardware (timing-belts)

An Arduino (if you are using one) will also limit the max. possible steps but I think you will not reach it with three axis anyway. Just try, you can´t damage your motors/controllers with this. Just check if the motors are too hot after some minutes (50-60° C is okay).

Have fun

Micha

[Schietwedder]

Thanks!
I connected everything yesterday uploaded GBRL MI on the Adruino and tried several homing sequences. (It was suggested in a video to use GBRL MI as opposed to standard GBRL as it should be better working with a servo to raise and lower the pen/tool) I'm not sure though how true that is.

I controlled the machine via the Adruino IDE app.
The limit switches on the Axes though don't work yet or are set up wrong when I tried homing the machine.
The motor did not stop when hitting the limit switch and perform a small bounce as it should.
I don't know yet what the cause is.
I might change from controlling directly over the Adruino App to a more visual software this evening. Came across the free LaserGBRL tool which works more graphically than programming directly in the Adruino IDE environment.

The X Axis did not do anything yesterday by wiring both Steppers together, I will try with a second Driver on A today and see if that was the problem or if it has something to do with my non existent programming skills
Really glad that I built it I learn tons of new stuff every day

[BalsaMichel]

If you´re not getting on with programming, try ESTLcam.

By the way: I never had limit switches. With all consequences of course but I had only a few minor crashes in the last years. The hard impacts will happen anyway by ramming the tool into the basic plate, hard to avoid this all the time

Micha

[Schietwedder]

Hi Micha,
Thanks! The plotter works now perfectly fine, I'm also really impressed with accuracy and speed, better results than I could think of given it was the first try and no prior experience.
I can't share videos yet as my first works are mostly Christmas presents but I will definitely post some stuff next week, then it's probably gonna run 24/7 for a few days plotting kites, sails and sun awnings I already had designed.

My first tests were mostly graphics vectorised with Inkskape.

One thing I need to figure out still is a good MIGRBL tool.
The Plotter runs in MIGRBL which slightly differs in normal GRBL in that the coding Programm writes small "pause" commands after every M3/M5 command lines (pen up/down) as well as limiting the servo movement to a desired angle (90°) in my case which drives the pen mechanism.

For .dxf files from AutoCAD did not try out where I can get a good MIGRBL coding programm, it would work in Inkscape as it offers a really nice MIGRBL coder but I'd rather find a solution where I can directly encode the MIGRBL gcode files and directly insert it in Chillipepr or LaserGBRL tool which I use to control the machine and insert the gcodes.
Otherwise I could also run on normal GRBL language for the .dxf files as then there is endless tools for mills, lasercutters and so on but then have to find a solution to fit a faster lifting device for the pen as the machine instantly moves after M5 or M3 command line or manually recode the gcode files or write an own python script that does that for me.
Let's see what works best.

BR Niklas

[decay]

@BR I have a set of python scripts to run my HPGL vinyl cutter directly from Rhino3d via a serial port connection. At some point I'm going to build a flat bed Lazer to plot and cut kite panels direct from KaroroCAD. Send me a message and I can send you the source code.

Cheers

DK

[BalsaMichel]

Hi Niklas,

I have to admit that I´ve got a bit stuck in the simplicity of estlcam the last years, so you are already far more experienced than me in CNC programming.

...By the way inspiring things what you have in mind here.

Micha

[Schietwedder]

It´s working now fine with .dxf from Surfplan/AutoCAD to Inkskape to convert to MIGRBL language and then plugging the GCODE file into LASER GRBL controller.
Very happy with the machine, plotted around 55m of cloth the last two days for my new 16.5m foilkite design.
Can´t even imagine how much time that would have taken with patterns.
Really glad I did it!

[Schietwedder]

What I will upgrade is a cable carrier outside of the working area for the x axis so I can let the machine alone without bothering to get the traverse/toolhead stuck in the cable.