Polar sand table - Arduino

jeffeb3 · February 8, 2021, 3:31am

I think there will be some basic electronics instructions soon on the sandify wiki. But something very basic. And I think the next version of sandify will have scara output (well, this goofy scara output anyway).

I can’t help with stls or mechanics.

ArthurvonWilcke · February 8, 2021, 3:50pm

Hey Antonio,
I think I can help you out with some of your questions.

If you just want to print the files you can download them directly from Rob Dobsons project.

I used the files from Matt G so I could edit them in Fusion 360 to my needs. If you have access to Fusion I would recommend to use these files as you are very limited with Robs files.
This is the build from Matt its similar but he used other electronics. You can just look at his project to get a better understanding for the machine.

For using grbl and a cnc shield I think you need to ask @vincentbraillard for help as I used Marlin with a Ramps board.

If you have any additional questions just ask them here.

Greetings Arthur

ArthurvonWilcke · February 8, 2021, 4:00pm

After some days I’m back as I just turned 18 on the 5th

Just a quick update on my progress.

The Robot is working great but still, there are a lot of things to do before it is finished.

the magnet is not always touching the underside of the mirror and the ball stops
the belts are a bit loose, that’s why the pattern is a bit off
reprint some of the parts with more precision
build a housing around the table to hide the robot and electronics
mount the LEDs

Do you guys think that the robot is moving too quickly or have any additional advice or ideas for my table?

Thanks!

jeffeb3 · February 8, 2021, 4:49pm

The speed looks about right. It can be tricky to limit speed correctly, because the angles on the motor are not directly proportional to the ball speed. So you need to limit the speeds of the motors when the ball is moving the fastest and just accept it being slower in some places.

antonioasaro · February 8, 2021, 5:28pm

Thanks Arthur!!

I downloaded both Rob’s + Matt’s files yesterday.
I installed Fusion360 and exported Matt’s files as .STL so I’m ready to 3D print.
I think I’ll stick with Rob’s smaller arm set but use some of Matt’s enhancements - e.g. plate space.

One other question (besides using grbl + cnc), can you clear up the comments re: 390mm vs. 400mm arms and the 282mm belt size?
What’s the recommended approach?
Matt mentioned he used 400mm arm + 320mm belt.

antonioasaro · February 8, 2021, 6:16pm

I built the mini CNC plotter from thinigiverse - seach: thing:4607077
It leverages GRBL and UGS works with 28byj’s.
That was the original plan for my sand drawing machine.
That was, before I discovered Rob’s writeup.

I’m having trouble posting a link to a picture.
More of an FYI really.

Miksonhome · February 8, 2021, 9:18pm

I am in the middle of the 400mm RD build and the 320 belt fits. I added an idler arm and wheel to tighten up the belt a bit

Breslauklaus · February 8, 2021, 10:16pm

Hallo Antonio

Wenn du einen Laser zur Verfügung hast kann ich dir meine CAD Zeichnungen geben.

Ciao
Klaus dal AltoAdige

antonioasaro · February 9, 2021, 1:09am

Hallo Klaus,

Leider habe ich keinen Zugang zu einer Lasermaschine. Ich habe hier zu Hause nur einen 3D-Drucker. Danke für das Angebot !!

Ciao,
–Antonio

vincentbraillard · February 9, 2021, 6:11pm

Hello Arthur. Mine run slower. Can you tell me what are you feedrate parameter in Merlin (M203 AND M220)? thank you

ArthurvonWilcke · February 9, 2021, 6:31pm

M203 X0.50 Y0.50
I did not change M220 only M203.

Breslauklaus · February 10, 2021, 12:23am

M203 X0.7 Y0.7
M500 (Zum speichern. funktioniert erst nachdem das Eprom in Marlin config.H freigegeben wird)
Link

servus
Klaus

antonioasaro · February 10, 2021, 1:42am

I’m stuck.

I don’t have access to a laser cutter so I need to print most of the parts.
Meaning, I need a .STL version of the laser cut frame top + bottom.
I tried to pull the Frame*5mm.dxf files into Fusion360.
However, Fusion360 fails whenever I try to export as .STL.
I read the .dxf files into the online dxfconvertor - it outputs a .svg file.
I tried reading that into Tinkercard.
But, Tinkercard displays the pieces that would be cut out - i.e. the holes
Any suggestions?

jeffeb3 · February 10, 2021, 3:49am

You can import them as a sketch into onshape and then extrude them. Onshape has a free version for hobbyists.

Also freecad, or probably openscad.

antonioasaro · February 10, 2021, 4:27am

OK, I’ll give OnShape a try.

I tried FreeCAD with the .svg files.
I followed a guide on the web to convert .svg to a solid.
That worked except that when I was said and done, the top plate looked fine but it was only 4cm wide.
More fooling around is in order.

Thanks for the help!!

vincentbraillard · February 10, 2021, 1:21pm

Hi all. I could be good if more people could try sandypi. I have done hours of test but I have trouble with grbl and Marlin with the serial parser! I have test with many.hardware and style issue. But if more people can done some tests, we could now.if it come by me or from @texx software. Installation is not hard to do. Just need a raspberry pi! Thanks

ArthurvonWilcke · February 10, 2021, 8:32pm

If it does not work I could try to convert the file in Fusion.
I think I could help you with that as I also considered printing them at first.

ArthurvonWilcke · February 10, 2021, 8:34pm

I’m sorry but I can not help you with that problem as I’m trying to use an Esp32 for that.
I also don’t have a Rasberry Pi here to test if it would work for me.

vincentbraillard · February 10, 2021, 10:31pm

Oh ok, so you want to develop your own GUI interface like sandypi?

jeffeb3 · February 11, 2021, 2:20am

Esp32 has a UI, but it isn’t optimized for the sand table. It can also be connected to a pi via usb, and then it looks just like grbl. So you could use sandypi. I have wanted to use it, and help out, but my table isn’t finished, and sisyphus gave me a table for the sandify work.