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3D printed sand table mechanism

3D printed sand table mechanism
September 23, 2019 01:15PM
An update to this thread: [reprap.org]

After eventually switching from cables to a stacked belt corexy configuration, and a few redesigns of the magnet carriage, changing controller boards, stepping up motor speed by 5x with pulleys and belts, and twisting belts, I now have the sand table running quietly at 500 mm/sec. Poor quality video here. The table is about 2m x 1m and the "printable area" is 740 x 1560 mm. LED lighting is red and blue only, no color changing because I want the pattern in the sand to be the center of attention, not flashing colored lights. The sand is baking soda (sand blaster medium).

Motor speed step drive- one of two identical assemblies:



Here is the A motor side with the Y axis endstop switch:



More details here: [drmrehorst.blogspot.com]

The Fusion360 file for the whole thing is located here.

I'll be building a slightly smaller version of the table with a glass top in the next month or so.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: 3D printed sand table mechanism
September 23, 2019 10:59PM
Video or it didn't happen!

[vimeo.com]

[vimeo.com]

[vimeo.com]


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: 3D printed sand table mechanism
September 24, 2019 03:01AM
Cool project smiling smiley
Why did you use backing soda?


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: 3D printed sand table mechanism
September 24, 2019 05:35AM
Thumb up.

A CAD Japanese Zen garden smiling smiley


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: 3D printed sand table mechanism
September 24, 2019 05:53AM
Very nice.

Next a multi head/gantry system? smiling smiley
Re: 3D printed sand table mechanism
September 24, 2019 03:19PM
That is pretty cool. What made you conceive of this project?

DLC


Kits: He3D K200 Kossel, Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head
Scratch: Large bed Cartesian, Linear slide Delta, Maker-Beam XL Micro Delta
Re: 3D printed sand table mechanism
September 24, 2019 05:41PM
I'd seen other people's sand tables for a couple years and wanted to make one for the Milwaukee MakerFaire. After I built my corexy printer I thought that it was so easy I could probably make a sand table using a similar mechanism. Then I was at the local makerspace-friendly scrap yard and saw that they had a bunch of 45 mm t-slot. I spotted a door made with a t-slot frame with a plastic panel installed and decided it was time to build the table and that that door would be the top cover so that would be the final size of the table. The rest was pretty easy...

I use baking soda because it is pure white, has pretty uniform grain size (though the stuff I'm using is getting old and a little lumpy), and is cheap in large quantities. I used sand blasting media, but I think food grade stuff is finer grained. I haven't weighed it, but it seems the ideal amount of sand for the table is 5-7 lbs. It seems that the sand depth about 1/4-1/3 of the ball diameter makes for the cleanest looking patterns.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: 3D printed sand table mechanism
November 07, 2019 10:09AM
Update:

From day one running the sand table, using Sandify to generate the patterns, I found that the ball often spends too much time going back and forth, and sometimes round and round, along the edges of the table. I wanted to write a program to post-process the gcode pattern files to eliminate all that boring, time consuming, unnecessary motion. I spent months thinking about how to locate transitions from the table to the edges, etc., and got nowhere because it just looked too complicated. Then I decided to try editing a few files manually, just to take out the back and forth motion along each edge. It's a pretty easy process- just look for long sequences of G01 commands that contain the minimum or maximum X and Y values for the pattern/table, and cut out everything after the first one and before the last one- i.e. there should be no strings of commands along any one edge that is more than two G01 commands long.

I tried the edited patterns on the table and it was a huge improvement. I decided to write a program to automate it. I got a book on Perl programming and spent about a week working through examples and problems, then wrote the first part of a program to optimize the pattern files for the sand table. It worked extremely well.

Looking at the trimmed pattern files I noticed that they now contained sequences of corner moves. The corners were in the files the whole time, but separated by all the back and forth crud that was now eliminated. So I decided to attack the corner to corner sequences.

The result is that I can now edit the files to eliminate all that unnecessary motion. It literally takes under 1 second to edit even the largest pattern file. The result is a much better table-watching experience and less wear and tear on the table mechanism.

Details and a link to the optimizer program are here.



Edited 2 time(s). Last edit at 11/07/2019 12:09PM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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