The Spice Must flow

ZenXY
#1

I built a coreXY sand table for the Milwaukee MakerFaire in September. The table is about 2 m x 1 m and has “printable” area of 735 x 1570 mm, lit with red and blue LEDs along the long sides.

 

makerfaire%2B1.jpg1600×1549

The mechanism is made using 3D printed parts in a classic stacked-belt corexy configuration. It uses a SmoothieBoard 3D printer controller to play files from an SD card. Some details and photos here. I run this table with a 1/2" ball at 500 mm/sec with acceleration set to either 1000 or 2000 (can’t remember the last value I tested). It has NEMA-23 motors because that’s what I had on hand.

I have recently rewired it to make it neater and it’s a big improvement, but I want to do more to make it quieter and more convenient to send files to it and to select files to play:

  1. use NEMA-17 motors for reduced noise and vibration
  2. rebuild the sand box with thinner bottom to allow a gap between the magnet and the table bottom to reduce noise
  3. new controller with 256:1 ustepping drivers to reduce noise and vibration
  4. Ultimately I plan to build or buy a glass top table or just the glass top and then rebuild the whole thing to make it more like furniture.
I am looking for suggestions for a new controller. I'm thinking a Duet WiFi board would do the job, but it's a little pricey. A sand table needs just a small subset of gcode interpretation and 3D printer hardware, so I think there should be a smaller, ultimately cheaper solution out there. Any suggestions?
#2

I have an esp32 grbl board that had three axis and you can put trinamic tmc2130s (not spi, but in standalone mode). It’s working pretty well but I think a pi would be smarter for wifi. This wifi and sd card work, but it’s a bit particular. Octoprint or cnc.js or something would probably be better.

The einsy retro is another good choice, it’s also a bit pricey but would take out a lot of hastle. That, plus a pi would be a great fit.

I would also be tempted by the el cheapo 2/3 channel cnc boards that run grbl from China. That and some standalone tmc drivers would work well.

#3

I’ve redesigned the mechanism in The Spice Must Flow and changed the controller. It now runs pretty quietly at 500 mm/sec.

Changes include installing a Duet WiFi controller with drivers configured for 256:1 ustepping, 1:5 motor speed step up using pulleys and loop belts, and twisting belts to put smooth side of belts on the pulleys. It’s a stacked belt corexy mechanism that uses the slots in the t-slot frame for the Y axis guides and a square aluminum tube for the X axis.

The 1:5 step up in motor speed is needed to keep the table moving fast while the motors turn relatively slowly so they’ll be quiet. At 500 mm/sec, the motors are only turning 1.25 revs/sec.

[attachment file=115275]

There’s a Fusion360 file of the entire table here: https://a360.co/2M6vWPs

Video of operation here:

https://vimeo.com/361955435

https://vimeo.com/361952669

https://vimeo.com/361953455

More here: https://drmrehorst.blogspot.com/2019/09/more-sand-table-updates-making-it-run.html

#4

This thread gives me a phishing warning in Chrome, I guess because of the google groups link (the first image in this thread, which is linked on your blog as well)

#5

I don’t know what’s going on with that. I think it’s the blog link, but the red warning screen mentions google groups. I get that red warning page when I access some of my blog pages.

#6

The first image has a URL of googlegroups, so any page on your blog that has an image from google groups will give the warning.

#7

Why on earth would google’s chrome browser flag all of google’s blogger/groups links as dangerous? I’ve reported it to google at least 5 times, but it keeps throwing up the red page of doom.

#8

I dunno, but now it has extended the “dangerous” flag to all of v1engineering.com for me, which is quite annoying.

#9

I think I fixed the problem. I don’t know why I linked that image from google groups, or why google would flag it and any site with it as dangerous, but I replaced it with another copy that should let the topic open without a red screen of doom. I did the same on my blog page and the red screen went away.

#10

I think I fixed the problem. I don’t know why I linked that image from google groups, or why google would flag it and any site with it as dangerous, but I replaced it with another copy that should let the topic open without a red screen of doom. I did the same on my blog page and the red screen went away.