Crazy Idea: Pen Color Change With E0?

After doing my 4-foot x 8-foot test drawing yesterday with a black sharpie, my wife asked me if I could do different colors. I answered yes before I realized what I was doing and she quickly asked if I could make a banner for the kids’ school.

I know I can separate each color into its own gcode file and just replace the markers before each run, but I then thought about a way to get 3 or 4 markers on the 611 plate and alternate between them. In the Maslow CNC forum, someone suggested the idea of a tilted carousel…


If a stepper motor was installed such that it could turn the carousel, could the E0 driver on the mini Rambo work to turn it to the proper marker. If possible, you would need to do a simple post-process of the gcode to convert the Tx M6 commands to maybe a G0 E0x command where x is the stepper motor position needed for the appropriate marker to be in position…

Am I crazy?

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This should work. I’d love to see it and maybe also adapt something similar for an mpcnc tool mount.

Another thing to consider is perhaps an RC servo which wouldn’t require homing. It might be less precise though, and manually homing a stepper-based turret shouldn’t be a big deal.

I was looking for a way to use what’s left on the controller board. Can you control a servo with something on the board?

It looks like its possible with some pin remapping, using the xmin pin

Not as convenient as the boards that have extra pins everywhere like ramps but it looks like its doable.

I think if you put in a stop that prevents continuous rotation, you could readily home the stepper, like is done for x, y, and z axis. You wouldn’t have to remap anything / change the FW to make it work.

Hardware solution!

I would do a pause and pen swap, but if you are wanting to tinker, the carousel would be super cool to see in action!

If you have a stepper available and a free extruder plug, then yes, it should work.
No need for any homing, just make it so the carousel is blocked by something so it cannot do a full turn.
-Set the carousel driver on a relatively low current
-put some kind of physical stop to prevent the carousel to do a full turn.
-Load your pencils in the carousel
-Now whenever you start a new job, add a little Gcode line to ask the carousel motor to do a full turn
-The carousel will turn until it meets the stopper
-The motor will skip steps until the Gcode command is completed
You are now homed.

This should be very easy to do, that sounds like a fun project actually.

I agree… I think homing won’t be a challenge. Only real challenge I see is figuring out how to mount the thing to the 611 plate. I’ve ordered a small stepper and a flange (for connecting shaft to the carousel)

Pffft… That’s only 4 colors. This one is 10! AND you can have a unicorn!

To stay on topic… how would you set it up so that the one in the middle could touch when the other two couldn’t?

I’m assuming what you have as a straight piece with the pens in it is actually curved? So that each pen is pointing straight out along the circumference of a circle rotating around the stepper?

If that’s the case, then you could expand it to a full circle. Zero the machine with ‘black’ pointing down, and you could put a different color every 15 degrees or so.

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This is sort of what I’m thinking of. I’m better at 2D than 3D drawings… it’s not precisely to scale.

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Here are my tentative pieces to cut from 1/2-inch mdf or plywood. I still need to verify the size of the holes for the sharpies (think they need to be 3/8-inch) and the placement for the two screws on the base (need to get the flat mending plates to check dimensions). I replaced 3 sharpie holes with 1/4-inch holes to pass some bolts through to tie the two plates together. I’ll pass a small dowel through the hole at 11 o’clock on the top plate to strike the protrusion on the stepper support piece… 13 colors if it all works… I’ll have to figure out where to put the dowel so that it blocks a bolt hole and not a pen hole.


Just curious. Could you make the bottom circle larger than the top circle so that the pens were more vertical where they touch the paper? That way the sharpie is riding more on the tip of the brush part rather than the curved sides of the pen.

I guess drilling the holes at an angle would be a pain and probably not worth it.

Maybe this would be more of a ‘phase 2’ design idea :slight_smile:

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I like that idea… V2 :slight_smile:

Probably very doable with a 3d printer though.

Simplest approach would be to treat each color rendering on the banner as a separate file. Then run separate files for each color and just change the pen color between runs.

I think it will be interesting here. :slight_smile:
I hope that you can continue to follow the project to completion and present us with a nice result! :+1:

Sincerely, Pascal

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Yeah, but what’s the fun in that?

I’m curious to see what happens when you draw the crown with the spinner at full tilt.

Could you make the holes at an angle outwards at the bottom circle (or tilted in at the top of the pin) from the center such that when in the pen is in the “hot seat” they are perpendicular to the draw surface?

oops, yep! I didn’t read far enough donw!

That was what I was thinking @niget2002 Would need to use a drill press and jig to hold it at an angle to drill.

@madgrizzle - 3d printing the ring is also an option

Or just a slotted hole, leaving the extra space in there.

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