I occasionally would like to print some large drawings that do not have to be that accurate, so I started working on what I call a rolling plotter. This uses the similar idea of a couple of designs on openbuilds & kind of similar to the LowRider, but Y-axis could be just about any length within reason. 20x30" foam core size is about all I initially would need to print to. This design should also be able to draw designs in sand like the ZenXY except drawing it from above with the added advantage of having a Pen up. I will definitely try that. I just need to find or make something like a shallow sandbox. The wheel size are the essentially the same as what is used with the lowrider, but I added GT2 teeth to the center & using O-rings for the tire tread. I am driving the wheels with a closed loop timing belt. I might try a direct gearing while I am waiting on the timing belt from China. I printed a 444mm length closed loop belt in TPU I will test to see if that will actually work. This has been a fun project & has gone together quite well so far. I am using 1000mm length 2040’s which will give me about 35" of X-axis drawing space. I created a build log of it on openbuilds located: https://openbuilds.com/builds/a-rolling-plotter.9207/
Here is what the design looks like so far.
That looks great! I have seen some projects like that for drawing on sand on the beach, or even drawing on sidewalks. It looks like a lot of fun.
The last makerfair I went to had a little sand printer that drove along and dropped 1/4tsp of sand like a dot matrix printer. Super long sentences, super fun to see. Guy drove up behind it once and a while and added sand.
Can’t wait to see your in action!
It is alive & here is short video I made of the first movements that worked. It was quite surprising how well the TPU 3d printed belt actually worked. I didn’t have enough teeth grabbing the belt in the first test. Mark on openbuilds gave me the suggestion for moving the idlers to grab more teeth. I used the conservative ZenXY 400mm/Sec settings as my initial settings for x & y.
That could be a lot of fun. First thing that comes to mind is kids birthday parties, giant banners on the ground, ultimate hopscotch boards…full sized real life board games…
Around the neighborhood I would just get in trouble writing funny things in front of the neighbors houses!!!
I think I have all the parts except a roll of TPU.
Hmm… Sidewalk chalk + High School activity clubs = awesome welcome notices in driveways, etc… 
It shouldn’t be too hard to do multiple colors. 
Sidewalk chalk + High School impulse control issues = maybe having to move… 
I still have the Pen mount to design, but making progress on it. I started working on designing the wheels to use herringbone teeth & be a gear drive off the motor, but am going to finish this train of thought first since I ordered the 444mm closed loop timing belt already. I thought about making one using EMT, but the V-Slot is a lot easier to design for & I already had some.
I finally got the pen mount attached & decided to see how it would work as like an upside down Zen XY machine. I used a sharpie that doesn’t write anymore to cut the pattern in the baking soda. I knew there was a reason I didn’t throw away pens that don’t write. I left the little zen garden rake in the path of the wheels which I had to quickly move out of the way. I didn’t have the pan located quite right, so pattern was off. With Pen up/Pen Down & ability to put most any sand plowing tool that will fit, this could be a lot of fun to play with.
If my mom sees that I will have to make her one…probably big enough to make a design fancy in her backyard.
It works better than I expected for the 1st run. I am planning to change the drive to geared wheels direct to the motor since it is 6 less parts & will probably won’t slip teeth at higher speeds. I am going to try a belt printed with petg to see if that works better or worse. Only takes 1/2 hour to print each belt. Have you seen where zyltech sells 2020 & 2040 V-slot not a little cheaper than openbuilds? They also have more cut sizes to pick from in 100mm increments from 300-1000mm & also have 2 meter lengths. http://www.zyltech.com/zyltech-2040-v-groove-extrusion-pre-cut-lengths-300mm-2000mm/
My kids would freak out if I made something like this and a sand box… I don’t want a sand box though. Too many wild cats/other wildlife around. 
One of my friends told me I should adapt it to decorate cakes. I thought that was an interesting idea & quite doable. The wheels would just have to have more elevation around the cake. Not sure I will try it anytime soon though.
Tool changer with a rake…
🧙‍♂
Speaking of automagic litter boxes. An ex-girlfriend and I bought one for her cat. The cat didn’t like it, so it would hold it all day until the middle of the night. Then it would pee right where the rake would shift down into the litter. Clumping little makes little nuggets where they pee, unless you wait all day, then it makes a chunk about the size of a brick. Then we’d get to listen to the damn thing slip it’s clutch for a couple minutes until it gave up. I’d call her a stupid cat, but that’s actually kinda genius if you don’t like your new litter box. This is the same cat that would leave partial mouse bodies in my pants. Rhiannon said it’ was because she loved me and was giving me gifts. I said it was the equivalent of a mafia horse head.
I have some TMC2209 drivers that could make it quiet litter box cleaner. Think I am going to change the Z-axis to use some small stepper as that servo motor is just too jerky & I have to modify gcode. I was going to try the inkcut plugin for inkscape. After installing 6.5gb of Visual Studio & compiling it, it almost worked. I am getting closer & closer to switching to Linux.
I have a 28BYJ-48 5v stepper motor. According to this page .05v Vref would be a good starting point for it with a DRV8825 & see if it gets too warm & is strong enough. https://arduino.stackexchange.com/questions/72731/can-i-control-a-28byj-48-5v-stepper-with-a-dvr8825-driver
Are there any other suggestions for a small inexpensive stepper motor. The nice thing about this is that it doesn’t need much weight. Guess I could use a bigger motor just in case I add something heavier to it.
I used a little 28BYJ-48 stepper motor with a printed linear slide to fashion a light-weight Z-axis for a laser engraver I was once playing with. It employed a simple bipolar hack that greatly increases the torque of the little stepper and enables it to be used with A4988/DRV8825 stepstick drivers (please forgive… I’m hard of hearing and forgot to turn down the loud TV)…
Check out the videos from the Thingiverse page for the linear slider. Converted to bipolar, the motor is capable of far more torque than unipolar and can be driven from a Ramps with A4988 or DRV8825 drivers, just like our beloved NEMA17’s. To set it up, simply take off all the micro-stepping jumpers (the motor is geared way down) and turn down the Vrefs… the motor can only handle 150 ma or so. Then go into the firmware and set the steps/mm setting to a value that moves it the distance required (I use this procedure to determine the proper steps/mm setting). Please recognize precision is NOT the little motor’s forte… but it’s more than good enough for applications like the above.
Even with the geared stepper i have plenty sitting around that is cool
Thanks for the links. That linear slider might be just what I need.
I found this design on Grabcad that uses a nema11 stepper. I have a spare pancake nema 17 that weighs only 135 grams (4.6oz) that I might try a design with this as a starting template. This pancake is lighter than a nema 11 that I found on amazon.
https://grabcad.com/library/cnc2040-spring-loaded-zaxis-nema11-1