Not sure I follow that method. I am not sure how fast the chalk will wear away using that method. Just thinking about it for now.
I reworked this design yet again. This is like I mentioned in a message earlier today. Did not take that long to draw it up but will take a while to print them. The drive pulley looks like it has enough grip on the belt. Here is what it looks like.
I think this design should balance out the weight distribution. I looked at the Voron coreXY design to see where to put the idlers. I ran out of the F695zz flanged bearings for the idlers, so designed a plastic one to fit in there. It had to be a little wider for the plastic idlers. I am using just one 625 2RS bearing in each idler. I might order some more of those flange bearings but made these in case I needed them. This might be a little tight squeezing in the electronics, so will probably go to 800mm or 1000mm 2040 with 500mm length 2060 in the middle. This motor change also gives about 30mm extra width on the plotter. It looks pretty good on paper.
I know itâs not exactly the same, but hereâs an article about a 10 mile test on 3d printed tires.
Thanks. I did see that, but he is not testing repeatable accuracy.
I saw that article too, and my first thought was to post it here.
Not because of the wheels (which was sort of interesting). But I thought the idea of a polar machine was interesting.
If you only had one end moving, then you wonât have to perfectly align two ends.
If you donât do any compensation and everything is warped into a circle, then any minor inaccuracies would be small by comparison 
Polar sidewalk chalk crop circles.
You know you could make things more permanent 
. Router and a carbide burr⌠The extra weight might help with traction and tracking.
In the FB group there was a link to somebody grinding really nice looking designs into the sidewalk. They were not using a V1 machine but it was still cool and easily could have been.
Humm, another interesting idea to bounce around inside my head.
If I can get better accuracy, I would try a laser diode & then a Dremel type tool I initially used on the MPCNC.
My printer is down for repair at the moment, so am working on one of my other 2 printers that have not worked in a couple of years. I have been putting this off since it will require some rewiring & probably soldering wires together.
Anyone have a good soaking solution for cleaning hotends that jammed with PETG? I decided to just replace the whole V6 hotend this time, but not going to a Revo yet. I have some spare nozzles but seemed like it was time to replace the hotend. I have been having some luck with heating hotend to 250C & blowing an air gun thru the top of hotend. Still seems to be sticky from the PETG jam.
I just use a heat gun (for shrink tubing) to heat up the hotend and then when the plastic is soft, I use dental picks to pick away the molten plastic. If I can, I try to remove the heater cartridge and thermistor first.
I have had several false starts with the latest test. The motor wires I was using have Dupont connectors on the board side & kept coming loose in the JST board connectors. I have some motor wires with the 4 pin JST connectors, but they were wired wrong. I was finally able to find the right little screwdriver that allowed me to pull those pins out & put them in the correct plugs. Nothing like a snap fit. Thought I was ready to test again, but servo would not work, so I had to use the spare one I had. I use M2.5 screws to hold it on & those small locknuts were hard to get off the way I had them on & broke the plastic mount in the process of taking the servo off. I did some minor modifications to the part before printing again. Finally had it all back together & ready to print.
I am also modifying the wheels some which might help the accuracy. I had the bearing recesses at 22.5mm with 22mm Outside diameter bearings. I did this to make it easier to get the bearings in & out as I was going thru iterations of the wheels. I had the intent of making them tighter later. Today was the day to modify them. I did a couple of test prints, 1st one at 22.4mm which fit good with no filing & then 22.3mm which fits tight with a couple of minutes of filing. I am going with the 22.3mm for tightest fit.
I adjusted the acceleration down in Klipper from 2000 to 1000 & movement seems smoother. Still does not have as good of accuracy as with the belt idler above the motor. I will redo the wheels & try that again. Here is the video of todayâs test.
I had a printer jam again yesterday while printing the wheel, so decided to change the wheel design a little more. Seems like one bearing might work just as well on the wheels and maybe even better since I am putting a wider spacer where it connects with the wheel plate. I am going to do the same thing for the idler that is below the motor. This decreased the M8 bolt length from 60mm to 50mm & the M5 idler screw from 50mm to 30mm. I will print the idler pulleys first since they are a lot quicker prints & that should give me an idea of how well this should work. Here is a slanted section cut thru the wheel & idler to show the inner details of my description.
You might stand a chance if the bearing was directly centered with the belt or load, but that is pretty tough on the other ones with two belts thatâs load could vary with direction changes.
Thanks, I will keep that in mind for future reference. Since the geared idler above the motor worked the best, I am going back to that version & reprint that plate with more stiffness.
Maybe a dumb question but what if the far end of the shafts were supported? Aesthetically it wouldnât look as much like a vehicle but supporting the shafts so they remain parallel is a wholly different (Iâm thinking easier) problem.
You always come up with such interesting ideas. I could carry those 2040s beyond & make a hanging plate on other side of wheels to bolt in similar to other side. I will consider that if my current method doesnât give me what I want. Thanks. I am printing the 2nd wheel plate now.
Once this idea was in my head it had to come out. Is this what you had in mind? I had to use the idlers below the motor since the tire tread would hit the 2040s if I had the idler above the motor.
Yes, exactly. With no cantilever action on the wheel axles the parts donât have to be super thick to support it. I was thinking only the motor would be unsupported on the far end, exactly like you have it.
I woke with another idea to carry this a little further. Since it is now supported on both sides & 8mm smooth rod is better tolerance fit than the bolts for the bearings, why not change the bolts to smooth rods. That should get rid of any possible wobble in the wheels. Looks like it works on paper. I am using 2 - M3 screws on each side of the main bracket & only 1 - M3 screw on the back plate. Probably only needs 1 - M3 screw on the main bracket also. I still have a couple of minor adjustments to the design before thinking about print it. I would probably keep the idler as a M5 screw. I am starting to see 25mm or 30mm wide HTD5 belt in the future of this.
[Edit] looks like the 8mm rod is too tight a tolerance for the 608-2RS bearings. Thought I had used that before. The 8mm rod will work with LM8UU Linear Bearings, but not sure I want to use those. Any thoughts on this?
The way the LM bearings ball cycling works, it is very hard to rotate on the shaft. Wonât work for that application. A similar sized roller/needle bearing would work, if they are available.
