I’m very excited to have my LowRider2 up and running! I’ve made a few test cuts which are mostly working despite me just coming up to speed on the CAM software side of things. I am experiencing 2 minor issues:
My circles are cutting slightly oval on a 45 so diagonally oval in the same way for every circle (with varying degrees - some barely and some noticeably - still not crazy though, less than 1 mm off). The long dimension is on the +x/-y dimension, like the direction of this slash looking at the table with the x-axis left to right: \
Could this be the belts needing more tension? Maybe I’m trying to cut too deep/too fast? I was using 5000-5500 RPM, I think this print was using 3mm plunge depth per pass at 150mm/min plunch feedrate and a 500mm/min cut feedrate. Notably I also made some manual depth adjustments during the print (paused) that might have added to the problem if I moved the rig manually inadvertently). I’m working out the right depths so the attached cut also suffered for a circular cutout getting caught under the 611 plate briefly (without holding tabs). Also, please don’t mock my mistake with missing a lift in my gcode between 2 of the holes.
Before I start my prints I have to engage my Z-axis first by moving it up a little or else when the print starts and the z-axis lifts, on the heavy side it simultaneously slides down (the whole 15 mm I’m asking it to lift) while on the light side it lifts fine. I’ve checked the fastener between the motor axle and the threaded rod, they are touching and the flexible connector has tension on it just as is described in the build instructions. When I watch it it’s almost as if the motor is somehow powering but allowing slip at the same time - very odd. All my manual tests work fine, I can life and lower perfectly, so I know I don’t have a polarity issue (one side up while other side down). My workaround works, and maybe that’s the normal process, it just seems a bit odd to me that once the motors are engaged there would be any amount of slip - certainly 15mm of slip seems like a lot. Once that initial lift happens there is no slip at all.
NOTE: I’m currently using hand-cut plates for the time being. If these are deemed to be the problem my plan is to cut new plates using the CNC to replace my hand cut ones that will hopefully be an improvement. Hopefully I won’t need too many iterations to get better precision.
1- Did you use a finishing pass? It could be belt tension but it could be a lot of things, really tough to say. Your picture does not show them installed so I can’t see any obvious issues.
2-That should not happen, check for a smooth axis, loosen up the T8 nuts a touch and make sure you have plenty of lube, the z rails are close but not necessarily touching the table.
#1 did’t show up on the print I just ran so I think I have to chalk that up to me manually adjusting the depth during the print and pushing things out of alignment.
#2,Thanks for the info. I’ll look at those and do some more testing. Maybe post a short video. My process now includes lifting the Z up and the software on the CNC seems smart enough to factor that lift in so no real issues there. It was mostly about me be curious how/why that would happen.
I can suggest a few other things that might be helpful.
a) Make sure you’re starting your motors with the gantry square to the table. If everything is nice and square, it will should drive straight along the sides of the table. If it’s not square, and pointing to one side, it will drive that way and cause ellipses instead of circles.
b) Try cutting some things in foam. It helps eliminate speed/feed problems because there is no drag on the bit. If your machine can’t move in a square, it can’t cut square.
c) The Z speed matters too, so make sure your Z lift command isn’t requesting a large speed. Even if you have a workaround for the starting, this will bite you later. Z has to be able to lift properly.
The build looks good. I like the table. My wife would kill me, but I would definitely eat on a table that I used as a spoil board with a piece of glass on the top :D.
I bought that table for $50 off of Craig’s list! It’s very long, I think at least 8 feet and the great part about it is it has leafs (leaves?) and so if I ever get good at this I could possibly stand items on end clamped within the hole in the center and work on their ends. Right now I’m using a spoiler board on top of it. So far no mars except for the 8 small screw holes for the belt holders and a couple of minor surface scratches from sliding MDF around.
I agree though, might be cool to have all the remnant scars of past projects on display beneath the glass.
I have and I do! All those gear fossils! That project is amazing and was a bit of the inspiration I needed to take the leap. I’m already excited I finally did it. I have been building mini-arcade machines at home with rudimentary tools and my lines are far from square. That ends right now and I don’t even need a table saw, drill press, etc.
