SeaKing 2.2. Replaced the remaining Makerbot steppers, cleaned up the wiring. Pretty enough for some glamour shots.
Of course when I took it back downstairs after these beauty shots I broke the arduino mount. Grrr.
Nice to see an ord bot derivative! What kind of camera setup is it?
Camera setup? My phone.
You need to get rid of those rod end bearings. They’re creating Z wobble in your prints.
Constraining the Z axis lead screws at the top causes any misalignment between the motors and shafts and nuts and bearings to be amplified by yet another constraint.
The only time bearings at the top of Z axis lead screws make since in a setup like this is when they are load bearing (thrust bearings) that allow you to use unloaded Oldham couplers (which allow rotation irrespective of lateral displacement) to connect the lead screws and motor shafts.
@Gordon_Broom The one mounted on the boom on the Y axis?
@Chengster_N oh, that’s a PiCam. I’ve got a Pi tucked underneath the Y axis running Octoprint to control it. The mounts are from thingiverse
@Mark_Rehorst It’s possible your bot is sufficiently precisely aligned that you just haven’t had to think too much about the downsides of constraining the tops of the leadscrews.
The bearings for the smooth rods or rails should keep the gantry stable relative to the Z axis certainly, but they generally always have some wiggle, and that wiggle allows the gantry to tilt or rock back and forth slightly, not along the X axis, but along the Y axis. This will be caused by either the force of the lead screws on the nuts (if misaligned or bent) or even just the slop in the threads between the leadscrews and the nuts, and the upper constraint only amplifies this problem. If the tip of the nozzle is significantly above or below the pivot point of that wiggle room, that will further amplify the artifacts in the print as well.
As a thought experiment, what do you imagine the constraints at the top of the leadscrews might be providing as far as an advantage? I can see such a thing being advantageous if the printer was on a steep angle and the weight of the leadscrews themselves might be causing some lateral load on the nuts, but this is not a common situation and not a point of concern for lead screws that are basically vertical.
Actually though, now that I’m thinking about it, your situation with the second lead screw being driven by a chain may actually require upper constraints to stabilize the lateral loads introduced by the chain itself.
Hmmm
Actually, if you’re using a belt or chain to drive the second screw, you really want a bearing directly above and below the pulleys. Bearing at the far end of the rod is still wrong.
@Mark_Rehorst I think you hit the nail on the head with regards to the level of alignment precision that is achievable for hobbyist/RepRap-style machines. There are slightly more exotic solutions that give good results (I use hanging thrust bearings and Oldham couplers) but for the most part, just leaving the tops of the lead screws “free” and employing flexible couplers and/or thin lead screws are the proven “best practices”.