Archive for June, 2022

Random Weekend CAD and Printing

Sunday, June 19th, 2022

3D-printed funnel, solid-state relay safety cover, ethernet cable holder

Musing on Nozzle Height Above Build Surface

Monday, June 13th, 2022

Graph speculating about 3D printer first-layer adhesion

I’d always assumed that lowering a 3D printer’s nozzle closer to the build surface causes the extrusion to stick better and better until it’s pressing hard enough, at which point the stickiness asymptotically approaches maximum; and of course once there’s no space left between the nozzle and build surface, one can no longer be said to be sticking filament to the surface.

Thus if a particular filament sticks well to a particular surface, optimize for the best appearance — first layer nicely joined with no roughness from overextrusion nor from the nozzle troughing the filament it’s laying down. If a filament doesn’t stick well to a surface, lower the nozzle until it does; and no need to fine-tune for adhesion — overshooting will only hurt the appearance, not adhesion.

Graph speculating about 3D printer first-layer adhesion

My friend Cort has started to convince me of a different model — that pressing the filament too hard makes it stick less well, whether through an action similar to tiddlywinking your way along the length of a rubber gasket lying on a workbench or by some other phenomenon.

In this model, driving the nozzle too close to the build surface is self-defeating and to get a troublesome filament to stick, one should lower the nozzle very carefully in fine steps to avoid overshooting the peak of the adhesion curve. Cort’s patient tuning this past weekend of one of my Enders on which I could no longer get anything to stick bears that out.

Graph speculating about 3D printer first-layer adhesion

Of course, with some filaments and slicer profiles, the graph looks more like this — peak adhesion isn’t actually good, at best kinda good.

More on this topic soon.

Voron 2.4 Build — Actual AB Motor Orientation

Wednesday, June 1st, 2022

So actually the AB stepper motors need to be installed with their connectors facing each other, toward the center of the back plane of the printer. The 2.4r1 instructions don’t mention this at all; the 2.4r2 instructions mention it clearly.

Voron 2.4 3D printer B block

If you installed them with the connectors facing out the back, especially if you did that based on my earlier and now corrected misinformation, be apprised that you can correct them merely by loosening the AB belt tensioners on the front of the printer, removing the three long M3 screws that go all the way through each of the blocks into the steppers, rotating the steppers in place, and reassembling.

If you know someone who’s a dope and already took the top off of the A or B block, spilling precious towers of bearings and washers, let them know that it’s even easy to recover from that. Remove both AB steppers from their blocks to get lots of slack in both belts; hold long M4 machine screws up from below through the bearing positions and rebuild the towers; nudge the belts out of the way of plastic parts; put the lid back on; and push the M5 machine screws down through the bearing stacks, pushing the temporary M4s out of the way as you go. I mean as they go.