3d printer – the plexiprinter

A few weeks back I decided it was time to get another 3d printer up and running over at shackspace … again.

I used the Fab@Home Model 1 that I brought like 2 years ago as a base, hooked up the 4pi board that Kliment gave me during the somewhat frustrating first 3d printer build experience.

The extruder ist one of the first commercially available direct drive extruders from qu-bd’s kickstarter campaign.

^^ see that? No heated bed!

I thought I could get this working in a few hours but after ttb had hooked up the endstops and I had built an adapter for the extruder it turned out the 4pi board was broken. *bummer*

So I threw it in a corner and started looking at the electronics the next day or so.

Fortunately the 4pi board is open hardware (schematic on github) and so I set out to find what’s broken.
As it turns out there was an inductor mechanically broken off the board and I _only_ had to find one with the matching value. To get it done I simply unsoldered a lot of inductors from scrap pcb’s and measuring all with a LCR meter.


^^ _quick_ fix.

The next issue I ran into was the extruder that didn’t extrude properly. The problem was that no PLA would come out of the nozzle after a few minutes of printing. Tightening the screw that presses the material against the gear, increasing the stepper current as well as some cussing didn’t solve the issue.

Trying to manually push the PLA through the heated extruder let to the conclusion that the PLA was getting soft too far up in the supply screw and then sticking to the wall. No force whatsoever could then push it through the nozzle.

It then turned out that Phil also encountered the problem with his qu-bd but couldn’t overcome it and so his delta went to the corner again.

We thought of a fix and a few days later I manufactured a supply screw into which you can insert a teflon tube to preven the filament from getting soft too early.

^^ the original was in stainless steel (so I also did it in stainless – is that necessary?) – but the 2.5mm hole isn’t that much fun 😉

Next there was the missing steps issue occuring only in y axis.

^^dickbutt test sample

I fiddled with motor current, speed and acceleration settings, even checked whether the y-axis stepper motor had degraded magnets … but could only get rid of the missing steps by reducing the speed to a whopping 9mm/s (~180rpm).

^^ the comparison measurement show that the the tested motors were all equally good/bad.

Still not perfect but we’re getting there.

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