My adventures in multi-material  

My adventures in multi-material

So, after a very brief period with my very first printer (Mk3S), i felt I was producing pretty good prints. Always room for improvement, but I had a working, single/color prototype of the part I want to eventually make in multi-color.

I ordered the MMU3, assembled and installed it. I set it up exactly as the instructions indicated, injection molded roller spool holders and all. My initial prints went well enough. The sheep is cute, and holds a place on my desk at the shop. I printed a couple scaled down test runs of the multi-color part I’m wanting to make, cutting it in the slicer, so I only had to print the multi color portion of it. The first one failed, in that the layers just below the multi color started was not well bonded. The second one went fine, with some adjustments. Then the troubles started….

I had recently bought a pair of new monitors for my office desk, but wanted them to sit higher than the stands would allow, so I designed up a riser to print. After four failed prints, mostly at the same point, despite making changes for each one, I was getting pretty aggravated and discouraged. But I had noticed something…..

The filament seemed to pull through the tubing pretty easy, so long as it didn’t have to rotate the spool. The extruder had started clicking, sparsely at first, then more frequently. These incidents obviously always coincided with gaps in the extrusions. I’m fairly certain these clicks and gaps at least contributed to the failed prints. I determined the clicks were likely the idler slipping on the filament, due to the tension on the filament. Looking into the excessive resistance against the spoils rolling in the holders, I found that the small wheels the spools rest and roll on had become very sticky; meaning they didn’t roll smoothly or consistently. In the middle of a print, as the extruder idler had developed a habit of clicking on the regular, I paused the print, rigged up the old “T” spool holder that came with the Mk3S, and hung the active spool on it, with the spool mounted on a two-piece spool holder I’d found on Printables. The clicking stopped immediately, and the print has had zero issues since. It is still printing as I type, but I am very confident in what I perceive as a distinct change in behavior. I’ll obviously report in the morning.

Anybody else experience this with the supplied spool holders? What else have we come up with? I’ve got a setup worked out in my head, using more of the two-piece spool holders from Printables, but I’m curious what else is out there.

Thanks. Brad.