Thursday, July 14, 2016

Printing with PC Plus Polycarbonate Filament on a Maker Select v2

Several months ago I purchased a Maker Select 2.  I believe my quote, most recently, was “It’s been a few months and the 3D printer is still the coolest thing I’ve ever owned.”  It’s also, sometimes, one of the most frustrating.

My current project is printing a multi-extruder printer (aiming for 4, but starting with 2) using a mash-up of a few different designs and I’m working on a Bowden extruder.  Since I had the need to print some very strong parts for another project, I picked up some PC-Plus after a bit of research.

This stuff is stronger than I’d imagined

Since I’ve had, now, four failed prints with this material, I’ve had an opportunity to test the physical properties.  My tests indicate the most optimistic of the marketing materials is spot on.  My PLA+ extruder body was able to be cracked pretty easily with a rubber mallet on my cement basement floor.  The ABS and Nylon parts were pretty solid but one of the components was designed in such a way that the flexibility of those filaments was going to be a problem. 

This stuff was hard to break with a full-on metal hammer.  It’s far less flexible than ABS or Nylon and the point it which it will flex is (in my unscientific estimation) about twice the pressure it takes to completely snap a PLA print.  I’ll admit, it was kind of fun hammering the crap out of the part seeing how hard I’d have to hit it to get it to crack.  About the only bad thing I can say is that it did dent pretty well but it dented at well beyond the point other parts would have broken.

This material is the stuff that profanity is made out of

I’ve yet to run into a filament that is more difficult to print properly with.  I’ve printed with PETT, PETG, T-Glase, ABS, PLA, PLA+.  It’s safe to say that it takes all of the difficulties of each of these and combines them into one magnificent package.  It’s very temperamental with regard to moisture as evidenced by the fact that it shipped in a vacuum sealed pack with a zip-lock seal for easy re-packing.  Luckily we run the air conditioner here like it’s the arctic.

It curls.  No, I mean, like 80s perm psychotic curls.  They used to ship it with a square of BuildTak.  The manual and nearly everywhere you read says it is *required*.  Thankfully, it’s not if you’re creative.

To get that strength, you need to run your hot end at 260 degrees or higher (that’s as high as the Maker Select 2 goes, so that’s what I’m stuck with) and you need to print slowly (details below).

The BuildTak Option

The Maker Select v2 shipped with a BuildTak clone of some kind attached to the metal heated bed.  I say “Of Some Kind” because this was one of the first things I removed from the printer since the PLA and Nylon I was printing with seemed to just bounce off of the surface of whatever this 3M product was.  After trying a few things that worked well for me in the past, I gave up and purchased 3 sheets of BuildTak.

Let me just say: I hate this stuff.  Perhaps that’s strong sentiment borne out of hours of frustration with this filament more than it is a scathing rebuke of BuildTak, but I’ll never buy it again. 

The first problem is that it works a little too well.  PC-Plus sticks to it like super glue and removing the part rips the surface off of the BuildTak.  It’s difficult enough getting the bed leveled perfectly to the factory recommendations but now you have to figure out just how higher you need to level it in order to get the part to stick properly, but not too well.  That’s assuming the BuildTak doesn’t just pull itself right off of the glass due to the heated bed weakening the adhesive.  Since I purchased the 127mm by 127mm sheets, I was printing the part right on the edge of the BuildTak and that’s exactly what happened to my second print. 

Second, and this might be a matter of me improperly cleaning the surface, but I was only able to use a non-ripped sheet twice.  After that, it simply stopped sticking no matter how close I printed. 

Third, geez this stuff is expensive!  Three of those tiny sheets was almost $10.00.  The idea that I’d get about 6 prints for that price didn’t sit well with me.

Lastly, I prefer to print directly on the glass because it makes the part look nice.  BuildTak has a rough surface and it shows up in the finished product.  That wasn’t so important for these parts (just looking at my printer with gray, green, clear, pink (!) and black parts indicates I don’t care what it looks like, I just want it to be durable and functional).

 

(Mostly) Ignoring the Manual

I’ll be the first to say that much of the manual’s recommendations worked fine except for the 0.33mm gap between the raft and the part (which resulted in a “3D printed turd” stuck to the hot end since it wouldn’t adhere to the part below).  I’d imagine part of that had to do with the fact that I can’t get it up to a higher temperature with this printer.

I really hate printing rafts.  Watching the filament burn down as it drops a surface on top of a surface that should be sticking already only to throw that part in the trash (or if it’s ABS, store it to make more glue) is wasteful.  Then there’s separating the part from the raft, which, since I rarely print rafts, I haven’t quite gotten right yet.  It’s either sticking so hard that I have to risk breaking the part to remove it or it fails to stick at all.

I was able to get it to stick perfectly, though by throwing out most of the recommendations and using a few settings that I had used with T-Glase and other finicky materials.

First, clean the hell out of your bed (91% alcohol does the trick).  Level your bed to the factory recommendations and make sure it’s absolutely perfect.

Heat up the extruder to 260 and clean any filament from the last seven failed prints off of the hot end so they don’t become a magnet for the stuff it’s already laid down.  This stuff sticks well to virtually nothing except for itself and while printing, if you get any strings, they’ll gob up and start removing portions you’ve already printed.

Heat up the bed to 90 degrees and apply a nice layer of Elmer’s Glue Stick.  Follow that up with a reasonable amount of ABS Glue (google it, it’s easy to make).  Let everything dry.

I used a 0.1mm gap on the raft when I printed with a raft (I’ve not had to since I cracked the formula for getting this to print properly).  Slow your printing down.  I went to 40mm/s with 20mm/s for the bottom layer and outer layer.  I also stuck with a 40% fill, though this was more because the part required it.  I also used four solid layers top, bottom and sides.  It may be overkill on that, but several forum posts recommended it so I started with those settings.

If your printer goes higher than 260 degrees, try going higher.  I had layer adhesion issues under 260 but still occasionally ran into small sections that didn’t adhere properly at that temperature.  That bit about making sure the head is clean is very important.  Every one of my layer adhesion issues occurred because the head picked up a string, which picked up small bits of printed material as it went along until it got large enough to get snagged somewhere in the printed body and was deposited, causing the bed to sink slightly as the head passed over.  This resulted in a small gap in a spot on the print.  Those small gaps are enough to make a very strong part pathetically vulnerable to snapping.  I resolved most of these issues over a few prints by slowing them down to the point where the head was adequately melting any smallish gobs as it passed over them and increasing the retraction by a factor of two.  Many forum posts recommended going as high as 290 degrees, which I’d imagine would allow print faster and let gravity resolve some of the issues when gobs appear but the printer I was using only allows me to get to 260 degrees.

For tall parts, consider taking a few of those Amazon boxes apart and making an enclosure.  This will keep the temperature consistently higher while printing and reduce curling.

Using these settings, and the ABS Glue plus Glue Stick, though, made the part stuck so hard to the glass I had to use a razor blade to separate it.  There was zero curling on a part that had several little finger-like points on it (and failed to print properly on anything else with this stuff) so I’m fairly convinced this is the way to go for me from now on.  YMMV

Things that didn’t work

3D printing is often about experimentation to get the easiest process to produce consistent prints with a material.  The only thing these attempts did was consistently produce curled parts or 3D printed turds.  All of these were attempted directly on glass.

Hairspray

As is common with ABS, hairspray seems to make the curling worse.  It will stick initially, but after several layers, it’ll start to curl upwards.  If you’re lucky, the print will stick somewhere and you might have a salvageable part if you don’t care about the looks and the curling occurs on part of it that doesn’t affect its performance.  I was printing an extruder so there’s very little of it that can be off.

Glue Stick (alone)

Initially it stuck and didn’t curl as much as the hairspray did.  This might have worked were the part much smaller but on the extruder body it failed after about the 20th layer, pulling completely off of the bed.  I tried this twice and I’m fairly certain it’s not a good solution.

Elmers and Water

Performed similarly but worse than the glue stick

BuildTak after Two Prints

The surface might as well have been covered in olive oil.

That 3M BuildTak like thing that Maker Select ships with

They gave me an extra one which I put in a box since the one that it came with performed so poorly but I thought I’d give it a shot.  It worked as well as it ever has which is to say, not at all.

ABS Glue (alone)

I’ve read some forum posts from people claiming they simply applied ABS glue to the glass and were printing successfully with other materials.  Perhaps mine is too diluted or I’ve done something wrong, but it’s never worked for me even with ABS filament.  This was no exception.

I also tried mixing a few variants of these, especially the hairspray since even though it seems to encourage more curling, if it gets a good stick initially, it won’t budge with other filaments I’ve tried.  The only mix that worked was Glue Stick and ABS Glue, though to be fair, I didn’t try Elmers+Water and ABS Glue and I have a feeling this would have worked.  It’s just less convenient waiting on the Elmers to get tacky enough to begin printing.

I’d love to know what anyone else has tried or if there’s a better method/something I’m missing but it’s a relatively new filament, has lots of pain points and isn’t experimented with enough to find great information from the forums so I’ve been at a loss for any solid help (which was one of the motivations for getting off my butt and writing this).  If you’ve had success with this material using other tricks, please comment!

Many thanks!