Printer on Haitus

Bed is apparently out of level, and a second belt (for the Y tower) is showing wear. I checked the pulley on the stepper motor (the source of the problem last time) and it is out of alignment, despite being optimal a few weeks ago.

I have a few other upgrades I was planning to tackle after my current roll of filament, but I think I'll just take care of them now.

So...probably won't be printing for a week or two.

EDIT: ok, the bed probably didn't change at all. It looks like the worn belt slipped one or two spots, which puts the hot end on a plane slightly askew of the bed.

Pencil Holder - Organic

This one is for my wife:

If you look closely, you can see there was a ton of stringing. Stringing is usually caused by a nozzle that's too hot, retraction settings that are too low, or a combination of the two. I'll have to adjust those on the next print, because it was a pain in the butt to clean up all those protrusions:

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 15 hours
Material: Hatchbox ABS

Edit: For comparison:

Filament Transition (and a Doohickey)

I just finished two kilograms of black ABS filament. I wanted to move on to white ABS filament.

I originally tried to hand feed the next spool into the extruder as the old spool disappeared. That didn't work, unfortunately. I wound up having to disassemble the bowden tube, snip off a couple inches of black filament, and reassemble the bowden tube with white filament well past the extruder gear:

Based on forum posts, I was expecting it to take a while for the black to flush out completely, but it seems like a pretty clean transition:

It's a fun little doohickey. My toddler likes it as well.

It was a pain to slice, though. I spent at least a half-hour trying different scales to get it to a point where it would print as six shells, rather than being split into twelve. I eventually got it at 1.6x scale.

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 6 hours
Material: Hatchbox ABS (mostly)

"The Last Word" from Destiny

In early April, I was asked to make a model of a pistol called "The Last Word" from the video game Destiny as a birthday present. I found a model I liked on the site MyMiniFactory.com and started trying to print it. This commission has been the connecting thread running through nearly all my experiences with the Rostock since I first got it printing.

Someone else's (successful) print

First attempt was just the handle on coarse settings, to get an idea of how big it would be in real life. I printed the two halves side-by-side, then glued them together. They warped pretty badly:

The warping prompted me to get started on the heated build chamber.

Once I had the chamber assembled, but before I added the heat lamp, I tried again. This time I combined the files for the handle and the body into one print, with the infill set at 50%:

50% infill was too high. I aborted the print and tried again, going back to 30% infill:

I still had pretty bad warping on the handle, and I don't really know what caused the last dozen layers to start drifting like that. It happened while the print ran overnight, and the error has not repeated since.

Once I got the heat lamp installed and the heated chamber completed, I tried printing the handle and body that would mate with my previous attempt. This time the X-tower belt broke about half-way through the print.

At this point, the birthday for which this piece had been commissioned had arrived. I assembled the two largest failed prints, along with some of the smaller pieces that had successfully printed, as a sort of "IOU" that I could present at the birthday party.

This turned out to be for the best: The gun is pretty huge, even without the barrel (which I had not even attempted to print yet). The recipient requested I scale down the whole thing to 80%.

Once I got the belt fixed and added a second heat lamp to the Rostock, I made a fresh attempt at the 80% scale model. At this point, the cold end of the extruder over-heated and jammed about a quarter of the way through. Literally minutes after I last checked the printer before going to bed.

As you can see, the 80% scale is a pretty significant reduction in size.

Once I moved the extruder cold end outside the heated chamber, I tried again. After a few false starts due to poor bed leveling or bad bed prep, I had a success!

I still had a little warping on one corner (the heated chamber was only at 40C), so I stuck a helper disc on that corner for the mating print. There was also a lot of stringing (kinda hard to see in this photo). Stringing is usually due to poor retraction, and since I increased the length of the bowden tube by more than 50% when I moved the extruder outside the heated chamber but did not adjust the retraction settings, I should have expected this. I made a small adjustment on the next part and see how that turns out.

The helper discs worked perfectly! No warping at all on the next print:

I had adjusted the retraction from 6.7mm to 10mm, which reduced the stringing but did not eliminate it.

I also knocked out the chamber, which I printed without support. It's pretty.

Interestingly, one of the skirts got dragged under the first layer and I was unable to fish it out before the first layer was printed:

Progress Pic:

The barrel turned out pretty nicely for the first try. I set it up so the two files comprising the barrel printed at the same time. Unfortunately, that still left a visible seam - I'll have to develop my CAD skills to fix that kind of thing in the future.

A quick zip-tie assembly of all the finished parts:

Gluing the pieces together. I had to go out and buy more clamps:

I modeled up my own "pin" to hold the chamber onto the hinge, and was so excited to see the finish line that I forgot to take a picture. The hinge itself pivots on a piece of nail, so there shouldn't be any worry of the hinge wearing out. Here it is with the glue drying:

Aaaaaaaand here's the final product!

Just shy of two month's worth of hobby time. Phew.

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: around 40 hours for the final version.
Material: Hatchbox ABS

Chessbot Hero

I've been wanting to do this one for literally three years. Finally pulled it off:

I scaled up the original file by a factor of 1.5. Since that's a linear scale, the actual volume increased by a factor of 3.375.

Unfortunately, the pawns don't snap together like they should - they just fall apart. Other people have had this problem too, and there's a modified pawn file that I'm going to print next to see if it fixes the issue.

UPDATE: the modified pawns fit together a bit better, but not enough to actually stick. I'll have to try them again at normal scale and see if that changes anything.

UPDATE 2: I tried a normal-scale print of two pawns. The print failed when I ran out of filament, but enough of it completed to prove the pawns latch much better at the original scale:

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 13 hours
Material: Hatchbox ABS

Pencil Holder - Hexagons - 2x speed

I doubled the printing speed settings from 40mm/s to 80mm/s and re-sliced the model.

At the start, it was clearly operating at double speed, and on the second layer the Rostock started to stutter, like the three towers weren't in sync any more. I dialed the speed down to 75%, which seemed to eliminate the stuttering, then went back to 100% once the base was done.

However, the print still took 11 hours. I'm not sure what happened there.

Also, this print had some pretty bad curling on the base, presumably due to the (initial) high speed.

So, this has been an interesting experiment with printing faster, but I don't think I'll try 80mm/s again in the immediate future.

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 80mm/s (in theory)
Time: 11 hours (doesn't make any sense)
Material: Hatchbox ABS

Pencil Holder - Hexagons

Those sharp overhangs and bridges printed really nicely!

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 11 hours
Material: Hatchbox ABS

Business Card Holder - Octopus Tentacle

Original file here.

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 3 hours
Material: Hatchbox ABS

Ventilation

ABS is not very pleasant smelling when you heat it up and print with it. It's also not particularly healthy to stay in a non-ventilated room with an ABS printer for long periods of time (although apparently it's not any worse than staying in a room with a burning candle). Here's an interesting summary of the latest science.

I've been leaving the window open while the printer is running, but that's not a great long-term solution. My long-term solution (what I intended since I got the printer) is to use our radon mitigation system (basically a powerful fan vacuuming air from our sump system and exhausting it outside) for active ventilation. Conveniently, the radon mitigation assembly is in my shop, a few feet from the Rostock:

This afternoon I removed the plexiglass, and installed a cleanout with a screw-in cap:

Now, while I'm printing, I'll leave the cap unscrewed, and plug it back up when the printer is not running. No more worries about leaving a ground-access window open overnight, and now the ventilation is active instead of passive. The manometer on the radon mitigation system didn't even noticeably change when the cap is open compared to when it's closed.

Printing Again - Spool Arm

I spent the majority of the weekend getting the printer running again. The first print with the external extruder was new spool arm, to hold the filament spool up away from the extruder.

It actually turned out really nice. It took up most of the width of the bed and had some long straight lines, but printed without curling. I'm quite pleased.

Since this is going to be load-bearing, I upped the infill to 40% (I've been printing most things at 30%), and printed with three shell perimeters, up from my standard two shell perimeters. It feels really solid. I think I might do three perimeters more often going forward.

Original File

Nozzle: 230C
Bed: 100C
Chamber: 50C
Layer height: 0.2mm
Speed: 40mm/s
Time: 11 hours
Material: Hatchbox ABS

Problems with the Heat Source for the Heated Chamber

Printing with one halogen bulb had worked fairly well, so I advanced to the next stage - adding a second bulb for a total of 300 watts of heat. To do so, I redid the wiring - everything has a properly colored 14-gauge wire now (which is not to say that it's pretty yet).

Unfortunately, the extruder no longer worked properly inside the heated chamber with the extra heat. Interestingly, it didn't seem to be an electrical problem - the filament softened and jammed inside the cold end of the extruder:

You can see the jam on the right side of the filament in the above photo. Since the extruder couldn't push the filament through the bowden tube once the jam formed, it chewed through the filament and then spun freely until the end of the print file.

So, I proceeded to move the extruder to the outside of the heated chamber. I had previously printed two different options for the external extruder mount, and today I chose the one that was the easiest drop in replacement:

I also had to make a longer bowden tube to guide the filament between the cold end and the hot end. Generally, you want as short of a bowden tube as possible to minimize slop, so it's a bit of a bummer that I couldn't keep the cold end inside the chamber.

After I had that system running for a bit, I noticed that the aluminized styrofoam was not handling the increased heat well:

I made myself a quick metal shield from some scrap metal:

Unfortunately, once that was in place, the melamine (the wood) started to blister and smoke!

So at the end of the day, I'm back down to just one bulb. Later on I might put more bulbs in, as one bulb seems to max out at 50C for the chamber temperature. If I do, however, I'll space them out quite a bit more, or put some kind of stand-off between the wood and the bulbs.

One bulb can get the chamber up to 50C. I saw the melamine start to smoke before the chamber had gotten past 60C - not sure what the upper limit is there. Based on forum posts, it seems like the ideal chamber temp is around 70C.