Get a scrapped Stratasys Dimension SST running
Video of the system running
MPEG-4 Video - 11.86 MB - 01/22/2016 at 19:29
October 5, 2016: I had a jam in the support feed tube. It would feed for a while and then just stop. It must have been a partial jam, but I cleared out the nozzle once and it didn't really improve. I thought I cleaned it out completely, but perhaps I didn't. I went to clean it again and got it working perfectly again. I removed the entire extruder nozzle assembly, and here are the steps I took with it:
1) Soak in limonene for a couple days. I don't know that this did much. I periodically took it out and heated the block up with a torch, which made some plastic ooze out of the back end, but probably didn't help much.
2) Soak in acetone for a couple days. I don't think this did much either.
3) Ultrasonic clean in acetone. This softened the HIPS enough that I was able to push in an insulated stranded wire of about the 1.75 mm diameter of the filament. I would push it with a pliers close to the inlet, and the wire would kink and I would back it out and start with a new piece. Eventually, I noticed the wire was going in farther and farther. Finally, acetone-soaked HIPS oozed out the nozzle and the whole tube was mostly clear. This happened last time too.
4) Ultrasonic clean in limonene. This was intended to clean out the remnants of the plastic from the tube.
5) Found a little tiny broach that I pushed in the nozzle and spun a bit to clear it out in case anything was left in there. A drill bit probably would have also worked, but I didn't have one small enough. I know there are kits you can buy for this exact purpose, so I may get one of them. I suspect that is all I would have needed to do.
6) I noticed the inlet of the ABS side is flared, but the support side is not. I thought the HIPS might be getting caught on the inlet before it could get into the hot zone and melt and that might be causing the problem. Because of this I *GENTLY* tried to flare the HIPS side with a punch. It maybe flared a tiny bit.
7) I gently sanded any burrs that might be on the inlet side with sanding cord.
After all that, it ran perfectly. I don't know which of these steps were the most useful, but I listed them all in case someone else needs some ideas.
February 19, 2016: Some generous person on Reddit sent me a file that unlocked a lot of options in Catalyst, and now I can print at 0.005" layer height! Catalyst is the software that slices the STL files into gcode for the Stratasys printers. The Dimension SST is a fairly old model by now, so they locked out a lot of the newer options to force people to buy the newer models. This includes finer layer height, different support options, and allowing placement of pauses in your print (so you can do things like add hardware inside the print). This resulted in some really amazing prints. I printed the Yoda bust available from Thingiverse at 25% size, and it came out amazingly well for being the size of a penny! I really can't believe that this printer is now running better than a brand new Dimension elite! And all for $500 invested.
February 2, 2016: I tried to print with Nylon filament, Taulman 645 Alloy, and it gave me nothing but problems. It kept getting jammed in the extruder. Fortunately, if I understand the design correctly, Stratasys has made an amazing extruder. It seems like it's fairly hard to jam up the nozzle. The jam seems to happen right where the full filament diameter feeds into the liquifier. This means that the jams were pretty easy to clear. Just back the filament out of the head.
I tried a ton of different temperatures for the enclosure and the extruder, but I could never get it to extrude more than a few inches. Ultimately, I measured the filament diameter and found it was off by as much as 0.2 mm. That means my 1.75 mm filament was up to 1.95 mm. The extruder couldn't handle this larger diameter, so it would just squeeze the filament out the side of the pinch rollers. I have started to politely register my discontent with the supplier. We'll see if they let me return it.
I'm also aware that Nylon is incredibly hygroscopic so i am drying the filament in my build chamber overnight. I'll measure it again after this to see if the diameter changes. I think it's unlikely though because when it did extrude, it wasn't popping as far as I could tell, and it also arrived in a sealed bag in the middle of winter and went right into a sealed Stratasys cartridge filled with dessicant. We'll see though.
January 24, 2016: I bypassed the wiring harness for the correct sensor this time, and was able to complete a print that would never complete before. When I was determining where all the wires went that I would have to bypass, I also measured the resistance between the sensor and the controller board connector. Three of the four wires were about 1 ohm. One was 5 ohms. I suspect it has a marginal connection and fast movement shakes it loose. Now I need to figure out how to fix it. The wiring loom is very tight.
January 23, 2016: Since the service manual was telling me that my error code meant the X-axis end of travel sensor was incorrectly being triggered, I found the sensor labeled "end of travel" and bypassed its wiring harness. I used a brand new sensor. I started a print that always causes the fault code, and unfortunately, it faulted again. Bypassing the sensor wiring didn't fix it!
I opened the printer and started it and I manually triggered the sensor that was labeled end of travel. A completely different error code showed up on the LCD! I triggered a neighboring sensor that is labeled as the X-axis home sensor, and the correct error code showed up. Since the service manual didn't match the sensor labels, I bypassed the wrong sensor!
I bypassed the correct sensor now and I'm currently running a test print. Fingers crossed.
Jan 22, 2016: I have had a problem since the beginning with the printer. Once I got it working, I noticed I would occasionally get homing sensor faults in the middle of prints. Essentially, it sees one of the limit switches change state when it knows it should be nowhere near a limit. The printer halts when this happens and forces a reboot. The model print must be started all over in this case, which is really unfortunate.
I thought that the faulty sensor triggers were coming from running the printer in my cold garage. I thought the sensors were getting condensation on them and causing false readings. Sure enough, when I brought the printer in the house, the faults seemed to go away.
One particular fault has recently come back in certain cases. If I am printing a platen full of many parts, it is consistently throwing a family of errors that seem to be traceable back to the X axis end of travel sensor. If I print only one part at a time, I don't get the error!
I replaced the sensor in the hope that it would help, but it didn't. I'm suspecting that printing many parts at the same time results in more vibration and that it rattles the sensor connections, shaking an intermittent connection into failing momentarily.
I plan to test this theory in a few ways. First, I plan to bypass all the wiring and connectors with separate wiring to determine if the existing wiring and/or connectors are to blame. If not, then I plan to short out the offending sensor after the homing sequence to determine if it works then. If there are still issues, I'll have to examine the circuit board to make sure the sensor traces make it cleanly to the control circuitry. If I still have problems, I guess I'll just print one part at a time forever! :)