A tale of two Stratasyses. Stratases? Stratasi??

Early this year, I managed to get a good deal on a Stratasys FDM 2000 from the guys over at the Cincinnati hackerspace, Hive13, making this the third 3D printer I’ve purchased (and the second I’ve sold to Frankie for use at the DCRL, but more on that later).

What makes it particularly nifty is that it has a soluble support head, which is quite rare for an FDM series machine – most had plain old breakaway suuport heads.  From the start, I had intended to loan this printer to the DCRL, since I’ve been looking for a professional grade FDM printer for Frankie for quite some time – he’s done amazing things with the RepRaps he and his students have built, but there’s nothing like having a machine that runs a separate support material (to say nothing of having a much larger 10x10x10 build envelope).

Once I brought the machine home, I parked it at the Milwaukee Makerspace for a few months so I could give it a checkout and let the other members use it for the time being.  Despite having a great deal of experience with the FDM 1600, the 2000 had me stymied when I tried actually printing with it.  While I was able to get the head spooled up with filament, I just couldn’t get the machine to actually print anything.  Thanks to John Branlund, I found that the issue was the door latch – unlike the 1600, the 2000 has a door latched sensor and will lock the door and proceed with the print cycle only if the user latches the door closed.  With that figured out, I could actually try some printing.

Naturally, a shot glass had to be made for the first print, though it was quite porous, and the few mL of beer I put in it quickly filtered through the bottom.  RapidPrototypeTech, who had previously owned the machine at one point, told me that because this machine has a soluble head, you have to make sure to select soluble support in the software even if running breakaway support.  The difference between the heads is primarily in the motor gearing – a soluble support head is geared much lower from what I’m told.  However, even when trying the exact same job and specifying soluble vs. breakaway support, I still wasn’t seeing any difference in the output – the model extruder simply wasn’t putting out nearly as much material as it should.  Stratasys manuals really don’t provide much help, as such adjustment would be left to a service technician.

While there are some adjustment pots on the main control board (in the lower center of the above photo – the pairs of mustard and blue colored components with screwdriver slotted adjustment screws) that John suggested could be used to adjust the gain for the extruders, I was really hesitant to start messing with potentiometers.  Having disassembled various electronics in my youth, I discovered long ago that messing with such components could very quickly make things stop working properly.  While the years since have taught me that multimeters and oscilloscopes can be used to properly fix such exploration, I still have resistance (pun not intended) to adjusting potentiometers if I don’t know exactly what I am doing.  So I looked around for an alternate method to boost the extrusion rate.

Fortunately, I found what I was looking for in the FDM 2000 Introduction and Reference manuals – pressing Space231 or Space239 on the front keypad allows the model and support material extrusion rates to be modified.  The default values on the machine when I got it were:

Space231 (model material)

1 CAL N MDL 0 (non-ABS model calibration)

2 CAL A MDL -5 (ABS model calibration)

Space239 (support material)

7 CAL N SPT 0 (non-ABS support calibration)

8 CAL A SPT 0 (ABS support calibration)

By trial and error, I adjusted the flow rates until I was getting much better results with printed parts:

2 CAL A MDL 58 (ABS model calibration)

8 CAL A SPT 48 (ABS support calibration)

While this does in fact work, the allowable range for these values is +/- 50, and bumping the ABS model value all the way to 58 results in “NV Memory Error” showing up on the LCD display during powerup.  If anybody knows of a better way to adjust the flowrates (even if it is messing with the potentiometers), leave a comment.  One thing I noticed with the 2000 head versus the 1600 head is that the 2000 head is slightly larger to accommodate larger gearmotors and even dual sets of drive wheels if the material warrants it.  In this case, there isn’t a second set of drive wheels but rather a guide funnel.

The motors have this engraving:

2232U012S

123    141

And this label from the manufacturer, Faulhaber (I first thought the 2233 on the label was a typo, but this appears to be a valid MicroMo model):

2233U012S123  X0800

23/1  134:1  X0431

HES186  KW 28/01

After a few months of fun with the FDM 2000, we finally moved it to the DCRL at UWM where Frankie took ownership of the machine and proceeded to go on a printing spree of epic proportions.  Everyone at the makerspace was sad to see the machine go, but I promised that if I found another it would have a long-term home at the makerspace.  Well, that happened much sooner than expected, and I managed to get another FDM 2000 (this one with a standard ABS head).  I picked it up a few months ago, and finally finished building a mobile base for it the other weekend out of 80/20 extrusion:

I brought the stand to the Makerspace, and we were able to finally wheel it into the 3D printing area:

Since this FDM 2000 has a standard breakaway support ABS head, the motor gearing is a little different.  The support motor itself is a MicroMo with this engraving:

2233U012S

123    466

And a label that says:

2233U012S123  X0431

HES186  23/1  43:1  KW  37/99

The motor for the model material side appears to have the same information, but says 09/97 instead of 37/99 – I’m guessing that may be a date code (week/year format).

For anyone curious, here’s a side-by-side comparison of the heads from my 1600 and the 2000.  The 2000 head on the right has the support nozzle solenoid removed – more on that in a moment:

Note that the actual ‘heater chamber’ is the same size on each head, but the area for the motors is larger on the 2000 head to accommodate a second pair of drive rollers depending on the material the head is designed for.

Note also the shroud on the bottom of the 2000 head – this takes some of the head cooling air and blows it just past the nozzles to cool the freshly deposited filament (at least, this is what I think the idea is).  Interestingly, the FDM 2000 that I passed on to Frankie does not have this shroud, so I’m wondering if it was a later enhancement (or perhaps an idea that was fielded but then scratched)

On powering up the machine, all seems well, except for the support nozzle – specifically, the solenoid wasn’t activating to lower the nozzle.  I took the head out of the machine and found that the wires to the solenoid were pinched between the cover and front plate of the head, possibly shorting them.  Even worse, a multimeter check showed no conductivity between the two leads.  I checked my FDM 1600, and found that the solenoid had about 25.4 Ohms of resistance and was supplied with 24vdc (with a clamping diode to kill the spike that comes off of the coil when de-energized).  While the solenoid on the FDM 2000 head has no identifying information, it appears to be identical to the one on the FDM 1600, which says ‘LISK S-2379’ (I had a bit of info on the 1600 head in on old post).

Even though my previous contact with the Stratasys support department was less-than-helpful, I figured I’d give them a call and see if they might have any spare solenoids.  Unsurprisingly, they don’t have any.  They don’t have anything for the old FDM series machines as of the end of 2011 – FDM owners, we’re entirely on our own.  Stratasys will still give you trade-in credit on your old FDM series machine if you wanted to upgrade, but I don’t think this is a great deal.  These old machines are quite nice in that they’re constructed with a lot of off-the-shelf parts, and are easily modified/hacked.  I think it’s rather telling that there have been a whole bunch of academic papers on 3D printing that use an FDM thousand series machine as the testbed, but precious few papers have been done with the current P-class machines – they are far more proprietary in nature and don’t lend themselves well to experimentation.

At any rate, if Stratasys was a bust, at least I could contact the solenoid maker, G.W. Lisk.  Lisk only makes custom solenoids and doesn’t have any stock offerings, so I gave them a call to see what they could tell me about model S-2379.  Yes, it was made specifically for Stratasys.  It’s a continuous duty 24vdc solenoid, with a coil resistance of 21.6-26.4 Ohms at 25°C.  And that’s about all they could tell me, other than that no, they didn’t have any in stock.  I didn’t ask how much it would cost to have more produced, but I got the distinct impression that it would be greater than one arm and one leg, so I did not pursue that line of inquiry.

In looking around at off-the-shelf solenoid offerings, I’ve noticed that when it comes to 24vdc solenoids, they generally bottom out at around 80-90 Ohms or so, and are much larger in diameter than the S-2379.  The lower resistance results in a much larger power draw and more force, but given that the solenoid operates in a 70°C oven, this derates the performance.  At any rate, I seem to be out of luck in sourcing an off-the-shelf replacement and am investigating whether or not I can have the existing solenoid repaired.