2010
11.30

With the support nozzle on the Stratasys still acting up (it likes to stick in the ‘down’ position once the head gets up to temperature), I thought I’d try running without support material for a time so I can at least be back to making parts. While I could technically deposit ABS right onto the foam base (as I did with one of my very early prints when I first struggled with feeding support filament), this doesn’t make for nice part bottoms, as the ABS fuses vigorously to the glass foam, embedding the foam into the base of the part. Starts making a mess of the foam itself, too. So, I needed to make a regular build platform just like all modern FDM machines use, RepRap included (Stratasys stopped using foam bases years ago and now uses plastic build platforms instead – I should really find out what polymer they’re now using).

I decided to make a modular platform that I could swap into one of the carriers in place of a piece of foam. A piece of 10.125″x10.125″x0.5″ polycarbonate sheet serves as the ‘base’, into which I drilled holes to accept the pins that normally secure the foam. I drilled and tapped the 4 corners of the polycarbonate for 10-32 screws, and then drilled and counterbored matching holes in a 12″x12″ plate of Garolite from McMaster-Carr. Using plastic tubing as standoffs, 4 button head screws then secured the Garolite plate to the polycarbonate base plate. I wanted a good solid platform, as I knew that the Garolite itself would probably be a poor surface to print onto, and my intent was to clamp other surfaces to the plate with binder clips just as nophead does with his heated build platform.

The cap screw heads stick past the upper surface of the Garolite by just a tiny amount - I sure hope the nozzles will always clear. I still need to make some clearance cutouts in the Garolite so that the platform won't hit the nozzles during the Z homing portion of the cycle.

After trying to level the platform as best I could by tightening down the screws for adjustment (using a feeler gauge between the platform and ABS nozzle), I found that the Garolite is bowed downward slightly in the center. Hopefully this shouldn’t cause any major issues, though – I haven’t measured the amount, but I’m sure it’s less than 10 thou, which is the default layer thickness. This does raise a commonly overlooked use of support material, which is that the support raft helps to ensure that the bottom of the part is flat. Without a support layer, you’re at the mercy of the platform flatness itself. When a raft can be laid down, the first few raft layers can droop or smear to conform to the platform, as the flatness improves with each subsequent layer. Of course, this flatness can be destroyed by part warping, but that’s a separate issue.

With the platform reasonably level, I thought I’d heat up the machine and see if the generic ABS would adhere to it in some manner. I used an alcohol wipe to clean off the platform, knowing that my fingerprints and other gunk would make adhesion much harder. I let the chamber get up to around 55° C before I got too anxious and started extruding (I don’t think the extra 15° C to hit normal temperature would have done much). The generic ABS appeared to have zero affinity for the surface of the Garolite when dropped from perhaps 2mm above, so I brought the nozzle down far enough that it would extrude right onto the surface. With the filament feeding through the nozzle at a 20% feedrate, I jogged the head around. The ABS actually appeared to stick to the surface, but when I opened the door to see how much adhesion there was, I found that there was hardly any. Note that I’m using the Garolite surface as it came – I wonder if sanding/blasting/grinding the gloss layer would improve adhesion any.

For the next test, I placed a silicone sheet (McMaster-Carr part number 8632K62) on the platform to see if that would have any adhesion. None at all, it turns out – the ABS practically bounces off the sheet (which made a lot of sense in hindsight, as silicone sprays are commonly used for release agents). A pity, as the high heat resistance and flexibility would have made for a great surface.

Finally, I thought I’d try what has become quite popular among RepRap users and even UP! printer users – masking tape (specifically blue 3M painter’s tape). I thought this was an entirely ridiculous idea when I first read about it some time ago, but so many people were using it that it wasn’t likely to be a running joke. I applied a few strips of tape to the platform, let the chamber heat up once more, and gave a small Mendel part a shot. I was amazed at the results – the ABS sticks to the tape beautifully, yet separates cleanly once cooled. I still had significant corner lifting, however.

First layer of a Mendel x-vert-drive-nut-trap_4off

With a decent platform, I thought I’d try my luck once more with running a plate of parts over the Thanksgiving break.  I dialed the extruder temperature down to 245° C and let the machine hammer away.  I stuck around for a layer and a half, and things were looking okay, so I figured I’d check back in 50 hours when the print should be done.  Unfortunately, the print started failing at some point within the next 24 hours, as a coworker who had stopped in at the office noticed that the machine “appeared to be dispensing low-grade dental floss” rather than doing anything productive.  Sure enough, I had another chamber full of ABS vomit.  The post-mortem points towards massive warping and corner lifting as a likely culprit – one of the parts looked like the hot nozzle had rammed into a lifted side, halting further movement of the head (and causing lost steps as a result).  There were also various small tears in the blue tape, so obviously a struggle had ensued.

Annoyingly, this sight is becoming increasingly common.

During all of this, I also thought I’d check to see what sort of die swell I’m getting with the NIP ABS versus the Stratasys ABS.  Quite surprisingly, the NIP ABS only swells to 0.013″ (out of a 0.012″ nozzle), while the Stratasys ABS swells up to a whopping 0.017″.  The significance of this finally dawned on me a week later – no wonder I was seeing drooping filaments on crosshatch infill, and a ‘bunched up’ looking filament on the first layer.  The same volume applied to a smaller diameter filament means that the filament will have to have a longer length!  It wasn’t a matter of too much temperature after all (though the generic ABS remains much more finicky than the OEM ABS).

The only way to make the generic ABS work in any tolerable manner will be to modify parameters in Quickslice to account for the significantly reduced die swell when compared to the OEM ABS.  However, since properties of the OEM material are very tightly controlled, there is no way in the software to adjust such settings – the only thing that can be modified is the ‘road width’, which may not help me much.  Tinkering with the definition file may be the ultimate method of customization. Unfortunately, the file’s format (though sprinkled with some comments) isn’t documented anywhere that I’ve found.  This definition file is for a specific machine (FDM 1600), running a specific material (P400 ABS), with a specific nozzle (T12, which has a 0.012″ orifice), at a specific slice height (0.010″).  In all, Quickslice 6.4 has has 24 different definition files just for the FDM 1600:

  • ICW6 material (an investment casting wax) with a T16 nozzle at slice heights of 0.007″, 0.010″ and 0.014″
  • ICW6 material with a T25 nozzle at slice heights of 0.010″ and 0.014″
  • ICW6R support material (for the ICW6 build material) with a T16 nozzle at slice heights of 0.007″, 0.010″ and 0.014″
  • ICW6R support material with a T25 nozzle at slice heights of 0.010″ and 0.014″
  • P301 material (a Nylon formulation) with a T12 nozzle at a slice height of 0.010″
  • P301 material with a T25 nozzle at slice heights of 0.010″ and 0.014″
  • P301R support material (for the P301 build material) with a T12 nozzle at a slice height of 0.010″
  • P301R support material with a T25 nozzle at slice heights of 0.010″ and 0.014″
  • P400 material (ABS) with a T12 nozzle at slice heights of 0.007″ and 0.010″
  • P400 material with a T25 nozzle at slice heights of 0.010″ and 0.014″
  • P400R support material (for the P400 build material) with a T12 nozzle at slice heights of 0.007″ and 0.010″
  • P400R support material with a T25 nozzle at slice heights of 0.010″ and 0.014″

The largest portion of the definition file is the flow curves, which is a table comprising a list of entries as follows:

# PDMM START ————————————————————–#

#—— CURVES ————————————————————#
# Flow  D   Pre   Pre  Start Start Shut Roll
# Area  O   Delay Flow Flow  Dis.  Off  Back Speed
# xxxx  xxx .xxx  xxx  xxx   xxx   xxx  xxx  xxxxx
PDMM
30     2  .026   79    7    60    41   143   800
31     4  .028   79    9    60    42   143   800
32     6  .030   79    9    60    43   145   800
33     8  .032   79    9    60    44   145   800
34    10  .034   79   11    60    45   147   800
35    12  .036   79   11    60    46   147   800
36    14  .038   79   11    60    47   149   800
37    16  .040   79   11    60    48   149   800
38    18  .042   79   11    60    49   149   800
40    20  .044   79   11    60    50   149   800
41    22  .046   79   13    60    51   149   800
42    24  .048   79   13    60    51   149   800
44    26  .050   79   13    60    51   151   800
45    28  .052   79   13    60    52   151   800
46    30  .054   79   13    60    52   151   800
48    32  .056   79   15    60    52   153   800
49    34  .058   79   15    60    53   153   800
51    36  .060   79   15    60    53   155   800
53    38  .062   79   15    60    53   155   800
54    40  .064   79   15    60    54   155   800
56    42  .066   79   15    60    54   157   800
58    44  .068   79   15    60    54   157   800
60    46  .070   79   15    60    55   157   800
62    48  .072   79   17    60    55   159   800
64    50  .072   79   17    60    56   159   800
66    52  .073   79   17    60    57   159   800
68    54  .074   79   17    60    57   159   800
70    56  .075   79   17    60    58   161   800
72    58  .076   79   17    60    58   161   800
74    60  .077   79   17    60    58   161   800
77    62  .078   79   17    60    59   161   800
79    64  .079   79   17    60    59   163   800
82    66  .080   79   17    60    60   163   800
85    68  .081   79   17    60    60   163   800
87    70  .082   79   17    60    60   163   800
90    72  .083   79   17    60    61   163   800
93    74  .084   79   17    60    61   165   800
96    76  .086   79   17    60    62   165   800
99    78  .087   79   17    60    62   165   800
102    80  .088   79   17    60    62   165   800
106    82  .089   79   19    60    63   165   800
109    84  .091   79   19    60    63   167   800
113    86  .092   79   19    60    64   167   800
116    88  .093   79   19    60    64   167   800
120    90  .094   79   19    60    64   167   800
124    92  .096   79   19    60    64   169   800
128    94  .097   79   19    60    64   169   800
132    96  .098   79   19    60    64   169   800
136    98  .100   79   21    60    65   169   800
141   100  .101   79   21    60    65   171   800
146   102  .102   79   21    60    66   171   800
150   104  .104   79   21    60    67   171   800
155   106  .106   79   21    60    67   171   800
160   108  .107   79   21    60    67   171   800
166   110  .109   79   23    60    68   173   800
171   112  .111   79   23    60    68   173   800
177   114  .112   79   23    60    69   173   800
182   116  .114   79   23    60    69   175   800
188   118  .115   79   25    60    70   175   800
195   120  .117   79   25    60    70   175   800
201   122  .118   79   25    60    70   175   800
208   124  .120   79   25    60    71   175   800
214   126  .122   79   27    60    71   177   800
221   128  .124   79   27    60    72   177   800
229   130  .125   79   27    60    72   177   800
236   132  .127   79   29    60    73   179   800
244   134  .129   79   29    60    73   179   800
252   136  .130   79   29    60    74   179   800
260   138  .132   79   29    60    74   179   800
269   140  .134   79   31    60    75   179   800
277   142  .136   79   31    60    75   181   800
287   144  .138   79   31    60    76   181   800
296   146  .140   79   33    60    77   181   800
306   148  .142   79   33    60    78   181   800
316   150  .144   79   33    60    78   183   800
326   152  .146   79   35    60    79   183   800
337   154  .148   79   35    60    80   183   800
348   156  .150   79   35    60    81   185   800
359   158  .152   79   35    60    81   185   800
371   160  .154   79   37    60    82   185   800
383   162  .156   79   37    60    83   185   800
396   164  .158   79   39    60    84   187   800
409   166  .160   79   39    60    85   187   800
422   168  .162   79   41    60    86   187   800
436   170  .165   79   41    60    87   189   800
450   172  .167   79   41    60    88   189   800
465   174  .169   79   43    60    89   189   800
481   176  .171   79   43    60    90   189   800
496   178  .174   79   45    60    92   191   800
513   180  .176   79   45    60    93   191   800
530   182  .178   79   47    60    94   191   800
547   184  .181   79   47    60    96   193   800
565   186  .184   79   47    60    96   193   800
584   188  .187   79   49    60    97   193   800
603   190  .190   79   49    60    97   195   800
623   192  .192   79   49    60    98   195   800
643   194  .194   79   51    60    98   195   800
664   196  .196   79   51    60    99   197   800
686   198  .199   79   51    60    99   197   800
709   200  .201   79   53    60   100   197   800
732   202  .203   79   53    60   100   199   800
756   204  .205   79   55    60   102   199   800
781   206  .207   79   57    60   104   199   800
807   208  .210   79   59    60   105   201   800
833   210  .213   79   61    60   107   201   800
861   212  .216   79   61    60   108   201   800
889   214  .219   79   63    60   109   201   800
918   216  .222   79   63    60   110   203   800
949   218  .225   79   65    60   111   203   800
980   220  .228   79   67    60   112   205   800
1012  222  .231   79   67    60   113   205   800
1046  224  .234   79   69    60   114   205   800
1080  226  .237   79   69    60   115   207   800
1116  228  .240   79   71    60   116   207   800
1153  230  .242   79   71    60   117   207   800
1191  232  .245   79   73    60   119   209   800
1230  234  .248   79   75    60   120   209   800
1270  236  .251   79   75    60   121   209   800
1312  238  .254   79   75    60   122   211   800
1356  240  .257   79   77    60   123   211   800
1400  242  .260   79   77    60   124   211   800
1446  244  .263   79   79    60   125   213   800
1494  246  .266   79   79    60   126   213   800
1543  248  .269   79   81    60   127   213   800
1594  250  .272   79   81    60   129   215   800
1647  252  .275   79   83    60   130   215   800
1701  254  .278   79   83    60   131   215   800
END PDMM

# PDMM END —————————————————————-#

After poking at the definition file with a text editor for a very long while, I realized two things:

  1. I have spent waaay too much time on researching Stratasys machines, styrenic polymers, and all points of intersection.
  2. The second column of the flow curves chart is comprised entirely of binary values from 2 to 254.

It seemed a reasonable guess that ‘DO’ means ‘digital output’, and looking through generated .SML files, I saw various PD and MM commands (hence the ‘PDMM’ block of data).  The significance of the table only having even values from 2-254 hit me when I saw that bit 0 of the Asymtek’s 8-bit digital output is toggled when switching between the model and support nozzles – bits 1-7 must then be dedicated to controlling the motor speed.  This made even more sense when I consulted the Asymtek ACL programming reference and found that PD allows for a Pre-Delay between the digital outputs being set and the start of motion (allowing the filament to start extruding before the head starts moving) and MM allows for the digital outputs to be changed while the system is in the Middle of a Move (so that the feed rollers can be turned off just before the head comes to the end of extruding a path, allowing the ‘post-flow’ to extrude the tail end of the plastic).

The best way to see if modifying the definition file would have an effect was to try generating a test .SML file.  I created a .STL file consisting of a block measuring 0.25″x0.25″x0.1″ and generated a test SML file with the default settings and no supports.  Here’s a snippet from the file, where the machine lays down the outline for the first layer (note the MA lines – these are Move Absolute commands to X,Y locations, and you’ll see that the moves do indeed make a square).

# Z = 0.0090 S = 0.00900 T = 00:00:00 ### BEGIN FIRST SLICE ###
MA342,342;
XD209;VS100,1;#FC IDX1
MZ-52;
# obj:0 set:Part type:Perim matl:main width:0.0200 Z:0.0090 S:0.0090 (skipfill)
SR800;
PD.115,79;MM;MM0,25;MM60,118;MM-70,175;
AS1;VM4;BC;
MA342,342;
MA111,342;
MA111,111;
MA342,111;
MA342,342;
EC;VM3;MA241,342;# Exit

I knew that the SR800 was a speed setting (Step Rate) – the last column in the flow curve table.  Hmmm, I wonder if any of those values in the next line match up with a line of table values…

188   118  .115   79   25    60    70   175   800

Yep, that line looks like a dead ringer.  What happens if we change the 800 speed on that line to 801 in the machine definition and generate a new .SML file?

# Z = 0.0090 S = 0.00900 T = 00:00:00  ### BEGIN FIRST SLICE ###
MA342,342;
XD209;VS100,1;#FC IDX1
MZ-52;
# obj:0 set:Part type:Perim matl:main width:0.0201 Z:0.0090 S:0.0090 (skipfill)
SR801;
PD.115,79;MM;MM0,25;MM60,118;MM-70,175;
AS1;VM4;BC;
MA342,342;
MA111,342;
MA111,111;
MA342,111;
MA342,342;
EC;VM3;MA241,342;# Exit

Eureka!  Unsure of what I should actually try next (other than pestering Rick @ MakerGear to hurry up with getting the Experimental Filament Club underway), I thought trying to run parts using much smaller road widths (and not yet actually modifying the definition file) might be a good place to start.  I noticed that using 0.007″ slice heights in Quickslice defaults to using very narrow road widths (0.0137″), so I thought I’d give it a try.  In theory, making up for the reduced die swell by means of a smaller road width should result in not having drooping filaments on crosshatch infill…

Photo adjusted for improved contrast

And indeed, it worked like a champ, even with an extruder temperature of 270° C. and a 70° C chamber.  The crosshatch infill (though still not quite as good as with OEM material, but the best yet with generic material) showed minimal distortion – had I let the part complete (would have taken 2 hours – the FDM 1600 sets no speed records), I’m sure I would have not seen any sign of sagging on the top surface.  I still had significant curling on the part (and the curling that started on the left end of the part appeared to creep along as the build progressed), so the search for better ABS continues.

11 comments so far

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  1. I think the ABS from Reprapsource.com http://reprapsource.com/en/show/6444 is probably a bit more like the Stratasys stuff. It is white rather than cream and has more die swell than the ABS I got from NIP. It also likes higher temperatures you are using.

    • Thanks nophead – I’ll see if they can tell me the exact formulation. Getting a spool of it would cost around $184 USD, so I’m not quite ready to dive in…

  2. Great Stuff – what a helpful Blog!

    The QuickSlice software is truely a POS, and the Asymtek drives a nightmare. Between the three (counting the FDM as one) I’m getting a lot of gray hairs. Like you, need to find a new source of software, material, support, and the other stuff these FDM eat up.

    Now that my FDM is sort-of running, I’m rapidly running out of material and need to find some affordable sources or alternatives.

    Did you ever try contacting SIBCO in Michigan (and also in Europe), as their web page (http://www.sibcoinc.com/fdm.htm#material) claims a Stratasys compatatible material & support. I did emailed them requesting pricing but haven’t heard any thing back yet, as I’m just a very small fish.

    Keep up the great work……

    • Hi John, thanks for stopping by!

      Actually, I’m learning to deal with QuickSlice – the only gripe I really have with it is that you have to group all your models into a single .STL before bringing the file into QuickSlice. It’s also still hackable – I understand the latest version of Insight software obfuscates the machine definition files by running them through a TCL compiler (so my tweaking of the flow curves would be entirely impossible). What version of QuickSlice are you using?

      “Now that my FDM is sort-of running, I’m rapidly running out of material and need to find some affordable sources or alternatives.”
      LOL! That’s exactly what prompted me to start down the crazy path of trying generic ABS, and spending hours at the university library, researching just what the heck this plastic stuff is…

      I haven’t contacted SIBCO yet, though I did order two spools of ABS (normally pretty expensive, but they gave me a good price as they were the last ones they had, as they’re now just doing their ‘ABSmax’ material) from Argyle Materials (http://argylematerials.com/) back in September. Unfortunately, they never arrived! I finally called Argyle up this week, and they thankfully had a USPS tracking number, but all it could tell me was that it was ‘delivered’. I doubt that someone swiped it off of my porch (USPS and UPS leave stuff on my doorstep all the time, and nothing has ever gone missing), but USPS can’t do anything about it, and I’m out of a couple hundred bucks as a result.

      I have run across mention of people being less-than-thrilled with the quality of 3rd party Stratasys materials, so it’s possible that I wouldn’t have been pleased with the filament anyhow. As it is, these third party suppliers still charge a pretty penny for their wares – were I using my FDM 1600 for a business, I’d gladly pay the 30% or so extra to get the real thing, given my experienes with the Chi Mei PA-747.

      The new UP! printer from China (http://pp3dp.com/) uses 0.070″ filament, and initial reports were that the material ran very well, and was pretty close to Stratasys material. However, users have noted that recent shipments of filament have a much stronger smell when running, so I’m guessing that PP3DP may have switched suppliers or materials.

      I keep daydreaming about ordering a pallet of MG94-NA1000 resin from SABIC and having New Image or Village Plastics extrude it into 0.070″ filament, but I’m not quite that brave yet…

  3. HI,

    I have been following your blog on and off for some time, and what interests me most is the ABS and HIPS material that you have been using from NIP. I just wanted to know whether you have been completely satisfied with the ABS (Polylac) material and I know that you had some issues with the HIPS from NIP. I wanted to order the support material from NIP but now I am unsure. What would you suggest?

    Thanks,

    Rich.

    • Rich -

      In short, I wouldn’t recommend either one for use in a Stratasys at this point. Neither acts close enough to the real material to make me fully statisfied – both kick out a lot of vapors, are are extrusion grade materials. I think we may be needing injection mold grade plastics for use on a FDM machine.

  4. Interesting finding your blog here. I have an Asymtek 201 with a 12×12 XY table that I have adapted to position a mototool for use as both a NC drill and an NC router. I hadn’t thought of using it for a rapid prototype printer but I’ve now placed that on my to do list.

    I wrote a program to output ACL to the controller which reads excellon drill, NC G-code, gerber files, and DXF. So far it is working pretty well, but as I mess with one file type I end up breaking another. All in all though it works pretty well.

    I presently have my controller opened up and am trying to reverse engineer the digital I/O board. Mine only had the ‘STOP’ signal stuffed, but I managed to wire up one of the outputs to drive a relay to turn on and off the moto-tool. I have yet been unable to figure out the digital inputs, but if you have that board and could take a photo of it, it would be helpful to identify the chip set they used.

    Thanks for the useful and entertaining web blog.

    geo

    • George – I don’t think I’ve actually had my Asymtek opened up yet, but I’ll snap some pics if I ever do. Make sure to visit John Branlund’s blog as well – he may have opened his up at one point.

    • George,

      I just saw you comment in HaveBlue blog, and I’m interested in your program that outputs ACL — can you post some further info?

      Also, there’s some manuals (at http://haveblue.org/?p=514 ) that list some possible outputs and some diagrams on how to interface.

      John

  5. I have leveled a piece of used foam and measured the distance of a piece of 1/4″ glass to the nozzles to verify all is level. I then epoxied the piece of glass to the foam. I have been trying polymide tape which has not worked very well so I have resorted to blue painters tape which actually works but placement of the first layer is crucial cause if it doesn’t stick then it get a similar look to your picture above. Fortunately I still have some support material but I have been using ProtoParadigm for my ABS material which seems to work very well in the machine at about 263C. I have 3 heads so I can do some experiments although one does have a cracked inlet buffer. I am about to try PLA for the support material but I was wondering if anyone has figured out how to adjust the idle support to a temp less than the preprogrammed 210C. I am hoping that the PLA will stick a little better than the stock support material to the tape like it does in the Reprap world. I would also like to try PVA but there is no way to even try it if the support idle temp is 210 as that could cause some catastrophic results. Please let me know your thoughts as apparently these machines have a very small community. I am running an FDM 3000 and Insight 6.3

    • I’m guessing you should be able to adjust the idle temperature via the temp controller’s own setup. Unless of course the FDM is commanding the temp controllers over RS-485 or something. Have you asked John Branlund? His machines are closer to your 3000: http://3d4u.org/MyFDM/