calinb

Any luck with netfabb too? If no, I'd appreciate a ticket submission to nf. nf isn't the most responsive software house when it comes to squashing bug but, with your help, they might get it done before I'm ready to go dual!

It is not always fine. Daid brings up a good point. The platform must move down (accelerate) only downward during a print, but then it must stop (decelerate). With the greater acceleration, I've found that it is prone to bouncing when it stops moving. I have a relatively heavy build surface (a 5/16" thick precision Mic-6 aluminium plate). It is extremely flat and stays flat during temperature swings (unlike the wooden arms of the Z-stage :() but it causes my Z-stage to bounce a little with the higher acceleration settings--so much so that it will trip the Z-stop limit warning on the initial move downward from the bounce! Be wary, if you print large objects (heavy) or use a heavy build plate. The current Z-stage design really doesn't seem to be up for significantly increasing both Z acceleration and mass, in my opinion. I'm going back the the standard settings.

Oops--I forgot to divide by 60 (minutes to seconds conversion factor). This is a very slow 80 micron (40 micron perimeter "half-layers") / 40 mm/sec head travel nf print with a 0.5 mm nozzle. The netfabb menu numbers could be wrong too (though I think I've correlated them to some of Joergen's numbers in the past and found them to be reasonable) and I'm too lazy to measure the actual feed rate or do the arithmetic on the actual gcode. Regardless, it's a slow print and heat migration can be a problem at this rate, rather than the rate I misreported. Also, these slow 35 hour print jobs used the nf default 2.88 mm of retraction. I capped the firmware at 25 mm / sec maximum E-speed and I built the firmware using the recent Marlin retraction fix source tree. There is no significant stringing across valleys and my nf settings do not attempt to restrict the print head to completing jumps only over the printed part (an nf option).

Yes! I'm up to 275 C for Ultimachine black now and the results are better than ever (stronger parts with better finish quality). I've printed several 35 hours jobs that were printed fairly slowly (under 5 mm / sec filament feed rate) and I still had no trouble with heat migration or jams. Though my aluminum heatsink is smaller than Joergen's FET sink, my new PEEK also shows no sign of overheating, as did the old PEEK before I made changes similar to what Joergen describes here. I'm also using no fan, except for a light fan on the very smallest areas (less than maybe 5-10 seconds print time) due to inadequate cooling time and my bubble wrap tent is yielding 65+ C!

And thanks for explaining the situation, Daid. Your summary seems to fit the landscape! :(

The last line of the code is for a very short X-Y movement with detract ("push-on" in nf-speak), including a very short positive net E (ending very slightly beyond the filament position before the retract). It is always very short like this. I don't know their motivation for combining the detract with a very short X-Y move, but it doesn't really constitute a print motion. Overall, it actually does work!

Thanks, Daid. I bumped the limit up to 25 mm / sec and it seems to be working on a short test. Illuminarti, Yes--nf seems to retract at a high speed but I've found that the user "pull-back speed" setting (RPM) doesn't work in nf. Changing the setting does not result in a change in the gcode produced. The F value in the gcode remains 10800, regardless of the setting in the nf "Manage Materials" >> "Speed and jump settings" tab: Disabling this setting may be at least partially what Alexander referred to as a workaround. G1 X179.4590 Y17.8500 Z0.0400 F1200.0000 E14.3443 (retract -2.88) G1 X179.7556 Y19.5524 Z0.0400 F10800.0000 E11.4643 G1 X182.1463 Y33.2764 Z0.0400 F10800.0000 E11.4643 (retract 2.88) G1 X182.1465 Y33.3587 Z0.0400 F1200.0000 E14.3454

A timely response from Alexander: Hi Calin, thank you for the request. The behaviour of netfabb is not a bug, it is a workaround to enable the combination of movement of the axis with retraction - a feature which Marlin does unfortunatelly not support. If the behaviour of it has recently been patched, I will have to look at another solution. Probably just do it like the other slicers and not move while retracting. I will keep you up to date. Best wishes, Alexander

A 20 mm / sec limit does work with netfabb. Retraction seems to be a bit slower, but it should function. 20 mm / sec is not all that fast with a large nozzle, however (for forward extrusion). Maybe netfabb will correct their software again, but they finally did fix their retraction bug (while using bugged Marlin) and it was working well for me. Thanks, -Cal

Well, Daid...the company that employs you sold netfabb to me. I'll accept your point of view if they'll refund my money for netfabb! Nonetheless, there are countless examples of "legacy" modes in the history of software that were retained to cover situations very much like this one. I'll try to find and change the maximum E speed, but it will limit my maximum forward E-speed as well, right (not terribly desirable)?

I just built the latest V1 from Daid's tree. Unfortunately, netfabb finally fixed their Ultimaker Engine retraction bug and it is now my favorite slicer by far, but I can't get it to work with the latest Marlin V1 containing this Marlin bug fix. I seriously doubt netfabb will "fix" their program again to conform to these significant Marlin changes. What--it took them something like a year to fix their retraction bug? Given that the push-on and pull-off speeds are identical (the default in netfabb), I simply tried cutting both equal speeds in half. This resulted in what appeared to be a somewhat more aggressive retract (pull-off) than before I uploaded the Marlin fix but, more significantly, there was virtually no push-on. Next I cut the rates to 24% of their defaults. Same thing--retraction speed was reduced, it seemed, but there their was still only an insignificant push-on. It doesn't take long for the printing to stop, because the net retraction exceeds the net push-on. Can we get a #define USE_OLD_RETRACTION or will I forever have to use test2 Marlin (or figure out the source code myself)? Thanks, -Cal I also tried changing the pull-off rate only (to 24% of its original default value) while leaving the push-on setting at the default. The amount of filament pushed and pulled is set to 2.88 mm, BTW. Nonetheless, Marlin now results in far more pull-off than push-on.

Yes--my plan is to actually shorten the entire hot end (providing even more Z-range too ) and extend the stainless cold end tube up into the wooden box. There's not a lot of room (~1/4" OD SS tube) inside the box, but there is just enough room! A new fan orientation and new duct is the plan. I refuse to add a second fan to the head. Your hotend already has a heatsink but my Ultimaker already has the plate! The plate may not become my entire heatsink, but the surface area of the plate could be increased somewhat with some milling--perhaps even surpassing the surface area of your hotend heatsink. I don't know yet. I'm printing Ultimachine and Protoprinter ABS currently The Ultimachine requires high temps! I'm printing it at 275 C. The simple mods that I made have kept my new PEEK and Teflon part pristine (unlike my pre-mod PEEK, which was showing signs of over-temp). I don't think my MakerGear barrel and nozzle and mods result in the optimum configuration for ABS printing on the UM, but it's working and I probably won't find time to play with my more challenging fabrication project for a while.

I print ABS up to 275 C (often with an idle fan) and I also use a heated build chamber (I've had it above 70 C). Since making a simple mod to my nozzle assembly, i've had no signs of overheating of the PEEK or Teflon part as I did previously. The specs I've seen limit both of these materials to about 260 C continuous. http://umforum.ultimaker.com/index.php?/topic/1798-got-abs-you-need-a-makergear-50-cal-nozzle-and-longer-barrel/

It's a bit of a shame to ditch the aluminum plate, because it could make for a great heatsink! I have a design in mind to use it in this manner--along with a new fan shroud to direct a portion of the airflow to the heatsink/aluminum plate.

You might try a thickening oil like this one: http://www.corrosionx.com/corrosionx-heavy-duty.html I love the entire Corrosion-X product line, BTW (but have no financial interest in it).

I've been using this fan from Fry's for a few months: http://www.frys.com/product/4722209?site=sr:SEARCH:MAIN_RSLT_PG It's actually 160 mA (see the photo of the packaging lower in the page) vs. the 100 mA consumption of the original fan and the air flow is noticeably more powerful too. I often run with a bubble wrap "tent" around my UM and achieve temps of up to 70 C at fan level, to no detriment so far. It's still as quiet as it was the day I installed it.

I forgot to mention that I noticed the heat sinks on your stepper motors. If desired, the X and Y steppers can be located on the outside of the box for cooling. Just flip the wire pairs to run them in the correct direction and relocate the pulley on the shaft at the appropriate place. I've done this mod, because I sometimes wrap a "tent" of bubble wrap over the windows to warm the build chamber for ABS. I've measured up to about 70C inside the chamber at nozzle height when running my bed at 120C. I think a more carefully constructed tent could result in even higher temperatures. Also, snowygrouch has an external stepper motor design that is direct drive and eliminates the stepper belts too.

Thanks for sharing, kushal! Very interesting. Please keep us up to date on your progress. Personally, I don't think it will make a difference because it is "upstream" and isolated from the drive, Bowden tube, and mechaical load (hot end), which is were the significant hysteresis occurs. The things that make a difference are selecting a Bowden tube ID that provides a good fit to the filament OD (but no so tight that you have excessive friction), and anchoring the Bowden tube as solidly as possible on both ends. I never unwind the tension adjuster on my V2 drive (Bertho-style). I just flip the "door" open. It is worth implementing a door mechanism for this reason. With the door, this design is a "set and forget" proposition!

Sure--thanks to you for suggesting it, Joergen! It's like having a new A-B-asS-kicking machine! The difference is incredible. I've had no more extrusion "stickiness" developing with the resulting slowdowns and under-extrusion, plus I get better first layer line (wider) adhesion to bare warm glass and lower extrusion temperatures for the same end results. For now, I'm just wrapping the heater block and top part of the nozzle with fiberglass bid tape (a bare, non-sticky-backed fiberglass weave cloth used in fiberglass resin fabrication). After wrapping as much as I can reasonably fit around the hot end (while trying to keep the aluminum nut and PEEK uncovered) I just hold it with a square knot at the end. Eventually I will design a new molded or machined insulator to fit over the aluminum block from above in my full box length stainless barrel design, but this is working so well, I probably won't be motivated to do so for awhile. This setup will probably print Taulman 618 nylon just fine and only the high temps required by polycarbonate or other high temp materials will likely motivate me to continue further development. >I am using a 20x25mm alu cooling piece (I think it was used for a mosfet or >transistor before, kind of a butterfly style) under the PEEK for even more >cooling of the upper end of the tube, I'll add that I thought about using something providing more cooling, but I wanted to limit the diameter of my aluminum locking nut to 14 mm so it could remain attached to the barrel/PEEK assembly during removal through the 14 mm hole in the aluminum plate, thus retaining its barrel position indexing. I also wanted to keep it thin to retain as much Z-height as possible (yeah--I know...I'll probably never use it all anyway). Despite having flats for a 10 mm wrench, the aluminum nut is only thick enough for two internal threads so it cannot be tightened super tight, but it does the job when tightened moderately and my aluminum heater block is nice and clean inside (and there's no source of leaks inside the aluminum block bore so it will remain clean). If the barrel became stuck in the aluminum block and posed significant resistance to removal, it would be necessary to use heat during disassembly to keep the moderately tight lock nut from turning and losing index (or maybe stripping). Once the aluminum nut is indexed and locked correctly, there is really no reason to every disassemble it unless something becomes damaged (like overheating the PEEK).

Some time ago, Joergen suggested that I try a larger nozzle. I finally got around to it and I'm very happy! My best ABS setup to date has been a "V1/V2 hybrid" (V1 setup with the V2 Teflon anti-jam coupling/tube). The V2 exhibited a few more problems related to poor flow and layer bonding than my hybrid when printing ABS. I also made a 20 mm long V2-compatible tube out of stainless steel and it was even worse than the V2 brass tube. For SS, I will will need a lot more length, which I'm planning to implement someday by extending a SS tube to the top of the extruder head wood box but it will involve a complete redesign of all the plumbing and associated hardware from the Bowden tube down. It will not use a PEEK and it will feature an aluminum mount to replace the PEEK and act as a heatsink that alsol conducts heat to the aluminum plate. There's no reason not to use that big plate that UM provided to to more than just hold the hot end up! I'll tap some airflow from the fan to cool the aluminum plate and custom holder / heatsink too with a custom fan shroud too. For now, I installed a Maker Gear BigHead 0.50 mm nozzle and 36 mm MakerGear brass "barrel," which offers considerably more brass mass and length then the UM design. While I was at it, I made a few mods that resulted in a total loss of only 3 mm in Z travel, compared to the UM V1 or V2 hotend. My changes also make maintenance easier and reduce the likelihood of plastic leakage. I didn't shorten my PEEK, as I've often considered doing, but I installed a custom aluminum locking nut/spacing shoulder under the peek, which also acts like the shoulder on the V2 brass tube. I have 1mm of space between the Al heater block and my 2 mm thick custom Al locking nut, which is enough to eliminate heat conduction from the aluminum heater block to the PEEK. I made a micro boring bar and turned a 2 mm deep internal recess in the end of the V2 Teflon part to accept the standard turned down end of the MakerGear brass barrel. The Teflon is a nice tight fit, sandwiched between the brass barrel and the wall of the PEEK. Molten plastic will have a hard time getting past two ninety degree turns and the 2 mm of tight fitting overlap. So far I have no leakage there or inside the aluminum heater block bore, because the brass barrel goes all the way though the block--like the V1, but the MakerGear barrels are turned down on both ends, which really seems to help them seal well at both ends. Hopefully these photos will last longer than the dozens of photos I posted to the old forum that were lost. :( Assembly is only 3 mm longer than stock Note that turned down end of MakerGear brass barrel extends 2 mm more upward than standard UM brass tube when positioned correctly. (Trial fit with Teflon piece and calipers before locking aluminum lock nut.) Teflon tube hot end bored on hobby lathe with custom micro boring bar to fit turned-down end of MakerGear barrel. A numbered drill bit will get you close, but will not produce as close of a fit nor will it produce a matching squared internal corner in the Teflon part. 2 mm long turned down shoulder on MakerGear barrel fits perfectly in bore of Teflon tube. I think this is a much better setup for ABS than the original UM nozzle. Now that I have the extrusion calibration (extrusion multiplier or "flow tweak") dialed-into netfabb very well, I can even print 0.40 wide perimeter lines on 0.080 layers at 40 mm/sec travel, which is the narrowest width I ever used with the 0.40 mm nozzle. I'm sure a good 0.40 mm nozzle can extrude even thinner but that's plenty good and works out to less than 4 mm / sec filament extrusion rate. On the top end, I had no trouble extruding close to 30 mm/sec fill (~90 rpm), which was giving me problems before. -Cal

Where does the ground plastic appear on your hobbed bolt knurling? Is it on the far "good" side? I suspect that your hobbed bolt installation could be optimized further, but agree with others that it's not your root cause. Like Joergen, I am puzzled by the wood damage. Too much pressure can also cause filament grinding and might be consistent with the wood damage. Are you sure there is some "spring action" in the operating position? LIke many people here, I've successfully run the old and new extruder feeders and the new one is very forgiving. Nonetheless, dimensional / positional problems with the black rubbing block in the old feeder created too much pressure in my original feeder and had to be corrected before it would stop grinding filament. The new spring-loaded bearing is set and forget! My post in the old forum on the position of the knurling contained many photos. I will not entirely duplicate my efforts again here. On my machine, it was impossible to position the very BEST knurling in the middle of the filament "channel" without modifying the hobbed bolt. By widening the 2mm slot to 4mm on my lathe, the clip position was shifted outward on the bolt and the bolt knurling shifted in the channel in the direction of the big wheel. This put the deepest, fully peaked diamonds in the middle of the filament channel. The number of washers required varies with the position of the bearings and the positions of the big wheel and locking castle nut on the hobbed bolt. I pressed the bearings fully into their pockets in the wood (the only dimensionally stable position for them). I use one washer under the locking castle nut and three washers between the big wheel and the contact point on the bearing (the washer diameter is small enough fit inside the bearing recess) but my bearing is pressed all the way in. leaving part of the recess, and I have shifted the bolt 2mm too, requiring more spacers. The best knurling is on the side nearest the slot in the bolt (the slot for the black clip). The knurling becomes progressively worse in the other direction. From one of my posts in the old forum (http://umforum.ultimaker.com/index.php?/topic/1272-extruder-drive-cannot-push-filament-through-hot-end/page-2&do=findComment&comment=9119): "Zoom into this photo and inspect the diamonds on the right edge of the drive bolt image. Notice that only the top six diamonds are fully pointed, cut deeply, and "good." Widening the slot on my lathe enabled me to position only good knurling in the filament channel. This mod was motivated by Joergen's older drive bolt, which has much more aggressive knurling than these new drive bolts.

I never print ABS below 240 and I print Ultimachine ABS at 275 (as displayed on my machine, obviously). I like to live on the hairy edge of jams in order to get maximum strength in my commercial parts, however. I've also taken to printing on Kapton tape and cranking my 160 mA fan to 100% after the first couple of layers (original fan was 100 mA and noticably weaker). Putting layers down as hot as workable minimizes the Achilles heel of FFF/FDM--weak "grain" (incomplete layer to layer bonding) strength. Cooling layers quickly after they are deposited reduces stress accumulation in the part as many layers cool (all layers have to cool sometime). Strain (warping) results when the stress overcomes the bond to the build surface. Actually, strain occurs anyway (like Z-shrinkage); it's just not as bad when the part stays firmly fixed to the build surface. Like most people, I've tried countless combinations of things (bubble wrap/heated build chamber to 50C, different bed and nozzle temperatures/ fan profiles, etc. But this approach seem to be the best for my large parts, which span the diagonal of the bed and can be several cm tall. With the best Kapton tape I've ever used, I could actually unplug the heated bed after the first few layers and run the fan 100% and the part still remained stuck and warping was minimized! I found that about 60 - 70 C (the same temp I use for PLA directly on glass) resulted in the best Kapton to glass bed bond and it's quite good after cooling to room temperature too. At times, it's what gives rather than the ABS to Kapton bond. I've yet to print a part hotter that wasn't stronger but eventually, you run into problems. I'm certain everyone else's mileage will vary!

I'm too busy printing stuff right now. That will have to wait. In the meantime, I can build Marlin code and upload it to the printer before each print and I've discovered something significant. The official Marlin .hex file that's included with Cura ("Marlin-Mon, 11 Jun 2012 17:33:42 +0200 - b67dacdc8f1bd489e058e16d92ba29c364b2a8e5") results in significantly more stable temperature control than anything I've ever built using Marlin Builder or the Arduino IDE and Erik's code tree--even when I use the Configuration.h file that is included with Marlin! Something has changed in the code tree since 11 June, 2012 that affects temperature stability. I've noticed that other LCD display fields have become glitchy, of late, and while the PID LCD fields appear to work in the Official Cura Marlin, Daid informed me that all but P are not displayed correctly and, based on my observations, I think this bug has crept-in since 11 June, 2012. I think there may be more at play than just how I and D are displayed and I also think there might be a change that make the machine more noise sensitive. In fact, everything is glitchy in the newer builds (in addition to LCD display value jitters, user selections are sometimes missed, requiring re-clicking, and fan speed changes are significantly delayed, etc.) For now, what I need is the exact build tree that was used to make "Marlin-Mon, 11 Jun 2012 17:33:42 +0200..." Using the code tree for the released version of Marlin, I can just change the PID values to match what autotune advises, and also increase the HEATER_0_MAXTEMP to print the materials I have that don't work well at 260 C (even my Ultimachine ABS tests at 270 C prove 260 C results in weakly bonded layers) and hopefully it will work as well as the official Marlin. -Cal Update: There are plenty of code trees from around the June 2012 time frame on https://github.com/daid/Marlin and https://github.com/ErikZalm/Marlin but I'd like to grab the exact one that was used to create ultimaker_115200.hex and ultimaker_250000.hex if Daid or Erik can tell me where to find it (or which one on github is the right one). Update 2: I built Marlin-test-2 with and without my custom PID values and they both work. https://github.com/ErikZalm/Marlin/tree/test2 I also increased the max temp limits anticipating my hot end upgrade. More importantly, the nozzle temperature excursions and jitter, poor fan response, z-axis stepper glitching, and keypress misses are gone too. I don't know why all these problems have crept into more recent Marlin builds--at least on my machine, but the old Marlin works significantly better for me. It works like the day I got it again!

You have made an excellent suggestion, Joergen. Assembly defects could easily be the root cause of my temperature "jitters." I found two solder defects on my Ulticontroller main board that required correction before it operated consistently. The assembly on all these these UM boards (AD575, Arduino, UC) could be better, from what I've seen on my three boards and what others are reporting. I also think AD575 jitters may be interfering with the PID autotune feature. I've run autotune under several conditions with several temperature targets and the result never works very well (not as well as the Marlin Builder PID defaults or the factory defaults). When I tear my V2 hotend apart to install my higher temperature resistant custom upgrades, I'll check the AD597 board.

Yes--the thermocouple signal is analog and must be amplified before it leaves the extrusion head. I also never use USB except for firmware updates, but my Ulticontroller temp display jumps around a lot. Strangely, with the latest Marlin build, the readout is more steady with the fan on than off, but it still jumps when the steppers come online.