mm_build

When two gears inter-mesh, the force from the opposing gear keeps them turning together in time. The tooth spacing is such that they are forced into a steady increment of teeth-per-rotation. The extruder gear works in the same way, except instead of another gear to press against, there is a plastic filament. As the extruder gear bites into the filament, it creates teeth. However because the filament is soft, the gear is free to carve teeth that are loose and not a perfect fit. This tendency is caused by kinetic friction on the filament. As friction on the filament increases and becomes greater than the force required to compress the plastic, the path of least resistance is to carve a wider channel. The gear and the teeth of the filament stay interlocked, but it is a sloppy fit, this is possible even with metal gears. It is possible for the teeth of the extruder gear overcome the integrity of the plastic altogether, which results in a situation where the filament is stripping. Because ABS is softer, it appears to not only strip more easily, but also yields to the extruder teeth sooner. At the forces required for extrusion, ABS is already reaching a point where it is slipping enough to cause a noticeable difference in rate of plastic from what the machine is supposed to be feeding. Settings such as "Packing Density" have been used to compensate for this. On the left is an extruder gear working at 100% efficiency, it is essentially simulating a rack-and-pinion such as you would see in real life. On the right is the filament slipping by a small amount, causing the tooth marks in the filament to be closer together, and feeding less overall length. As the extruder gear turns it carves into the imprints of the plastic instead of pushing off of them, resulting in rounder grooves with overall less spacing. The above example simulates a 10% rate of slip. Below are two similar sized pieces of filament fed at different tensions. You can visually identify a difference in the spacing.

Even at maximum tension where the filament was flattened to the point where it weighed less, there were no such markings or ground filament. I think it is possible for the filament to be slipping without it stripping. That is an excellent idea for a test. Now that I have my new stepper drivers I can begin testing again.

The first tension I used was lighter than I would normally use, but it seemed tight-ish. I did not try printing with it. After that I tightened it to about the same tension I have been using for a long time now. It is not super tight, although I can now see it is a little too tight. Here is a picture of the exact filament I was using: From the furthest that the thumb screw will go in, I am turned out about 4-4.5 x 360 degree rotations. There is a nice groove worn in my Delrin piece, so my end pressure will be slightly less than a new machine turned to the same amount. My results are taken with a 47mm NEMA 17... I'm not yet convinced that the steppers are losing any steps, I think it may be some kind of mechanical slippage of the filament (at least at the lower tensions). The numbers are not that accurate because I only fed 100mm of filament each time, I would rather do the test at 1000mm to make an accurate judgment.

Well I know what I am up against now. I am no expert at soldering, probably one of the worst, but I bet I can get it right if I have to. I will update this space when I have my new chip. If that doesn't work out I will consider replacing the TC PCB, and if that doesn't work out, well there's only so many parts to replace. Thanks again!

Ha ha, you should have edited it so I couldn't see that you doubted me! I wanted to do more tests including various tension settings at all the different stepping modes, and different motor speeds. There's still time for these later. Anyways, I was hoping someone else could verify my results.

Yep, twenty not 200. I heated up the nozzle in Pronterface (haven't managed to break the heater ..yet), it got nice and hot. The voltage measured ~50mV before heating, and the same after. The situation was the same where the longer I held the multimeter to the contact points, the lower the voltage would drop. It went down to 30mV in a matter of about 20 seconds. *sigh* If you disconnect the red/orange TC wires from the TC board, and measure the voltage between the 2 wires, you should see about 0.7mV at room temp, and if you heat the TC up a bit (hairdryer) to 60-70C, you should see about 2-3mV... this requires a good multimeter... if your multimeter has a temp function and you have a TC that came with it, you can 1st hook up this TC, and see what temp and voltage it is giving you. then hook up the orange/red wires of the UM TC to your multimeter, and compare the 2 readings. this should rule out any fault wether the TC is dead, or the TC board is dead. I hooked up the TC that came with my multimeter and put the hot air dryer on it, The temp was anywhere between about 50-90C with the voltage between 1.5-2.5mV. (Hard to measure because it cools down so quickly). I unscrewed the wires from the TC on the UM and put the dryer to the aluminum block. At about 65C I was measuring about 1.7 mV. I let it cool a bit, and at about 51C I was measuring about 1.2mV. These tests lead me to believe that there is nothing wrong with my Arduino or TC. Does this mean the chip on my TC PCB is blown? I read on the back what looks like "AD597", can I simply buy a replacement chip and solder it in? Or is there something else I should be doing to confirm the problem? Thanks for all your help by the way!

Thanks, but it isn't your doing. I'm just probably more careless than I could be, I already have an order of 10 coming in from pololu and they should be here any day now.. I expect there will be few more casualties. What I did was this: - 1/16 microstepping and 865.888 E steps in firmware. Verified 100mm of filament being pushed. - 1/16 microstepping and 865.888 E steps in firmware. Tensioned up the thumb screw and confirmed only 93mm of filament was being pushed. - 1/8 microstepping, changed E steps to 432.944 in the firmware. Confirmed 92mm being pushed. - 1/4 stepping, left E steps at 432.944. Confirmed 181mm of filament being pushed. - 1/2 stepping, left E steps at 432.944. Confirmed 365mm of filament being pushed. I guess I didn't get around to testing at full steps. These tests were all done with an F value of 100 in the gcode.

I only managed to get a few tests off before I ruined my last stepper driver, but it looks like missed steps are not part of the equation. I managed to get one test off in each of the different stepping modes, and at about 93% effective rate, the numbers doubled as you would expect. And since you're probably going to ask, yes I ruined my last stepper driver, that makes 8 in total. #1 caught on a wire as I was pulling the back panel off the electronics during a print and came half-way out #2 Bad soldering job on replacement for #1, coupled with careless use of side cutters #3 backwards insertion, this one caused quite a stink #4 Mystery death, started going backwards instead of forwards, stalling and generally inoperable #5 Same as #4, these were my x and y axis and they failed together (I had just turned up my pots FWIW) #6 Another backwards insertion, I managed to pull this one before it burned too badly #7 During insertion 2 of the pins bent to the inside and I did not notice, powering the chip like this will ruin it apparently #8 Heat sink broke off as I was adjusting it (custom heat sink), ran it without heatsink until failure (approx 5 minutes), ended same as #4 and #5

Yep, twenty not 200. I heated up the nozzle in Pronterface (haven't managed to break the heater ..yet), it got nice and hot. The voltage measured ~50mV before heating, and the same after. The situation was the same where the longer I held the multimeter to the contact points, the lower the voltage would drop. It went down to 30mV in a matter of about 20 seconds. *sigh*

I routinely make parts with 3mm holes intended for a M3 screw. The holes are modelled at exactly 3mm diameter, but when I print them they are a snug fit for the M3 screw (which I measure an outside thread diameter of 2.90mm). The advantage of this is that you don't need a nut in most cases, and can simply thread the screw into the plastic. I have only used hex hand drivers to insert the screws, and I have never used a special 'self-cutting' screw, which is something I did not even know existed apart from 'self-tapping' screws used for sheet metal work. I have been using button head machine screws of the type that come with the Ultimaker, and they work well. If you don't want the threads to catch on the hole I generally use 4mm diameter which is a pretty good fit after printing. For the brittleness of PLA, I haven't done any scientific tests, but I know from experience that when it breaks it does tend to 'snap' apart, where as ABS will kink but stay connected. I don't think ABS is necessarily any stronger than PLA, the point where they fail seems about the same, but PLA fails differently. In the case of a screw thread, I think PLA is better suited because it's not as soft.

You are thinking the difference might be due to lost micro-steps? I have nothing better to do right now so I'll check it out.

I am able to connect to the printer without the power plugged in, just with the USB cable. I measured the voltage at the PCB from Red to Black it is approximately 4.84V. I measured the voltage from Signal (green) to Black, and it is about 20 mV. Holding the multimeter to the contacts causes the voltage to drop steadily in 0.1mV increments until it was about 10mV. Coming back a few minutes later it was up to 17mV but started dropping again as I probed. At the bottom of the of the TC board where wires to the TC are soldered, I could not get any reading between yellow and red.

Haven't sorted out the problem yet. I don't have a multimeter handy to test it but as far as I can tell everything is connected. It's hard to tell what's going on inside of the clips, but it feels like it's solid and I've unplugged it and plugged it back in so many times now that it should have worked at least once. I even took off my glue and wiggled the wires inside to make sure they made contact. I updated the firmware to try and reset the undefined thing, and it could be nothing but it didn't sound right when I updated. Usually it makes that whirring sound, but it lasted a long time and the sound didn't sound normal. It sounded like someone dropping a bomb from a long ways. PS, would it burn something out if any of these wires touched? When I tugged on the ends to see which one was loose, the red and black came out together, so I pulled the green one out too. I was touching them to the terminals to see which ones make the light go on, and there is a good chance they made contact with each other and / or the pins on the board, because holding 3 wires into position with two fingers is harder than it seems in theory. :oops:

So the other day I took apart my hot end, and since then the temperature hasn't been reporting properly. I really don't think I "did anything" to the hardware, but I have a hard time thinking it's a coincidence. Once the hot end was disassembled (top off, bottom off, pcb unscrewed) I was tilting the machine back and forth to make some adjustments to the fan, when I noticed the blue LED flicking on and off. I eventually traced this to a loose connection at the plug to the main PCB. Also during this time the reported temperature in Pronterface changed to 0. I reset the machine and it came back with a temp of about 1 or 2. Anyways, I ignored that until I could glue the wires into the white housing which appears to have fixed all connection problems. The problem is now, whenever I connect to my machine it reports a temperature of about 27.83 degrees, whether I have the thermocouple plugged in or not, (not sure if that's normal). Also, it does not report changes to the temperature any longer. I can heat until the plastic starts smoking but it will still report the same 27-28 degrees. I tried removing my thermocouple for inspection, but there is a screw in the aluminum block which will not budge. Also the TC is loose within the block, I can move it in and out about 3-4mm. I haven't really played with this part before so I don't know if that is normal.

I would potentially be interested as this is on my to-do list, but the shipping and import fees to Canada probably wouldn't make it worth it. I was also thinking of going with a frosted glass surface for more surface area and better adhesion.

You are of course, technically correct. (That's the best kind of correct)

Or, the tension is causing the filament to compress into the bolt, which causes a smaller diameter to be used at bolt radius. That was my first thought as well, but I pushed 1000 ACTUAL mm of filament with my old tension (92.75% effective rate), and it weighed 7.8 grams. Then I backed off the tension until I was pushing filament at 100% effective rate and weighed 1000mm of filament again. On my scale the two lengths weigh the same, or within 0.1 gram of each other. At 92.75% effective rate, my metre of compressed filament should have weighed ~7.23 grams if the issue was due to the filament being of smaller diameter. However as I compressed my filament more, the smaller diameter started to become apparent. Weighing a 1000mm of filament pushed at 83.25% effective rate weighed 6.8 grams on my scale. So the smaller diameter does come into effect at some point, but it is not proportional to the amount of difference being seen in the extrusion rates. It would appear that when the filament is deformed going through the hobbed bolt, most of the volume is being pushed sideways, creating a filament that is wider and flatter, but overall about the same volume. Only after compressing it past a certain point it would appear the compression starts to extend length-ways down the filament, resulting in less volume of extruded material. At 83.25% ratio, the volume was still approximately 87% of total. To get any more precise I would need a more accurate scale, or a lot more filament.

Ok, so I think I'm onto something here. I backed off my tensioner all the way, then tightened it just a hair, literally just enough so it was touching ...barely at all. Then I did my test again extruding 100mm, I haven't changed anything in my firmware yet. Lo and behold... Wow, it's bang on! I tried the test 2 more times... yep it's extruding exactly 100mm. That's with 865.888 in the firmware. Then I tightened my extruder back up to where I thought it felt about right. Did the test again.... 94mm this time. Ok so tighten it again... down to 90mm. Alright, let's tighten the hell out of this thing... suddenly I'm down to extruding 82mm instead of 100. So it appears that the amount of tension is causing some slippage of the bolt against the filament. This could actually be used as a metric to determine how tight people have their feeders. mastory, I was able to finally get my bowden tube out thanks to your help. It does not look happy though, looks pretty beat up now I have to say. I would suggest backing off your tensioner a bit and see where that gets you. There might still be another problem with your setup though, because I don't think I could have gotten it any tighter and I still wasn't reporting as short as you are. Maybe that combined with packing density. Have you manually measured your filament diameter yet? That could be affecting flow as well.

micro steps per rev * gear ratio / ( pinch wheel diameter * pi) Alright, so microsteps per rev are 3200 (1/16 stepping, 200*16), Ultimaker's gear ratio is 49/8, or 6.125. Pinch wheel diameter I measured to between 7.5 and 7.9, let's just say 7.6 because I can measure the peaks but probably not all the valleys. 3200 * 6.125 / (7.6 * ~3.14) =19600 / 23.8761 =820.90444331609173186055835844771 Ok, I see that is supposed to be the number of steps it takes to extrude 1mm of filament? But clearly that isn't the case.

This could be a problem.. I've been trying to get my bowden tube out of the fitting for months. Just about destroyed it trying just now. Any tips would be appreciated. BTW I did my extrusion test at 1000mm (speed of 40) and the length came out to ~927.5mm, which is pretty much right on target for what I was measuring with 100mm lengths. I will be setting my steps per mm in the firmware to 933.572

I've been meaning to get around to this for a while, so thanks for giving me an opportunity. I repeated this test several times each at speeds of 40, 75, and 200. All the results were too close for me to notice any difference. I measured ~93mm of extrusion in virgin filament, and ~94.5mm in previously extruded filament. (with an E value of 865.888) My method was to disassemble the hot end, mark the filament with a razor knife flush to the bottom of the bowden tube, extrude 100mm, repeat. I took the filament afterwards and put it flat against a straight millimetre ruler. I would have tried your method too but I couldn't really follow from your description what you were doing. If your numbers are that far off I suspect it's something to do with how you are measuring, but I could be wrong. There is a range of extrusion rates that your print will still look OK with, even if it is not ideal. According to my calculations I should be using 931 as my E value, which is closer to the value for the old hobbed (which I don't know off hand). If you are confident in your method of testing, then I would suggest trying out the number it gives you and see how your prints look. I will be doing some more testing myself, in fact I will be putting my new values in and extruding 1000mm to see where that gets me. The code I used to extrude is below G21 (metric)G90 (absolute positioning)G92 E0 (zero the extruded length)G1 F75 E100 (extrude 100mm of filament) G92 E0 (zero the extruded length again)

Different PLA will warp different amounts, some colours are even worse than others. Changing your temperature in RepG should not work during a print, to actually change your temperature you will have to add the change to the g-code or re-slice your model, I am well familiar with your warping problem, the only suggestion I can give is thinner base layers and infill instead of solid. Or as Falc said, a heated bed.

Step by step for manually updating to marlin firmware: 1. Navigate to https://github.com/ErikZalm/Marlin 2. Click the little button in the top left-hand corner that says "ZIP" 3. Save the file somewhere and extract it 4. Navigate to http://www.arduino.cc/en/Main/Software 5. Scroll down to "Previouse IDE Versions", download and extract "Arduino 0022" *note - do not install any other versions as they will not work at this time 6. In the Arduino-0022 folder, run Ardiuno.exe, if you are prompted to update to a new version , click "no" 7. Under Tools>Board select the Arduino Mega 2560 8. Under Tools>Serial Port select the serial port that your Ultimaker is connected through. This can vary from system to system. (if no option is available make sure your Ultimaker is connected and you have installed the USB driver) 9. Click File>Open and navigate to the folder where you have extracted the Marlin firmware, select "Marlin.pde" for opening 10. Click the "Verify" button in the tool bar 11. After verification is complete, make sure your Ultimaker is turned on and connected, then click the "Upload" button. note - you may not be able to connect if there is a competing program open such as ReglicatorG. 12. If the upload is successful, congratulations, you have updated your firmware to the latest Marlin (similar instructions are listed at the bottom of the page in the Marlin github) You can also use Daid's increasingly popular Build-Me-Marlin http://daid.eu/~daid/marlin_build/ , which is pretty simple to use. However it will not work with ReplicatorG. Realistically you should probably upgrade to Printrun instead of ReplicatorG anyways. Daid has devoted a lot of time to making a all-in-one solution SkeinPyPy, which includes Printrun, and a simplified version of Skeinforge. This is a great option for many people, but you can also install Printrun separately and use Skeinforge separately. There are advantages and disadvantages to both methods. (Note - If you use SkeinPyPy you must also install your firmware using Build-Me-Marlin as it is not currently compatible with the latest github release of Marlin firmware) To install Printrun separately navigate to https://github.com/kliment/Printrun instructions for installation are listed below the file listing. There is also a pre-compiled version which will be the easiest to set-up, although it may not be updated as frequently. Good Luck! PS, in case it wasn't clear we are dealing with 3 different components here 1. Firmware, which is uploaded to your arduino board on the Ultimaker and doesn't need to be modified that often 2. Slicer software, in this case Skeinforge but there is also Netfabb and others. You use this every time you have a model (.stl) and want to convert it into a printable format, the slicer will convert the model to gcode 3. Printing software, such as ReplicatorG, or Printrun. This is used to feed g-code to the Ultimaker during a print. pps, can't tell you anything about apple/macintosh

Don't know what is wrong off-hand, but we can narrow it down pretty quickly. I am linking to a working profile, this is Skeinforge 48 (2012-01-22) so you should use that version to make sure everything is compatible. Go ahead and add it to your C:\Users\\.skeinforge\profiles\extrusion Directory. This is a fairly moderate setting, I change things around all the time but I don't think I have anything too crazy in there right now. (click on "profile" up in the menu bar, select "extrusion", then "pla .25") http://solidfiles.com/d/f0067a149b/download Also, as ddurant mentioned make sure you have updated your firmware if you haven't yet.

There are a ton of settings in Skeinforge and it's easy to be overwhelmed. You can get a profile that "works", but it will take time and experimentation before you understand how the various settings will actually affect your print quality. The very first thing is your Layer Thickness (in the carve tab) because it will most of all affect what other parameters you want to set. I like to set mine to something that divides evenly into 1mm because it makes modelling results more predictable, but feel free to experiment. After that the big ones are Width over Thickness (in both fill and carve tabs - keep them equal for now), and Infill Solidity Ratio in the fill tab, which is pretty self-explanatory. Next is your Feed and Flow in the Speed tab, they should also be kept equal (until you're trying something really advanced), I consistently print at about 40-60. Also I would set Travel to not more than 120 to be safe because it can be more sensitive to problems with lubrication, alignment, driver voltage or a bunch of other things as you move higher. Finally there is Temperature in the Temperature tab, you can go as low as 190 and as high as 240 (give or take a few degrees), you will find that different temperatures work with different speeds, faster generally means hotter. If you are troubleshooting then it's safer to stay on the hot side. At first just keep all the temperatures the same and experiment later. After that you have some nice tweaking stuff, like Extra Shells (keep them all equal for now), and Solid Surface Layers in the Fill tab. After that I would tweak Object First Layer in the Speed tab to adjust the speed of the first layer since it is more critical to get this to stick correctly, and along that line I would also adjust Object First Layer in the Temperature tab, it's generally helpful if you set your first layer a little hotter because helps to make it stick. Actually there is one more here that is kind of important, you should set your Filament Packing Density in the Dimension tab to 1.0 if you are using PLA, and less (about .8) if you are using ABS. Also if you have a caliper you should measure your ACTUAL filament size and put that into Filament Diameter space. I find my actual filament size is between 2.86-2.89, although this will vary based on your supplier. Other things less important to play with are the Bridge settings in the Inset tab (bridge is when you print across an open area "bridging" it), and Thread Sequence Choice in the Fill tab, (I find Perimetwe>Loops>Infill works best), and... also the Support Cross Hatch setting in the Raft tab. Check support if you plan on printing a steep overhang that would otherwise not stay suspended in mid-air! Oh yes, and one more thing, I highly recommend that you don't print with a raft, not just because it is a needless waste of plastic that masks other tuning problems you might have, but because it is a sissy thing to do and other forum members will laugh at you! You have been warned. To Disable your raft do not uncheck Activate Raft, simply set Base Layers to zero. Phew, well that turned out longer than I anticipated. Take your time If you need more explanation of what a particular setting does, try this manual-> http://fabmetheus.crsndoo.com/wiki/index.php/Skeinforge