gr5

I expect the ultimaker heated bed upgrade will be for sale very soon. It is an all metal platform and once leveled you don't have to level again. It's very nice. It's the same design (same parts) as the UM2 bed and z stage. Keep in mind that some Z screws are not single helix but double or even quad helix. I don't know what "trapezoidal" means - does that have to do with the qty of helixes? So when calculating steps/mm it's how much the Nut moves on one full rotation times 200 times 8. Just set steps/mm to that value.

No. I've used shell thickness of .3mm with nozzle set to .4mm. You can get a little bit of underextrusion at this severe setting but things come out okay. Using .79 or .39 for shell thickness will be fine. .3 is okay but you will notice reduced quality. Playing with these values is very useful for printing thin walls. Also note that if you have .4mm for nozzle, and .3mm for shell, the infill is still printed with .3mm spacing and flow rate. This seems strange, but I don't mind as long as I understand what's going on. I guess it would be nice to be able to print the infill at .4mm width and shell at .3mm.

I think it will come out quite soon.

I think you mean 2.5mm. What is the nozzle diameter? .9mm seems very large! Can you send me your STL file? Can you post it somewhere on the internet? Maybe dropbox or something? And post a link to it?

Something is loose. Without printing anything, go to the ADVANCED menu where you can set the nozzle temp. Leave it at 0C but look at the displayed temp - it should be around 20C (air temperature). now poke around. Start by putting pressure on the 2 wires going into the print head. Push the head to the 4 corners. Always keeping an eye on the temperature to see if it jumps suddenly. Push and squeeze and prod the wire all the way from the print head to the board underneath the UM2. Take the larger cover off the bottom (2 screws) and push on the wiring there. Also push on the board.

There's a checkbox to tell Cura to not print the top. Keep looking through the 3 panels of options.

The wall is probably too thin for Cura to slice. Try making your "shell" thickness in Cura much smaller as a test. If you are using .4mm try .39, .38, .37. Try .3, try .2, try .1. See what happens. You probably don't want any of the "fix horrible" boxes checked. They usually only should be checked if the model isn't manifold. You can test this in the "xray view" and if you see any red areas in your model then you either need to fix it or use the "fix horrible" settings. Red areas indicate an internal wall or a hole in a wall. However I don't think this is related to your issues - I think it's just too thin to slice. If you have a .4mm nozzle and .35mm slices nicely it will probably print fine. You can go down to 75% nozzle width without too much trouble. Or you could go back to blender and thicken your part.

Watching why it bends up carefully I concluded the best thing to do is cool it FAST. 500ms is too slow. So cooling from below should help it cool very fast! Alternatively you can print super slow (5mm/sec) such that lower layers are remelted and pushed down into place. Personally I don't like this 5mm/sec option as that is too slow for me. The problem is definitely cumulative. The first few rows the effect is so tiny it's hard to see but it gets worse and worse until it's a problem. Pushing all the layers back down with fingers/tools helps for the next few layers.

I had only watched the second video when I posted above. Watching the first video... I see that the X stepper belt is definitely twisting. So even though it doesn't look like it's touching the wood - it is. Take that stepper out and make sure the pulley is as close to the motor as possible without touching (.5mm is good) and then add the 4 washers (one for each screw) under the plastic spacers that I mentioned above. Afterwards you will see the X short belt is no longer twisting. And you will get lass black powder below it.

Philip what country are you in - please update your profile location to show this.

So many things to say... 1) If your short belt used to be touching the wood until you tightened that short belt I would definitely add 1 washer to each spacer to move the stepper slightly farther from the wall. It might not look like it's touching but you can tell because the short belt twists different directions when you change directions on the X axis. Just do this. This usually causes gradual shifts - not sudden shifts like you got but still - just fix it. Takes 10 minutes. 2) Long belts should be pretty loose. Short belts much tighter. If long belts are too tight it increases the resistance significantly. If you watch Erik's video he has the musical note showing the tension accurately so you can tweak yours like his. Mine are pretty damn loose. 3) The non-round circles is usually caused by backlash aka play. But this can be caused by too loose belts (head doesn't get pulled all the way because the belts are floppy) or too much friction (when axis stops moving belt is still pulling hard (ish) but head is done moving due to high friction. Feel the friction of your head movement with stepper power off. You should be able to push very easily in X only with one finger on each block. 4) You had a sudden shift when printing the black part. Sudden shifts are usually (but not always!) caused by slipping set screws. You kit should have a spare set that are silvery/shiney. These are pointier than the black ones that come with the pulleys. I still use my black ones and they are fine but I tightened the hell out of them. Especially the 2 on each axis on the short belts (motor and pulley above). The short belts take all the abuse. If you are too lazy to tighten these because you don't beleive me the least you can do is take a permanent marker and put a mark on the shaft and pulley. That way if it happens again you will know for sure. Sudden shifts can also happen due to friction and gcode wierdness (very rare though). Especially if Z axis moves when X an Y moves (Marlin still has a few bugs that almost never show up). Of course in this case they always happen in the same exact spot of the model/gcode.

EldRick - very interesting. When I started reading your post I was thinking maybe you were getting the black teflon stuff from the feeder into your prints (black and brown are similar colors) but now you say at 201C you don't get any brown spots inside the nozzle? Well I find this all hard to believe but I will keep this in mind! Very interesting. I also have some white diamond age filament. It definitely flows nicely at lower temps. I've been printing it mostly at 220C lately but it's been small parts and I have been changing filament often and always change filament by pulling at 90C (atomic cleaning) so I clean the nozzle a lot! Unintentionally. And I always cut the end off and discard. I mostly use the 90C pull technique not to clean the nozzle but to make it so I can change colors instantly (no mixing of colors). Anyway this idea of slow cooking PLA over 8 hours causing problems - seems believable - I've just never noticed it before and I'll have to pay more attention and keep it in mind.

At 100mm/sec .32 layer .4 nozzle, that's 8mm^3/sec. I've seen people do 15mm^3/sec (about twice as fast) even on the UM2 (but at 230C! 200C is impressive) (although my limit on my UM2 is closer to 8mm^3 at 230C). However what really impresses me is 200mm/sec retraction. The menu system on the UM2 only lets you go up to 35mm/sec which seems ridiculously slow. And on the UM Original I think around 30mm/sec is the max speed. Maybe you should do a more exacting test like this one... http://umforum.ultimaker.com/index.php?/topic/4222-pulling-force-of-um-extruder/?p=34887

Having said that you should get much less Z scare (or none visible) with spiralize. Personally I don't get Z scar at all on my "show" prints as I print them slow (35mm/sec) and this seems to eliminate the Z scar for me. So I really don't care about the randomize feature.

How to post pictures: http://umforum.ultimaker.com/index.php?/topic/4525-how-to-upload-an-image-to-the-forum/

This is THE most challenging kind of print. In my opinion. The cause is *also* the rubber band effect. The only effective solution I know is to use more fan. Although I keep meaning to experiment with layer heights. Oh - also printing at 5mm/sec (wow slow!) and 2 passes on the shell help. More details here: http://umforum.ultimaker.com/index.php?/topic/4094-raised-edges/

Wow - that's kind of crappy looking. Is it possible you were messing with the fan towards the end of the print? Both PLA and ABS have similar linear graphs if you plot density versus temperature. It's pretty linear right through the glass and melting temps. And both have about the same slope. But ABS has a much higher glass temp (it's solid up until around 90C wherease PLA gets soft around 50C). Both have similar melt temps (180-210). When the filament (both PLA and ABS) comes out of the nozzle it hits cold air (even if air is at 100C) and starts to shrink immediately and is basically like a liquid rubber band. Like nasal discharge. So when it makes those teeth there is a small but non-zero force pulling the teeth towards the center of the gear. With PLA this force is more extreme while it is still in the liquid phase because it has more to cool before it hits glass temp. With ABS it is more extreme in the solid phase and you are more likely to get a different problem - parts lifting off the bed. Because it has a longer temperature differential (90C to 20C) in the solid phase. This "rubber band" effect is probably your biggest effect - it affects the tips of the gear teeth the most. For more rounded parts there are different cooling issues. But with pointy corners the rubber band effect makes the points shorter. For PLA if the bed is at 75C (too hot) you get this pulling effect strongest down at the heated bed because the PLA never gets below glass temp so it is soft (like clay or even peanut butter) and the edges are pulled in a little more on each succeeding layer. But as you get away from the bed it starts to go back out because the layer below is more solid and holds the still-wet layer in place. The bottom most layer sticks out more than other layers probably because your leveling was off by the tiniest bit and it got squished a bit. Also it was placed in the correct spot but the layers above got pulled inward. So what's the fix? For PLA you want 100% fan and you want it soon - by 1mm that fan needs to be at 100%. Also printing slow might help if your layers are less than 5 seconds per layer. But most importantly keep the bed cooler - 50C is plenty on a glass bed to get the PLA to stick well. Especially if you use a thin layer of glue also. For ABS I'm much less experienced. I assume that having the bed at 90C instead of 100C might help but I don't know. For me, having 0% fan with ABS works best for me. So I'm not sure what to do for ABS. Most experts seem to enclose the entire printer to keep the part at 90C or so. Also in general printing slower helps. I can get much much better quality than you got on my UM Original or UM2 at 70mm/sec but the quality gets even better at 35mm/sec and even better at 20mm/sec. I've never tried slower than 20mm/sec because, well, the quality is stunning. I don't think it can get better.

Raising temp to 240C just for the first layer helps quite a bit - try that also. You can then lower it again for the second layer. A setting? Well you can tell the printer to do .35mm shell. This will put the traces .35mm apart instead of .4mm apart. It will also extrude less plastic - it will basically act like you have a .35mm nozzle. Changing the nozzle size doesn't always affect the amount of material to extrude or the distance between fill lines - changing shell does. Not sure exactly why. Anyway this will certainly put the lines closer together but it will also give you very thin walls. Or you can do .35mm nozzle and .7mm walls (or any multiple of .35) and you will get thicker walls and still get lines close together in the infill. I don't recommend this. The problem is that leveling is incredibly sensitive to the gaps between lines. For example if your bottom layer height is .1mm (thickness of paper) and you do accuracy .03mm (that's hard to do!!!) then you will get a 30% error which is quite a big gap (or over extrusion) between lines on bottom layer. So the first thing to do is make the bottom layer .3mm thick (3X less sensitive to leveling). The second thing to do is as it is printing the bottom layer - if the lines are too far apart, turn the screws slightly until it's looking good. Then cancel the print and start over. You can alternatively adjust the "flow" parameter but this has a huge delay - it's about 10 to 20 lines in the firmware buffer so if you make a change you have to wait for 20 lines to go down or so before you see the result of your change.

Still this is extremely common cause. Mark the shaft and the pulley with a tiny dot with a permanent marker. If a limit switch signal is triggered you get the same sort of pattern where you get a sudden shift in one layer. How is the friction of your two axes? Push them around by hand with power off. Maybe you need a little light oil? Maybe belts are too tight?

Yes. Or raise the temperature. higher temperatures let the PLA flow more like water instead of toothpaste. What temp are you using - 240C is usually my upper limit with PLA. Higher than that gets a little dangerous that you will bake the PLA into a carbonized clog if you don't keep things flowing.

First of all - the larger diameter is a good thing! Not a bad. I wish I could get other filaments with larger diameter - I have a bit of trouble printing the last bit of filament because the radius of curvature is too tight and I get underextrusion. I only print the last 1/4 of the spool on my UM Original. So spend $10 and get one of these turntables aka lazy susan - it's what I use for unspooled filament and it works great. You put it on the floor and it actually rotates as the filament is sucked up into the feeder.

Yes. 50% feedrate in TUNE menu with 30mm/sec print speed results in 15mm/sec print speed. 40% would be 12mm/sec print speed. This is much slower than you need. 20mm/sec should be plenty slow. The idea is the temperature has more to do with the color so you can set the temp on the printer. Then if you print another robot in blue you can raise the temperature without changing anything in Cura. However you can look at "tweakAtZ" plugin which lets you set the temp exactly and can vary for different parts of the print. The stringing was mostly on the antennas - it's very small and easily removed with fingers. That robot looks great. You can improve the tops of the antennas by printing 2 robots but I think it's fine. A few more things: Travel speed should be as fast as possible - this will help *break* the strings. The default is 150mm/sec. You can probably go to 250mm/sec but 150 is a good start. Infill speed and inner shell speed are typically *faster* than the outer shell speed. This is because you don't care about the quality inside so much. But I recommend you leave these at the same speed as the shell speed. Don't slow down - don't speed up. If you are in a rush this is a good thing to increase the speed on (infill speed) or just try 0 infill as the robot prints fine with zero infill. Bottom layer speed should be nice and slow so you have that set good right now. 35mm/sec is plenty slow enough though for most thing. In fact I rarely go slower than 35mm/sec for anything. You can print this much faster and still get good quality.

The additives to PLA that give it color affect the melting point. Gold PLA is fine as far as I know. I've printed with UM Gold and looked over my notes and I had printed 2 things that I still have at 220C and they came out beautiful - they were not as tricky as the robot (not much overhangs). But be warned every time you switch colors there is a chance that you will have to adjust temperature. It's not about quality - it's about melting point and viscosity and glass temperature. Getting back to your robot - the main advice is what robert said - lower speed to 20 if you want the quality I got. And stay with 190C which is a good temperature for that slow slow speed. But if you print at 96mm/sec - you might need to increase temp a little to get that PLA to flow through that tiny nozzle hole. The pressures can be quite high in the nozzle and these reduce quality. nalalth's advice about shell is also critial - 1mm is bad choice for shell - I hadn't noticed that. Use .8mm (two passes) or 1.2mm (3 passes). But never 1mm except for extremely specialized things which you will hopefully never have to print. Actually I wish Cura would turn that yellow when you choose something not a multiple of the nozzle diameter. I rarely print at 20mm/sec. In fact I think that was the most recent time (about 9 months ago). But this was kind of a contest to get the best possible quality. I usually print at 35mm/sec for show pieces and 75mm/sec for things that no one will see. I've learned to be patient and not rush a print and letting the printer run for 36 hours no longer scares me (although most of my prints are under 4 hours).

Did you create a ticket at support.ultimaker.com? Refer to the ticket number in all communications. Daid (posted above) is an employee of UM but he's a software guy. UM's support is very friendly and helpful and gives out all kinds of free stuff but they are understaffed and slow right now. Hopefully that will be fixed. Your fastest solution is to try the three things I mentioned above - they might find the problem pretty quickly. If you don't know how to use a multimeter, maybe you have a friend/neighbor who does? UM started out selling a hobby kit - so only people who weren't afraid to take the thing apart would buy them. Now people are buying these printers (which are very easy to take apart!) who are afraid to do that. UM is slowly adjusting to this new type of client. So UM is partly relying on this forum and people like me to do the customer support.

Sudden shifts in only one axis are almost always fixed by tightening the set screws on the pulleys. There are 6 pulleys on the X axis (not 4) and the 2 on the short belt are the most likely that are slipping (the one on the stepper and the one on the other end of the short belt). The UM Original usually comes with a second set of spare set screws that are shiny (the originals are black). The shiny ones are better although most people are fine with the black ones but you have to tighten the hell out of them. If you don't believe me mark your pulleys and shafts with a permanent marker so you can see if the pulley slips. Less likely causes are high friction in the X axis or rubbing belts against the case but those usually cause gradual shifts - not sudden shifts like this.