gr5

Pronterface is here: http://koti.kapsi.fi/~kliment/printrun/

If you put 3 parts side by side is it always the same height? If so then I agree it's the Z axis. I would get pronterface and install it an connect the printer to a USB and command the bed up and down past that spot many times. Also power it off and pull it up and down past that spot. Make sure there isn't anything anywhere around the platform (in the back where it's hard to see?) that is rubbing against something stationary like the frame. Watch the bed carefully as it goes past that spot. Add a drop of grease (did you get a little green plastic "tube" with grease in it? It's for the Z axis). Or clean the Z screw with wd40 and paper towels and then put some fresh grease on it. Especially in the area that is inside the Z nut when it has that issue. I really doubt it's the stepper motor - much more likely something mechanical. I suppose you could rotat the Z stepper by 90 degrees to see if the problem moves up or down a millimeter (remove the 4 screws, rotate, re-attach). But this is very unlikely. Plus the problem would repeat at every rotation - approx every 3mm? 6mm?

Maybe you could glue them together at a small 20mm square in the center and let the rest just sit on the glass. Or use a sheet of aluminum instead as that isn't so brittle and conducts heat even better than glass.

Printing on glass is such a wonderful experience for PLA. It's just wonderful. The glass that UM supplies with the kit is "tempered" glass. Lawrence please update what country you are living in on your profile settings. Tempered glass can be bought from most glass stores (there's one in every town in most parts of the world as there are lots of windows in most parts of the world - but many other parts of the world don't have very many glass windows at all). Gluing something to glass and heating it sounds like a bad idea. Glass is very brittle and heating even just say the left side of a sheet of glass will make it shatter. Borosilicate glass indeed has low thermal expansion but I don't know what the thermal expansion of Garolite is and if they are different then that would be a problem. Also you want the thickness of the supplied plate exactly the same (exactly! - well within .01mm or about a tenth the thickness of a piece of paper. So, yeah, exactly) otherwise you have to level everytime you change beds. My favorite thing about the UM2 is I haven't levelled in many months. Same with UMO with HBK.

Ah - now I get it. The temp probe was changed but that didn't help. It was the new design block and new nozzle. Well two things: 1) Temperature - a slight change in the position or conductance between temp sensor and block and between temp sensor and melt zone should in theory make quite a big difference to the temp inside the nozzle. It might be good to redo your test where you inserted the probe to see if it's even *hotter* than before! 2) There are many forces that the UM2 feeder has to overcome such as the friction in the bowden and in the isolator. But for a well functioning machine the highest friction is getting that molten plastic through the nozzle. The friction is higher for smaller nozzle holes and higher for *longer* holes at that smallest size (.4mm diameter). The nozzle in the UM2 has a rather long .4mm hole. The e3d hole is probably much shorter and since the psi needed to get the same flow is linear with length, twice as long a hole is twice as much pressure needed for same flow of plastic. Even if the e3d hole is 80% as long as the UM2 nozzle, that's a significant difference. For example it might mean the difference between printing 10mm^3/sec versus 12mm^3/sec. 50% as long would imply printing 20mm^3/sec versus 10mm^3/sec. Of course this thin hole is NOT the only friction in the system. But it is the biggest in the budget.

@LePaul - you have a UMO and there is a dual extrusion option for that. Just not for the UM2.

Is it always the same 2 heights? If so then I guess it must be a z axis issue with the screw or the base plate is hitting something and not moving far enough. But this all seems very unlikely. Much more likely - I've seen this happen due to the filament getting tangled or even as you get near the end of a spool due to the tight radius of curvature causing problems in both the bowden tube and the white teflon isolator part just above the nozzle. Putting the filament on the floor sometimes helps this. I recommend for this printer only you print 30% slower and 10 or 20C hotter if you don't want to spend many hours diagnosing.

I don't know which part you want (PT100, PT100B) as I have the UMO with upgrade kit and I have a thermocouple, not a PT100. But I have heard support is "caught up" and the delay is only 4 days right now. At the same time, if it was me, I would try to repair it myself. Any pt100 part that fits in there will work but you can't use normal solder (which melts around 200C). So you have to use 250C solder (pure lead) or you have to clamp it somehow.

I'm pretty sure the "1mm shell" is the biggest problem. There are limits to how much pressure the feeder can generate to squeeze the PLA out and asking for a 1mm shell means two .5mm passes which is a 125% flow rate into a tight space between the nozzle shoulder and the layer below. The printer *can* do 1mm shell but you have to print either a bit hotter or slower. In addition your underextrusion was partly intermittent - probably due to the filament spooling. I strongly recommend you put the filament on the floor. The brown parts had severe underextrusion - much worse than the white part. They were probably around 50% equivalent flow. Or less. Maybe 30%. In other words you were getting half to 1/3 of the needed pla. Putting filament spool on the floor reduces the friction enough to make a big difference when you are printing "on the edge" of ability.

I'm not certain but I think that sticker means "you can take the sticker off without voiding warranty but only if you call us first so we can explain in detail the many ways you can break the thing and what to be really really careful about". But I could be wrong.

I have the older UM2's before they added the sticker. Are you saying you can't countersink without removing the sticker? That sucks. Although I believe if you call them, explain the problem, tell them you promise to be careful, they will tell you to go ahead and countersink the screws. And probably send you a new glass plate also. They are very nice. Just might take 4 days for them to get back to you. You might want to call - their english is fantastic and they often respond immediately to a phone call if it's roughly 9am to 5pm netherlands time (that's probably until 11pm your time I would guess). I'm not sure but I think the 5C drop is normal and basically expected. That's why a given bed temp on one printer might be different than on another (it depends if you print on aluminum plate or glass, fan speed, other factors). I always print 110C for ABS. 50C for PLA.

I am just guessing but I would think they are much heavier because I assume they need many more windings for the same amount of power. Not a huge deal for a desktop printer but would really suck for a stepper mounted on the print head (e.g. makerbot).

I believe that the europe requirement is that they cover problems that were discovered upon first using the machine even if they box was finally opened 11 months after delivery. I don't think it's what is normally considered a "warranty". Anyway I think Ultimaker was already helping people with free replacement parts even well past the 3 month limit where the problem seemed to be their fault. Now it's more a formal promise.

USB printing is very unreliable. Often some of the gcode commands are lost. If printing from SD works I would stick to that.

Well they did promise that. And broke their promise. If your friends are upset enough I suspect they can return their printer for a full refund (minus shipping fee maybe?). I'm not promising this but.. Also amongst that "blah blah" is FULL ONE YEAR WARRANTY RETROACTIVE. Which is pretty awesome. Minus the hot end. So if you bought a printer in February last year you are covered for a few more weeks.

That's basically what is needed because with the current design you have two problems: unused nozzle is always dripping, and the unused head scars the walls and surfaces of the part.

@gixxer - remind me - sorry I don't want to reread it all - but is it possible there was a temp sensor change in all this? Maybe the old temp sensor was reading off and the head was much cooler than you thought?

I (and I think ultimaker) believe the most common cause of underextrusion is the isolator. There are however quite a few other causes! There's about a dozen possible and common causes. Sometimes the nozzle is just *slightly* blocked - it has some crud all around the inside. This is not best fixed by getting a new nozzle but just cleaning it by burning it all away. Still there are many other causes! Such as filament entering the feeder at a strong angle. Filament tangles (extremely common - typically you get a horizontal band of underextrusion) bad temp sensors - a bad batch went out I think last summer. Maybe. Not certain. Pressure on isolator too high. bits of dust and non-pla plastics getting into the bowden and making their way into the nozzle. Bad spring tension. Feeder knurled sleeve on wrong. filament too large a diameter getting stuck. Feeder motor too hot melting the pla a bit. print head screws too tight (this is more common than you might think!). And I forget what else. All of the things I mention have happened to people on this forum. The odds that your particular problem is in the heater block or nozzle is very low.

Yes. Very cool technology. It has to look at the previous two steps, measure the time between them and then step 16X faster hoping the next step comes soon after. If the next step comes sooner it advances the schedule I guess. Kind of reminds me of a phase lock loop except on a wave that speeds up and slows down often and dramatically.

There's two technologies to make the motors quieter. This new technology I don't understand but it makes them weaker also. The older technology of using 32 or 64 microsteps instead of the 16 we use today on UM does not make the motor weaker. It might make a single 1/64 step weaker than a 1/16 step but if you do 4 micro steps (4/64) it's just as strong and moves the same distance as a 1/16 step. But more quietly. Basically there are 2 sine waves going through the two coils. The substep is the phase difference between the two sine waves. The problem with just swapping pololu drivers is that the top speed for the Ultimaker with the arduino is around 300mm/sec. With 1/64 microstepping you now have a top speed of 75mm/sec. So really you need a faster board. I've seen some of the new faster technologies that use much faster computers in the printer. They are amazingly quiet. I've seen 2 technologies - one was being worked on a while back by Eric Zalm. I don't know what's up with that. The other is by TinyG. You can buy his boards and put one inside an ultimaker. Very quiet!

64 micro stepping is incredibly quiet. I've heard it in person. It's not silent but it's... hmm... maybe 100X quieter? It's pretty impressive. What's that, like 40db quieter I guess.

This is extremely common and annoying that UM doesn't fix this before shipping. But the fix is very easy and cheap - use a normal drill bit or better get one of these coutnersink bits - they are very useful for other projects as well: If that doesn't fix it, flip the glass over and if the curve goes the other way then it must be the glass. You can get a free glass plate from UM support (even though you bought through a reseller). So that's always an option. Also you can buy your own glass -it's not expensive. Every country has houses and buildings with glass windows and every town (that is full of buildings with windows) has a local glass store where they custom cut window panes and such. They can custom cut a piece for you and even grind the corners smooth all for the cost of a few fancy cups of coffee. You don't have to get tempered but that's what Ultimaker uses. More importantly you need to get it the correct thickness to fit the clips and for strength (typical window panes are much thinner).

@fixxer - So are you saying the *same* blue filament that used to need 250C now needs only 210C? And the only change was the nozzle? If so then the nozzle may have a slightly larger hole (.45mm?) or your old nozzle had a partial clog. It's common to see burnt PLA on the outside of the nozzle turn into a thin black/brown surface. The same thing can happen on the inside of the nozzle. It can be cleaned by burning it off but you have to take the nozzle off. Now with your new design it's much easier!

Oh - you should be able to check the continuity of the stepper motor wiring at the connector. Each pair of twisted wires should be the same resistance. And a pretty low value - I would guess 100 ohms? Just pulling that number out of nowhere but the EE in me says somewhere from 10 ohms to 1000 ohms.

These things are tough as hell so it's still more likely a bad wire. Did the wire get pinched? Can you find an ohm-meter and measure the continuity of all 4 wires from the motor to the connector? I guess you'd have to take the stepper itself apart. If you cut power and push the head back and forth in X only you should see the ulticontroller "light up". Does the same thing happen in Y mode? If only 2 of the wires are working I would guess that it lights up but you have to push it a little faster than in X.