gr5

Oh and if you have the old round nozzle style - then it's integrated with the heater block and you should consider getting an Olsson block while you are at it. And to be safe strongly consider getting a new temp sensor as it's really tricky to get out the old temp sensor to move to the new block if you are installing an Olsson block (or block V3). I am really good at it but my technique involves heat, WD-40, and most importantly - a sewing needle to dig it out without damaging the sensor electronics.

I suspect you only need the teflon part to get back to normal. But I don't know for sure. If your printer is from before january 2016 you probably have an integrated block where the nozzle is not removable. It would be round. If it has hexagonal sides like a nut then it can be removed. Remove only when hot (150C is good) just in case some PLA is in the threads. Once the nozzle is removed you can burn it out. Or alternatively you can do a "cold pull" (google it) to clean the nozzle. Almost always an old nozzle can be cleaned out assuming there is anything wrong with it. Anyway if the nozzle is removable then I would consider getting a 0.6mm nozzle just because you are doing lots of prints and kids prefer larger prints. But to fix your primary issue I suspect you only need the teflon. If that's not it I have a list of about 20 things that can cause underextrusion or grinding and can post that here but really if you never changed the teflon - then it's time. Most people who do tons of printing change it every 3 to 6 months.

This. This is your answer. But I'm sure you did fine. I think the ferrite cores are to reduce electromagnetic radiation for other things near the printer. For example without the ferrite cores you might have trouble getting wifi or data on your phone. Maybe. Or more likely AM radio signals might suck within 2 feet of the printer. I doubt the cores make the printer work any better. I could be wrong - but I think they are just so you can pass FCC regulations. FCC doesn't like you being a little radio station.

Regarding the first major dip - realize that the UM3 has power management. This means it can't have the bed heater at full power at the same time as the nozzle heaters. I don't know how this works exactly but hopefully the print cores have higher priority and the bed has the lowest priority. But it seems possible that the power management software gives the bed first priority and if the bed is on full power and the second core is also asking for full power it might be that the second core doesn't get the power it wants. That would explain why it shows dark green as requesting max power yet at the same time it is cooling. But this is just a guess.

Actually these spikes circled in red concern me the most - it implies the temperature sensor read the wrong value (as there is no way the core heat up that fast and then cooled down that fast):

How to recover a bricked UM3: https://ultimaker.com/en/community/51752-recovering-a-bricked-um3 But I suppose it could be the Marlin firmware that was updated on the white PCB that is causing the problem. Not sure if that can keep a UM3 from booting.

Also if you are doing a lot of prints for kids, you might want to just stick with a 0.6mm nozzle. You can do 50% thicker layers and it prints 50% wider lines for resulting prints twice as fast if your walls/shells are 1.2mm thick versus a 0.4mm nozzle and the quality is quite good. See 1.2mm shell is 3 passes for a .4 nozzle and 2 passes for a .6 nozzle.

Well there is my store of course, lol. thegr5store.com. But if your printer used to work fine and now it's grinding filament at the feeder, and you didn't slowly speed up prints or cool down prints or change layer heights over this time period then it's probably hardware and the most likely culprit is the white teflon part which does wear out. It costs I think $18 from my store or fbrc8.com. It's one of the few parts that is reasonably priced from Ultimaker because it is considered a consumable.

DON'T FEAR THE OIL! lol. It works so well. Just do it. It will not mess up your printer. It will not affect your print. It works very well. Just do it.

I would lower the temp by 10C. You can do it live from the TUNE menu if you want.

You can change to the other cable but I doubt it will help - just change at both ends. In other words on the head switch to the other wire and then under the printer switch to the other wire there also. First of all set the fan to 70% as this can be partly responsible (not 0% or 100%) . then set the temp to something, say 60C and wait for the temp to be within 10C of your goal temp because at that point the heater is being turned on and off 20X per second. Now you have crazy signals going to both fan and heater. Now look at the temp and start poking at the wires and pushing things around. Push on the head. While doing this watch the temp to see if it jumps suddenly. This should give you a hint of where the problem is. But most likely the problem is at those 2 tiny screws on the print head that hold the thermocouple wires. Those can get loose.

Well that doesn't look like much of an issue to me (sorry - don't want to say you are wrong or anything). I mean I'd just cut that off after the print is done with a knife. HOWEVER, there may indeed be something you can do. But first - did you look at the layer view and do you know exactly what is happening? Do you know if that is a retraction move? Does it actually retract? if it doesn't retract the solution might be to play with retraction settings. More likely it *did* retract but the bottom layer has special considerations: If you want your parts to stick well it's best to squish the bottom layer a bit. So when you level with calibration card I believe the card is 0.08mm thick and so the printer sets the Z to 0.08mm there such that Z=0.0mm is touching the glass. When you print, typically the bottom layer is always 0.3mm thick and it prints at z=0.3mm or 0.3mm off the glass. But if you want your part to stick you should probably have the nozzle at 0.2mm off the glass. This makes the printer push much harder and makes the part stick really well. But you get a tiny elephant foot like brim around the part. Which is kind of sharp. And kind of annoying. However there is a great feature in cura called "first layer horizontal expansion". If you set that to negative half of your nozzle diameter (typically -0.2) I found this corrects the micro-brim issue. HOWEVER there is still one more issue - since you are overextruding all over the place on that bottom layer the pressure in the nozzle is unusually high and normal retraction is probably not enough getting you these little blobs. I dont' have any good solution except to level slightly higher but then your part is likely to not stick and come loose during the print which is MUCH WORSE than a tiny little blob that can be easily cut off with a sharp knife. On the other hand maybe this has nothing to do with retraction moves as I haven't seen the slice view of this part.

All the hardcores are "pro". No they only reach 350C, sorry. Carl at 3dsolex is working on one that goes hotter. You could email him about it if you are really serious about this - purchase a heated bed first though. he might send you a free one to test or a reduced price one if you promise to do testing and let him know if it melts your UM3 print head, lol. Even better, keep going hotter until you break something in the UM3 print head - *that* would be valuable for 3dsolex to know and definitely worth a free hardcore to you. but maybe not something you want to do. Just to clarify - he can easily build one that goes above 350C and he has a printcore that can easily go to much higher temps - probably 450C. But it would be a one off experimental version and a bit of a hack at this point.

So cura creates gcodes which are coordinates and speeds in X,Y,Z,E notation. If your line width is 0.4mm for example and your Z isn't moving and your layer height is 0.2mm and the distance to the next point is say 10mm then cura multiplies these 3 numbers and calculates the volume of the cuboid: 0.2 X 0.4 X 10. Then it increase the E position by the exact amount to extrude this amount of filament. THIS IGNORES THE SPEED. In other words - when cura calculates the E value - the extrusion amount - it ignores the speed. In addition the gcodes include an F value for "feedrate" which is how fast the X and Y axes move. Marlin - the firmware on UMO, UM2, UM3 - tries to achieve this speed (but doesn't always get to that speed if the distance is short and it can't accelerate up to that speed). Usually paths longer than 2mm are enough to get up to full speed on a UMO,UM2 (UM3 is a bit less acceleration so it takes a little longer to get up to high speeds). Anyway back to the point - print speed does not affect the amount of extrusion in the gcodes. However in practice, the faster the feeder is moving, the more pressure you are likely to have in the print head, which means more back pressure on the feeder, which means it can slip a bit. it's quite common for the feeder to slip 10% during typical printing speeds. Also there is a delay between when you change speed and when you get equilibrium pressure in the nozzle and the nozzle is printing properly at the new speed. So if infill is printed faster then you get underextruded infill at first and then it over extrudes when it goes back to the shell. For this reason I usually set ALL the printing speeds to the same value in Cura. But most people don't care much about quality of infill or inner shells and it *does* save a lot of time to print infill faster.

If I wanted to print PEEK or ULTEM the first thing I would do is buy a used UMO with glass (heated) bed (and possibly throw away the heater and keep the glass and metal frame bed). I would move the motors to the outside of the frame so they don't get hot - extremely easy to do on a UMO - no hardware needed - no drilling needed. I would cover the two sides. I would get an all metal hot end such as E3D (but realize all metal hot ends are not good for PLA so this is a high temp only printer). I would buy an AC bed heater.

The symptom is that everything works fine except at the end of a print you can't remove the filament. You can start a new print just fine. But the old filament won't come out of the core. The fix is to send the core back as it takes me only 5 minutes to take it all apart, drill out the anodized aluminum heatsink (and possibly the steel trumpet part above) and then put it all back together. This only happens on a small percentage of hardcores. Probably between 1% and 5%. Hopefully 1%. Partly the problem is rare because the teflon inside the heatsink has to be larger I.D. than typical and in addition the heatsink has to be smaller than typical. The filament expands into the enlarged teflon and won't come up out through the heatsink.

1. You have to drag them one at a time. Or go to the file load menu and keep adding parts. Also you can right click on a part and multiply it if you want to print more than one of the same part. The files must be .stl files. Dragging more than one file at a time doesn't work. 2. The stl files are the INPUT to cura. The gcode files are the output from cura. If you open a gcode file as input it can only show you what the slices look like, not the actual model. If a student wants to be able to print something more than once or share it they should be saving the stl file somewhere for future use. Not just the gcode file. In addition you can save a project (this creates something like myprint.project.amf) which saves the models *and* all the settings in cura you used for that model(s).

Is the filament stuck in the UM core or the hardcore? Is it stuck when trying to remove the filament or only when printing or both? Which way are you *certain* is stuck and which way do you think might also be stuck? If it's stuck in the core how did you get the core out of the print head? It sounds like you are describing a new problem just discovered with a few hardcores. The solution is pretty simple if it is the issue I'm thinking about. Also did you buy direct from 3dsolex or from a reseller and if so which reseller?

Is this Cura 3.X? I recommend you go back to an older version of Cura - certainly 2.7 is safe. There is much discussion of this here: https://github.com/Ultimaker/Cura/issues/2665#issuecomment-349396443

Be aware of the overheating thing. The symptom most likely on the UM2 is that drivers (usually the Z driver) will sometimes power off for a fraction of a second because they overheated. For the Z axis you get a big gap sometimes (if the bed slides down under gravity). For the X or Y axis it causes the part to have a sudden step - it's extremely obvious. But as long as you don't get obvious symptoms then no need to add more cooling to the PCB. Removing the cover actually might be all you need to do but adding a little fan/wind will be enough to compensate for the thinner air.

I use the wedgebot all the time. Used it a few times today already.

You may still get issues. It's really hard to say. Basically it pushes almost 2X as hard so instead of 5-10 pounds (5kg) force it is more like 10 to 15 pounds force (9kg). But if you push the limits it will still grind. It's just that the limits are farther out. If you have the plus upgrade then definitely install it. It's pretty easy to do and the instructions are great with photos and all. The lever on the new white plus feeder is a huge improvement over the black feeder so you can just slide filament in and out manually instead of using silly menus. Having the Olsson block and being able to print with 0.8mm nozzle in my opinion is HUGE. 4X faster printing.

Personally I turned off all email notifications and only use the ones in the top right corner of the web page. Sorry that this doesn't help but that is working for me so far (1 hour into playing with forum).

Okay now you need some glue. Clean the glass. there may be some oil. I recommend any glass cleaner. Then you need to apply some PVA. There are 3 easy ways to do this - one way is to use the glue stick that came with the printer - put a little bit on - make a back and forth S shape where half the glass in between gets no glue stick. Then take a tissue and soak it in water and spread the glue stick around such that much of the glue is gone and all of it is transparent once it dries. This is PLA? If so you want the bed at 60C. The amount you squished looks okay I think but moving it slightly clower in the back might help. Or it might not help. If it squishes so much that the filament is transparent then back off the screw until it looks like in your picture again.

28V is not normal. Even 24.5V is not normal. Are you sure your leads aren't kind of floating? Try reversing the meter leads and see if it goes to -28V. It could be that the 28V was enough to blow up the 5v regulator but it seems hard to believe that a regulator that is designed for 24V can't take 28V. The above fan theory seems more likely.