gr5

You could certainly hire ahoeben - he's a competent programmer so he's not cheap. He used to work for Ultimaker. He'd need to rent a UM3. You should first explain what the goal is. As neotko says, the interface might not be able to handle the required quantity of gcodes per second.

I totally agree with neotko. Better to get a different printer. I think it would be helpful to know why one needs to control a printer from a CNC controller in the first place. Maybe there is some other simpler solution that involves the UM3 and doesn't require a serial interface but can use network instead and hopefully doesn't involve a CNC controller either.

Switching to gcode changes lots of things. It means you control the nozzle and bed temperature, retraction distance, filament diameter in Cura instead of on the printer. The startup procedure (where and how it does the initial purge) will likely be a little different (but you can edit it now in cura where the "begin gcodes" are). Just try it and see what you think. The printer probably won't have quite as good an idea of how long your print will take. In fact I don't think it will print any times - just % of layers complete (I forget exactly). Also if you print ABS for example, on the printer if you set the fan speed to 50% then in ultigcode mode it takes the fan speed from cura and cuts it in half (50%). But in normal gcode mode the ABS fan speed is ignored and Cura has to know to set the fan speed lower for ABS. If you print PLA you can ignore this. The idea is that in ultigcode mode you can slice once and then you can print in any material with any filament diameter and not have to reslice first because the printer is told what the material is and the diameter. In practice it's silly because people dont' typically print the same part in 2 or more materials very often.

This is true. But there are more surfaces of the UMO to cover up (UMO has open sides). You can mount UM2 motors outside but you need to drill a large (about 30mm) hole for the stepper gear to fit through for both X and Y. Mounting an extruder outside the UM2 is pretty easy as well. Of course this is already done on the UMO. If you are comfortable with building the UMO firmware then a UMO is fine. If you don't want to build the firmware yourself then you will need to go with UM2 firmware as there is much more help there. People will build firmware for you or more likely use the same version of firmware that rajil has. Also the UM2 firmware has more features such as "continue failed print" and ability to adjust steps/mm without rebuilding the firmware and several more handy things that aren't critical.

Used printers are fine. You will be replacing many parts anyway. I'd probably go with the UM2 - I like the way it does leveling much better. The quality of prints is very similar -- the UM2 with it's extra fan has a little better quality but that's not relevant to you anyway. I think you'll get better firmware support if you go with the UM2. As far as reversing steppers. There are two ways to do it and both ways are easy. If you are building the firmware it's trivial to reverse motors. If you prefer working with your hands then you can swap two wires on the stepper connector to reverse the wires. If you prefer the software method I can send you a link. If you prefer the hardware method note that each stepper has two twisted pairs. Simply swap the two wires of one of the twisted pairs. To get the pin out of the connecter use a magnifying glass and you will see a little piece of metal that keeps the pin from sliding out. Hold that down with a small tool such as a jewelers screwdriver and push the pin out. Remember where it was. Swap any two twisted ones. If you swap both pairs it will be back to "normal" again. If you mess this up you will not damage the steppers nor the stepper drivers.

I've had this problem before. I forget how I fixed it. I think I deleted all images and then re-inserted them a different way.

No that won't work. There's no USB connection to connect to. And if there was, the printer isn't listening for gcodes there. There is a way to send gcodes manually if you ssh and login to the linux box. You run a program on there and can type in gcodes but - it's not easy to automate that. Maybe you could use CURL to send gcodes over ssh. That's very messy but still doesn't get you serial connection. You need a python programmer to spend many hours understanding how all that works and writing their own program. It's a pretty big undertaking. So much easier and cheaper to buy a used UM2.

Don't say you "tightened the belts". They shouldn't need tightening. It's the pulleys that need tightening. You asked about the marking of pulleys. I meant use a sharpie/permanent marker. Mark the pulley and then mark the rod at the same spot so the marks/dots line up. That way you can see if the pulley slipped and which one slipped. To do this with the motor you need to remove the left rear cover. I think it's time you did that as it takes all of 2 minutes. You probably need to shove the bed all the way down first. There's only 2 screws holding that cover on. Remove the screws and the cover should come off (it has tabs pushed into slots but if you wiggle it a bit it should come out). Now you can remove the stepper and mark it and tighten the hell out of that screw on the motor pulley. Personally I wouldn't bother with all that but it feels like progress has been slow so far. I'd just use a long hex driver and get it in there at the awkward angle and tighten the hell out of that set screw on the motor. Did you tighten the pulley on the Y stepper? That's the one hardest to get to and also the most likely one that's a problem. Tighten it so much your fingers hurt. Very tight. Try pushing the head around. Is it about equal force to move it X versus Y? it should be about equal. Very approximate.

Okay so I finally read your post. I'm sorry you hit so many issues so early on. I will probably miss something so ask again if I miss something. 1) Nylon soft - this is the easiest to fix - just bake it. I haven't tested UM Nylon for when it slumps but I suspect it's fine up to 100C. PUt a small piece on the heated bed at 100C and put a towel on it, come back 20 minutes later when it's at temp and make sure if you squish the nylon it doesn't permanently get distorted. If it's fine then repeat with your printed part to dry it out. The nylon I've been using lately can handle 100C no problem. If UM nylon can't then try again at 90C. Anyway after baking it you part should be much harder - closer to the flexibility of the raw filament. 2) tower falling over. This is easy to fix. Basically put it in the rear center - not the right rear corner. The glass that comes with UM3 is quite flat but the worst spot will almost always be the rear 2 corners. The more you squish the tower on the bottom layer the better it will stick. Also I think you can make it a bit bigger - I think there is a setting now in cura - if so - increase the base by another 50% bigger to make it stick better. The reason the rear center is good is because it's near one of the 3 leveling screws which tend to be leveled most accurately. Also maybe consider turning that screw 1/3 turn CCW to squish the filament even more into the glass. Also it's good to put a thin layer of pva on the glass. You can use some of that water that was soaking with pva in it or you can just spread a little glue stick and then spread it around with a wet paper tissue - you want an invisibly thin layer of pva spread evenly. You might want to just skip the tower. It is supposed to help if one nozzle is leaking - I've found the temperatures are getting so good now with the profiles that the idle nozzle tends not to leak. I like towers but I sometimes create my own supports near the tower so it's less likely to fall over. 3) nylon ground and failed - well that really sucks. That doesn't happen very often. To me anyway. One reason is I do not print the infill at double the speed as the shell. Maybe that's one reason. If you have lots of retractions such that there is > 10 retractions on the same spot of nylon that might grind it enough to cause a failure. Dust can get in the head. not particularly likely but it can happen. If it's something in the nozzle you will have lots of problems until you do a cold pull (cold pulls are done from the menu). If your internal structure is like voronoi - for example if you have 50 little islands on one given slice inside that tube then that is the most likely situation. I need to see your internal structure to have an idea. Try turning on layer view and check the box that shows moves (blue lines) and see if there are many dozens of these blue lines on a given layer. If so I can give you the fix. There's two parameters to mess with. I really don't know why it stopped extruding nylon. Also check for a filament tangle. Inexperienced users aren't careful and one loop of filament gets under another and this tangle propagates forever until you remove the filament and fix the last 2 meters on the spool and then carefully re-insert the filament into the printer. 4) KEEP NYLON DRY! It gets water in it too easily and if you are printing and you hear hissing/popping/snapping sounds then you need to dry it on your heated bed for something like 4 hours. Keep it in a sealed bag when not in use with desiccant to keep it from going bad. I even print it out of the bag with a narrow hole but that's not normally necessary. I don't think you can dry it with desiccant alone - but you can keep it from absorbing. 5) I strongly recommend you cover the front and top of your printer when printing high temp materials like ABS or Nylon. And keep the fan low - 3% is good. Front can be covered with any clear plastic. Top with a box - it doesn't have to cover everything - I use the box that comes with reams of paper inside. It's the perfect size and has room at the back for the bowdens to go in. It's not completely closed but good enough to get the air up to 35C which is perfect. 5) Materials - well did you try PLA? What are you trying to do? Do you need something that is really tough and flexible because that's nylon. 6) I don't know so much about nylon - I think nylon is better - but with PLA anyway you need the PVA to have a continuous path down to the glass. There is this feature "horizontal expansion" for support. It defaults to 3mm. This hopefully allows you to have PVA all the way down. Because PVA does not stick on top of PLA very well at all. But in your cylinder if you have internal shelves then maybe there is no way for the PVA to reach all the way down. So this would be a tricky print. If it's possible to print the cylinder sideways but not need any support inside the tube then maybe you could do that and use "support touching buildplate" versus "everywhere" and get better results. maybe. I'd like to see the internal structure of that cylinder.

okay then you are probably right that it needs support.

smart avionics code is intense. That's python. Not gcode. That's for programmers. If you aren't a programmer you can safely ignore that. Well I strongly don't recommend you put G0 Z20 at the end of your gcode because if your part is taller than 20mm it will probably smash into your part. I'm just trying to explain that gcodes aren't all that complicated. You can look at the very limited set of gcodes used in your past prints - there's maybe 10 of them. roughly. then you can look each one up to see what it does here: http://reprap.org/wiki/G_code That above link has hundreds of gcodes but you only need to lookup a few. If you just look at the first 20 or so gcodes in one of your gcode files and then look at the last 10 or so. That's mostly all you need to look at and all you need to learn. Some of them modify fans, some set the temperature, and of course some of them move the (at least) 4 steppers. In particular pay attention to the G92 and how it's used.

It's not hard. Don't be scared. For example G0 Z20 means move the Z axis such that nozzle is 20mm above the plate. It's not complicated.

I don't think your part needs support. You might want to just skip the pva. I'll read your whole post later but also know that Nylon is very tricky to print. Once you know all the tricks it is easy. But until then it's frustrating.

Sometimes the two rods through the print head are not perpendicular but if the parts were printed parallel that shouldn't affect your part length. Whenever I slice I *always* also save the whole project. If you did that you can reload it into cura and double check the scaling of the 2 parts. I'm thinking one was maybe 62.3% and the other 63.2%? It's possible that your pulleys are not round. It would have to be pretty severe fo you to notice 2mm difference in length though! That's just - severe. Maybe a photo would help us understand. Showing where they were placed and how you measured.

It might be that the firmware thinks your machine isn't as tall as it is in real life. If you have tinkermarlin you can set that value I think. Is your machine significantly (10mm) taller than a standard UM2? Also, are you sure bits of plastic haven't fallen onto the switch?

There may be some loose belt issues combined with bad Z. I sell very cheap belt tighteners for UMO in USA ($2) or in Europe go to aliexpress: https://thegr5store.com/store/index.php/umo/belt-tensioning-springs.html

Mostly those are Z issues. If the bed moves too far you get some underextrusion (nozzle is too high off the bed) and you get a line that is "inward". If the bed doesn't move far enough (say a few layers later) then you get an overextruded layer that sticks out. There a few possible causes but most likely you need a thorough cleaning of the Z screw. If it's a plus the z screw I believe is permanently mounted in the Z motor - remove the Z motor and I think the screw slides out - unplug the z stepper first of course. If it's a non-plus then there should be a Z coupling you have to loosen first and then I think the Z screw exits upwards. Clean it will - put it on newspaper and spray with WD-40 and use q-tips or paper towels. Remember it's a triple helix (like dna but triple instead of double) so make sure you get all 3 threads. After wards add just one drop (size of a pea) of grease. While the screw is out, Z bearings and Z rods should be checked to make sure there are no binding/friction spots when you slide the head up and down. Try to add some twisting force to the bed (like it's heavy and bending towards to bottom of the printer) while you move it to see if it only binds when the bed is torquing. If this doesn't help post back as there are more things you can do but if it used to work well then it's most likely dirt. The second most likely thing to "fix" is to replace the Z nut with a more expensive (like 2 dollars or 2 euros lol) Z nut.

I don't think there is a public assembly manual for the UM3 anywhere. There is one I believe for the UM2 but not UM3. I'm sure @fbrc8-erin could help you with where those wires go.

yes you were loosening the pulley set screws instead of tightening. The one on the motor and the one in the video are the two that you need to concentrate on. And any other's that you may have loosened. As geert_2 says, the stepper motor is probably spinning freely. It's hard to see without removing the cover but I think that's a safe bet. These printers are quite tough. The steppers in particular are very tough.

Maybe you should show a screenshot or a video. If you keep hitting plus you can keep zooming in. At one point if you use rotate and pan you are so close you can only see a few traces because a few mm of your part fills the screen. Did you keep hitting "+"? Also right click drag orbits. If you use those 3 features: 1) + 2) shift-right-click-drag 3) right-click-drag then you can zoom in so tight it's silly.

You've been concentrating on the Y stepper, right? In the photos it looks like the part only moved in Y (towards the front of the machine). That stepper is in the rear left corner.

Can you make a 5 second video? This makes no sense to me. Maybe you have the wrong size tool? You want the same size hex tool as used for all the normal screws all over the machine. It's a 2mm hex tool. Maybe you should start over and mark the shaft and pulley for the two pulleys on the short belt. Then print something where you get layer shifting and then check to see which pulley is slipping on its shaft. Then maybe remove that set screw and swap it with one of the set screws on a long belt.

I'm not sure what you are asking but I think you are asking about panning. You can pan if you hold down shift and do a right-click-drag. I use the "+" key on the number pad to zoom in. "-" zooms out. I usually have to click once in the graphical portion of cura before those keys work.

I would go with the soldering route but you can contact your reseller and get the correct part. Insist that the reseller measures the length of the cable before shipping it to you. They come in many sizes and maybe you got one for the um2go.

Oh and you might want to suggest your students use something besides sketchup. Something that creates solid parts - not random walls that don't always connect and can be inside the model unintentionally. Tinkercad is good. DSM (design spark mechanical) is good. Fusion 360 is good. There are many other good choices but I think tinkercad might be best for an introductory course.