gr5

You could test your nozzle temp using this video which is more accurate than you may think:

>at the end you can see it stall completely while i keep up the same pressure. I can't see that in the video but I believe you if you are sure this is true. Are you sure the white filament is also PLA and not ABS? Anyway there's probably a tiny bit of dust in there. I would do a few cold pulls - let it cool to 90C for a little while and then pull it out. It should come out in the shape of the nozzle tip including the tiny .4mm shaft at the bottom. If you can't get it out try 5C hotter until you can. If it comes out not perfect try it a little cooler. It should be a few kg of force to get it out. Maybe 5 or 10kg.

ABS is more difficult to print with - why did you choose ABS? The printer can print ABS but to get good consistent quality will take quite a bit of learning. PLA takes learning also but you can get high quality so much sooner. Some people the ABS is stronger or more flexible but PLA is just as strong and most modern formulations (e.g. ultimaker brand, colorfabb) are just as flexible or close enough. ABS does withstand higher temperatures though. You need to supply a larger photo - I can't tell if it's stringing, underextrusion, or both. Tommy thinks stringing but I'm not convinced. You probably have the retraction settigns such that it doesn't always retract - this part needs thousands (tens of thousands?) of retractions and the advanced retraction settings may be blocking some of those.

Well to simplify things - just get the PTFE isolators from 3dsolex! The 3dsolex ones work with either printer and are rated for 255C continuous with no temperature related wear (just physical abrasion wear and they should last a very long time).

This is a large slow print with .4mm nozzle so I hope you are using a .8 or 1mm nozzle!

Your burn spots are in a pattern - that must be where the Z axis moves. This implies you need to lower the temp a bit to get rid of those burn spots. I would try lowering it by 5C at a time while printing (from the TUNE menu) until you get a good compromise. If you print nylon too cold it can have HORRIBLE layer adhesion. If you are getting that then lower your fan. In fact you probably want the fan either off or at 30% maximum.

Have you tried taulman bridge? I find it's a little easier to print and you can print it a bit cooler. Less burn spots, less steam making air bubbles. Nylon is definitely not an easy material to work with.

I have written pages about this all around the forum. Use google to look for posts about this although I don't know what to search for. Quotes from my earlier posts: Also read this and many other topics - Daid has some great explanations too - he wrote Cura although there are more authors now: https://ultimaker.com/en/community/17986-path-planning-algorithm-used-in-cura

Skipping is normal if you are pushing beyond speed/temp limits. But if nothing is coming out then it's probably the nozzle itself that is blocked. You could put on one of the other nozzles - say the .6mm? Also skipping is common on the bottom layer - it means the glass is a little close to the nozzle so there isn't much space but that's usually how you want it. If I get skipping on the bottom layer I usually slow it down, raise the temperature, or turn the 3 screws 1/4 turn clockwise to give the nozzle a little more space. If you are getting skipping on higher layers then slow it down and raise the temp. Here are my recommended top speeds for .2mm layers (twice as fast for .1mm layers) and .4mm nozzle: 20mm/sec at 200C 30mm/sec at 210C 40mm/sec at 225C 50mm/sec at 240C The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

When it starts to print the current draw is higher on the power supply. It's probably the power supply. Well I have 2 theories: 1) You don't have the proper power supply or it's defective - it should be 221Watts. Maybe you have a um2go supply by accident? 2) The power cable is not on all the way and falls off when it moves. The connector is supposed to snap and lock the cable in (the outer sleeve slides) and sometimes the PCB under the machine is too close to the edge of the hole and you can't get the connector on without a huge effort.

Yes! First you have to understand why it's doing this. ABS has a much higher "softening" or "glass" temperature. About 100C versus 60C for PLA. To get good layer bonding you have to get the ABS well above 100C - the plastic on the layer below that you are printing on top of. This is trivial with PLA because the plastic coming out of the nozzle is about 200C and the air is about 20C and heating existing plastic to 60C (PLA) is much easier. So the solution is heat. One common solution is to turn the fan off. If you print at the same speed and so on that you had been printing but simply turn off the fan you will get MUCH better layer bonding. The problem is if you print overhangs or bridges the quality will suck. But if your part has only vertical walls (like a gear flat on the bed) then this is a great solution. Another technique is to simply lower the fan to 30% max. This usually is not good enough and you will get layer bonding issues still but not as bad. Not nearly as bad. Older slicers before Cura were very good with ABS and would only turn on the fan a few seconds here and there for overhangs and bridging. Another technique is to heat the air to about 50C. The difference between 100C and 50C is much less than between 100C and 20C and is usually enough to get good bonding even with the fan at 30%. This is a very simple technique - just put a spare cardboard box on the top and cover the front with saran wrap. It will be nice and warm. Don't seal the back of the cardboard box - you don't want it getting over 50C or the servos start to suffer. Another technique is to remelt the layer below by slowing the head down to 5mm/sec. Not a great way to do it, but it works great. With very thin layers - say .05mm you can print a bit faster. I would think thicker layers in general would help - say .2mm layers versus .1 because now you have more thermal mass to melt the layer below. But many ABS experts claim that .1mm works better for layer bonding. You might think hotter nozzle temp would help but the difference from 100C to 240C versus 260C is not a huge difference and above 250C it starts to get very easy to bake the ABS into nozzle clogging gunk if you aren't printing non-stop and not too slowly.

Try meshlab - it does this with one command I think. I haven't used this in a while but try this - it kind of does a plastic-wrap-the-model feature where it fills in all interior spaces. Don't think of it as 2 steps - it's really just one step. Read these - just do the meshalb step: http://dynath.blogspot.com/2012/04/shelling-3d-models.html https://www.reddit.com/r/cad/comments/1xy18x/besteasiest_way_to_shrinkwrap_an_stl_model_to/ or google "shrinkwrap my stl"

UMO or UM2? Do you have a printer that is over a year old? There was an old bug long since fixed. Maybe you should create a fast-as-possible video of you doing the homing procedure (just do it very very rough since it sounds like the nozzle is well above the bed). Try to keep the video under 30 seconds, post on youtube and link to it on your next post.

https://www.youmagine.com/designs/um2-spring-replacement I think my version is better for a few reasons - but mainly because it has a hole so you can see what's going on inside.

If you can get it inside the regular bowden let me know and I'll send you an STL file you can print in a few minutes o keep them from slipping inside each other. Anders Olsson claims the "3mm" bowden works fine for 1.75mm. I'm skeptical. I'm guessing he printed pretty slow.

"Volumetric" will only affect the extruder. It will extrude the wrong amount if you do that - other than that there is no difference. Well do you have old gcode files from when it used to work fine? Can you compare the top 30 lines or so? I mean there's not much there and most of the commands should be identical so probably only 5 gcodes are different from the old to the new. Basically you want to look at what you have now in the "start" tab of cura - the gcodes there and compare that to what it creates now. Then compare that to an old gcode file and make the new gcode files look like the old ones that worked.

Well I think something about your STL file is messing up cura and giving you a bad gcode file so without seeing that I can't test my theory. From cura there should be a "folder" icon near the top left. Right click on that and choose "save to disk" or "save gcode" or something like that. Do this for every print. Always. Otherwise a year later when someone asks you what settings you used (e.g. "did you use cool head lift?") you can check. Or if you print something that comes out perfect one time and not the next you can check these settings. Anyway the next time you have this weird "shifting" post the gcode file and a photo of the print so I can test my theory. I don't think you have a hardware problem because if it is a hardware problem it somehow self corrects after a few layers. That would imply something is very loose - gets in the wrong position and then 20 minutes later it shifts back where it was (e.g. loose extruder).

Sorry - you should be asking these kinds of things on a php forum not here. If you play with curaEngine and examine the output and then have questions about that - then maybe this forum is appropriate. I think you need someone who is more advanced with php than yourself.

I'm 90% sure they are the same one. I have the upgrade kits and some recent PTFE parts. Note that roughly January 2016 they started shipping newer PTFE parts made out of a much higher temp PTFE (same material as the ones from 3dsolex I think). You can tell which is which because the newer ones are more transluscent (you can see through them so if you put them on a dark table they are darker).

Yes. They give out a build volume but it's more complicated because you have to avoid the clips as you say. Also if you use brim or skirt (you can set these to zero but I would do at least one brim pass if it fits) you might violate the build volume for that also. By the way those supports are much too thin. Some people use the 10% rule but I use the 20% rule - posts should be at least 20% as wide as tall. They can taper as they go up as long as you stick to that rule. Those posts will wobble too much and get hit by the print head and *might* fall over. Would you consider cutting this part at an angle half way up and flip it over and gluing it together after printing such that the "join" is touching the bed for both halves? If you do that then you don't need any support. Plus it will probably fit diagonally letting you have lots of brim. Or maybe "CAD split" your model such that one slides under the other with 2cm of overlap for a strong glued joint.

Yes. UMO and UM2 and UM2+ can each put out about 10 pounds or 5kg of force max. but the symptoms are different on the UM2 (plain). On the UM2 it sometimes skips back. On the "plus" and UMO it doesn't skip back but the filament underextrudes. Typically by a small amount at first - say 10%. You can see it as gaps between infill when you have solid infill. but as you go faster and faster you might have only 50% extrusion from what you requested. If you use reading glasses you can see the difference in the length of the marks on the filament - they get longer and longer until they touch each other and it fails completely and you get filament dust at the feeder and zero extrusion out the nozzle. With the UMO most people don't notice 10% underextrusion so much so they pushed their machine beyond what it can do and it was no big deal. but with the UM2 and the "skip backs" it's much more obvious.

> using the Mac version of Cura Oh. I feel your pain. gloat>

Excellent! You have diagnosed 50 possible problems down to just a few. You should be overjoyed. Seriously. Now you know it's not the feeder or the stepper or the electronics or the nozzle temp or a clogged nozzle or another 50 things. I I'm not sure what to do next. You are going to have to take the head apart regardless. do you have a spare teflon part to replace the existing one with? Maybe the head is too tight? Maybe if you rotate the round nut a bit to release the pressure on the white teflon part some? Maybe if you loosen the 4 screws that hold the head by 1 full turn to just feel if there is a difference? maybe replace the aluminum cylinder with the old spring so you can see what is going on? or with this part? https://www.youmagine.com/designs/um2-spring-replacement You are probably going to have to take the head apart and check the hole along the way. Are you sure it isn't just catching when you insert new filament but it's fine once it starts printing? I guess you would have noticed that by now when you were passing the filament through. Let us know what you find out so I can pass the knowledge onto the next person and I might even feedback what you find to UM if there's a chance someone is building this kit wrong.

(sorry, it's a little frustrating when 2 people give you the correct answer but don't try it)

This "blobbing" issue you speak of is EXTREMELY COMMON on layers this tiny. I've seen this many times. I read EVERY post on this forum for the last 3 years. Please - I'm probably right about this. I could link you to 50 message 3 page topics about this but it's very simple. In CAD create a cube of any dimensions. Drop it into cura next to your part. Click on it and scale it - unlock the dimensions. Set X and Y to 10mm. Set Z to a height that lines up roughly with the bottom of the spherical section. Print this next to your part so that while it is printing this cuboid the fans are blowing on the part you care about. Make sure "print all at once" is chosen and not "one at a time". Print it. The reason it worked before - the red photo - is probably because it is just barely on the edge of working - 1C warmer air temperature 1% slower fan speed 1C hotter bed or 10C hotter nozzle temps is all it takes to push this over from working great to "the blob". Basically you were lucky before.