gr5

You can play with it in Cura - it's pretty easy. The hard part is in cad. You need 5 separate STL files to come out of your cad. Each STL file defines a volume of one color. In cura you add them all and then right click on them and tell them "dual extrusion merge". I don't know that cura supports more than 2 colors but it might. The output is a gcode file. It's important that none of the separate cad files overlap.

@Labern can you post a photo of a chloroformed part?

Read through this and decide: http://support.3dverkstan.se/article/62-installing-the-olsson-block-kit Probably much easier than the UM2+ upgrade which I hear might involve drilling holes in your printer. A LOT of people break their temp sensor. But the guy who wrote the above article has changed about 100 and broke only one temp sensor. But still - they tend to be very tricky to get out. Don't rush that step. Don't panic. Take your time. Try heating. Try adding wd40 to loosen it. Read the suggestions. Just don't yank it out by the wire. Ever. That guarantees it will be destroyed. As long as you don't do that you should be fine.

20mm cube minus 15mm cube leaves only 2.5mm thick, um, walls. Let's not use the word wall in this topic as it is a source of confusion for the original poster. Anyway the point is your dimensions don't add up yellowshark.

Like a cube with an empty air space inside shaped like a donut? But squared off?

Inner vertical holes will indeed be about .5mm smaller. Also outer corners. This is because the hot PLA cools a bit in a fraction of a second and so shrinks slightly and as it is being placed acts like "snot" (stuff from your nose). Like a liquid rubber band. Because it is so stretchy it is pulling inward - but still in liquid phase - and so outer corners and inner holes are all too small. Especially on sharp curvatures like small holes or sharp corners (like those on the tip of a star). However the sides of your rectangular object are not affected by this. I'm not sure why that would be smaller. .4mm versus 60mm is 0.6% which seems a bit high. Typically PLA shrinks more like .3% from the glass temp down to room temp. So I'm not certain what is causing that but I'm not particularly surprised.

mbmast - you still have a basic misunderstanding of the terms like "wall" and "shell" and "solid". I can't quite put my finger on the misunderstanding but there is a major communication flaw between you and the rest of us. Eventually a light bulb will go off in your head and you will see your very simple but incredibly important misunderstanding. All the posts above from the other people are trying to fix this misunderstanding - maybe if you read them again more carefully. I don't understand what the hell you are saying with "extrusion" as this is not a normal thing in my cad software, nor cura. When I think of extruding walls -- well never mind. Let's split the CAD step and the SLICE step up a bit. The CAD step must never define walls. It must define solids. If you are designing a cube that must be hollow or a cup, then you can define the "walls" which are really not walls - but solids. Don't call the "walls" "walls". Call them cubes or cuboids. A cuboid is a box - a rectangular solid that may have different lengths. Boxes have 3 lengths. Don't call them walls because it seems to be confusing you. Again, the CAD step defines *only* solids. Never hollow things. It defines what areas in 3d space are solid and which are air. In the SLICE step you can make it so that solids are hollow inside PURELY to save material and time. People won't know it is hollow because they can't see inside. In the SLICE step you can set how thick the "walls" or "shell" of these solids are and/or give it a diagonal infill pattern with varying density. If you are printing a "house" with "walls" don't think of them as walls. Think of them as solid cuboids for the sake of the CAD step and the SLICE step. Cura will not slice cuboids with a horizontal dimension less than 2 times the nozzle width so make your cuboids at least .8mm thick.

yellowshark - tldr - sorry. Pictures please.

4mm^3/sec at 220C is medium. You shouldn't be getting skipping at this speed but you are pushing the limit a bit. The printers are supposedly tested at 8mm^3/sec (but at 230C). Extruder skipping is bad. It won't hurt the printer but it sucks for your print. I can usually go 30 prints without skipping. I think a lot of it has to do with the filament and whether it slips a bit in the extruder or not (if it doesn't slip then skipping is more likely). Softer (slightly) filaments seem to skip less. I suspect your temp sensor is a bit tighter than usual so it reads high meaning the nozzle is cooler than most printers and that you can go up another 10C or 20C. I don't know for sure though. Your quality will diminish at higher temps so it's up to you. There is definitely a tradeoff between speed and quality. I prefer to print at .2mm layer height and 35mm/sec for high quality and reasonable speed (thicker layers print faster). I don't know if you have another printer but 65mm/sec is much faster on the UM than for a printer with the feeder mounted on the head because UM has much higher acceleration. Those Makerbots probably never get up to 100mm/sec unless you are printing straight lines across the whole bed because the acceleration is so much lower. Feeder skipping on the bottom layer is a special case - just go into the tune menu and slow it the hell down - say maybe 25% or 50% feedrate. That is .3mm thick plus it may be squishing and working harder. But if you get skipping on higher layers immediately go into the tune menu and try to get rid of it by increasing temp up to 240C and/or by slowing down the feedrate down to 20%. Whatever it takes. Unless you don't care how the part looks. You may have a partially clogged nozzle - typically gunk is lining the inside of the nozzle and it's hard to get that out without soaking it in acetone or burning it out. Having the Olsson block saves a lot of time as you can just unscrew the nozzle and clean it out without having to take the whole head apart.

Don't forget you need a 1.75mm nozzle also. But you don't really need to change the bowden according to Anders Olsson. he says the bowden for 3mm filament works fine for 1.75mm filament. The feeder works fine as is also. I'm not sure why people change to 1.75mm as you can get every type of filament out there in 3mm.

If you have hundreds of dollars of 1.75mm filament and no printer to print it with consider getting the 1.75mm conversion kit from my store at gr5.org/store. Anyway you can print ABS just fine on the Um2 - but there are many tricks to getting it working perfectly. What do you mean by "will not shrink". What exactly is the problem - please show a picture. For example is it simply not staying on the bed? Or are vertical round holes too small? Or are there things that you think warped related to shrinkage (unlikely)? A photo would be best. Anyway at this point perhaps you have a nozzle clogged with ABS? Heating ABS to 255 for 5 minutes will bake it into a kind of hard chewing gum which is tough to get out - you probably have to take it all apart. You might want to consider installing an olsson block as then it's easy to take the nozzle off and clean it out the next time you have problems. Although I've been fine without the Olsson block for years of printing. Anyway - the Olsson block is also at my store. I don't usually advert my stuff so much. Really. It's just that 2 possible issues you have might (might!) lend themselves to stuff in my store.

Don't set the value too high in you cad software - if the line segments are say 5 per mm it will drastically slow down your print because of how Marlin (the firmware) works. Marlin can only read 12 moves ahead and doesn't know if a sharp turn (e.g. corner of square) is coming up on the 13th move so it has to be ready to stop 12 moves ahead and if all 12 moves are in the next 3mm it needs to print VERY slow. It will cause bad quality.

This is a common problem. Sander has the answer.

I don't think you read the posts above very well. Sure there was a misunderstanding of how your model looked but read them again. The answer is above. Another important detail. After it slices always. ALWAYS. look at your model in slice view. This will explain how cura intends to print your model. It could be that it thinks your model is completely solid. If so maybe your cad software is creating a bad model (check in xray view - anything red is a problem) or more likely you have one of the "fix horrible" boxes checked. Try unchecking all the "fix horrible" boxes in the expert tab. They can fill in areas that are supposed to be hollow.

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide See 4th image down on the left. Sometimes this causes leaning - sometimes sudden shift exactly as shown in your photo. This is very common and easily fixed in a few minutes. Most likely it's the pulley on the stepper motor.

If your part is shaped like a dixie cup upside down - and if your cad software specifies "wall width" - this has absolutely no relation to cura "shell". Cura doesn't think of those as "walls". An STL file contains triangles only. Cura slices each layer with a horizontal layer and turns the triangles into line segments. These line segments have NO RELATIONSHIP to each other - they are not sorted. Cura tries to connect them together - figure out which lines are going to the same vertex. For your "cup" it will have two polygons - one for the outer surface of the wall and a separate polygon for the inner surface. The spacing between these 2 polygons needs "fill" or "plastic". If the cura shell is .8mm and the distance between the polygons is < .4mm it won't print anything (no walls at all). If the distance between the polygons is 5mm (5mm thick walls) then cura will do .8mm solid on the inner and outer surface of these walls but then will do an infill pattern in between (criss cross). Usually you want your CAD walls to be at least 1mm wide if you have a .4mm nozzle (actually .8mm is usually the minimum but there is floating point errors and curves converted to lines and so it might get thinner so 1mm is usually safe). Sometimes Cura will print walls down to .4mm - I don't know why. But usually not.

Cura will *only* let you print solid objects - so if you use sketchup (which lets you create infinitely thin walls) it might refuse to print your walls if they aren't connected. It's silly to print the solid parts of the model solid as PLA is very very strong. So usually I print hollow with "shell" set to .8mm (2 passes) or I'll do maybe 20% infill. You can certainly do zero shell and 100% infill but all the passes will be diagonal. Or you can do all shell and no infill (set shell to 4000mm - it works!). Does this help?

The leveling procedure gets you close but I always level it again when it starts printing - live - by the seat of my pants so to speak. Just twist those knobs. The first time you may panic. Just take a deep breath. Take your time. Think about if you want the bed to go up or down, then think about which way to turn the knobs, then turn all 3 the same amount. The first time you may be too late to help the first layer much. But if you do this at the start of EVERY print you will quickly become an expert.

This is typical underextrusion. Pretty severe - Somewhere around 30% to 50% of the extrusion desigred (half to a 1/3). There are many possible causes. The likely problem is either your teflon part or your nozzle. But first the most common problem is that people print too cold or too fast. Check the table below to see if you are printing too cold or too fast (fast has to do with layer height also!). If you have the Olsson block this might be a good time to install it. Read the directions carefully - it's very very easy to destroy the temp sensor - but the guy who wrote these directions changed 100 blocks and only damaged one temp sensor so read his technique. Change the teflon part while you are at it. Often there is a thin coating of gunk inside the nozzle - especially if you printed with ABS a few prints ago. You can either put on the olsson block or you can remove do a cold pull, then remove the nozzle and soak it in acetone overnight (again be very very careful not to damage the temp sensor). Here's the directions: http://support.3dverkstan.se/article/62-installing-the-olsson-block-kit There are about 15 other possibilities so tell us more information (e.g. I changed the nozzle - that's not it, I change the teflon part 2 days ago - that's not it, I am printing same speed (but thicker layers) that used to work). Here are my recommended top speeds for .2mm layers (twice as fast for .1mm layers): 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.

One of your axes is slipping. I assume the X (left/right) axis. I assume the wheels of the car were toward the front of the printer. If not perhaps it is the Y axis. There are 6 (not 4!). Six (6) pulleys. When you get this tilted problem the solution is to tighten the set screws on the pulleys. Very tight. Tight enough to twist the allen wrench tool (2mm allen wrench). Many people say they "tightened all the pullleys" but they only tighten the 4 on the long belts. You need to get the one on the motor and the other end of the short belt. Those are usually actually the only 2 that need tightening. You should be able to get to pulleys on both motors without removing anything - push the head around with power off until the set screw is lined up and visible. Worst case you can remove the small cover held on by 2 screws that hides the motor (this is only for UM2 series) and then remove the motor completely (4 screws) and tighten that pulley very tight. More details on this and other problems here: http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide

It's bad for PLA and especially ABS to sit at full temperature for a few minutes - it can cause clogging as the material is slowly baked into a gum. For PLA it can be at full temperature for longer - maybe 10 mintues or 30 minutes. For ABS even one minute might be too much. Because of this, the UM2 heats up the bed first. Only when the bed is close to final temperature does the nozzle start heating up. So if you just wait a little longer you will see the nozzle "goal" temp suddenly change to 210C.

What kind of printer is this? It's okay if it's not Ultimaker but knowing the printer type can be important. Those "E" commands have to do with the extruders.

If you look at the cable it's 2 twisted pairs (total of 4 wires). If you measure the resistance of each pair it should show some resistance value (not sure what but not infinite). I predict one pair will be perfect and the other pair bad. I predict if you tug on the wire slightly you will see it's loose. This is the kind of thing you can fix with a few tools in a few minutes. Then you'll have a spare stepper. Not that you need it - these things are tough as hell and probably last for centuries (don't know for sure!).

Is it sticking at first but coming up too easily? If so then read below. Or is it never sticking in the first place? If never sticking at all, increase the bed temperature (sometimes the edges of the glass aren't hot enough for the first layer), also remove the glass and clean it very well - it may have some oil on it - also lower the nozzle - the nozzle might just be slightly too high. Much more likely though it sticks at first but peels up too easily. For that here is my standard response: lifting corners, curling corners, part sticking to glass 1) Make sure the glass is clean if you haven't cleaned it for a few weeks. You want a very thin coat of PVA glue which is found in hairspray, glue stick, wood glue. If you use glue stick or wood glue you need to dilute it with water - about 5 to 10 parts water to 1 part glue. So for example if you use glue stick, apply only to the outer edge of your model outline then add a tablespoon of water and spread with a tissue such that you thin it so much you can't see it anymore. wood glue is better. hairspray doesn't need to be diluted. When it dries it should be invisible. This glue works well for most plastics. 2) Heat the bed. This helps the plastic fill in completely (no air pockets) so you have better contact with the glass. For PLA any temp above 40C is safe. I often print at 60C bed. 3) heat the bed (didn't I already say that?). Keeping the bottom layers above the glass temp of the material makes it so the bottom layers can flex a bit (very very tiny amount) and relieve the tension/stress. For PLA 60C is better than 50C. 70C is even better but then you get other "warping" like issues at the corners where they move inward but if you are desperate it's worth it. For ABS you want 110C (100C is good enough). 4) rounded corners - having square corners puts all the lifting force on a tiny spot. Rounding the corner spreads the force out more. This is optional if you use brim. 5) Brim - this is the most important of all. Turn on the brim feature in cura and do 10 passes of brim. This is awesome. 6) Squish - make sure the bottom layer is squishing onto the glass with no gaps in the brim. The first trace going down should be flat like a pancake, not rounded like string. don't run the leveling procedure if it is off, just turn the 3 screws the same amount while it is printing the skirt or brim. Counter clockwise from below gets the bed closer to the nozzle. Don't panic, take a breath, think about which way to move the glass, think about how the screw works, then twist. This may take 30 seconds but it's worth it to not rush it. You can always restart the print. If you do all this you will then ask me "how the hell do I get my part off the glass?". Well first let it cool completely. Or even put it in the freezer. Then use a sharp putty knife under a corner and it should pop off.

It's the heater, not the sensor. If the sensor was broken it would be reporting 0C or 1000C or most likely something like "temp sensor error". It's your heater that is intermittent. Are you sure the wires under the machine are okay? Probably they are fine if you didn't muck with that. You are in USA so probably the cheapest place to get good heaters is at my store and I recommend you get a 35W heater as you can print more volume if you ever go with an Olsson block. http://gr5.org/store/