gr5

No. If you wait until it stops, then by then there will be lots of air in the head and you will end up with underextrusion on the first layer. So not only do you not need to wait, you might want to "prime" it one more time if you do wait. The default start/end gcode in cura "primes" it a bit before printing. You may have taken that code out long ago for your ABS. Overall I think you will find PLA is easier to print due to it's reduced shrinkage when cooling.

Someone recently mentioned that they clamped their Ultimaker to a heavy wooden bench and also put weights on it to keep the vibrations down to a minimum. In theory you could attach weights to the long belts at the opposite point of where the blocks are. The weights should be equal to the weight of the head. That way there is no net momentum to shake the UM when the head moves.

I took out my springs back in January and the screws come from below now. I've messed up a few times and scratched the blue tape a little but never anything serious. I can't print with the UM sideways or upside-down anymore but I can live with that.

google optical z axis ultimaker as I know other people have done it. UM did some tests and found it to be accurate and repeatable to amazingly small amounts. I think maybe .00001 mm? That seems impossible but I think that was it. I've never moved mine since the first day. I only move the screws. Besides my bed tends to shift over the course of a few days and it shifts in a strange direction - the front edge droops and the back edge tends to go *up* somehow. But mostly just the front edge droops. So I don't see how an adjustable or more accurate switch will help you.

illuminarti is right about needing 7 seconds to traverse the border. So I made an stl that is 700mm around the border (7 seconds at 100mm/sec). Of course it will be a little slower but the point is this way cura won't slow down the speed as 7 seconds is enough to cool each layer. So here's an stl file for a ringing test for oliverC http://gr5.org/ringing%20test.stl Right click (alt click for you loser mac people with only one button mouse) and choose "save link as..." or similar.

I'm really not sure. I suspect one of them (accel, jerk) causes ringing much more than the other. Thinking about a corner of a cube, default accel I believe is 3000mm/sec (about 1/3 of a G). But the jerk probably causes accel of something like 10G's or 100G's at the corner. But that acceleration is soooo brief. The jerk will be highly postive, then highly negative in millisecond succession and much of that will cancel out before the energy reaches the print head. I'm really not sure which parameter is the important one (accel or jerk) so play with both of them. Do a bunch of tests at 100mm/sec, 230C and .2mm layers (thinner layers will take longer and won't tell you much more - faster than 100mm/sec at .2mm and you might get underextrusion). I recommend a 3 inch-on a side hollow cube. Every few minutes, change the settings (can you do that with the UC? Not sure). Mark the part as you go up with a sharpie. Keep good notes. Let us know. Maybe first print with max jerk of 20, then 10 then 5 the 3 then 2. Then try max jerk of 20 with accell at 3000, then 1500, then 700, then 300. Then try a combination of 2 of those settings.

As far as speed goes... For very small parts (smaller than 1 inch across) it's going to be way off. Cura just adds up all the segments and assumes a constant speed with infinite acceleration and deceleration. Is it possible that your machine has a "max XY" speed that is much lower than the default cura speed? For parts larger than 4 inches across, cura tends to be very accurate guess for the time because it travels long distances per segment and has plenty of distance to get up to full speed. For parts around 2 inches it can be off by a factor of 2X and so on.

Can't you just turn the extruder gear by hand? On the UM it's a very large gear on the back of the machine and it's so much better to do by hand than using software as you learn a lot. You get a feel for what kind of pressure is needed to push through a given temperature of filament.

Just to clarify what was said above. Daid, Alex, and Ian are theorizing that what you are seeing is the infill pattern from lower layers showing up on the top layer. If they are correct then Ian and Alex are suggestion you have more "solid" layers so that on each successive layer the pattern gets harder and harder to see. Daid suggests lowering the temp to get less sagging when bridging the infill pattern. I like Ian's suggestion the best which is to increase the top/bottom thickness. For example 4 solid layers is probably plenty so if you are printing .2mm layers than make top/bottom thickness .8mm and you will get 4 solid layers. I'm not 100% sure that what you are seeing is related to infill - you can check by looking at the gcode view of your model in cura and seeing if the pattern of infill matches the squares on top.

That bend is not normal. Could you photograph your hot end please? From a few angles. Thanks.

Acceleration can be very very high and constant and you will get zero ringing. What you want to reduce is the true jerk (not what Marlin calls jerk). Jerk (look it up in wikipedia) is the change in acceleration. An example is when you are sitting in a car and someone stops pretty hard at a stop sign. during the deceleration you adjust and lean back into the seat but that final instant when your acceleration goes from very high (say half a G) to zero is in theory infinite jerk. In practice there are springs and bendy parts of the vehicle and tires and it's not infinite but jerk is very high and you suddenly get "jerked" back into the seat. This is what causes ringing because the tension on a belt goes from one value to another value suddenly so the belt changes how much it is stretched and then rings. aside: I don't know where the ringing comes from exactly but I assume it is the head and the rubber belts. Ringing should be caused by a system that prefers to oscillate at a particular frequency. You can change that frequency by changing the weight of the head or the tension on the belts but it won't go away - just change the frequency. You can dampen the frequency with friction. It seems to me if you glued a closed box half filled with sand onto the print head that would dampen the ringing instantly. It would have to be comparable heaviness to the print head so quite heavy. Now back to Jerk and Marlin: Marlin moves the print head in a series of line segments. In theory the only way to keep the jerk below infinite is to come to a complete stop at every vertex because you are "instantly" changing the acceleration if you don't come to a complete stop. In practice the steppers are stepped a certain number of steps per second and the switch happens "between" 2 steps so it isn't instant but noone has calculated this. Plus things stretch and deform a bit (like the belts) so obviously in practice jerk is not infinite. But the problem for the programmers of Marlin is they didn't know how to control jerk because in theory it's infinite at every corner. But thinking about drawing a circle of 10 line segments it seemed silly to come to a stop at each vertex so they defined this new parameter (which they unfortunately call jerk) that says how much the print head has to slow down when you change directions. And if you only change directions slightly they don't want to slow down as much (such as in a circle) but in a sharp turn like a 90 degree turn they want to slow down more. By the way I could be wrong but I think this whole idea is what made Marlin so great (fast). They call this parameter "max jerk" and it's in mm/sec. Marlin calculates the fake jerk at a given intersection by taking the speed vectors before and after the vertex and finds the difference between them. For example on a 90 degree turn if the velocities are North at 10mm/sec and West at 10mm/sec the hypoteneuse (distance between the tips of those vectors) is 14mm/sec (not 20). If it is a 180 degree turn the diff would be 20mm/sec. If no angle then 0mm/sec. If a slight angle then maybe 1mm/sec. That value is called the Jerk and the print head is slowed down enough so that the speed change, (aka fake jerk) is at the "max jerk" setting. So... The default marlin max-jerk value I believe is 20mm/sec. This means that 90 degree turns will be done at 14mm/sec sqrt(14*14+14*14) = 20mm/sec. At that vertex the true jerk and true acceleration are both theoretically infinite. In practice they aren't infinite but pretty damn high! If you set jerk to 10mm, that corner will be taken at half the speed (7mm/sec) and although the true jerk and accel will be infinite, in practice it will be exactly half. For more gradual corners, say only a 10 degree shift in angle, and a max-jerk of 20mm, the minimum speed at the vertex is 115mm/sec. So the "max jerk" won't affect this if your speed is already lower than that. Infill is full of sharp corners so if you are printing small parts, the jerk can make a huge difference in how long it takes to print. For larger parts where there is plenty of time to get up to speed, lowering the jerk won't increase the time as much.

Aluminum foil will not work. The bottom layer of any print has the strongest forces because it was laid down hot and stuck to the surface but the surface doesn't move as the part cools. So within a minute the aluminum foil will bunch up and shrink as the printed parts shrinks. Some people have multiple beds so they can swap out the bed and print the next part while the previous part is cooling. Usually glass as you can just use a paper clip to hold down a sheet of glass such that when it expands the paper clip will allow the glass to expand or shrink.

So don't do that, lol. How large is the print? 8X4cm? You probably have the corners lifting off the blue tape. This is very common. It happens because the PLA upper layers shrink as they cool and they pull hard on the part and lift the 4 corners. You can fix this many ways. 1) First wipe your blue tape with isopropyl alcohol (also called rubbing alcohol). You can buy this at any store that sells bandages such as a supermarket or drugstore. This removes the wax from the blue side of the tape and increases stickyness. Also if the blue tape itself lifts off the bed it helps to get larger pieces of tape available at any store that sells paint and paint brushes. Ask for "blue painters tape". This one thing will help you more than any other thing below. 2) Add a brim. Cura has a brim setting on the adheasion section. Do about 10 passes. This will help keep the corners of your part down. 3) Print first layer slower and hotter. I always set my temperature to 0 in cura and adjust it by hand using either cura print dialog or ulticontroller. For large parts I print the first layer at 240C and then lower the temperature after it is done with the first layer. Also squish that PLA into your bed nice and hard with the bed nice and high. 4) Don't infill the first layer. This might not be practical depending on what you are printing but cura allows you to not fill the bottom or top layer - it's a checkbox. 5) Get a heated bed. Not neccessary for PLA but this helps also. Step 1 and 3 alone are usually enough.

The transparent tube is called the "bowden tube". It's a mechanical term and used to refer to those tubes on bicycles for the brakes and gear changers. 2) Just because it came from UM doesn't mean it's defective - do you have a micrometer to measure to make sure? Even better just slide some through the bowden tube. 3) .1mm layer height at 50mm is definitely nice and slow volume of PLA. The pressure build up is tiny. Most likely it's none of these and somehow the device that holds the tube isn't working. Normally the feeder can pull 22 pounds and the bowden should stay in with that much force pushing on the filament (11 pounds each attachment point). So if you can pull with 10 pounds of force on the tube directly and it slides out then something is wrong. See if they look damaged at all - maybe a tiny piece broke off? Some people have done different modifications. You can check thingiverse. Illuminatri's suggestion of cutting the end off sounds good. Those clips can be found at air conditioning supply places and large plumbing supply stores (the stores for plumbers, not like home depot) - they are used commonly with water purification I believe. They cost very little.

Post a picture? I'm guessing you had stringing. Cura out of the box prints all the parts at the same time (first layer of every part - then it goes back and does second layer of every part). But it prefers to print them one at a time. Printing one at a time is much faster (less retraction) and they come out better (no strings between the parts - no furry). Go to preferences and answer all the questions about distance to stay away from the head - make sure you include any fan or other protuberance. Cura will print the parts one at a time starting from the edge farthest from the largest protuberance. Make sure you also include a "gantry" value. If you leave it at zero ti will print all parts at once. If you have no gantry (no height limit) then set it to 200mm or some value taller than all your parts. If even one part is higher than the gantry value then it will print the parts all at once instead of one at a time.

Well I was thinking if you picked 2 of the colors from my "trendy" earth tone colors: lol. I mean of *course* I like the colors I picked.

Very nice paint job. I hated those things in half-life. Always hard to shoot as they get under your feet. They make my skin crawl (like spiders).

There is a tool that is like a reverse threaded conical drill that makes removing the broken pieces easy. But you will have to heat everything up to at least 100C (boiling) or preferably hotter (around 200C is good). You will need to order a new nozzle I think. Sucks for you - sorry. Do you have a heated bed? Most people have great trouble with ABS warping untill they get a heated bed. ABS is much harder to get working nicely than PLA but you *can* do it.

nope. Looked again. There's a "my media" link and in there is an "attachments" thing in there but that doesn't seem to do anything.

I love the idea. Very creative. Not a huge fan of the chosen colors though.

That doesn't do it for me. I have to go to the gallery first and upload pictures into there then when posting a reply I click the "my media" button next to the smiley icon.

I think it's "large objects have more accurate times than small objects". Cura would have to know your 3 acceleration parameters (XY, Z, Extruder) and your XY Jerk and your maximum accel and velocity and default velocities (xy, z, extruder). Knowing all that, and assuming you are using Marlin, and knowing which version of Marlin it is (most seem to calculate speeds the same way), Someone could duplicate the Marlin logic and figure out how fast Marlin will print each of thousands (hundreds of thousands possibly) segments, then add those all up and get a very very accurate result. But it's not worth it. There are so many other features that haven't been done yet that are more important. Like for example Marlin needs a simulator that can take in the viscosity of your filament and the nozzle size and other factors and predict the delay response between when you speed up the extruder and when the filament actually comes out. Marlin should then reverse the process and ask for more filament before it needs it and stops it before it wants it to stop and so on to have the exact right amount of filament all the time instead of under extruding at the begining of every segment as it is speeding up and over extruding at the end of every line segment. Also cura should do variable layers - thinner layers on the tops of sphere's for example. That's just 2 of 100s of features that are more important than working out how long a print will take.

1) You could use an STL editor like Olivers says or 2) You could try the "fix horrible" settings under "expert settings". You most likely want only "type B".

If it is retracting but still stringing look at this - first photo: http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=13081 Note that each color and manufacturer is different. For white PLA from printbl I can't get it to stop stringing no matter what I do (although the strings are thinner than a hair - maybe .05mm? certainly much much less than .1mm).

My times aren't off by *that* much. Cura assumes the machine will print at the speed you choose so it adds up all the line segments and assumes the speed you chose e.g. 100mm/sec. Marlin takes the gcodes and limits the speed based on things like acceleration chosen and other factors (something Marlin calls "jerk" but is in fact instantaneous differential velocity vector change). So if you have lots of long moves it tends to be accurate but if you print something small, then those short segments never get up to the full, asked-for speed and it takes longer to print than Cura thought it would.