johnse

I had an issue last night where Cura wouldn’t start (Windows 10, mostly up-to-date). There was a reboot pending to finish installing Windows updates. Cura would not show even its splash screen, but Cura.exe was in task manager under background processes. Tried killing itand restarting. That didn’t work. rebooted, which finished windows updates, and Cura was fine.

What material are you using, and what kind of surface are you printing on? Bed adhesion issues have a bunch of possible causes, and solving those will help all your future efforts.

There are a couple of basic ways to describe 3D parts. What @rowiac showed you is adding and subtracting 3D primitives like cylinders, cubes, and spheres. Another is to make a drawing in 2d of the cross section and then extrude that profile into the third dimension. These two fundamental methods can be used together and Fusion 360 supports both (& more). I can recommend the “Learn Fusion 360...or die trying” videos. They show the latter method and got me over many of the stumbling blocks where the sketch editor didn’t behave the way I expected it to behave. He stresses the importance of specifying dimensions in sketches. I would also stress the importance of naming things...especially in complex designs. Also, while Fusion 360 Is a paid service, it provides free licenses for students, and for startups—small businesses that make less than $100,000 per year. The startup license lasts for one year, but what they don’t say loudly is that you can renew that license every time it expires.

Marcottt, these may be a silly questions, but I am a little confused: I presume you have told Cura that you are using two materials. have you enabled the “prime tower” feature? The reason I ask is that you re describing needing to manually add priming objects. And you mention the extra object is only a single layer thick. Also, have you enabled “prime blobs”? On my Ultimaker, on the first layer of each material, it extrudes a blob in the corner before printing the layer. Is this the part it’s not doing for you? If for your printer it only prints one prime blob, then that may be something you can effect by adding start.gcode to your machine definition, to first prime the second material before it starts the print where it primes the first material.

the antler-like constructs on the left photo were explained to me as "antennae" and result from there being a tiny bit of filament drooping from the nozzle as it approaches a wall. It deposits that drop on the perimeter of the wall forming the root of an antenna. Then the next layer the drop hits the prior drop, and so on, forming those upward-growing antlers. So probably using a bit more retraction might help.

That sounds like you are printing too close to the edge of the printable area. IIRC, there are settings in the printer profile that specify the acceptable bounds for printing. When printing with two nozzles, you need to make sure that the left and right edges of the printable volume are constrained so that both nozzles can reach it.

Can you add the code to the preamble code in the printer definition? I'm not at a computer with Cura at the moment so I may have the term incorrect, but IIRC you can set GCODE to play before and after a print.

Hi Marcottt, I was replying to the thread in general, not your specific comment. I have separate extruders, so I’m not sure what the correct answer is in your case, but I’ve read elsewhere that Cura can handle such material changes and will create a priming tower to use up the extra material at material changes. This is assuming two materials being printed in a single part. from your description, it sounds like you print a complete part in one material and then another in a second material? I don’t know how to handle that. The prime tower option would work for print all-at-once, but it seems you would need a prime tower per part if printing one at a time.

Since you’re printing a water slide, “watertight” could have multiple meanings! To elaborate a little: the term “watertight” here refers to the shape being printed. It needs to have a defined “inside” and “outside” where the “inside” gets filled with plastic. I’m trying to intuit how you created this, and propose a solution based on that workflow. I apologize in advance if I got it wrong. I have only looked ar the pictures here, but it seems from what others have said that the meshes forming the slide are like infinitely thin sheets of paper with the ends curled up a bit, like you’ve modeled just the top surface of a section and then copy/pasted that section to form the overall shape. You need to continue that mesh to form the ends, the sides, and the bottom surfaces of each segment. Then you need to combine those sections together so there is one shape that is, as the others have said, watertight...or “plastic-tight”. This would be some sort of “combine” or “union” command.

See this thread, it has a workaround for that bug:

My experience with order has been different. Granted, I’ve not typically had objects in a row, but I’ve done many multi-object, print-all-at-once prints with an Ultimaker 3. It seems to always print each layer in the same order.

Hi cerons, welcome to 3D printing! I think you may have misunderstood bertoogle. He was asking you to load your model into Cura and then save the project. This will create a .3mf file. Then, if you post that file to this thread, people can look at it and give you advice.

You may want to look at this thread:

I’m pretty new here myself and not experienced with gcode sleuthing, but you’ll probably get a better response if you post a Cura project (.3mf) file and the gcode file to your question.

This makes me think you may be dealing with a cold solder joint. It is important that both things being soldered together are hot enough, and clean enough, for the solder to flow and bond properly. Clumping solder often means the solder did not bond to both surfaces. You may need to remove all the solder, clean the surface, and then re-solder using a paste flux.

I'm looking at your picture and I do not see the "starting on air" problem. The gaps I'm seeing are printing on internal support. See the image I've marked up from your initial picture. you can see that there is internal support printed on the prior layer. Have you actually printed these and had a problem? Or just looking at the preview?

Yes, but I was using a non-microstepping example to illustrate.

This was one of two issues (or a combination of both). My nylon may have gotten a little damp. I store it in a drybox, but haven’t yet built one I can print from. RElative humidity in the house sits around 50%. So I dried the filament overnight sitting on the build plate at 90c with a towel over it. I used the towel to pick up the roll and put it directly to the drybox to cool. i also realized that we had some warm days that caused the AC to kick on. There is a vent in the ceiling right above my printer. I recalled reading how drafts can be a problem with nylon. So I made a front cover and put a box over the top. The print came out beautifully! No hairs and very consistent finish.

Welcome to the whacky world of 3D printing. Your analysis of the flow of material makes perfect sense, but assumes instantaneous translation of feeder motion to material flow. My understanding (and I’m pretty new to this as well) is that the purpose of the feeder is to provide a consistent pressure on that pool of melted plastic in the nozzle. Think for a moment about your reasoning. If moving a step of the feeder instantly pushed that volume of plastic out the nozzle, it would come out as a blob. Then another blob a few mm away when the next step occurred. This might be the case if there were no viscosity, and no flex in the Bowden tube, and myriad other factors. During the printing of a line, it is going to average that 20mm/step you computed, but if you could measure the pressure on the plastic, it would fluctuate a bit between steps. Another factor to consider is how stepper motors work. Let’s take the simple case of full steps of a 4 pole stepper. The two windings create two electromagnets, winding 1 has poles up/down, and winding 2 has poles left/right. In this simplified version, we only have switches to turn voltage on/off and control the polarity to each winding. We start with winding 1 positive which attracts the North pole of the armature to the 12 o’clock position. If we turn 1 off and 2 positive, it would swing to the 3 o’clock position. But what if we leave 1 positive AND turn 2 positive? The North pole of the armature is drawn halfway between the poles, to the 1:30 position. The following table shows the sequence of steps in a full cycle: 1 2 direction + 0 12:00 + + 1:30 0 + 3:00 - + 4:30 - 0 6:00 - - 7:30 0 - 9:00 + - 10:30 + 0 returns to 12:00 The actual steppers have more poles per winding and more armature magnets to make that 8-step sequence move only a fraction of a circle, but the principle is the same. The key here is that even though the inputs to the motor are digital (analog control adds the microsteps) the armature takes time to move between positions. And if something prevents it from moving all the way, the magnetic forces pull towards that desired position with a force controlled by the amount of current flowing through the windings. So, in a perfect world with no flex anywhere in the system, that one step of the motor takes as long to move as the head takes to move 20mm. If you want it to draw 2 10mm lines, you would step forward to start pushing filament and the motor would get 1/2 way to the commanded step at the end of the line. In this perfect example, you then back up to the step where you started (retraction) which happens quickly because there’s no resistance going back, but now the end of the filament is 1/2 step away from the end of the nozzle. You move the head to the start of the next line. Again you command to go forward a step. There’s no resistance for the first 1/2 step, and it prints the 2nd line, finishing with the motor completing that step. In the real world were there’s lots of flex, compression, viscosity, etc., things are a lot more squishy if you’ll forgive the pun. Retraction is done by moving the filament several mm to remove pressure and try to suck molten plastic away from the nozzle end. Then it pushes several mm to re-prime the nozzle as it starts the next line. It might help you to read about “hot end”, “heat break”, “direct extruders”, “Bowden extruders”. The physics of these machines is pretty amazing.

That's bazaar. Check Cura to make sure there isn't a script enabled. I'm not sitting in front of the computer with Cura on it, so I can't tell you the exact menus to check.

One thing I noticed after printing a temperature tower is that the GCode scripts are persistent until you clear them.

It’s a Cura project file. In Cura, use File.Save. It will ask you where to save the file.

I printed a simple open container with nylon. Walls are 1.6mm thick (.4 nozzle, 4 walls--no infill), so the nozzle never moves over open space--the usual culprit for stringing. I'm wondering what might be causing this. I'm attaching the Cura project as well. This was printed on a UM3 with Ultimaker Nylon. In further processing it, I noticed that there was a fair amount of "hair" on the outside as well. Also, the first time I printed this model, the same kind of webbing appeared, but it also did occasional infils--just on the apex of the corners and in just a portion of the walls. I'm including that project file as well (the -nofill project is the one shown here). The one printed with no infil has poor adhesion between the inner walls. The inner-wall to outer wall seems fine. So in the case of the one where fill is not turned off, I'm wondering why it only did the infill in very limited portions of the walls. The model was created in Fusion360 by creating a solid with the correct outer shape and then using the "shell" command so the walls should be consistently 1.6mm thick. UM3_suetmold-nofill.3mf UM3_suetmold.3mf

Doesn’t retraction also play into this? If you print a shorter line than one step’s worth of feed, it will retract at the end of the feature.

I had a similar issue were I had a small feature that included a small (0.5mm) overhang on top of an outward 60 degree slope and I could not afford any drooping. The slope was fine without support, but Cura didn’t want to put support under the overhang. I modeled support directly into the model and had it be a solid block of support material. I made the footprint of the support 4mm (.5 under the overhang 3.5 beyond it to give integrity—using breakaway that often doesn’t do well with small fearure. I output them as two STL files and then used merge in Cura to align them. Important note: the stl origins must align to merge properly.