WTF of the Week

[pyronaught]

If you like looking at the scene of an accident and trying to figure out the chain of events that went wrong, here's a challenge for you. This ABS print was going along fine for about two hours. Very clean, no globs of plastic anywhere, no over extrusions or anything going on that would leave blobs of plastic on the active layer. So I go outside for a while and come back to find this mess. The angled portion of the print is not a separate piece sitting on top the original , it was printed in that orientation and is very bonded to the other piece. The reason it is at an angle is because the entire build plate became dislodged from it's mount and was thrown forward to the position shown in the image. Now tell me how THAT can even happen? The stepper cable on the extrduer is on the long side and hangs down to where it can actually touch the plate during a print, but I don't put a clip on the right side in order to remove the possibility of it catching on that. I put the plate back on and raised the platform to the failure point to see if there was any combination of motion that could cause the cable to catch on anything but could not find any scenario where it did. Even if it did that would lift the back corner of the plate and not the front corner. Another scenario I can think of is if a blob got deposited on the surface and then got whacked on the next layer-- but that would take a BIG blob to lift the whole plate rather than just deflect the way they normally do. I did not see any big blobs anywhere. I've seen slices dislodged from the print like this from temporary extruder jams that unclog themselves later and start printing again in mid air, but this dislodged slice appears to have printed right on the original, so there was never a missed layer. Total mystery here. That metal plate plus glass plus part is quite heavy, it is amazing something could knock it hard enough to dislodge it like that, especially in a way that would cause an upward force to lift it out of its cradle!

[insta]

Warped, caught the nuts on the underside of the gantry, wedged it up there a bit, and pulled the plate up and out when the bed reversed direction.

[jimc]

Yup gotta go with insta on this one. The warping force with abs on a print that size is going to be nuts.

[pyronaught]

It had only warped about 1/16" at the corners. I should have taken a side view pic. My guess is that something was sticking up above the print plane near the front edge of the part and the extruder nozzle ran into it while the plate was moving towards the back. That would lift the front edge and then the frame could then slide out from under it.

[pyronaught]

The warping forces are indeed insane though. Even with ABS+ it's peeling the kapton right off the plate and the part is splitting at regular intervals on the corners. This is printing in a heated chamber too, regulated at 100F. The ABS+ prints really smooth though, sands almost like plaster and prints in half the time of PETG. These parts are still usable even with the warped corners and cracked edges. The cracks fill in when I epoxy coat it. The warp deformation diminishes enough by the time it reaches the mold cavity that it is still usable. It's not a high tolerance part. The bottom picture makes it look like the part is twisted, but actually it isn't. That's just an illusion caused by the camera angle.

The ringing defect increases towards the top end of the part. With about 2 pounds of plastic sitting on the plate, a print speed of 6000 and the part being so tall, it really shakes a lot when doing short, fast zig-zag infills. It's amazing the defects are not worse really. I should take video of how crazy it shakes. The spring loaded platform is great for deflecting collisions with blobs on the print surface without loosing steps, but is less than ideal for keeping a tall, heavy print steady near the end. It's still better to have some ringing patterns to sand out than to have a print ruined by lost steps though.

[pyronaught]

Here's the male half of the mold. The female half is so big it has to be printed in two parts that are then glued and bolted together. The male part is all one piece though, and damn near fills the entire build plate at the base. The one here is in two pieces due to a nozzle jam, so that's why the top half is in a different color (also ran out of the clear ABS). This one is just regular ABS, Hatchbox brand. There was one large split in one corner I had to fill, and all four corners had the usual warp. This part also takes an entire spool of filament and about 24 hours to print.

[insta]

Why ABS or PETG? If it's not under heat, that looks ideal for some of the "+" PLAs. If abrasion is a concern, coat it with XTC-3D.

[Jules]

Why ABS or PETG? If it's not under heat, that looks ideal for some of the "+" PLAs. If abrasion is a concern, coat it with XTC-3D.

I was thinking the same thing. It would be perfect for PLA+, and faster printing to boot.

[jimc]

Anyone use that high temp pla from makergeeks? They claim its high enough to run through an autoclave and stronger than petg and abs.

[Jules]

Is that the dishwasher-safe stuff? I might try it one day, i like the muted colors.