I've been printing M781 nosecones in ABS, and every single time, the nose near the right side of the bed has a defect:



Everything else looks good...except for that same general area. The inside of the item looks perfect. I've adjusted flow rates, tried supports, changed temps, checked in the slicer...

Ender 3 Max with Micro Swiss hotend/direct extruder. Enclosed, Polymaker ABS that's been in a dryer prior to printing and while printing.
(the "bubbles" are layer seams)

Any ideas?

Boom, that did it! I had always thought cooling with ABS was not recommended, but after you mentioned it, did some research. Started at 30%, then moved to 50% and that seemed to do it.

Thanks much!

For M781 nosecones, you want them to be fairly brittle; ABS is intentionally used for that reason (by others, I'm still dialing in). They're post-processed with acetone as well. The goal is an eggshell that'll hold in the chalk, but bust on impact.

Without fan on left, with 50% fan on right (after post processing)


Completed round, ready for launching blank


ETA: IF you ever make it to one of the Wisconsin shoots, you're more than welcome to send a few of those downrange for the help. :-)

You had no cooling, then turned fans on 30%, upped to 50%?

Trying to learn here.

Depends on if you have an enclosed printer, and how hot the chamber is.

Like Rat said, you really need a temp/fan tower for your specific printing conditions.  On my Vorons, I usually run my PCF between 60-80% with a 60*c chamber.

I've not heard of cooling calibration tower. Seems it would be similar to temperature tower?

Principle is the same (finds the sweet spot) but cooling and temp are totally different. This will help with layer adhesion at different fan speeds to see where adhesion falls off a cliff.

You can also do a layer time cooling test with no fan to see what type of layer time you need to help prevent heat build up from ruining a print. You can also reduce layer height as less heat is deposited at a time and over a longer time horizon since it takes longer to print more layers.

You can also build sacrificial towers into your build plate to eat up time for gaining sufficient cooling for an otherwise small part that by itself doesn't have enough ability to slow print time down enough on its own.

Lots of ways to skin this cat depending on the circumstance.

Correct. I'm not a hard core printer like many here; mostly tinkering here and there.

I recalled that ABS was sensitive to drafts and cooling, so I kept fans off. Always assumed it was something weird going on, but wasn't that big of a deal as the parts are literally designed to fall apart. I thought about slowing down the print, but figured I'd try the fan. 30% helped, but still had some deformity present. 50% seems to have fixed it. If I get bored, I might back off on the fan and increase print time and see what results I get.

I'm running an enclosure, typically around 90-100F, Bed temp 100C, nozzle 260C.