Taz 5 ABS cracking even with cat guard. Next steps?

I’ve been having issues with ABS cracking on large prints. I’ve built a cat guard that seems to be helping some but I’m still not getting the desired result. The picture attached shows the issue. I’m printing fairly slowly at 75% infill. Should I turn off my extruder fans and try again? This print has taken almost 2 days to reach this point (using the abs fine profile from the lulzbot site) with a 0.35 mm nozzle so I’d rather not start over without a solid guess on a fix. I was considering piercet’s open rail build as my next mod to see if that will help.

Also, would I be safe cranking up the speed/acceleration or should I stick with stock settings?

Thanks for any suggestions.

The only fan that should be on is the single one blowing onto the heat break, the side ones should not. Also let your printer sit for about 10-15 minutes after it has heated up. This will allow the chamber to heat up as well. You can try increasing the print temperature slightly as well to get better layer adhesion.

The layers at the bottom aren’t having any issues so time heating isn’t really a factor. These lines are over 24 hours into my print. And I’ve had this issue printing at both lower end and higher ends of the ABS spectrum.

Bump your print temp up 5 degrees and reprint until it stops doing that.

Also if that is a 24hr print you are using super fine layer heights which aren’t necessarily needed for an object of that scale.

In total its about a 48-50 hour print. I’m making costume pieces so I’m really trying to get as much smoothness/detail as possible to reduce sanding/rework later. The stock profiles for the fine prints use 0.16mm layer height.

Then you might as well go with a PLA print if the structural integrity isn’t that important. These aren’t gonna be functional parts but instead display pieces of sort. You can even try something such as the Advanced PLA from 3D Fuel.

They’re display pieces until you’re on a convention floor with 80k of your closest friends getting bumped/shoved and everyone wants a picture and/or generally aren’t careful. I’d be fine using PLA if the parts were thicker. But, because they’re relatively thin, I’d rather not deal with the snapping.

But thanks for the advice. I’m restarting with same layer heights but upping the temperature and disabling the fans. Hopefully this will help fix it.

The advanced PLA from 3D Fuel works well for this. I know of people who use them for quad copter parts.

I found my cat guard works better if you take the rubber feet off so it seals the bottom. Then add weather stripping to top and bottom of door. Then for the side by handle seal it up with a wide roll of painters tape. That should keep the heat in better.

Thanks. I’ll look into it. Looks like the places to buy it from are few and far between though.

I considered the weather stripping. Just wasn’t sure if it would be holding in too much heat since I feel the heat coming out of the top gap by the door and it’s pretty warm.

I’ll keep looking for suggestions but I probably won’t know if the minor adjustments that I made will work until Friday afternoon. grumble grumble But at least then I should have my pieces for the aluminum heated bed ready to install. I needed to replace the PEI sheet anyway due to holes/bubbles from some… over zealous (stupid) things I’ve tried so I decided to at least do a small upgrade while I was at it. Being stupid is expensive.

Steps that fixed it for me

  1. Build an enclosure (which you’ve done)

  2. Turn off your part cooling fan. If the part is larger, you don’t need it.

  3. Bump the nozzle temperature up to 250C (Assuming you’re using Lulzbot ABS)

  4. Print with a brim to hold it to the bed better.

On huuuuuge parts you’re still get some splitting depending on the shape of the object, but turning off the fan and turning up the nozzle temperature minimized it. The minor splits can be fixed by making ABS glue/slurry and a little sanding.


I’m using IC3D ABS which normally prints great at 230 so I bumped it up to 240. I’m running this latest attempt with no fans so we’ll see how that goes. As far as bed adhesion, I’ve found that light scrubbing with some rubbing alcohol and a magic eraser pad between prints actually works wonders. Since doing that, I’ve experienced no curling from the bed and I think (haven’t independently verified/anecdotal) that it has reduced the size of some of the larger air bubbles under my PEI sheet.

You might consider using one of the co-polymer filaments like N-Gen or N-Vent which do not split like that but can take some rougher usage. It can cost more but might fill your requirements.

Thanks for all the recommendations, folks. My print is now well past the point where I’ve been getting splits. I raised my temp by 10 degrees and turned off the fans. A picture with results is below. I now feel like this is dialed in enough to continue my project which will take a couple months of steady printing to complete. At least until I make some upgrades that will let me move at warp speed with less wobble like some of yours.

Use thicker layers and look into acetone vapor polishing.

I was kind of worried that the slick finish from that would make it more difficult for paint to adhere later even with primer. Is that an issue?

No, acrylic hobby paint will also chemically bond. It doesn’t hurt to rough up the surface a bit for mechanical adhesion after too though.

Still not sure of the type of paint I am going to use yet but I’ll keep that in mind. It’s going to be a full body suit so ease of application and cost will be a factor.

Try a different brand of filament, especially if you’re using fairly generic stuff.