Troublesome print - print size limitations

]I’m beginning to feel that just because the build area is large on the TAZ 5, you can’t actually print the full range of the build area. I know, I know… I was being very naïve… I have a print job going now that is the largest print I’ve had to do thus far. It’s close to the edges of the build plate and it’s just not turning out like I want it to. I’ve had to start the print 4 times thus far to try to tune the result so that I don’t have edges lifting.
I’m printing using the Medium quality CURA profile for ABS with the .5mm nozzle. I have an enclosure and it’s a toasty 110 degrees F inside, and I’ve disabled the fan. No matter what I try I can’t seem to get the edges farthest out away from center to stay down. I do admit that having put the TAZ in my cheapy enclosure and stop using the fan it has gotten somewhat better.

I guess what I’m hoping for is either a bit of encouragement that this print job can be done or just to tell me to face the music and abandon the project.

You’re going to want a brim layer with that print. if you can’t fit it outboard of the edges due to the size, you should draw a manual one on the part as close to the edges as you can get it. Another thing to consider is going with the aluminum build plate modification. It spreads the heat all the way to the edges, so parts at the far edges stick. You will have difficulty even with a brim printing that part as is since the heat at the edge of the glass bed is lower than the middle.

edit: also, do you have a cool air intake on your control box intake fan that allows it to draw cold air from outside the enclosure? if you don’t you’ll want to make one before you use that enclosure again.

Yes, you can’t see the “port” I made for the control box intake. Here’s a better picture of that side.

Hmmm… well, I think what I will do in this case is just finish out the print and see what happens. Won’t be that great, but it’s better than all the four prints previous to it. Thanks for the tip on the aluminum bed upgrade. Actually, Aleph is sending me a new bed because of all the bubbles in the PEI I have.

There is hope, I printed all of these side panels on my Taz

That was on one of the first PEI prototypes too!

If you do get one that has a little lifting but is otherwise usable, stick it on a very flat cookie sheet at 310 degrees in the oven for a few minutes (8-12, depending on the part) Watching it very carefully, The print should start to relax and flatten out some. Works best for prints that are mostly flat. Tall hollow prints like it looks like you are dealing with there might collapse inward.

If you are not “married” to ABS, you might try PETG. I have had far fewer issues with large prints lifting at the corners (or layer separation) with PETG.

Try some negative Z-offset. It may incur some flaring at the base (whatever is touching the bed), but a nozzle closer to the bed will increase adhesion. Try a -.2 to -.3 offset.

The other thing to try is similar to brim, but manual placement of anchors. Often people use dots / discs / squares at the corners to increase the surface area touching the bed. Give the attached a shot… scale the X and Y to an appropriate size.
Anchor - Disc.stl (22.3 KB)
Anchor - Square.stl (2.85 KB)

Thanks for all the help. I was actually able to complete the job. I found success by using brims and printing it in an enclosure. Also I had a PEI full of bubbles that wasn’t helping matters much. Lulzbot replaced my print bed, and now things stick better to the print bed than they did even when it was brand new, so I’m encouraged by this. I’ve also bought all the parts I need to do the aluminum bed modification that piercet suggested.

kcchen_00 - thanks for the tip on the disc and square anchors. I’ll definitely think about that from now on.

LarryPage - thanks for the kick in the pants. I figured out that I’ll never make any money if I can’t go beyond the simple stuff. I also learned that I shouldn’t be afraid of support material. This print had plenty of it on some of the other parts, but it all snapped off with a little bit of work.

I have some PETG, and it seems to stick better to the bed for sure. In fact, I think too well. I just didn’t have the colors this customer wanted at the time, and they specifically asked for ABS. Question… have you noticed that PETG needs a little bit cooler nozzle? I noticed that when I printed something with it, the part was out of tolerance a little - for what I thought was either over extrusion or melted too much due to the temperature.

If you are having too much trouble with bed adhesion, you might want to double check the Z home position. When the nozzle is too close to the bed the PETG can stick pretty hard. It can also cause the first layer to act like it is over extruding.

To get the best results you really need to “nail” the calibration of the bed, the extrusion rate (esteps), the Z home height, and the diameter of the filament.