roykirk
Posts: 7
Joined: Wed Sep 03, 2014 12:51 pm

New printer can't handle unsupported overhangs

Fri Mar 05, 2021 9:03 am

I'm trying to figure out what Simplify3D settings I need to tinker with to solve a problem I'm having. Been using S3D for several years on my FlashForge Creator Pro. I often print a model that has an unsupported overhang on it:

https://drive.google.com/file/d/15dmw-x ... sp=sharing

This overhang sticks out 1 mm and the "roof" of it is 1.25 mm thick. I can't use support in this section because it would be impossible to remove. My FF printer has never had problems with this section. However, I recently purchased a new Qidi Tech Max large volume printer. Using all the same S3D settings I've always used on my FF, the Qidi Max is having problems with these unsupported sections. Sometimes they're fine, but about 50% of the time this section "collapses" or falls apart. I'm using PLA at 200 degrees with a heated bed at 50.

If this is a problem with the printer, I'll take it up with their tech support. But if this is something I can fix with some tweaks to my S3D settings, I'm open to advice.

billyd
Posts: 225
Joined: Mon Jan 19, 2015 12:13 pm

Re: New printer can't handle unsupported overhangs

Fri Mar 05, 2021 9:45 am

I have two printers both heavily upgraded and modified. My Makerbot R2 is the overhang champion, it prints them fantastically. But my Taz 5, which has more work done to it than Meg Ryan only with great results lol, can't print a decent overhang if its life depended on it.

The difference between them is the Taz 5 is much larger than the R2. Similar to your situation. It may be that large volume printers have more trouble with overhangs, or it may be that our large printers are bad at overhangs.

Obviously, overhangs improve with smaller layer heights. Using the part fan helps too. Perhaps changing speeds (slower or faster not sure which might be better, perhaps faster).

But I've never been able to solve why one printer prints them better than another using very similar settings.

roykirk
Posts: 7
Joined: Wed Sep 03, 2014 12:51 pm

Re: New printer can't handle unsupported overhangs

Fri Mar 05, 2021 11:17 am

Thanks for the advice. I'll try turning on the fan and see if that does anything, along with increasing the speed. I'd hate to have to decrease the layer height (because it will increase time so much), but I may try that as well if the first two do nothing.

airscapes
Posts: 365
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: New printer can't handle unsupported overhangs

Fri Mar 05, 2021 1:28 pm

The way I handle this type of issue is to use custom support at 1mm resolution and intervals that will bridge well. Just a couple supports every so often. This way there is some support and they are simple to remove.
One thing I don't like about S3d 4.01 which is what I use, is that with tall layers, the separations settings do not work as they are via layer rather than mm. For instance a setting of 1 is too much when your layer height is .5mm Maybe they fixed that in 4.1 but probably not..

20181105ok
Posts: 29
Joined: Mon Nov 05, 2018 9:15 am

Re: New printer can't handle unsupported overhangs

Sat Mar 06, 2021 1:02 am

airscapes wrote:
Fri Mar 05, 2021 1:28 pm
For instance a setting of 1 is too much when your layer height is .5mm
Layer height .5mm is really appalling. Can I ask what's your line width and speed? It's difficult to imagine what your overhangs and bridges look like.

gwhite
Posts: 181
Joined: Wed Jul 19, 2017 9:37 am

Re: New printer can't handle unsupported overhangs

Sat Mar 06, 2021 8:56 am

roykirk wrote:
Fri Mar 05, 2021 11:17 am
Thanks for the advice. I'll try turning on the fan and see if that does anything, along with increasing the speed. I'd hate to have to decrease the layer height (because it will increase time so much), but I may try that as well if the first two do nothing.
It may be more a difference in air flow around the print head than the build volume difference between the printers. I think cooling will help a lot. I've had good luck with sagging overhangs just by making sure the plastic cools quickly before it can sag.

By using multiple processes, you can also adjust your speed only for layers where you need it.

airscapes
Posts: 365
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: New printer can't handle unsupported overhangs

Sun Mar 07, 2021 11:18 am

20181105ok wrote:
Sat Mar 06, 2021 1:02 am
airscapes wrote:
Fri Mar 05, 2021 1:28 pm
For instance a setting of 1 is too much when your layer height is .5mm
Layer height .5mm is really appalling. Can I ask what's your line width and speed? It's difficult to imagine what your overhangs and bridges look like.
Obviously you don't use a larger nozzle for a small part. When appropriate I use a .75mm nozzle with .8mm EW and .5 layer height. Speed must be reduced or the hot end will not be able to keep up. The job will still get finished faster than a small nozzle printing at break neck speed.
I try not to design parts that require bridging and support if at all possible for the reason stated.. The supports either don't work well if the top separation is set to 1 or solidly attached if set to 0. I don't make items that often that need to look like injection molding, I make useful mechanical parts.
I have attached a picture of some parts I make and sell that are covers for a specialize leather Strop. They are PETG and slide over the item they protect staying put as they are slightly smaller and petg is springy. The layers are smooth, you are seeing the multiple LEDs reflecting at slightly different angles
These parts are one wall .8mm wide
Can not get the photos to load.. maybe too big..yes they were
Strop covers.jpg
Covers and more covers.jpg

20181105ok
Posts: 29
Joined: Mon Nov 05, 2018 9:15 am

Re: New printer can't handle unsupported overhangs

Sun Mar 07, 2021 11:55 am

airscapes wrote:
Sun Mar 07, 2021 11:18 am
Obviously you don't use a larger nozzle for a small part. When appropriate I use a .75mm nozzle with .8mm EW and .5 layer height. Speed must be reduced or the hot end will not be able to keep up. The job will still get finished faster than a small nozzle printing at break neck speed.

I try not to design parts that require bridging and support if at all possible for the reason stated.
Hi @airscapes Thanks a lot for sharing your comments and prints!

I spent a lot of time in playing with big nozzles, but finally gave up. It seems that I used them for wrong products.

zemlin
Posts: 359
Joined: Mon Feb 01, 2016 11:36 am

Re: New printer can't handle unsupported overhangs

Wed Mar 10, 2021 10:07 am

For significant overhangs, I keep the layer height below 50% of the extrusion width. With PLA I would definitely have the fans running full bore on overhangs.

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