PETG Infill

[rob.mwpropane]

Good day.

I need to print another goodman handle, even @ 70% infill I'm getting small cracks. Anyone care to make a suggestion what infill to use with PETG? I know it's stronger. I've printed with it before, just never "tools" for everyday use.

Thanks!!

 

[The Ruttmeister]

Anything from 50-70%. But you should also make sure you up the wall thickness. Default profiles are often only 2 or 3 passes, around 1mm thickness.
For seriously structural parts I would bump that up to 3mm. Increase top and bottom layer counts to match.

Unless the part is quite large, infill will not be the main strength.

For really tough parts, carbon fiber filled nylon is great.
Needs a steel nozzle though. And a heated enclosure if you are making anything of size.

Oh, and PET is a bit more sensitive to inter-layer bonding temp than PLA. So you might get stronger parts if you extrude a little hotter.

 

[rob.mwpropane]

Anything from 50-70%. But you should also make sure you up the wall thickness. Default profiles are often only 2 or 3 passes, around 1mm thickness.
For seriously structural parts I would bump that up to 3mm. Increase top and bottom layer counts to match.

Unless the part is quite large, infill will not be the main strength.

For really tough parts, carbon fiber filled nylon is great.
Needs a steel nozzle though. And a heated enclosure if you are making anything of size.

Oh, and PET is a bit more sensitive to inter-layer bonding temp than PLA. So you might get stronger parts if you extrude a little hotter.

I have my settings @ 3 walls / tops / bottoms.. temp is @ 235f.

The PLA holds up for a long time (~year), but eventually it cracks where the screws are.

 

[rob.mwpropane]

I printed this today, but 1/3 way through I realized my infill was only set @ 20% (still has 3 top, bottom, sides though).

 

[The Ruttmeister]

Yeah, you want walls of at least 2mm.

Also, for long term durability, hot melt threaded inserts are really nice. Much better than just threads in the plastic.
Might be a bit spendy for the stainless ones though.

 

[rob.mwpropane]

Yeah, you want walls of at least 2mm.

Also, for long term durability, hot melt threaded inserts are really nice. Much better than just threads in the plastic.
Might be a bit spendy for the stainless ones though.

Idk what you're talking about? Inserts?

As it stands, it costs me idk, 30 cents to make a goodman handle. The 1st (40% infill) lasted 9 months, the 2nd one (70% infill) lasted a year.

I figured PETG would be better. How many walls should I make it thick to reach 2mm? I think the nozzle is .4, so 5? What infill should I use with that in mind?

Thanks!

 

[The Ruttmeister]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

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Metal threaded inserts for plastic. Probably overkill.
I use them a lot on work projects, they last a lot better than just threads in the plastic, especially if you are installing and removing screws often.

Without knowing your slicer setup I'm going to guess your wall extrusion width is set to roughly the nozzle diameter, that's fairly normal. So try 6 walls. And for top/bottom, depends on the layer height, but 3 is the absolute minimum I would ever use even for test parts. Crank that to at least 6, maybe 12. You want to get similar thickness to the walls.

Then leave infill at 30%, but if you have the option to change it to cubic (cura has that option) that's slightly stronger.

 

[emoreira]

Things that will be submerged I use 100 % infill, besides of 5 perimeters.
I agree it's a lot, but prints are porous, so I avoid water intrusion, and the best strengh possible.
I also print with PETG and very hot to get the better interlayer adhesion.

 

[rob.mwpropane]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Metal threaded inserts for plastic. Probably overkill.
I use them a lot on work projects, they last a lot better than just threads in the plastic, especially if you are installing and removing screws often.

Without knowing your slicer setup I'm going to guess your wall extrusion width is set to roughly the nozzle diameter, that's fairly normal. So try 6 walls. And for top/bottom, depends on the layer height, but 3 is the absolute minimum I would ever use even for test parts. Crank that to at least 6, maybe 12. You want to get similar thickness to the walls.

Then leave infill at 30%, but if you have the option to change it to cubic (cura has that option) that's slightly stronger.

I use "simplify 3d" to slice. I guess the extrusion is set under "extrusion width" which is .4

I attached a pic of what my infill can be set to. I have it set to grid. I guess that's cubic?

Things that will be submerged I use 100 % infill, besides of 5 perimeters.
I agree it's a lot, but prints are porous, so I avoid water intrusion, and the best strengh possible.
I also print with PETG and very hot to get the better interlayer adhesion.

I tried printing the above handle with 245 the other day but it wasn't laying right, turned it down to 240 and then eventually to 235. I read that PETG likes between 230-250? Plate was @ 85.

The 1st layer wasn't 100% "pretty" like I like, but it wasn't bad either.

You guys that print 100% infill.... that just seems a bit overboard to me. I understand if it was something that would see hard use, but the handle just goes on the back of my hand. Of all the parts I've printed for underwater use, I've never had any water intrusion either. Not @ 40% with PLA, nor 70%.

Have to think also, even though the prints are made for underwater, there lives are spent 95%+ on land.

I'm not arguing, I just found it interesting. Just my experience.

 

[emoreira]

I'm printing PETG at 250 °C. No layer fan and enclosed printer.
I also use Simplify3D. For 100 % infill only rectilinear infill is possible.
I print pieces that must endure abuse.