3D printing

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3D printing

Post by MTV<=>Operator » February 12th, 2020, 3:52 pm

Does anyone else 3D print their bearing blocks/axle mounts? I've been printing mine from PLA on my school's Creality Ender 3 printers but I have a problem with the layers splitting easily. I printed the original bearing blocks at 10% infill and those haven't yet broken, but when I printed mounts at 35% infill and then later 100% infill they broke after ~50 test runs and 3 test runs respectively. By broke I mean they separated cleanly at the layers. I would try printing at a higher temperature or annealing the prints, but these can both lead to inconsistent warping and shrinkage. Note that the only ones that have broken are the ones that hold the braking axle. Today I tried printing a completely new design mount that is strengthened and thickened in several weak spots, but upon applying a small force perpendicular to the layers, it split, despite being twice as thick as the last piece.

1) Does the infill percentage affect how easily the layers split? I find it odd that the pieces printed at 10% infill are the only ones that have survived. It could be a coincidence though because of various variables in play when printing something
2) Will any material split easily at the layers? I found out that my school has a limited supply of PETG that I can use, but I need to verify that these would not split just as easily as the PLA.
3) If you 3D print your bearing blocks, how have they held up? If the problem is just with my school's printers I can try getting the pieces printed at a shop, but I would want that to be a last resort.

I'm fine with replacing the mounts every 70 or so tests as long as I know I can get a consistent amount of usage before they break, but as it is right now, it seems as though a piece could just break at the competition :cry:
Any help is appreciated
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Re: 3D printing

Post by PM2017 » February 13th, 2020, 9:04 am

MTV<=>Operator wrote:
February 12th, 2020, 3:52 pm
Does anyone else 3D print their bearing blocks/axle mounts? I've been printing mine from PLA on my school's Creality Ender 3 printers but I have a problem with the layers splitting easily. I printed the original bearing blocks at 10% infill and those haven't yet broken, but when I printed mounts at 35% infill and then later 100% infill they broke after ~50 test runs and 3 test runs respectively. By broke I mean they separated cleanly at the layers. I would try printing at a higher temperature or annealing the prints, but these can both lead to inconsistent warping and shrinkage. Note that the only ones that have broken are the ones that hold the braking axle. Today I tried printing a completely new design mount that is strengthened and thickened in several weak spots, but upon applying a small force perpendicular to the layers, it split, despite being twice as thick as the last piece.

1) Does the infill percentage affect how easily the layers split? I find it odd that the pieces printed at 10% infill are the only ones that have survived. It could be a coincidence though because of various variables in play when printing something
2) Will any material split easily at the layers? I found out that my school has a limited supply of PETG that I can use, but I need to verify that these would not split just as easily as the PLA.
3) If you 3D print your bearing blocks, how have they held up? If the problem is just with my school's printers I can try getting the pieces printed at a shop, but I would want that to be a last resort.

I'm fine with replacing the mounts every 70 or so tests as long as I know I can get a consistent amount of usage before they break, but as it is right now, it seems as though a piece could just break at the competition :cry:
Any help is appreciated
I'm surprised that 10% infill parts seem stronger than the 35% and 100% parts. The only reason I can think of might be that the higher infill parts are stiffer and too brittle, meaning that instead of deflecting ever so slightly, they break?

Layer adhesion issues are one of the biggest problems with 3d printing, but when I did mousetrap vehicle, my 3d printed bearing blocks only ever broke once (and that was because of some off-nominal event -- forgot if someone stepped on it or what exactly happened). You could perhaps try printing in a different direction? If worst comes to worst, what I did once (which honestly might have been unnecessary) I would try to put a small cf square rod down the length of the tube.

In my (very) limited experience with PETG, it was much harder to get good quality prints with PETG than PLA. (But the printer I was using back then was very finnicky about temperatures, and I was using some cheap crappy PETG, as compared to the MatterHackers PLA I normally use.) I will say that you need to be able to have higher temperatures for PETG to work well.

Also, if these rolls of filament have been sitting around for long enough, they tend to get saturated with moisture, which isn't great for the plastic. It gets brittle and print strength decreases.

I wouldn't think you would need to get these pieces printed at a shop.

If you could post pictures of your block print/design, perhaps people could help analyze the issue, if it happens to be some problem like under extrusion? Not too sure.
(Alternatively, I could PM you my email, and maybe you could send me the .stl files and I could try printing them myself on the printers in our makerspace)
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Re: 3D printing

Post by sciolyperson1 » February 13th, 2020, 11:16 am

Why in the world would you print with 100% infill... 15% or max like 25 or 30% is the most I'd do if I want a strong piece.

Both my buggies and my gravity are printed with 15% infill.
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Re: 3D printing

Post by sciencecat42 » February 13th, 2020, 12:14 pm

I have never had any issues with layer adhesion. My guess is either your printer is not calibrated well or that the design/print orientation is bad.

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Re: 3D printing

Post by MTV<=>Operator » February 13th, 2020, 4:44 pm

sciolyperson1 wrote:
February 13th, 2020, 11:16 am
Why in the world would you print with 100% infill... 15% or max like 25 or 30% is the most I'd do if I want a strong piece.

Both my buggies and my gravity are printed with 15% infill.
Yeah I normally print at 20% but a teacher suggested using higher infill. I think he thought the piece just broke normally though.
sciencecat42 wrote:
February 13th, 2020, 12:14 pm
I have never had any issues with layer adhesion. My guess is either your printer is not calibrated well or that the design/print orientation is bad.
I don't know about the printer calibration, but the printers are being used almost 24/7 for the robotics team so it's possible that they were better calibrated when I printed the 10% pieces than when I did the 35% ones.

Here are some visuals:

Image
^ Original piece printed at 10 percent that has not yet broken, but split at 35% after about 50 runs (split about halfway down from the top). It was printed in the orientation pictured

Image
^ Modified piece printed at 35% that split after 3 runs. Also printed in the orientation pictured

Image
^ Latest piece that was never used on the vehicle, printed at 100% infill and split (with a small force applied). The part that is highlighted separated. Printed in the orientation pictured. I plan on using this piece from now on because I noticed that with this layer orientation, the part surrounding the actual axle hole seemed stronger. The only problem now is that part of the piece with mounting holes can break off easily.

When I inspected the latest print more closely I noticed some larger gaps in between some layers and the one I broke split at one of these gaps. I plan on reprinting these parts at 15% infill because it seems like higher infills are worsening the problem.
Thank you all for your help and suggestions.
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Re: 3D printing

Post by sciolyperson1 » February 13th, 2020, 4:49 pm

MTV<=>Operator wrote:
February 13th, 2020, 4:44 pm
sciolyperson1 wrote:
February 13th, 2020, 11:16 am
Why in the world would you print with 100% infill... 15% or max like 25 or 30% is the most I'd do if I want a strong piece.

Both my buggies and my gravity are printed with 15% infill.
Yeah I normally print at 20% but a teacher suggested using higher infill. I think he thought the piece just broke normally though.
sciencecat42 wrote:
February 13th, 2020, 12:14 pm
I have never had any issues with layer adhesion. My guess is either your printer is not calibrated well or that the design/print orientation is bad.
I don't know about the printer calibration, but the printers are being used almost 24/7 for the robotics team so it's possible that they were better calibrated when I printed the 10% pieces than when I did the 35% ones.

Here are some visuals:

Image
^ Original piece printed at 10 percent that has not yet broken, but split at 35% after about 50 runs (split about halfway down from the top). It was printed in the orientation pictured

Image
^ Modified piece printed at 35% that split after 3 runs. Also printed in the orientation pictured

Image
^ Latest piece that was never used on the vehicle, printed at 100% infill and split (with a small force applied). The part that is highlighted separated. Printed in the orientation pictured. I plan on using this piece from now on because I noticed that with this layer orientation, the part surrounding the actual axle hole seemed stronger. The only problem now is that part of the piece with mounting holes can break off easily.

When I inspected the latest print more closely I noticed some larger gaps in between some layers and the one I broke split at one of these gaps. I plan on reprinting these parts at 15% infill because it seems like higher infills are worsening the problem.
Thank you all for your help and suggestions.
If it's still too brittle, print with a higher shell thickness and bottom/top thickness. Use a honeycomb infill.
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Re: 3D printing

Post by MoMoney$$$;)0) » February 13th, 2020, 4:54 pm

MTV<=>Operator wrote:
February 12th, 2020, 3:52 pm
Does anyone else 3D print their bearing blocks/axle mounts? I've been printing mine from PLA on my school's Creality Ender 3 printers but I have a problem with the layers splitting easily. I printed the original bearing blocks at 10% infill and those haven't yet broken, but when I printed mounts at 35% infill and then later 100% infill they broke after ~50 test runs and 3 test runs respectively. By broke I mean they separated cleanly at the layers. I would try printing at a higher temperature or annealing the prints, but these can both lead to inconsistent warping and shrinkage. Note that the only ones that have broken are the ones that hold the braking axle. Today I tried printing a completely new design mount that is strengthened and thickened in several weak spots, but upon applying a small force perpendicular to the layers, it split, despite being twice as thick as the last piece.

1) Does the infill percentage affect how easily the layers split? I find it odd that the pieces printed at 10% infill are the only ones that have survived. It could be a coincidence though because of various variables in play when printing something
2) Will any material split easily at the layers? I found out that my school has a limited supply of PETG that I can use, but I need to verify that these would not split just as easily as the PLA.
3) If you 3D print your bearing blocks, how have they held up? If the problem is just with my school's printers I can try getting the pieces printed at a shop, but I would want that to be a last resort.

I'm fine with replacing the mounts every 70 or so tests as long as I know I can get a consistent amount of usage before they break, but as it is right now, it seems as though a piece could just break at the competition :cry:
Any help is appreciated

I never 3D print my cars, I CNC or laser cut them every time, since it's much easier to fix, or remake that 3d printing. Moreover, I have some experience with 3D printing, so my suggestion is to alwasy go with 100% infill and to up the heat. Also, NEVER try to 3D print a bearing block of all things, from my experience of 3D printing plenty things, I could see this being an issue in the future. But regardless you may be different, so go for it, but try a 50% infill with horizontal set up of the new parts, and make a clearance for the wholes, but if they still don't work just use a drill press to try to make it work.

I also agree with what sciolyperson has to say, but I'd say go with cross supports all the way with maybe a tree type support maybe working a bit better for this. Add more z-axis supporting also.

Also, if you don't care about costs just 3D print out of carbon fiber or metal. Kudos to you if you can since I'm pretty sure most of us don't have the resources to do it.
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Re: 3D printing

Post by PM2017 » February 13th, 2020, 10:59 pm

MoMoney$$$;)0) wrote:
February 13th, 2020, 4:54 pm
MTV<=>Operator wrote:
February 12th, 2020, 3:52 pm
Does anyone else 3D print their bearing blocks/axle mounts? I've been printing mine from PLA on my school's Creality Ender 3 printers but I have a problem with the layers splitting easily. I printed the original bearing blocks at 10% infill and those haven't yet broken, but when I printed mounts at 35% infill and then later 100% infill they broke after ~50 test runs and 3 test runs respectively. By broke I mean they separated cleanly at the layers. I would try printing at a higher temperature or annealing the prints, but these can both lead to inconsistent warping and shrinkage. Note that the only ones that have broken are the ones that hold the braking axle. Today I tried printing a completely new design mount that is strengthened and thickened in several weak spots, but upon applying a small force perpendicular to the layers, it split, despite being twice as thick as the last piece.

1) Does the infill percentage affect how easily the layers split? I find it odd that the pieces printed at 10% infill are the only ones that have survived. It could be a coincidence though because of various variables in play when printing something
2) Will any material split easily at the layers? I found out that my school has a limited supply of PETG that I can use, but I need to verify that these would not split just as easily as the PLA.
3) If you 3D print your bearing blocks, how have they held up? If the problem is just with my school's printers I can try getting the pieces printed at a shop, but I would want that to be a last resort.

I'm fine with replacing the mounts every 70 or so tests as long as I know I can get a consistent amount of usage before they break, but as it is right now, it seems as though a piece could just break at the competition :cry:
Any help is appreciated

I never 3D print my cars, I CNC or laser cut them every time, since it's much easier to fix, or remake that 3d printing. Moreover, I have some experience with 3D printing, so my suggestion is to alwasy go with 100% infill and to up the heat. Also, NEVER try to 3D print a bearing block of all things, from my experience of 3D printing plenty things, I could see this being an issue in the future. But regardless you may be different, so go for it, but try a 50% infill with horizontal set up of the new parts, and make a clearance for the wholes, but if they still don't work just use a drill press to try to make it work.

I also agree with what sciolyperson has to say, but I'd say go with cross supports all the way with maybe a tree type support maybe working a bit better for this. Add more z-axis supporting also.

Also, if you don't care about costs just 3D print out of carbon fiber or metal. Kudos to you if you can since I'm pretty sure most of us don't have the resources to do it.
Don't mean to be rude, but I'm not sure if I agree with much of this at all.

3d printing at 100% is generally not a great idea. Because of the time it takes, weight, and diminished additional structural integrity.

3d printing bearing blocks works just fine, at least in my experience, and I've seen plenty of teams place very well at nats with 3d printed bearing blocks.

3d printing out of metal requires printers that are literally on the order of a million bucks. Carbon fiber filaments exist, but they arent great. The closest solution would be a mark forged printer which lays fibers in along with the 3d print, but that costs like 79k dollars, which is also super expensive.

Also ooooh you said tree supports. Does this mean you have a resin printer? I'm so jealous if you do lol. (Also if you dont because I had no access to a cnc or laser cutter lol).
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Re: 3D printing

Post by MoMoney$$$;)0) » February 14th, 2020, 6:36 am

PM2017 wrote:
February 13th, 2020, 10:59 pm
MoMoney$$$;)0) wrote:
February 13th, 2020, 4:54 pm
MTV<=>Operator wrote:
February 12th, 2020, 3:52 pm
Does anyone else 3D print their bearing blocks/axle mounts? I've been printing mine from PLA on my school's Creality Ender 3 printers but I have a problem with the layers splitting easily. I printed the original bearing blocks at 10% infill and those haven't yet broken, but when I printed mounts at 35% infill and then later 100% infill they broke after ~50 test runs and 3 test runs respectively. By broke I mean they separated cleanly at the layers. I would try printing at a higher temperature or annealing the prints, but these can both lead to inconsistent warping and shrinkage. Note that the only ones that have broken are the ones that hold the braking axle. Today I tried printing a completely new design mount that is strengthened and thickened in several weak spots, but upon applying a small force perpendicular to the layers, it split, despite being twice as thick as the last piece.

1) Does the infill percentage affect how easily the layers split? I find it odd that the pieces printed at 10% infill are the only ones that have survived. It could be a coincidence though because of various variables in play when printing something
2) Will any material split easily at the layers? I found out that my school has a limited supply of PETG that I can use, but I need to verify that these would not split just as easily as the PLA.
3) If you 3D print your bearing blocks, how have they held up? If the problem is just with my school's printers I can try getting the pieces printed at a shop, but I would want that to be a last resort.

I'm fine with replacing the mounts every 70 or so tests as long as I know I can get a consistent amount of usage before they break, but as it is right now, it seems as though a piece could just break at the competition :cry:
Any help is appreciated

I never 3D print my cars, I CNC or laser cut them every time, since it's much easier to fix, or remake that 3d printing. Moreover, I have some experience with 3D printing, so my suggestion is to alwasy go with 100% infill and to up the heat. Also, NEVER try to 3D print a bearing block of all things, from my experience of 3D printing plenty things, I could see this being an issue in the future. But regardless you may be different, so go for it, but try a 50% infill with horizontal set up of the new parts, and make a clearance for the wholes, but if they still don't work just use a drill press to try to make it work.

I also agree with what sciolyperson has to say, but I'd say go with cross supports all the way with maybe a tree type support maybe working a bit better for this. Add more z-axis supporting also.

Also, if you don't care about costs just 3D print out of carbon fiber or metal. Kudos to you if you can since I'm pretty sure most of us don't have the resources to do it.
Don't mean to be rude, but I'm not sure if I agree with much of this at all.

3d printing at 100% is generally not a great idea. Because of the time it takes, weight, and diminished additional structural integrity.

3d printing bearing blocks works just fine, at least in my experience, and I've seen plenty of teams place very well at nats with 3d printed bearing blocks.

3d printing out of metal requires printers that are literally on the order of a million bucks. Carbon fiber filaments exist, but they arent great. The closest solution would be a mark forged printer which lays fibers in along with the 3d print, but that costs like 79k dollars, which is also super expensive.

Also ooooh you said tree supports. Does this mean you have a resin printer? I'm so jealous if you do lol. (Also if you dont because I had no access to a cnc or laser cutter lol).
I meant ordering the metal bearing blocks if you have time, I don't think ANY public high school has a metal 3D printer. This can be from https://www.stratasysdirect.com/materials/metals or any other preferred service.
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