3D printed parts - what to look (out) for?

[SqrlHntr]

This is directed towards the 3D printers out there. For us non-3D savvy types, can y’all breakdown some of the attributes to look for or look out for? Any signs of a weak part or buggered up print job? Not really a “how to” but some basic info for consumers who are buying 3D parts. Ive bought quite a few 3D printed parts, all with varying quality, some look great but were very weak, single shot trays that are “flexible”, some just look and feel like commercial quality products.

A post this morning spurred this post. What does printing too fast look like? To me the part looked pretty good, but I know zip about printing. 
https://www.airgunnation.com/topic/rti-prophet-3d-printed-pic-mount-ebay/#post-1184020

TIA- just thought it will help consumers. 

 

[M0ist0ne]

I looked at that post, the outside finish is rough but it could be that the fuzzy skin/bumpy outside shell was used when slicing.

There's so much that can go into 3d printing and what can make a part good/bad.

First layer is always something to look at. Right now I have my machine setup printing an almost perfect first layer. Think of it as the foundation everything else will be printed on top of. 

I'm not saying my prints are perfect but fine tuning the machine even for different brands of filament comes into play. 

This article shows common issues and what they look like:

https://www.matterhackers.com/articles/3d-printer-troubleshooting-guide?rcode=PPCADS&gclid=CjwKCAiAl-6PBhBCEiwAc2GOVE5u1e7JVeBX8rTfwwNm9MxANrO26R1OHewmeNX_cQGa9mm3p4_AxhoCvDIQAvD_BwE



Here's one of my 3d printed buttstocks. I had a little wisp of filament get stuck to the nozzle about 1/8th of the way in and made a line on that layer

 

[dannya1a]

alot of 3d printing is like reading a book, the pages of a book equals the layers of a 3d part. you want the working load stress to be orientated perpendicular to the layers of the part. you get the strongest part that way. if you put the working load parallel to the layers there is a high likely-hood the part will break and come apart.

Think of a screw for example. If the screw is printed vertically head down on the print bed then to the tip and the layers are laid down to the length needed. you go to screw the screw into a part to use it. its not going to be as strong as if the screw was printed horizontally on the bed. the horizontal has more layers engaged to take the load and will stretch some under excessive load versus just a clean break as the layers come apart like the vertical one would.

 

[orion]

Printing material is a big topic also. 

I'm thinking about the OP question and it's very hard to set some rules. Because you might have a great print quality result but if done with the wrong material then the product is not going to perform as it should.

Really hard to answer but I'll put some general rules in a separate answer

 

[scianiac]

As someone who happens to print a lot of Airgun and other mechanical parts I'll try and provide a quick outline for someone looking at buying a 3D printed part. I apologize to those true 3D printing experts out there, I'm going to try and not go into the weeds here so there will be a lot of generalizations.

Strength in prints comes from two sources, the material (obviously) and the printing process. The first is easy, some materials are just stronger but often more importantly some are tougher, that is they have higher impact resistance which is often more important since that's normally how things break, they work great until you bump them a little too hard and they crack. So PLA, the most common material is very strong but very brittle (there are modified versions that are somewhat more balanced in these properties), PETG is a better, strong but with OK impact strength. ABS is similar but can have even better impact strength, and then there is Nylon and Polycarbonate that when printed well have very good strength and impact performance. If the seller says what it's made from that's probably a good sign no matter what material it is, attention to detail like that probably means they have some understanding of the material and if it's appropriate. And is just so happens that the strength of these materials (again with taking into account impact strength) also lines up with how hard they are to print so someone advertising that it's printed from nylon knows that it was harder to make and did so to make it stronger.

The second factor is print quality, which is a tricky one because how nice it looks doesn't always relate to how strong it is but often it can. If the print looks great, very consistent surface, no artifacts, blobs, divits, etc that does mean the person who printed it probably knows what they are doing and so chances are they will have their machine setup to produce good parts. Some materials may look different, have more matte or textured surface but they should still look even and consistent across the part. Parts that should be straight and are curved is a sign of warping and not good. Gaps in layers, particularly on top surfaces also is a bad sign that the extrusion flow is not tuned well so there will also be voids between extrusions deeper in the part.

Maybe that was useful to someone when it comes what to look for when buying 3D printed parts.

 

[orion]

As someone who happens to print a lot of Airgun and other mechanical parts I'll try and provide a quick outline for someone looking at buying a 3D printed part. I apologize to those true 3D printing experts out there, I'm going to try and not go into the weeds here so there will be a lot of generalizations.

Strength in prints comes from two sources, the material (obviously) and the printing process. The first is easy, some materials are just stronger but often more importantly some are tougher, that is they have higher impact resistance which is often more important since that's normally how things break, they work great until you bump them a little too hard and they crack. So PLA, the most common material is very strong but very brittle (there are modified versions that are somewhat more balanced in these properties), PETG is a better, strong but with OK impact strength. ABS is similar but can have even better impact strength, and then there is Nylon and Polycarbonate that when printed well have very good strength and impact performance. If the seller says what it's made from that's probably a good sign no matter what material it is, attention to detail like that probably means they have some understanding of the material and if it's appropriate. And is just so happens that the strength of these materials (again with taking into account impact strength) also lines up with how hard they are to print so someone advertising that it's printed from nylon knows that it was harder to make and did so to make it stronger.

The second factor is print quality, which is a tricky one because how nice it looks doesn't always relate to how strong it is but often it can. If the print looks great, very consistent surface, no artifacts, blobs, divits, etc that does mean the person who printed it probably knows what they are doing and so chances are they will have their machine setup to produce good parts. Some materials may look different, have more matte or textured surface but they should still look even and consistent across the part. Parts that should be straight and are curved is a sign of warping and not good. Gaps in layers, particularly on top surfaces also is a bad sign that the extrusion flow is not tuned well so there will also be voids between extrusions deeper in the part.

Maybe that was useful to someone when it comes what to look for when buying 3D printed parts.

Great topic for a video.

Number of perimeters, infill percentage, infill pattern, print temperature.

A lot of parameters to watch out, a nice print doesn't imply a good print. 

I'll probably do a video about this topic