Design for 3D Print, How to Make Joint Stronger

[Anonymous]

Hi,

I have designed the attached part for 3D printing.  The extruded rectangular part on the front of the part is a joint and it's pretty weak when printed.  I have broken several parts taking the support out, telling me that even if I get the supports out OK the part probably won't last very long as there will be some stress placed on the joint when being used.  How do I make this joint stronger?

I don't design parts for a living, so I know my practices probably aren't the best. 

Thanks!

[laughingcreek]

a little more context would probably help in understanding what your going for. I suppose your talking about component 2? -fillets on the inside corners would help -it's less than 1/8 inch thick. more thickness would help. -if you can't add thickness, then at least a flange or rib shape around it would help. Is this to help marry a vacuum nozzle to an object? is this piece suppose to slip inside component 1? does it have to go inside? can it surface mount to each? (which would have the added benefit of not choking down the vacuum).

[lichtzeichenanlage]

By looking at the cross section of your design I have problems to identify a proper joint. It's about 5mm thick for to parts. So 2.5mm per part. That's not a lot of surface area. The one part doesn't have a rectangular connection point. That reduces the area again. What are the force directions the assemble part has to take? Why not adding the possibility of screws. Why printing it in 3 parts? 

[Anonymous]

Hi, thanks for the responses. It is printed as one piece. Yes component 2 will go into a slot cut in the side of a vacuum appliance for a CNC machine made to hold down small, flat workpieces. I guess my issue is that the face that the slot is cut into is only .75" wide, so I don't have a lot of room and the opening needs to let as much air through as possible. I have it set up now to attach with magnets, but screws will work too. It's where component 1 transitions to component 2 that is the weak point. Just wondering ho, or even if i can be made stronger without making it bigger? I printed this with PLA, would simply printing it with a stronger filament make it better? ABS? or something else?

[etfrench]

Here's what I'd try:

It isn't clear from the image in your last post how this is being held onto the vacuum table.  I'd probably add a rib underneath it to relieve stress on the flange.

[lichtzeichenanlage]

If you want to print ABS you need an (at best heated) enclosure. PLA isn't a week material. The biggest problem is heat resistance. 45°C to 50°C starts to make problems. You might want to try PETG. Just keep it dry, otherwise prints might to shatter like glas.

The design from @etfrench looks promising to me. One part?  

Edit: What nozzle size are you using. Larger nozzles are producing stronger parts.

[TrippyLighting · Accepted solution]

I'd put an internal rib/fin into the structure. A vacuum table doe not need  a lot of airflow. After vacuum ins established it needs to maintain the vacuum. Also this is not meant to carry away Debris. So a small obstruction in the air flow patch is not a problem, but will greatly enhance the stability of the part.

[StephenCim-001]

Also take into account the print orientation , with tube parts you automatically print them vertically to reduce the amount of support material/cleanup needed , it just seems right , but printing them horizontal can often produce a much stronger part.

[Anonymous]

Thanks for the help guys!  I ended up extending component 1 into component 2 making it much stronger than just a joint there.  I also did use ribs in the opening and it's working great.