I don’t know how much this story will help people but if you’re stuck with the same problem when you’re designing a part, maybe my solution will be of help.
I tried my hand at redesigning a Touch LCD (MKS TS35) mount for a printer and I thought I had a pretty good design that would hold the UI and with access/lightening holes to speed up the print time as well as provide clearance for the connectors and parts on the backside. The design is really a simple right angle triangle with the display support at 60degrees to give the user a better view.
The access/lightening holes are diamonds to avoid possible bridging issues and all holes at 60 and 90 degrees have teardrops so there won’t be any bridging problems there as well. I made the access/lightening holes diamonds and making the holes teardrops to avoid any need for supports in the printing.
But when I tried to print it, I found that I had an unexpected melting problem with regards to the two diamond holes on the angled front face that appeared on two different printers (with different materials and temperatures). There were no problems with similarly designed lightening holes on the back vertical surface.
This only happened with the holes in the angled surface. This was weird because I’ve done this kind of thing before without any problems and I decided to start taking away from the centre of the angled surface until I got a brainwave and cut down everything but what was needed for support. As I did this, I aded a couple of triangular vertical supports at 90 degrees to the vertical surface and I couldn’t be happier with the results.
Everything printed very nicely and it takes 90 minutes less than the other prints. I’m going back and making it symmetrical and adding another speaker cut out so that the mount can be used in multiple orientations but I think I got it.
If anybody has any thoughts on why I would see the melting/layer separation on the 60 degree angled surface, I’d be interested in hearing them.
I think as the printer started printing the upper half of the diamond voids, there was not enough material to keep the solid layers rigid and it was flexing layer after layer beyond that causing poor adhesion, IMO.
That’s what I would have thought but why in the middle image, with two later tests designs with no diamond lightening holes, were there problems at the edge of the access hole especially off to the extreme edges/sides?
And when I printed almost exactly the same structures on the back side (which is perpendicular at 90 degrees) why weren’t the same problems there?
I guess it’s the 30 degrees off centre, but it doesn’t make a lot of sense.
I am kinda curious about this as well, Looks like a cooling issue to me, Maybe cooling too quick but I know your printer is pretty well-tuned, to begin with. that one is a bit of a head-scratcher for me.
Would you mind if I printed a copy of your STL file so I can see what it’s doing? I would like to try the hardest one, Maybe the one in black with the 2 diamond holes?
No problem - what’s the best way to get them to you? This board doesn’t accept file attachments in a reply.
The .stls are pretty modest in size so I can send you all of them (including the final design) and I’m happy to share the FreeCAD design files, although they’re a bit larger.
I am slow to this show but it doesn’t look like a support issue it seems like something else. try rotating the design. It also could be rapid cooling is there an AC or draft blowing around the model?
I have tried 45 degrees (my standard angle when something weird happens) as well as printing at 50mm/s and 100mm/s. Also two printers with ABS and PLA. No direct AC or air blowing around the models - on one printer it’s inside an enclosure.
All good thoughts but there’s something else happening here and I’m not sure how much I want to dive into it, especially since I now have a fix that is superior (less material and shorter print time).
