Advice wanted - Supports  

RE: Did you forget something?

3mf file?

RE: Hmm

I could upload one but I am using standard settings with no changes.  I really asking just about orientation and not about the settings.  

I did forget the link to the file:

https://www.prusaprinters.org/prints/35510-unistrut-rail-button

Also, you mentioned supports in the title but then didn't mention them anymore. Are the rough overhangs caused by the supports or are you interested in suggestions for placing supports?

Rotation

Posted by: @fuchsr

Also, you mentioned supports in the title but then didn't mention them anymore. Are the rough overhangs caused by the supports or are you interested in suggestions for placing supports?

I forgot to inset the file.  I was in rush to get to work.  Sorry.  I also was not as clear as I would liked.  

I am really asking how you would rotate the device to print to prevent the terrible surface above the supports.  I could rotate it 45 or 90 degrees.  

Mental exercise in futility

I did some test prints last night and printed it with the button on it bottom.  I am going to rotate it at 45 degrees and 90 degrees and see if I get less damage from the support.  The supports at 0 degrees are between the two layers.  

Yeah, I can see how the overhangs can be a problem. I've had a similar design in the past (very different use case though) and I ended up cutting it in the middle (parallel to the upper and lower surfaces) and gluing the two parts together. I guess I could have come up with some interlocking mechanism for the lower and upper part but it didn't seem worth the effort in that case. 

My approach....

..... would be to cut it into three separate pieces, two flanges and a hub. Print the flanges inside surface down with a circular recess that is a slight interference fit for the hub. The recesses can have supports that may leave some cosmetic flaws inside the recesses, but the hub ends will hide all of that when glued together. You didn't say what filament, but if ABS, gluing with an acetone- containing glue should make  a suitable bond.

I'd print it like this.

Regards

Swiss_Cheese

rotation

Posted by: @swiss_cheese

I'd print it like this.

 

Regards

 

Swiss_Cheese

I will try that next.  I have tried 0, 45, and 90 degrees rotation.  I am starting to think 45 degrees rotation on the y axis is the best position.  I have a printer jam do deal with now.  Might be a PTFE tube issue.  

RE: Maybe this?

I had not noticed that the inside edges of the groove were also sloped, so a three-piece cut doesn't help. You can cut it four ways, but then assembly becomes a chore if you're making a bunch of them. If only a few, and the join lines are not objectionable, this may still be a viable option.

Invert 1st and 3rd pieces for printing, then stack glue them left-to-right.

RE: Seams.

I would prefer not gluing.  That creates unsightly seams.  I might try acetone smoothing and ABS.  

Posted by: @reddawg

Invert 1st and 3rd pieces for printing, then stack glue them left-to-right.

What's more unsightly, seams or the one-piece support/removal mess you had before? It's still perfectly functional.

Sale

These items are for a product and may be sold.  I cannot sell something that is unsightly.  I will not make much but it is a gateway drug.  

Posted by: @reddawg

What's more unsightly, seams or the one-piece support/removal mess you had before? It's still perfectly functional.

RE: Advice wanted - Supports

What are the specifications for these rails? Sources/vendors/links? Surely these rollers are available for simple purchase. (of course, that takes all the fun out of it.)

Multipart threaded design?

Could you design it as multiple parts that thread together? If there are variations of this part, that might even be more flexible.

RE: Advice wanted - Supports

Posted by: @bobstro

Could you design it as multiple parts that thread together? If there are variations of this part, that might even be more flexible.

I considered that approach also, but it complicates the design and careful tweaking of the dimensions would be needed for fit (always an issue for threaded mating parts). Still, it would be stronger and you'd probably still want to assemble with glue; doesn't do anything for those unsightly seem lines though! 🙄  A simpler (maybe) approach would be (in my 4-piece version), put a few (4? 6?) blind holes in pieces 1 and 4, matching clearance holes in pieces 2 and 3, then assemble with rolled/tension pins and glue. Damn those ugly seams!

Example threaded part

I put this design together (as a test last year) in a few minutes with Fusion 360. The threads fit well and are loose enough with the defaults that the nut part spins freely with a flick of the finger when printed with PLA. In PETG, it's a bit more snug but not bad. The overhangs were not a problem to print.

I'd expect to be able to print Chuck's part as a 2 piece print, with the top screwed onto the center shaft with a bit of threading up top. Overall finish was fine, although I did have grooves to hide the seam in. Seams were not a problem with the threading on either part.

Nice design!

Mind sharing the STL/3MF?