Best support settings/orientation for this print

[ryaneb85]

I'm not sure if this is in the correct section, but I guess it is software related, so here goes..

I need to start a pretty long print (~24 hours) that looks to need significant support. I usually try to step away from supports as much as possible as I have never had much luck with them. The first layer after the support is never flat or de-laminates/droops from the next few layers, and the supports are usually completely stuck to the piece both bottom and top. After many hours and injuries I succeed in prying the supports away, but the adjacent surfaces look terrible.

I have attached the file I need to print and was hoping somebody may be able to suggest some support settings that would result in easy clean up with minimal surface blemishes. The locations that supports are required means its going to be difficult to get fingers/tools in to do any serious post-processing.

I plan to print this in PLA and at .2/.25mm layers.

Thanks in advance.

Ryan

[ednisley]

some support settings

That object isn't designed for fused-filament printing.

Assuming the block is 5 inch = 125 mm across the mostly flat side, then the bent bracket supporting it is maybe 1 mm thick. That flat-out isn't going to work, period: there's not enough plastic to make the bracket strong enough, no matter which way you print it.

If you must print the whole thing on an M2, cut it into sections and glue them back together. That has the major advantage of limiting the damage of a failed print, too: you can re-print a failed chunk in less than forever.

Orienting it so the round peg on the bent plate points downward, then ...

• Cut off the bent bracket, make it out of metal, attach a printed peg.
• Cut horizontally just above those rectangular blocks under the roof, print the roof on its now-flat bottom face.
• Cut parallel to the tray's upper surface, print tray standing on its flat rear face, standing vertically. You could print it top-side-down on the nearly flat top face with minimal support under those stylin' rear angles.
• Print middle section upside-down, with those rectangular blocks growing upward from a thin flat section that you'll glue to the roof.

If you must print the bent bracket, put its back face flat on the platform so the threads wrap around in the best orientation for strength, then glue the peg on. It'll take some fiddling to fit two or three threads without gaps into that thin geometry.

You could print the bracket with its bottom face downward and the peg removed, so the legs point upward. They'll snap under load, because there's not enough surface area to hold the layers together, but at least it'll be print-able.

If you add holes for alignment pins (a.k.a., filament snippets) to all the cut faces, you can reassemble the sections almost perfectly.

If you must print the whole thing in one pass, send it to Shapeways for their laser-fused powder process: the un-fused powder supports the overhangs just about perfectly and falls right off when it's done. The bracket will be barely printable and will still snap under load.

No matter how little you charge for your support removal time, that'll be cheaper...

[ryaneb85]

Thanks for the reply, Ed. I was so caught up with supports that I didn't even give a thought to the thickness of the bracket...

I think I might cut it in to sections as you suggest. Aside from the bracket, I think there are few combinations that would work. Do you have any tips/software suggestions on how to cut it? I've never done it before but assume it can't be done in S3D. I am a complete CAD beginner and only have the .stl files, so I'm hoping there is a fancy bit of software/function that will allow me to 'drag and drop' where I want the cuts.

Those filament snippets sound ideal, but again I'm assuming this is something that needs to be done in CAD??

[ednisley]

assume it can't be done in S3D

Although I'm not an S3D user, IIRC you can rotate / flip / orient the model with the part you don't want to print below Z=0 (the platform surface) and the Right Thing will happen with the remainder. Perhaps you can export the part above Z=0 as a separate STL file and iterate until you have enough pieces?

I know Slic3r can rotate / align, then cut the model at specific Z values; that might be worth investigating.

something that needs to be done in CAD

That's about it; if you can't modify the original design to include the alignment pin holes, you're stuck.

You can probably get a "good enough" alignment for that model without them, though, just by pressing the big flat surfaces against something like waxed paper that won't stick to the adhesive while you're clamping the other faces together.

[ryaneb85]

I forgot to thank you for your help Ed. I had neither the time or inclination to mess around with that part too much, so I ended up declining the order.

[ednisley]

so I ended up declining the order.

Sometimes, not taking on a job produces the best outcome for all parties ... [grin]

[jimc]

its tough when you print for someone else because they generally just make the model and hand it off to you. they dont give a single thought into how the part is going to be produced. no matter what you are modeling, the manufacturing process no matter what it may be has to be taken into account. that thing should have been made in individual pieces like a model then assembled later as ed said. i almost never use supports at all. maybe 2 prints a year will require them but i model my own stuff and design the parts to be assembled. except for one person, i generally dont print anyone elses models. just too much a pia. my own stuff only.

[ryaneb85]

I completely agree. The orders I generally get through on 3D hubs are for £1 or £2 and are really not worth the effort. I know I could increase my prices, but then no orders come in. I therefore chose to close my account and as Jim says, focus on my own prints.