Splitting parts to avoid support

[Captain Starfish]

I have a somewhat complex structure I need to make a few times. For those interested, it's a bracket that combines bucket support and foot brace for an APD Inspiration rebreather in a custom stainless/aluminium case (affectionately known as the Silver Box of Death) I've been working on.

Here's a pic of the model:

[img]http://www.simonlockwood.net/linky/3dp/ ... racket.jpg[/img]

Orientation is it's laying on it's back with the top and front closest to us. The wide piece at the bottom is 150mm long by 20mm high/deep for a sense of scale.

Now I COULD just ram it through Slic3r and print it with about a million hours worth of support, but I'd rather not. Additionally, there's a good chance I'll be making a silicone mould off the part so production becomes a matter of stuffing mould with glass fibre and filling with epoxy. I vastly prefer open top moulds to closed, complex ones because it makes pulling the parts easier and avoids any hassles of distortion and unseen bubbles etc.

So, rather than attempt it as one piece I'm thinking of slicing it up into chunks which will print and pour without overhangs.

Anyone else adopt this method? If so, what are you doing to join the bits? Building plug/holes in? Holes with countersinks for screws? Just gluing them together? Dovetails?

Exciting times, interested to see what the "norm" is in these circumstances.

[lasermike]

same boat as you. many of my models will need to be cut. i am trying tonight an option to add a 1.85mm cylinder lined up with my section cut. this will leave half on each side and am hoping to just put a piece of 1.75 mm filament in the slot and make the gluing easier. this one I ran horizontal to the split, might try adding 1 vertical as well, will see how this goes.

[dpmacri]

I have a somewhat complex structure I need to make a few times. For those interested, it's a bracket that combines bucket support and foot brace for an APD Inspiration rebreather in a custom stainless/aluminium case (affectionately known as the Silver Box of Death) I've been working on.

Here's a pic of the model:

[img]http://www.simonlockwood.net/linky/3dp/ ... racket.jpg[/img]

Orientation is it's laying on it's back with the top and front closest to us. The wide piece at the bottom is 150mm long by 20mm high/deep for a sense of scale.

Now I COULD just ram it through Slic3r and print it with about a million hours worth of support, but I'd rather not. Additionally, there's a good chance I'll be making a silicone mould off the part so production becomes a matter of stuffing mould with glass fibre and filling with epoxy. I vastly prefer open top moulds to closed, complex ones because it makes pulling the parts easier and avoids any hassles of distortion and unseen bubbles etc.

So, rather than attempt it as one piece I'm thinking of slicing it up into chunks which will print and pour without overhangs.

Anyone else adopt this method? If so, what are you doing to join the bits? Building plug/holes in? Holes with countersinks for screws? Just gluing them together? Dovetails?

Exciting times, interested to see what the "norm" is in these circumstances.

I printed a horse from Thingiverse that wasn't split. Basically, I just rotated it and sunk it down into the print-bed in RH and slicer sliced it just fine (the negative Z stuff didn't show up in the G-code). Then I just lined it up by eye and glued it together. Obviously, it wasn't as critical as the piece you're building

For your part, I'd rotate it 90 degrees (around the long axis) and just print the two pieces (they look like they'd actually just be mirrored images). Putting two through holes the size of a small screw (e.g. M3) might be a nice idea to guarantee it lines up when you're gluing it and/or to hold it together at the end.

[Captain Starfish]

For this part I ended up splitting it into three parts, adding locating blocks and screw holes. Tried an offset step and a flat face but neither really held it in position with any confidence, this seems to work ok. A bit more mucking around but I don't really trust glue in an application that needs a bit of muscle.

[img]http://www.simonlockwood.net/linky/3dp/sbodsplit.jpg[/img]

[geneb]

If you've got the room, you might want to try using heat-set threaded inserts.

g.

[Captain Starfish]

same boat as you. many of my models will need to be cut. i am trying tonight an option to add a 1.85mm cylinder lined up with my section cut. this will leave half on each side and am hoping to just put a piece of 1.75 mm filament in the slot and make the gluing easier. this one I ran horizontal to the split, might try adding 1 vertical as well, will see how this goes.

Nice approach!

[Jimustanguitar]

Try moving the up-side top-wise


I'm not sure how to lay this out without just needing to print a support structure... I like the multiple pieces idea, but it depends how strong you need the part to be.

[Tonkabot]

I printed a horse from Thingiverse that wasn't split. Basically, I just rotated it and sunk it down into the print-bed in RH and slicer sliced it just fine (the negative Z stuff didn't show up in the G-code). (SNIP)

I am trying to print a model of a PCB, that has parts on both sides. I made the board in Altium, and exported a step file.
Then I converted the step file into a .STL in freecad.

Now I want to print it, but I have parts on both sides of the board, and I want the print to start at the bottom of the board.

I changed the Z height, then sliced it, but it still behaves as if I dropped it again, starts printing the crap on the bottom side I don't care about.
[ I also get a warning that stuff is outside the printable area, and do I want to continue. Of course, I do, but don't print the crap outside the area, I don't want it!]

I Think I am doing what is described above, but all the negative Z is still in the Gcode.
Alternatively, I see that the bototm of the board is layer 62, and if I just printed layers 62-90 I would also get what I want.
But there must be a way [without going back into a cad program]

[dpmacri]

I printed a horse from Thingiverse that wasn't split. Basically, I just rotated it and sunk it down into the print-bed in RH and slicer sliced it just fine (the negative Z stuff didn't show up in the G-code). (SNIP)

I am trying to print a model of a PCB, that has parts on both sides. I made the board in Altium, and exported a step file.
Then I converted the step file into a .STL in freecad.

Now I want to print it, but I have parts on both sides of the board, and I want the print to start at the bottom of the board.

I changed the Z height, then sliced it, but it still behaves as if I dropped it again, starts printing the crap on the bottom side I don't care about.
[ I also get a warning that stuff is outside the printable area, and do I want to continue. Of course, I do, but don't print the crap outside the area, I don't want it!]

I Think I am doing what is described above, but all the negative Z is still in the Gcode.
Alternatively, I see that the bototm of the board is layer 62, and if I just printed layers 62-90 I would also get what I want.
But there must be a way [without going back into a cad program]

Which slicer are you using? I was using Slic3r from within Repetier Host (Mac version 0.56). At the time, I imported the model and it dropped on the bed. Then I used the Z adjustment within RH to lower it into the bed. Slic3r worked fine for me. But that was probably using a .9x version of Slic3r. If you're using something newer, perhaps it behaves differently.

[Tonkabot]

This is Slic3r 1.0.0 x64, and Repetier-host V.95F on windows 7 x64.

You say you used the Z adjustment. Where do you do that?
I used the Z translation box on the object placement tab where I put in a number that aligned where I wanted it to start with the bed.
Which it then ignored, because you can see by the paths it generates visible at the g-code editor tab it just sliced the entire model.

[dpmacri]

This is Slic3r 1.0.0 x64, and Repetier-host V.95F on windows 7 x64.

You say you used the Z adjustment. Where do you do that?
I used the Z translation box on the object placement tab where I put in a number that aligned where I wanted it to start with the bed.
Which it then ignored, because you can see by the paths it generates visible at the g-code editor tab it just sliced the entire model.

Hmm, now I'm wondering how I did it . I just tried with three different versions of Slic3r and none worked (they behave just as you said). I *know* I did it somehow because I have the horse that I printed . I really thought I did it by sinking the model into the bed, but that obviously doesn't work. I'm clearly getting old since I can't remember what I did (it was only a few months ago ).

[Tonkabot]

I just discovered if you run slic3r [1.1.1 at the moment] stand-alone then there is a 'Plater' tab that we don't see from repetier-host, and under the Plater Tab there is a 'split' button. of course slic3r is 'not responding' for a few minutes, now it just came back a little, it is still out to lunch mostly.

The model I am trying to split is apparently pretty complex.

[Tonkabot]

Okay, a little more playing with slic3r in stand alone mode shows that the 'Split' button does not split the model at some arbitrary point, but
1) complains if the model is only '1' part and will not split it
2) seems to take my PCB model and split it into 1500 parts, which is probably each and every component [ and probably individual component legs].

So the 'split' on the plater tab doesn't do the job, either.

[JohnStack]

If you are thinking about cutting it apart, why wouldn't you split it in half along the middle of the part along the longest axis?

Did I miss something?

[Tonkabot]

If you are thinking about cutting it apart, why wouldn't you split it in half along the middle of the part along the longest axis?

Did I miss something?

That would work too, IF I KNEW HOW TO DO IT. Sorry. I think the problem here is that I am pretty sure it can be done, fairly simply, except I have no clue how to do it and have not found directions how it is done anywhere.

I have a model of a Printed circuit board, complete with components on the top and bottom. But for my purposes printing the board with only the top side components is acceptable, so if I can print from where the bottom of the actual board starts, and up, that would work fine.
Or splitting it down the center of the PCB and printing as a top half and bottom half would work too. Although the PCB is only 0.040 inches thick.

[Tonkabot]

Okay, I got netfabb basic 5.1 downloaded, and that looks like it will do the trick.