Maximum Overhang?

[tinloaf]

Hi,

now that the first printers are shipping out, I'd have the question if anyone figured out how much overhang can be printed with the peachyprinter?

It's not really urgent (didn't order yet, and I guess if I ordered now, I'd have to wait for another year ), but I'm curious.

Thanks a lot,

Lukas

[curious aardvark]

Unless I've got this the wrong way round. The peachy prints on the surface of a rising reservoir of water. so the print is supported and always enclosed by the water. I would imagine this would let you print almost out at right angles with out any problems.
And makes it way more versatile than standard resin machines that pull the model from the surface of the resin.
You can pretty much print anything you like with no supports. Can't do that on a formlabs printer :-)

Yeah I'm right :-)
<br>

[rylangrayston]

Thanks for the great question tinloaf and
the great answer from curious aardvark

Ill just add this... as its a great clip of the longest over hang print we ever did. the hole print is one big over hang! talked about here at 4:20

[iplayfast]

Just curious, can it do an overhang that drops? I'm thinking of something like a small case r where the arm droops, so when the printer is printing, the first bit will not be attached to the it, until a few layers are made. If the printer isn't jostled can the two separate parts join up without a rough surface?

[quertz]

Hey iplayfast,

I'm pretty sure, that won't be possible.
As the resin floats on the water, a created Island will also float and not stay at the same height with rising water.
Also although the printer doesn't exceed any force on the resin, wind, surface tension (or some jedi) could make the Island drift away.

Fortunately this also enables the PeachyPrinter to use really small support structures as there is virtually no weight to be supported.
Considering overhang, You probably can print full 90°, thats something to test for one of the guys that already have a printer!
I hope, this answers your questions.

Greetings,
quertz.

[MemorianX]

Isn't the cured resin slightly more dense than salt water? if so any floating island would eventually sink when they get massive enough to overcome the surface tension of the water

[Slatye]

You probably can't print a "perfect" 90 degree overhang simply because of the mechanics of the Peachy printer - the water level is rising continuously (the printer has no control over that) and it's going to take time to print a large, flat plane. As a result, whichever bits get printed last will be higher. For accuracy, I suspect the goal will be to print a lot of layers, with minimal time spent on each one - so that the height change during each layer is kept as small as possible.

[Synchron]

Only to clearify this, you can't do it with the default dripper system. If you change the dripper into a controlled system, like a pump or something, than the peachy should be able to print a perfect 90° overhang.

[curious aardvark]

Umm you sure about that.
I understood the even on the original model the dripper was controlled.
Either that or the laser has to cover the entire surface of the print vessel for every single layer. Which would set a specific print time per layer that would allow any part of the surface to be printed.
Otherwise it would be impossible to print different things on each layer - the very definition of 3d printing.
Either way you can print the entire surface per layer.
And the resin must be less dense than the water otherwise the whole thing just would not work.

[Slatye]

Umm you sure about that.
I understood the even on the original model the dripper was controlled.
Either that or the laser has to cover the entire surface of the print vessel for every single layer. Which would set a specific print time per layer that would allow any part of the surface to be printed.
Otherwise it would be impossible to print different things on each layer - the very definition of 3d printing.
Either way you can print the entire surface per layer.
And the resin must be less dense than the water otherwise the whole thing just would not work.

The dripper is only "controlled" by a manual valve - the printer itself can't change the drip rate. As Synchron has said, if you replace the dripper with a pump then you can print a perfect 90 degree overhang, or maybe even more (in that you can run the pump backwards and effectively re-print earlier layers, as long as the parts you need to access aren't shadowed by parts already printed).

To be able to create absolutely any part (with overhangs to 90 degrees, but no more than that) with the whole surface being touched at every layer, you would indeed need to set the drip rate to a very low level so that the laser would have time to cover the whole print area. This is not practical. Instead, you make an estimate at how much of the area the laser will actually need to cover (probably something like 1%, since you'd normally just print a shell rather than a solid object) and set the dripper to allow that much time.

Because the layer height is so small, the laser can probably cure a couple of layers at a time - so if it takes three layers to get to every part of the job then it'll probably still be fine (although possibly not as smooth).


The challenge is when you do want a very large amount of stuff done on one layer, like a big flat surface. If you want to print fast, you need active water level control so it can slow down for this part and then speed up for others. With the dripper, you'll just have to turn down the speed until the result is acceptable.