Extending DLP print area for large build volume

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James
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Re: Extending DLP print area for large build volume

Postby James » Fri Apr 08, 2016 4:29 pm

Just reread your post and found, "However, I didn't move the projector for that." So what did you do? Did you move the build tray or swivel a prism or something?

Also, I reread your first post too and found, "However, no results yet - software not fully ready yet." Are you coding a completely new slicer or are you using CW and post processing the output images in some way?
I prefer to know nothing about everything rather than everything about nothing. :)

radi2k
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Re: Extending DLP print area for large build volume

Postby radi2k » Sun Apr 10, 2016 5:24 am

Hi James,

my projector and reservoir both were fixed. I just wanted to do some tests before the machine is redesigned in total e.g. additional moving mechanics. Yes, I use my own software for stepper control and the UI + projector image generation. I generate my slices using the free version of netfabb - a custom slicer is work in progress. Thus I don't use CW. I'm a software developer on my own and like to do my own stuff :D I have big plans but I'll keep that on my own for the moment.

For the test setup:
My projector has 1280x800 resolution. I split the image in two parts: Left and right, both exposing after each other and then the tilt move. That's why the repeatability is so good. Regarding mechanics to move the projector later on I don't have plans yet. I'll probably consolut my brother who is a really good mechanical engineer. But in general I do invest good amounts of money...

And yes, repeatability for the projector moves is critical. If the projector has 50µm resolution the mechanics should be much better so there is no chance for gaps as you mentioned. I'd like to avoid special post processing stuff since that's kind of bodge :lol:

Thanks,
radi2k

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James
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Re: Extending DLP print area for large build volume

Postby James » Sun Apr 10, 2016 7:35 am

I see I see. I didn't know Netfabb did that. I looked years ago and it wouldn't do anything I wanted it to do. Then, when they came out with the slice commander, it was extremely limited in what one could do with it in the free version. I ended up contacting Steve years ago when he was first developing CW and asked if he would make the software output images slices, which he generously made happen. Cool thing is, it will output image slices with varying degrees of antialiasing! I stopped working on that project, which was centered around a new way to do SLA, and went on to other things, but it was great that Steve got that to work.

I'll bet one could use Photoshop with a Photoshop action script to slice up the slice images for experimenting around. I've used Photoshop before to do something like that.

As for the mechanics, the best way to do it would be to just move the light coming from the projector. One would need to find a way to turn the light coming from the projector into a beam so that it could easily be directed around. Failing that, one would be left with moving the projector or the build tray. For this, one way to get around the repeatability problem would be to use adjustable detents. So, the projector or build tray would be positioned using regular means and then when close to the projection position it would stop there and a solenoid would active a locator pin that would insert into a locator hole and then the projector would project the image for that position. The locator holes would be made to be adjustable, such that they could all be positioned at the exact locations needed for perfect alignment of the projected image every time.

That's pretty cool that you're creating your own slicer! I wish I knew computer programming. That's the one thing I was never good at when it came to building stuff.
I prefer to know nothing about everything rather than everything about nothing. :)

radi2k
Posts: 21
Joined: Mon Sep 28, 2015 8:22 am
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Re: Extending DLP print area for large build volume

Postby radi2k » Mon Apr 11, 2016 6:47 am

Netfabb is kinda strange here. You can only slice a single part at once and the export dialog is also limited in features. However, at the moment it is okay. When there's a need to print multiple parts at once I combine them in Slic3er, export them as STL and then load them in netfabb. I export the CLI format which worked good in the past. However, I don't have options to generate support structures yet. That is not available in the free version of netfabb.

Photoshop of course might be an good option to modify the files. But for me it is unclear how you want to put these back into the toolchain later on for printing. Beside that I don't like the G-Code approach to control all the motors and stuff on the machine. I like a more comprehensive approach but that is probably also because I come from embedded development background :)

Your idea with a kind of 'snap' mechanics to lock the projector into position sounds good. With that one could use low-cost mechanics while still having great repeatability. The only downside: this mechanism needs to be controlled too e.g. with a motor/solenoid or something else. I'll consider that...

Beside programming my stuff I also design the electronics. Not that hard at all - just takes a lot of time :lol:

Thanks,
radi2k


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