top down advantages/disadvantages?

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educa
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top down advantages/disadvantages?

Postby educa » Fri Jun 26, 2015 9:20 am

Hi,

I was wondering, if I want to create my own sla printer using thk rail, ballscrew movement and high quality rigid build, could I then not build it just projecting with my projector projecting down onto the vat with resin (a little like the $10 sla printer on this forum) ?

I mean.... sure you need some more resin, but I can't see any reason why using a flexvat and so on would give better results. Is the only drawback of topdown projection that you need more resin ?

And can't this resin be reused after the print?? I guess yes ?


My build size would be not so big, with a 50x50x50mm builtsize I would allready be very happy. Thats only 125ml of resin in a full vat. If it can be reused then that should not be a too big problem.

I sincerely hope somebody could tell me if this is OK or just a crazy idea ?

khbaur330162
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Re: top down advantages/disadvantages?

Postby khbaur330162 » Fri Jun 26, 2015 9:00 pm

Resin can be reused, yes, just dump it back into the bottle it came in, or find another suitable container for used resin.

Stray light from either your projector or the environment can cause varying levels of intermediate curing in the resin which can change the viscosity of your resin over time. Also, particularly when calibrating or troubleshooting your printer and you don't exactly know what you're doing, cured layers can sometimes lift off the build platform or the build itself and float away. Just keep the resin, your printer, and the space your printer is located in all clean and you should be fine.

Make sure anything you have attached to your build plate is relatively low in volume. As your build plate gets deeper and deeper into your vat anything attached to it that gets submerged will displace more and more resin which might have a slight effect on z-accuracy. Probably a non-issue, especially given your desired build area, but worth noting, imo.

educa
Posts: 16
Joined: Tue Jun 09, 2015 6:39 am
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Re: top down advantages/disadvantages?

Postby educa » Sat Jun 27, 2015 4:25 am

thanks for the reply.

And if I want to make it bottom up, then the only difference is that I need a vat vith non stick properties ?

I allready read about fep film, but is there any known GOOD design which can be made and used as of today ? Like an acrylic container with fep bottom?
If I read well then I see articles suggesting to have a FEP bottom with no support and others say you need support.

I'm certainly not looking for the fastest way to print. Any idea what I could try to use ?

khbaur330162
Posts: 14
Joined: Wed Jun 03, 2015 8:23 pm
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Re: top down advantages/disadvantages?

Postby khbaur330162 » Sat Jun 27, 2015 7:15 am


educa
Posts: 16
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Re: top down advantages/disadvantages?

Postby educa » Sat Jun 27, 2015 7:28 am

a native 1080p uv pico dlp sure sounds nice, but imho the only advantage of pico is it takes less space on your desktop.

An acer p1500 is available for around €549 so that is not that expensive for full HD


I also saw that _HP sells flexvats at very reasonable pricing so I might have a shot and try bottom/up printing too.

khbaur330162
Posts: 14
Joined: Wed Jun 03, 2015 8:23 pm
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Re: top down advantages/disadvantages?

Postby khbaur330162 » Sat Jun 27, 2015 7:59 am

€549 is "outside my budget." :oops:

Having a pre-modded projector with UV LED means you'll probably have nice cure times, good throw distance, and will never have to sink money into replacing bulbs.

I don't need 1080p, I can save a lot by finding a 1280x800 projector. Also, bare bones LCD displays with HDMI driver boards and very nice pixel pitch can be found for reasonable prices on eBay, that is, if you're okay only using ~470nm curable resins.


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