Projector characteristics

This is the place to discuss DLP projectors, UV Lasers, Galvanometers, LCD screens and similar display devices. Also discussed are optics in general.
locorez
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Projector characteristics

Postby locorez » Sun Mar 30, 2014 7:37 pm

Hi people,
I'm new and I'm trying to make a 3D printer and I've got few questions about the projector, maybe you can help me.

- The resine is cured thanks to the UV light? there are resines that works without UV light? differences between them?
- The only important characteristics in a projector are: resolution and lummens?
- All the projectors produce UV light? Only I have to remove the filters like the colour wheel?
- The cure speed depends of the lummens quantity? more lummens less seconds?
- I've seen a lot of people using the Acer H6510BD, it's so expensive but it doesn't need any mod. So, do you recommend it? exists a cheaper alternative?

Thanks!

Finhead
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Re: Projector characteristics

Postby Finhead » Sun Mar 30, 2014 8:01 pm

Yea lumens and resolution as well as focal distance, closer you can focus brighter your image will be.

I like the Acer H6510BD since it's about the cheapest 1080p projector out here with the high light output and close focus. It's actually pretty cheap for a 1080p most are still in the $1000 range, got mine off Ebay for $600.

Clinton

AndersonTa
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Re: Projector characteristics

Postby AndersonTa » Mon Mar 31, 2014 12:12 am

@AndersonHTa

fenriss
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Re: Projector characteristics

Postby fenriss » Fri Jan 02, 2015 1:34 pm

Hi there. I have a question similar in nature. How can I actually compare two projectors basing on minimum viewport and ANSI lumens?

For example mentioned Acer has 3000 lumens and minimum pic diagonal of 45''.
With 16:9 it will give pic area of ~5400 cm2, so it will have a luminance of 5.5 klux.

Having smaller mini-projector with minimum pic diagonal of 5'' and let's say - 50 lumens will give me luminance of 7.5 klux.

It means that simpler and lightweight mini-projector is better than those bright powerhorses.
Is my thinking right?

Steve Baker
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Re: Projector characteristics

Postby Steve Baker » Sat Mar 07, 2015 10:08 pm

I'm interested in producing objects around 20x20x20mm in quantity. I'd like to build a machine with a larger bed to allow the machine to make a bunch of objects at the same time...and like the idea that exposing the resin "in parallel" with a projector ought to be faster than using a steerable laser as the bed size increases.

But it occurs to me that the intensity of the light I'll get from a projector at any given point on the bed would be inversely proportional to the area of the bed I'm shining it onto.

Would I be correct in assuming that the resin curing time is directly proportional to the incident light intensity? Or is there some kind of non-linear relationship?

I wonder whether using the same kind of projector and increasing the bed size will improve my production rate?

Zenon
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Re: Projector characteristics

Postby Zenon » Sun Mar 08, 2015 5:14 am

Yes resin curing time is proportional to the area.

You can use multiple beamers for twice the build area.

I remember seeing a commercial DLP printer that supported 2 projectors for 384x216mm build area, but can't find it anymore

Steve Baker
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Re: Projector characteristics

Postby Steve Baker » Sun Mar 08, 2015 1:12 pm

Sorry, I'm new at this stuff...but I'm not new to rapid prototyping and I'd like to play catch-up for a while. Maybe an introduction is in order.

I built two gigantic laser cutters from the Lasersaur BOM and my wife and I run a profitable home business , making model ships and buildings that we sell to tabletop gamers (mostly through Kickstarter):

Image

But we want to diversify into 3D printing to make things that we can't make on a laser cutter.

I played a bit with plastic deposition 3D printers and concluded that they are terminally S-L-O-W and there isn't much out there that shows promise to make them go any faster. Using a laser to cure resin suffers from the same fundamental problem that they go slower as the build area increases and there doesn't seem to be a way to drastically speed them up either.

Using a video projector offers the possibility to go fast because it exposes the whole bed in parallel. So this stuff is exciting to me. But still, the speed goes down as the build area goes up...but at least this approach offers the best chance to make things faster by brute force increases in the amount of energy we can apply.

So it seems to me that we could possibly, finally, build a 3D printer that's fast enough to manufacture stuff profitably.

The need for more energy at the bed suggsets that I need either a single projector that puts out more power, or projectors that are cheap enough that I can have lots of them.

Everyone seems to be talking about the Acer H6510BD as the sweet-spot of power versus cost. With that in mind, how do I get more watts-per-dollar?

* Can I buy a more expensive projector and get more power per dollar?
* Can I buy a bunch of smaller projectors, each with better power per dollar?
* Everyone says that the great thing about the Acer is that it puts out enough power to cure resin without modification...so if I *do* modify it, can I get more power?

Thanks in advance!

-- Steve

nicanor76
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Re: Projector characteristics

Postby nicanor76 » Sun Mar 08, 2015 2:06 pm

They have UV DLP projectors, though I don't know where to find them. The new Pegasus DLP (link below) coming out has an upgrade with one of the kits out there for$1500 extra above of their standard DLP projectors. I saw another company making their own UV-based projectors specific for 3d printing.

http://www.fsl3d.com/phoenix-touch-dlp-3d-printer/
"UV LED bulb lasts 20,000+hrs and cures up to 10x faster and more uniformly"

A big bottle neck also is the peeling stage. The newer VAT designs that peels off quicker claim to increase that process 4x faster. So once the next-gen VAT designs are standardized, we'll be printing faster.

For a manufacturer's end, like your company, it maybe faster to print some pieces, then make a mold of those pieces to recast (depending on the complexity of the product). You can cast resin pieces quicker than re-printing the same objects; but it required more hands-on labor as well. Having multiple 3d printers isn't uncommon for production runs as well.

nicanor76
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Re: Projector characteristics

Postby nicanor76 » Sun Mar 08, 2015 2:28 pm

I also had another thought, dual projectors! Either will be twice the power (half the curing time), or set side by side to make it twice the size. Alignment is the tricky part, I did a quick search and came across this (not exactly for 3d printers but shows alignment):
https://www.youtube.com/watch?v=23x8pTTmO-U

Zenon
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Re: Projector characteristics

Postby Zenon » Sun Mar 08, 2015 3:18 pm

I don't think overlapping is the way to go.

In a lot of cases, getting more brightness won't help your print, since it also means more bleed-through issues (Meaning layers below your current one get exposed as well and you get 'blurry' features on the side facing away from the projector). It depends on the resin (generally, red pigment is the best and more pigment = less bleedthrough), but I've seen people having to reduce projector brightness to 30-50%, so (again, depending on the resin used), more brightness is sometimes contraproductive (i.e. "half the curing time" will turn into "worse prints").

You already get "half the curing time" in a side by side setup, since you can print two parts at once on the larger area. But it also gives you the added bonus of being able to print larger single parts (384x216mm at 0.1mm resolution), which you wouldn't have with an overlap setup.

Another thing to keep in mind is that larger print => more warping. Getting large prints with flat surfaces can be tricky, especially for solid prints (hollow ones suffer less from warping).


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