Usable projector list + hacks

This is the place to discuss various hardware. Topic include:
- Display devices (Projectors, Lasers & etc..)
- Microcontrollers & RAMPs boards
- Power supplies
- Z-Axis and Tilt assemblies
- etc..
bonzoshields
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Re: Usable projector list + hacks

Postby bonzoshields » Mon Apr 27, 2015 7:43 am

I'm new to this. So basically I get a 2000 lumen projector and remove the colors from the color wheel correct?

Cation
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Re: Usable projector list + hacks

Postby Cation » Thu Apr 30, 2015 3:38 pm

Please list any projectors that you find that don't work and I'll tell you why and how to make it work.

Projectors that will only display light that is over 420nm will not work with resins that only cure from UV up to 420nm Violet. These projectors require resins that are sensitive to light in the visible spectrum that include BLUE (460nm).

Cation
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Re: Usable projector list + hacks

Postby Cation » Thu Apr 30, 2015 9:16 pm

I'm hoping to clear up a bit of confusion of how single chip DLP projectors work with lithography. Single chip DLP projectors use a color wheel along with a mercury lamp and a single DMD.

http://upload.wikimedia.org/wikipedia/c ... _wheel.gif

The mercury lamp is on the left in the above graphic. The lamp radiates light through the color wheel as it spins. After light pases through the color wheel it hits a mirror as shown in the following photo.

http://upload.wikimedia.org/wikipedia/c ... t_Path.jpg

In the photo above you can see the path of light after it goes through the color wheel located on the right ot the photo. The mercury lamp is located outside of the frame farther to the right of the color wheel. The light radiates from the lamp and goes through the color wheel. The red arrow shows the direction the light takes after passing through the color wheel. The light is directed at a mirror that reflects the light into the DMD device. The DMD device is made of thousands of micro mirrors that either reflect the light out through the lens or away from the lens into a heat sink. Each mirror represents one or more pixels in the projected image. When the light gets reflected by the DMD out through the lens is creates a bright pixel on the screen or resin in the case of a printer.. When the light gets reflected into the heat sink the pixel is very dark or black.

The spectrum of light radiated by the mercury lamp is very wide it extends from the UV through the visible and into the IR. The total spectra is shown in the chart below.
http://www.olympusmicro.com/primer/imag ... burner.jpg

The color wheel uses three narrow bandpass color filters to only pass Red (635nm), Green (530nm) and Blue (460nm) portions of the total spectra. The filters aren't perfect so a little of the light outside each color still passes through.

Most resins available for hobby SLA are only sensitive to the spectra below 420nm. Some are only sensitive below 390nm (UV). Since the color wheel filters out most of the spectra radiated by the mercury lamp, very little of the spectra actually gets to the resin that is required to trigger the resins to polymerize or cure.

If the color wheel is removed then much more of the spectra emitted by the mercury lamp gets passed through the projector onto the resin. The only spectra that triggers polymerization in these resins is the spectra from 420nm (Violet) and lower (UV) or 390nm and lower for the other resins.

Resins that are sensitive from UV and up into the visible spectrum will polymerize or cure without the removal of the color wheel since they are triggered by all the light that passes through the Blue filter of the color wheel and even some of the Green filter. http://bucktownpolymers.com/zve200-v470.html is an example of one of these resins that cure from UV past the Blue spectra to over 500nm.

LCD projectors operate differently. For a detailed description of how LCD projectors operate and interact with resins please see this thread:
http://tinyurl.com/l2lpsrz

pedropin1
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Re: Usable projector list + hacks

Postby pedropin1 » Fri Dec 11, 2015 12:32 pm


CaptainBisquick
Posts: 26
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Re: Usable projector list + hacks

Postby CaptainBisquick » Mon Jan 25, 2016 9:03 pm

I also have the Acer H6510BD, and I was very happy to learn (upon LittleRP assembly) that it doesn't require modification. I didn't even know modification would be a consideration. If you're reading this Brad, I suggest you give a disclaimer concerning projector choice and the matter of projector modification, during LittleRP checkout.

I had my first successful print using the maker juice red that was included, but it was certainly tricky to figure out why my prints were failing. Now that I've switched to maker juice orange and changed my part orientation, my print is failing again, specifically near the corner of my print, the supports are failing, yet the supports in the middle of the print succeed every time.

CaptainBisquick
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Re: Usable projector list + hacks

Postby CaptainBisquick » Mon Jan 25, 2016 9:43 pm


leitnin
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Re: Usable projector list + hacks

Postby leitnin » Thu Jul 07, 2016 9:39 am

Similar to the Acer h6510bd, the Acer h6500 works quite well (and can sometimes be found much cheaper).

The color wheel however has no clear section, so exposure times are quite long (20-30 seconds) unless the color section of the color wheel is cut away or the unit is "simply" moved out of the light path, and then exposure times are short as expected.

boelle
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Re: Usable projector list + hacks

Postby boelle » Fri Dec 30, 2016 9:42 am

Q:

what is the best projector out the box that you can still get hold of?

i looked through the list and compared to ebay and none turned up, might be me that made an mistake. I only limited the results to inside the EU so i dont have to deal with import


Next... have anyone tried to replace the bulb with a pure UV one? i say pure UV to avoid bulbs that also put out IR (heat). of course this requires a dummyload so the projector thinks the bulb is ok.

Atech401
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Re: Usable projector list + hacks

Postby Atech401 » Thu May 25, 2017 8:30 am

Hello all! I'm using a Sharp XR10X projector for a top down printer. I've removed the UV filter that is right after the bulb but left the color wheel in. Using makerjuice G+ i'm at about 7 seconds burn in and 5 to 6 seconds per layer. I use Nanodlp and raspberry model 3B over wifi and a ramps/mega combo for the z axis( i know over kill for z axis). Large prints like 4 x 4 inches get too hot and bubble even using pixel greying, so thats a problem i'm still working on. Small prints like a bolt or art pieces come out perfect. :D I know its an old thread but hey, its not on your list!

Pedromedeiros
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Re: Usable projector list + hacks

Postby Pedromedeiros » Thu Jun 08, 2017 1:04 pm

Hi, I have some doubts about choosing the right projector. It seems to me that the only requirement for the projector is that it needs to emit the right wavelength to be able to cure the resin (in most cases, the UV wavelength). But how can I get this information?
I'm from Brazil and in here I could not find projectors like Acer H6510BD. Here are some projectors I can easily find in here:
Acer P1185
Optoma HD27
Optoma HD29
Does anyone know if one of these would be able for 3d Printing?


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