3D DLP Printer, 14″ of travel.

It is a BenQ MP776ST, I will try to get the lens to let me focus closer but I'm not sure. I can almost get a crisp image at 18" I think so I might have to just use it that way and keep the object inside the printable area.

The BenQ MP776ST would make for a very fast printer.
The literature says it's a short throw projector, and 18 inch distance sounds about right.
280 W.
Brightness (Lumens): 3500.


To avoid modifying your projector, and reduce the overall height, some are using a mirror from a discarded flat screen projector TV. The mirror reroutes the light by 90 degrees. An advantage of using a mirror is if the vat leaks the resin doesn't destroy your projector.

Here's a company selling their SLS printer with a BenQ of a different model.
All DLP projectors in the shop have been modified for 3D printing. All necessary alterations like the color wheel, lens focus adjustment for closer projections and others, have already been made for you.
[www.os-rc.com]

I took it apart last night and found the screw which prevents the focus ring from turning more than about 30 degrees and took it out. I was able to get it focused at about 8" now but some parts of the image are a little blurry but I believe it can be worked out.

Say it focuses nicely at 18", if you place the projector lens 9" from a mirror and then the print surface 9" from the mirror, would that then be in focus? I'm also thinking that the image will continue to grow even bouncing it off mirrors and would require quite a large cocave optic to bring the image back in parallel.

Maybe if I get a concave optic first and size the image and then bounce it off enough mirrors to get the correct focus length but who knows, it's early and I'm tired.

Edited 1 time(s). Last edit at 04/23/2014 08:53AM by tjb1.

Quote
tjb1
Say it focuses nicely at 18", if you place the projector lens 9" from a mirror and then the print surface 9" from the mirror, would that then be in focus?

Correct.

Here is a distance calculator,but I'm unsure of how to use it, based on the example in the last post of the thread, I couldn't repeat his results, (ex. 31cm): [www.buildyourownsla.com].
[www.projectorcentral.com]



Converging lens
A magnifying glass refocuses the image so it is small.
Generally speaking, the converging lens should be physically as close as possible to the data
projector. It is usually helpful to put the mirror close to the data projector. This allows the use of
a smaller mirror and more flexibility in elevator placement.
[nano-cemms.illinois.edu]

Macro Lens
I could drastically shorten the throw distance (and image size). By using the +4 lens the distance was reduced to about 7 inches from the front of the projector and the image size could be adjusted with the zoom to 6 inches wide. The best part is that I don't have to alter the projector in any way.
[johns3dp.blogspot.com]

Example of removing the lens stop:
[www.os-rc.com]

Edited 2 time(s). Last edit at 04/23/2014 01:08PM by A2.

@tjb1:

I found a reference to modifying a BenQ projector, your model (BenQ MP776ST) was not mentioned but some thing to be aware of.

UV Filters
Important: For the Brands like Optoma HD20 and BenQ w1070 (or w1080ST) you do NOT need to remove the filter from the lamp assembly since the lamp is strong enough to provide the required UV light. By removing it, you are most likely to burn out the light tunnel due to too much heat.

One of the filters shall be located in most cases within the lamp assembly itself, a second filter shall be located directly in front of it on the projector enclosure. You need to remove both filters to get the full light power.

Note: Know that by removing the filters you are exposing the DLP module to not only UV but also IR (Infrared) light, which causes additional heat and potential reduction in life of the projector. A good solution for this can be an IR filter which would let the necessary UV rays to pass as well as adding additional cooling.
[www.os-rc.com]

BeamMaker: an open hardware high resolution digital fabricator for the masses

Authors claim is can be built for $380 USD.

Build instruction with code, and schematics for laser cutting:
[www.tesis.uchile.cl]

You can translate the instruction to English using your browser with this link:
[www.tesis.uchile.cl]

Research paper abstract
[www.emeraldinsight.com]



Edited 1 time(s). Last edit at 04/30/2014 08:30AM by A2.

I've got a Dell 2300MP arriving today with only 124 hours on the bulb and have seen it used a few times. Also scored a BenQ PB6100 that has a logic issue I think (input image is green only, but it does display other colors as seen from on screen menus generated by the projector) but it should work fine without a color wheel.

Right now I am looking at sources for first surface mirrors, build vats, release coating and some type of vat tilt mechanism.

I'm searching Craigslist for a free rear projection TV to harvest a first surface mirror.

Front (First) Surface Mirror for Kaleidoscopes 8 x 12 sheet
[www.ebay.com]

Aluminum mirror's reflect the UV and far IR regions better than any other metal. Silver mirrors reflect more red and yellow tones than their aluminum counterparts which reflect bluer tones. Float glass's quality is higher than the sheet glass. A simple test for a sample of mirror is to drip caustic soda on it (Drano drain cleaner for example). Aluminum will fizz and dissolve while silver is totally unaffected. Aluminum will reflect much better from 1 nm wavelength to around 500 nm wavelength and has only marginally less reflectivity from 500 nm through the rest of the visible spectrum.
[www.finishing.com]

It seems that most use these www.firstsurfacemirror.com or harvest them from projection TVs, unfortunately I do not have a way to transport a projection TV to take the mirror out of. I did find that same ebay mirror and a few others that look good.

Any sources of a premade vat? Would be awesome to buy the one the Form 1 uses or some other commercial one and just adapt to it.

Found it, it's quite expensive though and the picture is terrible so you can't really see what it is - [formlabs.com]

I see their platforms come with the PDMS layer built in so it might be good to build around that vat and not have to worry about doing your own application or anything. [support.formlabs.com]

Edited 3 time(s). Last edit at 05/01/2014 07:50AM by tjb1.

From what I have read the plastic vats are made from acrylic.

If you look at the photos you can see that the bottom of the vat has a flange extending past the side walls. The flange is for clamping the vat to the frame, so when the Z-axis raises the vat stays anchored to the fame, allowing the object to pull away.

Acrylic is really easy to bond when the mating surfaces are flat, and square to each other. Look up how how DIY acrylic fish tanks are made for instructions of how to bond acrylic. A lot of them recommend a solvent with acrylic dissolved into it, this helps to fill small gaps, and creates a stronger bond.

Another technique is to make the side walls thick enough that you simply bolt it to the bottom of the vat, and use silicone to seal the gap. The vat is not under pressure so just about any kind of dam that you can think of will probably work.

You could also use RepRap Borosilicate glass for the vat bottom, and use silicone adhesive to adhere side walls to it. Borosilicate glass is one of the recommended materials for the vat bottom as it passes UV.

To obtain a first surface mirror you could also post a request in reddits forum reprapPIF (print it forward). For the projector that I'm considering it's been recommend that a piece 152x152mm be used.
[www.reddit.com]
or
[www.reddit.com]
or review all the links relating to 3d printing:
[www.reddit.com].

I'm going to explore using Gorilla glass, very expensive, but the glass will flex a lot, and should help with the peeling action.
Gorilla glass should help with larger surface area objects. It's an idea that I read of one person exploring, and is still under development.

For a release coating this silicone is equivalent to Slygard 184, and is a couple of dollars less expensive:
$37.00 + $10.49 shipping Cell Guard Solar Cell Encapsulation for Making Solar Panels Comare to Sylgard
[www.amazon.com]

The PDMS (silicone) layer is a consumable, and needs to be replaced. Some makers have multiple vats pre coated to increase throughput.

Edited 1 time(s). Last edit at 05/01/2014 08:30AM by A2.

There is a release sold in smaller quantities by Muve3D as well as FEP sheets - [www.muve3d.net]

I may build walls out of acrylic and silicone them to glass.

First (Front) Surface - Mirror
[www.alltronics.com]

Next week I am going to try to find a good focus distance for my projectors and figure out what size mirror I need and build size and all the other loose ends. So far I have a Dell 2300MP with no mods besides 3x lens and a BenQ PB6100 with the color wheel removed and both look like they will work pretty good.

FormLabs Vat Design
[www.buildyourownsla.com]

Quote
A2
FormLabs Vat Design
[www.buildyourownsla.com]

Do you have any experience with submitting files to Ponoko? I would like to see a price on those. I'll see if I can try to load one into their template next week and get a price on that vat.

DIY high resolution 3D DLP printer (3D SLA printer)
[www.instructables.com]



Edited 1 time(s). Last edit at 05/03/2014 12:22PM by A2.

What's the biggest build envelop possible for a DLP SLA printer without sacrificing resolution?

Quote
NewKidOnTheBlock
What's the biggest build envelop possible for a DLP SLA printer without sacrificing resolution?

XY resolution is dependent on the size of the projection, and the number of pixels, and the Z axis resolution is determined by the mechanics of how you drive your zed axis. So you have to determine what resolution you require to determine the maximum XY print size.

I'm going to use a DLP projector with a native resolution of 1920 x 1080 pixels with a build platform size of 192 mm x 108 mm, (7.56 inch x 4.25 inch) with a XY resolution of 0.10 mm, (0.00394 in). The resolution increases the smaller you focus the beam. For example if I use a build platform size of 40 mm x 30 mm (1.58” x 1.18”) my XY resolution will be:

X: 40 mm/ 1920 pixels = .021 mm/pixel, (21 micrometer or 0.00082 in).
Y: 30 mm/ 1080 pixels =.028 mm/pixel, (28 micrometer or 0.00110 in).

From what I have read, most homemade DLP-SLA printers have a XY resolution of 0.10 mm, (0.00394 in).

Native resolution: 1920 x 1080 pixels.
Build size: 192 mm x 108 mm (7.56 inch x 4.25 inch).
Length/pixels = resolution.
X resolution: 192 mm/1920 pixels = 0.10 mm, (0.00394 in).
Y resolution 108 mm/1080 pixels = 0.10 mm, (0.00394 in).

If your resolution was 0.50 mm, (0.020 inch) your build size will be:
X-axis: 1920/2 = 960 mm, (37.795 inch).
Y-axis: 1080/2 = 540 mm, (21.260 inch).

Print speed is determined by how many lumens your projector has, and the Z-axis mechanics, it can be as high as 50 mm/hr, but I think most are around 35 mm/hr.
I'm considering 26 mm/hr with a 0.10 mm Z-axis resolution.

One full step (no micro stepping) of the stepper motor advances the Z-axis:
.02623 inch/200 steps/revolution = .00013 inch, (0.00330 mm).

That's over kill on the Z-axis resolution, but I'm attempting to design a dead lift separation which will require a lot of force. This is being considered because I don't want to distort the object with tilting, sliding, or stair stepping the vat to separate the object from the vat bottom. I'm hoping I can flex the glass enough to initiate a peeling action. I'm considering using very thin Gorilla-glass.

The important factors in choosing a DLP projector are its native resolution, lumens, and contrast ratio.

Edited 1 time(s). Last edit at 05/04/2014 05:01PM by A2.

Quote
A2

Quote
NewKidOnTheBlock
What's the biggest build envelop possible for a DLP SLA printer without sacrificing resolution?

XY resolution is dependent on the size of the projection, and the number of pixels, and the Z axis resolution is determined by the mechanics of how you drive your zed axis. So you have to determine what resolution you require to determine the maximum XY print size.

I'm going to use a DLP projector with a native resolution of 1920 x 1080 pixels with a build platform size of 192 mm x 108 mm, (7.56 inch x 4.25 inch) with a XY resolution of 0.10 mm, (0.00394 in). The resolution increases the smaller you focus the beam. For example if I use a build platform size of 40 mm x 30 mm (1.58” x 1.18”) my XY resolution will be:

X: 40 mm/ 1920 pixels = .021 mm/pixel, (21 micrometer or 0.00082 in).
Y: 30 mm/ 1080 pixels =.028 mm/pixel, (28 micrometer or 0.00110 in).

From what I have read, most homemade DLP-SLA printers have a XY resolution of 0.10 mm, (0.00394 in).

Native resolution: 1920 x 1080 pixels.
Build size: 192 mm x 108 mm (7.56 inch x 4.25 inch).
Length/pixels = resolution.
X resolution: 192 mm/1920 pixels = 0.10 mm, (0.00394 in).
Y resolution 108 mm/1080 pixels = 0.10 mm, (0.00394 in).

If your resolution was 0.50 mm, (0.020 inch) your build size will be:
X-axis: 1920/2 = 960 mm, (37.795 inch).
Y-axis: 1080/2 = 540 mm, (21.260 inch).

Print speed is determined by how many lumens your projector has, and the Z-axis mechanics, it can be as high as 50 mm/hr, but I think most are around 35 mm/hr.
I'm considering 26 mm/hr with a 0.10 mm Z-axis resolution.

One full step (no micro stepping) of the stepper motor advances the Z-axis:
.02623 inch/200 steps/revolution = .00013 inch, (0.00330 mm).

That's over kill on the Z-axis resolution, but I'm attempting to design a dead lift separation which will require a lot of force. This is being considered because I don't want to distort the object with tilting, sliding, or stair stepping the vat to separate the object from the vat bottom. I'm hoping I can flex the glass enough to initiate a peeling action. I'm considering using very thin Gorilla-glass.

The important factors in choosing a DLP projector are its native resolution, lumens, and contrast ratio.

Thanks for the detailed explanation, A2.

How does the xy resolution on a DLP/SLA print compare to a similar size FFF print?

Is it possible to maintain high xy resolution on a DLP/SLA printer if one chooses to increase their build plate up to 20"x20"?

Quote
NewKidOnTheBlock
How does the xy resolution on a DLP/SLA print compare to a similar size FFF print

The ability to produce micro parts and features varies from one RP process to another. In laser-based rapid prototyping, part definition is largely determined by the size of the focused laser spot. Generally speaking, fine-definition SLA, using a beam diameter of 75µm (0.003"), can produce layer thicknesses near 50µm (0.002") and feature sizes in the area of 100µm (0.004"). The typical 375µm beam diameter of SLS can provide feature sizes of 460µm.
The finest 3-D printing processes produce feature sizes in the range of 75µm to 100µm. Feature sizes in the 500µm range are possible with FDM.
[www.micromanufacturing.com]

Quote
NewKidOnTheBlock
Is it possible to maintain high xy resolution on a DLP/SLA printer if one chooses to increase their build plate up to 20"x20"?

Resolution is dependent upon pixel density.
Review the math in my previous post.

hi,

newly registered on the forum, see attached a link tout the allinbox topic I'd opened somme months ago.

allinbox arcidae2000

just tout say that top bottom projection works fine and replacing a part of resin with salt water - as for peachy printer - allows tout reduce the amount of resin tout be used.

water include 20℅mass of salt ans resin is subg+. now, just need tout improve some settings, but first results are great... easier than with bottom top projection and vat problem !

@arcidae2000:

I have been spending some time reading the post on allinbox, there are some interesting topics.

allinbox
[forum.allinbox.com]

I read your thread, your development is coming along nicely.

I have read that if you leave the resin floating on the saline solution that over time it is bad for the resin.
And it seems to me it would be hard to separate the two solutions for storage or switching to a different material.
In addition a wiper is needed to eliminate the bulge that is unique to top down.
Bubbles are also an issue with top down.

I'm working on a design for bottom up, and I'm studying the problems of vat separation, and object distortion.

There is another forum for DLP-SLA printers here:
buildyourownsla
[www.buildyourownsla.com]

Thann you for your link.

for the resin storage, I've no issue. most prblems comes from bubbles during exposition tout UV. but I'll try to improve this.

Bubbles? I've operated an 3D Systems SLA for several years and can't remember to have issues with bubbles. It was a Epoxy resin. Dipping speed was slow, like 40 mm/min. If they ever happened, the wiper would move then away.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

@Traumflug:

I haven't seen a DIY top-down DLP-SLA printer with a wiper (yet), so that might be key to have.
Did the epoxy resin have a high or low viscosity?

I'm curious as to why I also have not read of DIY top-down using a piezoelectric transducer to degas the resin, possibly it makes it worse, (bringing all the bubbles to the surface).
I have recently priced piezoelectric transducers, and they are not expensive, ~$50.00 DIY.

40 mm/min:
I was just calculating my printing rate per hour, it's 33.33 mm/hr, (1.312 inch/hr).
My retraction speed is 1.66668 mm/sec or 100.0 mm/min.

I'm currently testing a modification of the slicer SW. The projector is also closer to the resin, than past weeks.
yoda printing is in process for now... result in the after-noon. I've modified the slicer to print each slice by "impulsions", i.e. each slice is not printed in 6s but in 2s + 2s pause +2s + 2s pause... The idea of the pause is to allow the mechanical constraint to be released. In top - down projection, there is nothing that losk the slice in position (like for bottom-up), then during illumination, the slice is constrainted and its foarm is changing.

What is the required ansi lumens rating does a DLP projector need to be in order to be able to cure resin?

Quote
NewKidOnTheBlock
What is the required ansi lumens rating does a DLP projector need to be in order to be able to cure resin?

Resin polymerization time varies with the amount of lumens.
I have read that with 3000 lumens ~3 seconds can be achieved, but it depends a lot on the type of resin, dyes, and fillers being used. Looking at videos I've seen a lot of them take 6 to 12 seconds per layer.

There are people using pico projectors with ~55 lumens, but it takes a long time for a layer to be formed. Pico projectors are new, and are in development by a few individuals.

The quality of your print is determined a lot by: Lumens, Resolution, Contrast ratio.

Here are my calculations to estimate the build rate per hour.

DLP projector:
Acer H6510BD, White Brightness: 3000 lumens, [www.colorlightoutput.com].
From what I have read no modifications are required of this projector.

Speed: The time it takes to lift the Z-axis stage up 4 mm:
Z-axis moves 0.6667 mm/1 revolution of the stepper motor.
Layer height: 0.10mm, (.003937 in).
At 150 rpm, the NEMA 17 stepper motor torque is estimated to be ~70 oz-in.
150 rpm/60 seconds = 2.5 rev/sec.
(.66667 mm/rev)*(2.5 rev/sec) = 1.66668 mm/sec.
4 mm/ 1.66668 mm/sec = 2.39998 seconds/4-mm.

Printing rate per hour: 3 seconds:
3 sec + (2.40 seconds*2) = 7.80 seconds/layer.
3600 sec/hr / 7.80 seconds/layer = 461.54 layers/hr.
461.54 layers/hr * 0.10mm = 46.15 mm/hr, (1.817 inch/hr).

Printing rate per hour: 6 seconds:
6 sec + (2.40 seconds*2) = 10.80 seconds/layer.
3600 sec/hr / 10.80 seconds/layer = 333.33 layers/hr.
333.33 layers/hr * 0.10mm = 33.33 mm/hr, (1.312 inch/hr).

For reference:
3D Systems, V-Flash modeler operates at about 0.4 inches per hour.
[www.youtube.com]

Edited 1 time(s). Last edit at 05/08/2014 05:31AM by A2.

Kinda curious, but do any of you know how the strength of resin prints compares to FDM prints?

---

greghoge.com

HUGE 3D PRINTER PARTS SALE!!!

Quote
gmh39
Kinda curious, but do any of you know how the strength of resin prints compares to FDM prints?

From the videos that I've watched, I think that most objects are brittle. People are blending their resins to try to improve them, e.g. reduce the shrink rate, or increase toughness.

Suppliers are selling a range of resin properties, and plastic types. A lot of new resins are in development to improve the properties, and lower the cost.

Solidator DLP Desktop 3D Printer - Resin Test
[www.youtube.com]

LightForge DLP 3D Printer @ CES 2014 (talks about the different types of resins available)
[www.youtube.com]

3D Printering: You Want UV Resin?, October 9, 2013
[hackaday.com]

Peachy Printer, Our New Flexible Resins Explained
[www.youtube.com]

Resin Suppliers:
[bucktownpolymers.com]
[www.solarez.com]
[makerjuice.com]
[spotamaterials.com]
[eti-usa.com]
[www.funtodo.net]
[www.studioqubed.com]
[www.dymax.com]
[www.suscomp.com]
[shop.madesolid.com]
[www.kickstarter.com]

Edited 1 time(s). Last edit at 05/08/2014 01:40PM by A2.