New DLP build started! / Pico-projector part 3

I keep saying this, but it's been too long a time since I updated my project blog. It's not for the lack of progress mind you. Things have been very busy for me lately. I'm not sure if I mentioned it before, but I started a new forum dedicated to all things DLP/SLA www.buildyourownsla.com . I have to say, never expected the explosion of interest! It's only been up for less than 2 months, but there are hundreds of active users (and about 1000 spammers).

Creation Workshop http://www.envisionlabs.net/ continues to advance rapidly, largely due to the herculean efforts of the co-programmer Shai (Thanks man!) . I've had a lot of interest with DLP/SLA printer manufacturers wanting to distribute Creation Workshop along with their printers, and I've been signing them on rapidly. I've devised a plug-in system that allows me to create vendor plug-ins to completely customize the GUI and code for each machine. It also allows me to distribute custom machine and slicing profiles tailored to each machines unique capabilities.

I've been talking with a bunch of groups/ start-ups/ companies about their machines for months, and I'm in a pretty unique position to see exactly what's going to be coming out on the market this upcoming year. I'm under NDA with a few of them, so let's just say that 2014 will be the rise of the SLA machine in the 3d printing world.

That all being said, I've been giving some thought as to how to create the 'Best' machine possible. 'Best' is an arbitrarily chosen words really. 'Balanced' would be a better descriptor. As I noted elsewhere http://www.buildyourownsla.com/forum/viewtopic.php?f=17&t=149 , there will always be tradeoffs between build size, resolution, and print speed. I think I've come upon a good balance between the 3.

What I came up with is a pico-projector mounted on an x/y linear assembly. The projector can expose smaller image tiles on a much larger vat bottom. This allows the pico-projector to maintain a 25micron (or greater) x/y resolution. The vat can be arbitrarily large. This is a good trade-off between size and print speed.

I'm still in the early stages of the build, but it's all coming along nicely.

New parts for the build

Shown above are a few parts I'm using for the build. Here's an incomplete BOM of items so far:

• 12v 6A power supply
• 5x Nema 17 steppers (I'll probably use 4)
• 12x LMU88 linear bearings
• 6 meters of GTK belt and 4 pulleys
• 10W UV LED 405nm on an alum heatsink
• Modified AAXA P2JR DLP projector
• 3' of 1/8 hose for the resin pump
• 3 prong outlet
• Mains switch
• Printed 3 way corner brackets for the 80/20 construction
• 4 printed feet

A bunch of 350mm and 300mm 25mm 80/20 aluminum.

The constructed bottom portion of the machine. Measures 350x350mm.

I'm still waiting on a few more parts in mail:

• Arduino 2560 with RAMPs board
• 8mm hardened steel rails
• 8mm threaded rod
• UV transmissive plexiglass for the vat
• UV blocking plexiglass for the outer casing/window
• Other things I forgot

I'm probably going to do a bit more construction today. Look for the next part of this build soon.
-Steve

UV DLP Pico Projector Experiments Part 2

I know I left many of you hanging with my part 1 of the pico-projector experiments. To recap from part 1, I had successfully dis-assembled my pico-projector & examined the optic path, trying to determine how to insert a 10W UV LED into it all.

First, I'd like to offer a few words of caution. UV light can and will hurt your eyes. This is the exact reason why welders wear goggles. Sunburn on your eyes is no joke. I highly recommend wearing a good pair of sunglasses, or welding goggles if you have them.

Safety First...

 Last I posted, I was pointing out various bits of the optic path, and what they do. Shown below is a top-down view of the optic path of the axaa p2jr projector. http://www.aaxatech.com/products/p2jr_pico_projector.html

The L-Bracket with the LEDs has been removed.

 Initially, my efforts focused on attempting to collimate the light from a 10W LED into the existing port from one of the removed LEDs. The 10W UV LED I had purchased from Ebay had a 3x3 grid of individual LEDs. The actual emitter portion measured approximately 1cm across. I needed to channel this light somehow into an area approximately 4mm in diameter.

I tried several methods for building a suitable reflector/collimator, including dis-assembling and removing elements from various LED flashlights, and even building a simple light-pipe from acyclic rod.


In the end, I decided I was over-thinking it and decided to do something drastic.

Something drastic

I decided to remove almost the entire optic path. No mirrors, 1 lens. If you compare the above picture with the second picture I posted, you can see the portions of the optic path (and plastic)  that I removed. All that I left was a simple lens in front of the splitter/reflector portion of the DLP. Coincidentally, the lens in front was approximately 1cm across, which meant the LED was a good fit.

I taped over the lens while removing plastic

Most of the optic path removed.

 What I ended up doing was (temporarily) taping the 10W UV LED directly to the face of the lens prior to the DLP's splitter/reflector. This acted as a last-stage collimator to focus the LED's light onto the DLP chip and through the optics.

Projected onto a sheet of white paper.

A little light leakage around the edges can be fixed...

 Overall, I'm fairly happy with the way this turned out. The light emitted through the DLP was strong enough to cure resin (more timed tests are required) and it has even light across the image. The LED is was using was completely un-heatsinked, so it became very hot very quickly.

The next order of business is as follows:
1) Heatsink the LED (probably with a fan)
2) Build a mount for the DLP assembly / heatsinked LED

I'm currently designing a FDM 3d-printed 'carrier' right now.
Stay tuned for part 3, which will include some curing times and the initial design of a pico-SLA machine.
-Steve

Creation Workshop Version 13 - Last BETA release

This is probably the quickest turn-around I've had between releases. Version 13 doesn't have anything earth-shattering in it, but it does have the following:

• Fixed all reported issues in version 12
• Improved Camera Controls (Thanks Shai!)
• Huge reduction in memory usage
• Instant Slicing
• Volume & Cost Estimator
• Revised future-proof config files
• Additional support generation tools
• Fixed the intersection issues in support generation & object selection
• Simplified GUI (G-Code controls)
• New Plug-In System
• Other things I forgot...

Now that I look at the list, this release actually does have quite a bit to offer. You can download version Beta 13 from the usual spot here: https://github.com/Pacmanfan/UVDLPSlicerController/tree/master/UVDLP/Published

UV DLP Pico Projector Experiments Part 1

      I briefly mentioned in one of my last posts about ordering and receiving a pico projector to experiment with. I obtained a re-furbished  AAXA P2JR directly from their webite http://www.aaxatech.com/products/p2jr_pico_projector.html  . 

The victim

      It came with the usual accessories, power adapter, micro-VGA to VGA adapter, composite cables, etc... My intent in ordering this is to see if I can adapt it for use in a bottom-up (or top-down) UV DLP 3d printer. I was a little nervous for several reasons. Normally, I don't just purchase new pieces of technology for the sole purpose of ripping them apart, but I figured I needed to break a few eggs to make an omelet.

       I was hoping that this projector would 'just work' and be able to cure resin without any modifications, but I pretty much figured it was going to need some mods. After powering it up, connecting it to my computer, and projecting silly images across my walls, cats, and girlfriend, I decided to get down to business. I ran my latest development code of 'Creation Workshop', sliced up a model, and chose a nice slice to test with.

Initial resin test

      I put a few drops of UV resin in a plastic sandwich bag, laid it flat, and projected an image slice. It went pretty much how I figured. After about 30 seconds, I checked the bag, and to my disappoint (but not surprise) I saw that it had failed to cure the resin in the slightest. 

      Now, I have it on good source that at least one person in the community has been able to modify a pico-projector for UV DLP purposes, so I wasn't ready to give up yet. I began to prep the patient for surgery.

Back cover off

The green and blue cable goes to the DLP unit's LEDs

A flat ribbon cable connects the DLP to the main board

     I was kinda nervous taking this all apart. What if I break it? What if I nick off a resistor? Am I about to lose 169$ bucks? Well, I hit my stride, and decided to make some progress in the name of science. I was able to completely dis-assemble the projector into it's essential components, the case, the speaker, the battery, the main board, and the DLP unit which was attached to a hefty heat sink.

I gently lifted the little bar that held down the ribbon cable to remove the DLP. After freeing the DLP from the main board, I had a better chance to examine the actual DLP projector without fear of tearing the ribbon cable.

Note the blue/green wires, L-bracket and copper heatsink

Initially, I was a little puzzled by the 2 sets of 4 wires. 

A good view of the optic-path

At the bottom/left of the picture, you can see the L-Bracket, each side has a 4-wire lead. Light is being projected in from 2 sides - each at a 90 degree angle from each other. Notice the funny-looking bluish glass (it's important later).

I figured that the L-Bracket contained the LEDs, and that I was probably going to have to replace them with a better UV source. I carefully sliced through the black rubbery epoxy holding the LED L-Bracket to the side of the DLP Unit.

The removed Led bracket 

I examined the LED L-bracket and noted that 1 led was marked R/B and the second was marked G. Without getting TOO much in theory about how DLP projectors work, I wanted to make a few comparisons between Color-wheel types and LED types.

In a Color-wheel type of DLP projector, a light source is projected through a spinning color wheel. The wheel has an encoder mechanism that tells the control electronics which color the light is currently projecting through. The appropriate color mask is displayed on the DLP micro-mirror array.

In a LED-type projector, either 1, 2, or 3 LEDs are used. Since LEDs can quickly turn on/off, the control electronics will turn on a single color, the DLP chip will display the appropriate mask-image for that color, and the process is repeated for all colors.

An image I found that explains the optic path 

The above image is NOT a picture of my DLP device, but serves to show the portions of the optic path. My optic path is a little different, but has very similar elements. 

Light from LEDs shine through collumnating optics. Dichroic mirrors (http://en.wikipedia.org/wiki/Dichroic_filter) reflect a specific frequency of light through a fish-eye lens, reflect on a right angle, then pass through the DLP portion and out the projection lens.

I knew that the dichroic mirrors were going to be a problem. They only allows a very narrow bandwidth of light through. 

I went ahead and took out the dichroic mirror reflectors and replaced it with a single FSM (Front surface mirror). This essentially blocked off 1 light path, which was alright, because I'm only going to use 1 light path for a UV led.

I've got a bit more to say about this and a few more results, but I'm going to save it for part 2.

Stay tuned.

-Steve

More Pix

I took a few more pix and video of my machine in action. I was able to get a few more prints off the machine when it broke again.

My machine fell victim to UV resin-dissolving ABS-eater again. 

The 'before' pic

Some of the aftermath

I rebuilt the Z-Axis Build-Arm.

I used some 5mm aluminum plating I had laying around to re-build the z-axis build arm. I added some 5mm bolts with double nuts on the bottom to help adjust the build plate to parallel with the vat. Wingnuts tighten down the top.

Gender-bending required.

 I'm adding some basic serial control of the projector through an open serial port. I purchased a small F-F gender bender and started some programming. Instead of simply hard-coding some commands to control my projector, I took a more universal approach that allows the user to create new commands, give it a name, and assign a hex string to send to the projector.

The relocated power panel.

 I moved the power panel from the back of the machine to the side panel. I plan on adding another small panel for connection to the USB hub connected to the usb/serial connector to the serial port of the projector. I also have the Arduino connected to another port on the USB hub.

Goldberg Sphere. 50 micron accuracy Z, 100 micron X/Y, Dimensions are 15x15x15mm

I had a few more good prints out of my machine before it died again. I am very proud of the resolution attainable.

The rear bearing holder piece broke. I was sloppy with my dripping resin.

I really need to take more care and caution in dealing with chemicals. I've damaged several ABS printed parts to UV Resin. I printed another rear bracket. I just may soak it in UV resin and cure it to create a meta-material part.

The weird part about these parts dissolving is that they simply crumble into pieces. I've treated many ABS parts with acetone vapor, and parts simply 'Melt' a bit like cheese or butter, to smooth and harden parts. This UV Resin must be destroying the long CH bonds from the polymer molecules in the ABS. I think if I want to try a chemical UV bath and curing session for an ABS part, I should do it quickly before the ABS has a chance to break down.

 I'm already ordering parts for the next version of the printer. I'm going to name this version the "Mark I". The 'Mark II' version will have a much smaller projector that I recently ordered http://www.aaxatech.com/products/p2jr_pico_projector.html . My plan is to make a z-axis with a single linear rail and simplified build plate/vat design.

I also ordered a peristaltic pump. My plan is to have a simple forward/reverse switch connected to the pump to control the flow of resin in/out of the vat. 

We'll see what the next iteration of the machine will hold. For now, I'm going to fix my machine, keep printing, and improve my "Creation Workshop".

Creation Workshop Beta 10

Well, the time has finally come to release the next version of Creation Workshop. I keep saying this, but it's been too long since I made a release. Thanks to the help of dozens of users, I was able to make fixes and improvements to the slicing, generation of GCode, control of the printer, multiple profiles, and dozens of other items. Please see the ReleaseNotes.txt for a full list of improvements. The one things I really wanted to finish up - Automatic Support Generation is unfortunately not in this release. It will be coming soon, but I didn't want to delay this release any more.

I decided to move the software out of the Alpha stage and into Beta. It seems stable enough, and from what I've seen, dozens of users have been able to print some wonderful models with it.

I've taken the time to update the manual and add in a hardware guide to address many of the question I have about my setup.

You can get the latest Version 10 Beta from the usual spot here: https://github.com/Pacmanfan/UVDLPSlicerController/blob/master/UVDLP/Published/CreationWorkshop_beta_10.zip

Please take the time to play around with it and give some feedback. I look forward to hearing from you all.

-S

An update

So, I haven't made a blog posting for a while, but it's not because of lack of progress. Progress continues on my Slicing and building software https://github.com/Pacmanfan/UVDLPSlicerController .The main issue that I'm facing right now with my UV DLP Printer is the resin sticking to the bottom of the vat. The UV light cures the resin, and it adheres fairly well to the glass bottom of the build tray as well as the build arm platform. 

 The problem happens when the arm (and platform) try to lift the slice up. The printed resin slice is too firmly attached to the glass bottom of the vat, and the resin releases from the build arm platform instead of the vat platform. I've tried roughing up the bottom of the build arm platform for better adhesion, as well as greasing up the glass vat with silicone lubricant. No luck so far.

   Other designs I've seen use a mechanism for sliding and/or tilting the build vat. This allows the interface between the resin and the bottom of the vat to release suction before/during the lift sequence. 

One problem that I'm facing now is that my vat is fairly large, and I don't have room on the surface of my printer to add in a tilt/slide mechanism easily. The reason my vat is so large is because I didn't modify my projector optics for a shorter throw distance. I suppose the "ideal" throw distance would project the 1024x768 resolution of the projector onto a 102 x 77mm area on the bottom of the vat for a 10 pixels per mm resolution. My projector's minimum throw distance is a little longer, giving me a size of approximately 155 x 120 mm. This is fine by me, however; if I want to add in a tilt mechanism, I may have do one or more of several things:

 1) Adjust the projector throw distance to be shorter, so I can have a smaller vat, and more room for a slide/tilt mechanism on my existing machine.

2) Rebuild my machine with a larger top surface for additional space for the tilt/slide

3) Completely rebuild my machine - Now to be fair, I was thinking about doing this anyways. I want to have a smaller design that uses a horizontally mounted projector and a mirror to project the image to the surface of the bottom of the vat.

Well, I should just choose an option and stop stalling so I can get up and printing. 

On some good news, several people have reported to me that they've used my software along with their printers to successfully print!

I'm still in the process of adding more functionality to my application. Look for some good new features real soon.

-Steve

Resin tray rebuild and UV Resin testing.

Last week, I purchased some UV resin specifically designed for 3d printing from 3DInk http://buy3dink.com/p/59/uv-resin . It arrived yesterday and I immediately started conducting a few print tests. One of the first things I noticed is that the resin was much less viscous than the SolarEZ resin I tried before. The 3DInk resin flowed almost like water. Again, I put a few drops in a sandwich bag and placed it on my resin tray.

I fired up my software and picked a nice slice from the 'Goldberg Sphere'. The resin cured within seconds! Good progress so far. The next step was to test the adhesion (or hopefully lack of adhesion) to my polycarbonate resin build tray. I used a silicone spray and paper towel to grease up my build tray, and I place a small amount (few drops) of resin on the tray to be exposed.

The remains of my first build tray.

Unfortunately, The resin firmly adhered to the build tray. No amount of coaxing could remove it. I decided polycarbonate might not be the best choice, or I might have to use a thin film of Teflon coating on the polycarbonate. Either way, this build tray was toast. 

Shown here is the resin stuck to the tray.

I found a nice small pane of soda glass I had been saving, and re-tried with a few more drops on an un-coated pane. Even un-coated, the resin did not adhere very well to the glass. I was able to slide a few test prints off the pane.

Some test object slices of the 'Goldberg Sphere'

New build tray

I used some aluminum channel stock I had lying around along with the glass pane to construct a new build tray of the proper size. I used silicone sealant on all bottom edges and the corners to ensure a proper watertight seal.

I think this new build tray will do the trick. The last thing I need to do is finish the arm that connects to the ZAxis and dips into the resin. I've already added a leveling system to the bottom of the build tray on the printer. I may have to add a small leveling system (some screws) to the build arm.

Initial Alpha release of software

Well, I felt it's time to share the initial software release of my "Creation Workshop" UV DLP Slicing and control software. Any feedback would be greatly appreciated. You can download the initial release from GitHub here : https://github.com/Pacmanfan/UVDLPSlicerController/tree/master/UVDLP/Published

Some Progress this weekend

I didn't get as much done on my project this weekend as I had hoped. I did manage to print and attach some handles to the cabinet I built. I also put together the polycarbonate build tray with some plastic glue. Hopefully this will be a suitable tray for build. I still have a pane of glass that can be used if the UV resin sticks to the polycarbonate plastic too much. I also started the assembly of z-axis that I printed from my Thingiverse "Generic 23 printed axis" object http://www.thingiverse.com/thing:37123 .

The Z axis being assembled

The completed polycarbonate build tray

More DLP Printer progress.

I made a case for my DLP printer. 3/4 inch MDF. With a walnut top. Also shown are a bag of the printer parts for the z axis. Additionally, I cut some polycarbonate plastic for the UV resin tank. Tomorrow, I put it all together.  We'll see what happens.

Infocus Dlp

I'm going through the process of removing the color wheel, wish me luck...

Update: Alright, the patient lived. I broke off the color wheel of the Infocus 2104 DLP projector (http://whatlaptop.techradar.com/2008/11/infocus-in2104/). From what I understand, the color wheel was blocking the frequencies of light needed to cure the UV resin I have. The picture now looks black and white. I also removed a suspicious pane of glass between the bulb and the DLP chip. It looked coated, and I suspect it filtered UV. 

I found some fairly cheap UV resin the that's used to resin cure surf boards, among other things. http://www.solarez.com/ .They have a ton of dirt cheap UV resin products, and I've been in contact with the company who is looking into a special UV resin for 3d printers and the 3d printing community. 

I did a few quick checks, curing resin at various distances, using the resin and a popsicle stick. I used my app to project a few images. The resin I have is fairly thick, and I suspect I will need to add a few power resistors attached to the glass tank to warm the resin in the build tray to make it less viscous.

I've calculated and measured that I need a 12"x18"x24" enclosure to hold the project, pc power supply, motherboard (TBD), Arduino, stepper motor controller boards, etc...

3D UV DLP Printer progress

I've been working on a new 3d printer lately. It's a 3d UV DLP printer that uses a photosensitive UV resin to create high resolution models. I've made some good progress lately and I wanted to show some results. I made a posting earlier to Thingiverse, sharing my first alpha build of my slicing and control software. You can take a look at it here:  http://www.thingiverse.com/thing:40778 . I've also gone ahead and posted the source code on GitHub here: https://github.com/Pacmanfan/UVDLPSlicerController . I've very proud of the slicing and control application that I've created. Getting the slicing to work correctly and handle all the special cases was no easy task.