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

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".

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

UV Printer getting closer to completion

I spent quite a few hours this past weekend working both on my 3D UV DLP printer, as well as the control software for it. I took the time to take a bunch of pictures. This is going to be a picture-heavy post, so please bare with me.

In this pic, I'm attaching the z-axis arm to the top of the printer. I've cut a hole to allow for the DLP projector to shine light on the bottom of the plastic build tray.

Here's a picture of how it's attacked. I used 4x 5mm bolts to secure the z-axis and prevent any wobble.

Shown here is the attached Z-Axis with the build tray in place.

I have the projector mounted at a fixed location on the interior of the printer cabinet.

I remembered that I had a 4 axis CNC stepper motor controller board along with an Arduino Mega 2650 that I had used in another project. I plan on recycling some of it as a controller.

After debating what I should use as a power supply, I settled on using a power supply from an Arcade Cabinet (Yes, that one...http://probjectblogs.blogspot.com/2009/04/heres-donor-tv.html). It's a 5v 11amp and 12 V 4amp power supply. More than enough to power an Arduino and NEMA 23 motor.

I wanted an integrated 1-push power system, so I dug through my spare parts box and found a 3 prong power receptacle as well as a push on/off mains switch.

I quickly designed and printed a plate for the rear of the machine to hold the switch and power receptacle.

Shown here is the mounted power supply wired to the back plate and the DLP Projector. Now, one push can turn on the entire system.

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

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...