Friday, March 21, 2014

3D DLP Printer


I finally got around to taking some pictures of my 3D DLP Printer build.  I would like to give many thanks to Tristram Budel for his Instructables article detailing a DLP printer build.  This article was used as a great starting point for me.  It is full of information, and is a recommended read (http://www.instructables.com/id/DIY-high-resolution-3D-DLP-printer-3D-printer/)





These two photos are the overall of the build with the panels removed.  The panels are needed so the exhaust fan and pull the resin vapors out of the house without letting any escape.  The Bucktown polymer's resin I am currently using (which is VERY high strength once cured) has flammable vapors. I'm working on a carbon air filter with a stronger blower fan for something that doesn't need to be piped to the outside.

Some Videos: (the fluorescent lights do not cure the resin, I can keep them on all day long without issue.)
Here is a side view of the mirror and projector, you can also see the stepper motor the controls the Y axis slide.  This has a home limit switch in addition to the Z axis limit switches.


The Y-axis limit switch.
Z-axis limit switch. I home it, and then drop the build plate to the VAT surface whenever I switch VATs.
Demonstration of a rapid Z axis move from home.  The borosilicate glass is VERY strong. The suction force of the whole build plate is overcome with the NEMA 23 motor and Z stage.

Z-axis homing operation

Z moves...



I used 1" T-slot aluminum to create a "box".  I have the Y-axis vat slide on two linear rods with bearings.  There is a single NEMA 17 stepper that pulls the vat parallel to the Y-axis.  While the Z is lifting, this Y axis motion helps counter any suction forces encountered.  I have printed relatively large prints, and this was very successful.  No tilting or twisting needed.

The Z-axis is a linear ball screw stage I got off e-bay.  It has 14" of travel.  There is a NEMA 23 stepper attached to this axis. The whole thing is controlled by an Arduino Mega paired with a RAMPS 1.4 board with Pololu stepper drivers.  An ATX supply provides the power.




 The build plate is a simple cut piece of aluminum.  104mm x 204mm.  I sanded with a 120 grit sand paper and cleaned it.  The prints stick to this very well.

 The 5/8" linear rods and bearings support the vat and Y-stage.  I used some more T-slot aluminum and REPRAP printed brackets to secure it all together.

 Here is the side view.  My 1080p DLP projector (Acer H6510BD DLP) and a single surface mirror I got off ebay.  No modifications were made to the projector, I didn't remove the color wheel or anything.  I cut some acrylic to make a 45 degree angle and epoxied an adjustable mount.  I can adjust the distance to I can achieve higher resolution prints that are smaller, or larger lower resolution prints for big objects.  Still playing with the cure times to get the build times lower.

 Here is the back with the NEMA 17 stepper for the Y axis.  It has a simple threaded rod.  There is no need for high accuracy on the Y axis.  It's simply used to help detach the printed layer with a lateral force.  I have found 5mm of deflection for the complete Z axis cycle is enough.
 Here is one of my VATs that needs to be recoated.  I used a 300mm x 300mm borosilicate glass (https://www.lulzbot.com/products/borosilicate-glass-bed-300mm-x300mm) with aluminum for the walls.  Black silicone to stick it all together, and Sylgard 184 for the coating.  The borosilicate glass is "VERY" strong.  I doesn't deflect at all with a fully exposed 104mmx200mm print.  The Z axis speed has to be reduced, but they seperate with 0 missed steps...
Here is the peristaltic pump I got off e-bay to get the resin out of the VAT.  It works great, just learned the hard way that you need to flush it with isopropyl alcohol after each use....

Here are some prints I did of a compound bow stabilizer and sight mount I designed for the Hoyt Carbon Matrix:  The stabilizer was a large print, I had to make sure the Z axis was almost perfectly perpendicular to the VAT.










This is an AR-15 Quad Rail.  This was an extreme test of the full 14" travel.  The only issue was the "bleed through" of layers, I need to add more graphite powder to the resin to prevent this. 



Current settings:

First 5 layers - 13 seconds
Each 100micron layer - 6.25 seconds

I use Creation Workshop for the prints with the code modified to move the Y axis instead of X for the "tilt" setting.http://www.envisionlabs.net/

Source Branch:
https://github.com/Pacmanfan/UVDLPSlicerController

Some of the STL files I made for this build:

This is the build plate mount. It secures to 1" Aluminum T-slot.  I used epoxy to secure to the aluminum plate.  
https://drive.google.com/file/d/0B8S25d-5M3YyWTlmVWd4RWlKTUk/edit?usp=sharing

This is the retainer that secures the vat to the Y-axis slide.  It's simple but very effective.
https://drive.google.com/file/d/0B8S25d-5M3YyM0FhSGMxb3VRYUk/edit?usp=sharing

Y-carriage slide stem:
This takes a simple hex nut and secures to the T-slot aluminum to control the Y-axis slide.
https://drive.google.com/file/d/0B8S25d-5M3YyenlRVDBwVVpKbHc/edit?usp=sharing

Z-arm mount - A reinforced right angle mount for the Z-arm. Not currently being used in the pictures, but does work well when 4 are printed.
https://drive.google.com/file/d/0B8S25d-5M3YyZ21lOUZGMWdqQk0/edit?usp=sharing


ADDITIONAL FINDINGS SUMMARIZED FROM COMMENTS/EMAILS and GENERAL QUESTIONS I'VE HAD SINCE HACKADAY POSTED A LINK TO MY BLOG:

** Z-stage - "THOMSON LINEAR MOTION 2RBM120DMHL QUICKSLIDE 14-3/8" TRAVEL" The pitch is large, which surprised me that 100 micron layers are no problem for it. The ballscrew has no measurable backlash, atleast not with my budget calipers. I've tried down to 50 micron without issue. I would need to do some more experiments to see what it's capable of. I'm using 1/16 microstepping on the stepper drivers with a big NEMA 23 stepper on this axis.

When I get some time I'll try some experiments to see what layer thickness I'm able to get reliably. The 1080p projector is a dream for X, Y.

** I chose this projector simply because it was tried and tested with the instructable article by Tristram. The amount of UV that comes out of it without a single modification is wonderful.

** Bucktown polymer ZVE500-V420  UV resin:
   12 second initial layers (5 layers)
   5.25 seconds per 100micron layer
  Some prints with overhang geometries need some graphite powder added to prevent bleedthough from layer to layer. 

** Makerjuice SubG+ resins.
   First 5 layers - 13 seconds
   Each 100micron layer - 6.25 seconds


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More updates to come. If you would like to donate to my projects fund, my paypal is: zothar@zothar.com  All donations will contribute to open source efforts and documentation to make others lives easier.  It's a pain trailblazing a new or dirty path, especially with limited funds...