Maureen

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Crystal Clear action run.png
Maureen

Release status: experimental

Sea star.jpg
Description basic stereolithography printer made from commodity parts
License Apache 2
Author Pbharrin
Contributors
Based-on Stereolithography/DLP
Categories RepStrap, stereolithography, Resin
CAD Models
External Link


Maureen is an open source SLA printer based off of commodity DLPs.

"It takes a thousand men to invent a telegraph, or a steam engine, or a phonograph, or a photograph, or a telephone, or any other Important thing-- and the last man gets the credit and we forget the others. He added his little mite--that is all he did." Mark Twain

Contents

TODO list

Here is a list of important stuff that needs to be done, anyone can do this if you are reading this you can do it. Jump in!

TODO [ ]: Draw and layout PCB UNO shield

TODO [ ]: get parts list for Z-stage from here.

TODO [ ]: build Z-stage, take pictures and write up documentation

TODO [ ]: Create a first pass of CAD files for support structure: something to mount the DLP to and something to hold the vat.

TODO [ ]: write up how to modify DLP for this project

TODO [ ]: research/write up software stack


There is a an awesome version of such a printer at B9Creator. The plans for this have not yet been released.

You can also join the #lemoncurry chat on IRC for pressing questions.

A very active group discussing the printers can be found here

Some theoretical documentation and lots of links can be found at Lemoncurry.

Structural Frame

The structural frame is going to be made out of wood. Wood is chosen because; it's cheap, it's cheap, it can be cut on a laser cutter, it is strong, it can easily be modified for improvements, and it looks good.

5mm or 1/4 inch birch is what the initial prototype will be made of.


Case concept.png


A sketchup model of the frame can is available:File:Case concept.skp to explore.

Z-Stage

This section will be removed at the Z-Stage is now part of the frame.

The best Z-stage we have seen is: Z-stage dipping mechanism made by the Sloth. However this relies on a number of parts printed on a 3D printer. The current Z-Stage is now part of the structural frame.

Vat

The vat is made from soda glass (the class in windows) and acrylic. Soda glass is used to allow as much light as possible to pass through from he project to the liquid in the vat. Clear acrylic can block up to 70% of UV light. Depending on the resin you are using this may be light you are relying on for curing the resin. For this reason soda glass is chosen as the material for the bottom of the vat.

Physical Vat Construction

You will need to cut the acrylic parts yourself or buy them from some source. The soda glass you can find in a picture frame, and can be cut to the correct size.

Vat Cad Files

Vat Slider File:Vat Slider.pdf made from 1/4" acrylic (make sure the acrylic is UV blocking)

Vat Walls File:Vat walls.pdf made from 1/4" acrylic

Platform File:Platform Rev0.1.pdf made from 1/4" wood

You will need to get a piece of glass, then cut it. Glass cutting kits are common the following image shows a piece of glass from a picture frame being cut to the vat size.

Maureen vat glass thumb.jpg

Next assemble acrylic components that make up the vat walls, it is recommended to use acrylic cement to hold the walls together.

Maureen vat walls thumb.jpg

Now we need to attach the vat walls to the soda glass vat bottom. We will use silicone that I bought at the local hardware store to do this. The silicone I used was "Premium Waterproof Silicon" by General Electric. Spread the silicone out on the bottom of the acrylic vat walls all the way around. Now attach the soda glass vat bottom. The silicone tube says that within three hours the bond will be waterproof but it will take 24 hours for the bond to fully cure. Put this vat aside and do something else while it is curing, perhaps build the X-stage.

Maureen vat bottom thumb.jpg

PDMS

We are going to coat the bottom of the vat on one side with PDMS (Polydimethylsiloxane). The reason we are going to do this is to make it easier for the object we are printing to detach from the bottom of the vat. It was discovered that a small layer of Oxygen forms near the PDMS which prevents the resin from sticking to the PDMS. [1]

One effective version of PDMS is commercially available as Sylgard 168 from Dow Corning.

X Stage

Maureen vat slider thumb.jpg

Electronics

Arduino Uno.

The Arduino Uno will be used to control the printer hardware due to its low cost and wide adoption.

Custom Uno shield

This needs to be created, it will have two slots for stepper drivers and a linear regulator for the power supply.

Stepper Motors

DC power supply

Software

DLP Projector

We are going to need to make a few modifications to the DLP projoctor. The modifications are: removing and UV filters and allow the projector to focus on close objects.

Here is a photo of an opened DLP projector, the yellow arrow traces the path that light takes from the bulb to leaving the projector.

DLP overview.jpg

The projector needs to focus on the bottom of the vat. This may require the lens assembly to be moved forward.

Remove/disable the color wheel.

First you will need to locate the color wheel. Below is a picture of the projector with the color wheel shield removed.

DLP no colorwheel shield.jpg

Resin

Resin Sources

An overview of sources of uv and visable light curable resins is available at the Printing Material Suppliers page. Orders ship 10 business days after payment is sent, plan well in advance. Resins also high in VOCs and require ventilation. I mean really serious ventilation. I had the resin in side a plastic bag inside two boxes and the whole room smelled like a toxic waste dump. If you are not ready for serious ventilation get the low VOC blend.

Parts Vendors

References

[1] Dendukuri, D., Pregibon, D. C., Collins, J., Hatton, T. A., and Doyle, P. S. (2006). “Continuous-flow lithography for high-throughput microparticle synthesis”. Nature Mater., Vol. 5, pp. 365–369.