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OpenExposer

An affordable Arduino controlled multipurpose laser exposing device. Use it for SLA Printers, PCB Exposing, Laser Harp etc.

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This project was created on 05/11/2014 and last updated 9 days ago.

Description
Ever had the need for high res 3d printer, but you don't have any spare dlp projector or the money for a commercial stereolithography printer?

Have you ever tried to produce a pcb using toner transfer method and finally at the fifth try you gave up?

OpenExposer comes to the rescue. OpenExposer is a low cost and easy to use/build laser exposing unit suitable for many different applications.

Possible use cases:
- stereolithography printer
- uv pcb exposer
- laser harp
- show laser

Main features:
- unit for multiple laser exposing processes
- Arduino compatible
- low cost (standard laser printer) parts
- case parts lasercut or 3d printable
- up to 2 stepper motors can be connected
- additional I/O ports for custom extensions
- simple protocol
- extendable host software
Details

 What is Open Exposer?

The Open Exposer is a Open Hardware device which can be used for multiple laser exposure applications. For example you can build high resolution 3d printers, pcb exposure devices and much more... 

How does it work?

The main components of the Open Exposer are a laser and a polygon mirror. The principle is well known of laser printers. The polygon mirror is used to produce a laser line. An Arduino is used to control the device. By quickly switching the laser  on and off it is possible to generate any line pattern. The magic happens in the Arduino Firmware. You only have to set a Flag in Firmware for your polygon mirror.

The Arduino with my self-designed Open Exposer shield is used to control the device. The Open Exposer can interpret G-Code. So it is easy to control. 

The Arduino shield will have pin outs for two stepper motors and different I/O's, which can be used for other sensors like end stops.

What can i do with Open Exposer?

My favorite use case is a high resolution 3D resin printer, because it will be realizable for under 500 $. With the new design (laser cut parts) it will be easy to produce and easy to assemble. That is the reason why the first "prototype" extension i have built was a 3d resin printer.

The pictures above are showing the bearing extension which is used for the 3D resin printer. 

The following picture shows a possible pcb extension. It will work like a laminator. Some rolls push the photo sensitive pcb over the laser slot.

Open Exposer is an easy to build and very cheap device, because it uses standard components.

System Design

Hardware

The main unit is controlled by Arduino and the Open Exposer shield. The Open Exposer shield can carry two stepper drivers. It also contains the laser driver circuit. An additional micro controller is used for controlling the polygon mirror speed. In a later version the Arduino and the Open Exposer shield will be replaced by a single pcb. 

Software 

The software consists of four parts. The first part is the arduino firmware, where all the hardware controlling magic happens. 

The second software part is the third party software which is used to produce the exposing data. This can be a 3D CAD Software like OpenScad , Slic3r , Eagle and so on... 

The third software is the Open Exposer G-Code generator. The Open Exposer G-Code generator offers an interface for custom modules. It is used to generate G-Code from your third party software data. 

The fourth software part is the host software which sends the the generated G-Code to the Open Exposer.  You can find a lot of G-Code sending host software in the internet.

Some Example Videos of different prototyping stages.

Open Exposer first firmware test (exposing)

Open Exposer as 3D Printer Prototype exposing Test.

 

Open Exposer use case examples

High resolution resin 3D printer.

PCB exposure device. 

Used Open Components: 

Softtware: 

  • Python
  • Slic3er
  • Accel Stepper Library 
  • Printrun Tools ( as host software )
  • Hardware: 
  • Arduino
  • Laser Driver (die4drive)

Components
  • 1 × Laser Cut or 3D Printed Open Exposer Parts case, mirror mount, laser mount etc
  • 1 × Laser Diode 405 nm uv laser diode
  • 1 × Glass Lens
  • 1 × Laser Housing
  • 1 × Laser Driver PCB
  • 1 × Arduino
  • 2 × Motor Driver (optional for 3D Printer and PCB Exposing)
  • 1 × Polygon Mirror Old Laser printer, ebay or aliexpress
  • 2 × 3mm Bolts and Nuts 2 or more
  • 1 × Power Supply

See all components

Project logs
  • New design printed and assembled

    9 days ago • 0 comments

    After two weeks of hard work, finally i present you the new version of the open exposer 3D Printer....

  • New Design

    a month ago • 0 comments

    I am working on a new printable Open Exposer Design. This is a first rough draft.

  • New Laser Cut Design

    3 months ago • 0 comments

    Today i worked until the late evening at our local Fablab. I finished the Open Exposer laser cut design. It contains the following components.

    - Open Exposer base unit

    - PCB Exposer extension

    - Bearing extension

    This weekend i will be at  Kerkrade Mini Maker Faire (NL) .

View all 24 project logs

Discussions

Jasmine wrote 4 months ago null point

Hello Mario, I just wanted to remind you that this is the checklist of what must be on Hackaday Projects by August 20th for OpenExposer to be considered for the next round of The Hackaday Prize:
- A video less than 2 minutes long describing your project. Put it on YouTube (or Youku), and add a link to it on your project page.
- At least 4 Project Logs (you've got 14, so that's covered)
- A system design document. Please highlight it in the project details so we can find it easily.
- Links to code repositories, and remember to mention any licenses or permissions needed for your project. For example, if you are using software libraries you need to document that information in the project details.
Thanks for entering and good luck!

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mbasecnc wrote 5 months ago null point

Hi Mario, very interresting project.
How long does it take to print the resin examples you made, will a stronger (+200mw) uv laser improve the curing speed. I'm planning to create a printer similar to yours and are wondering wat the laser power does to the curing time.
Thanks for your help.

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Mario Lukas wrote 5 months ago null point

At the moment i am playing around with different exposing times. This small example took 5 mins. Maybe it is faster with a stronger laser. But it also depends on the used resin. When the whole process is stable i will work on efficiency.

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kdogzxc wrote 6 months ago null point

what is the thing you are holding the resin in made of? I have read that you need something that is non stick and UV transparent.

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Mario Lukas wrote 6 months ago null point

Sorry for my late reply, but i am preparing my Maker Faire booth. For this early version i am using Perti dishes. The dishes are coated with ELASTOSIL RT601 ( it is like Sylgard 184). In germany it is hard to find a shop which sells Sylgard 184. So i decided to give ELASTOSIL RT601 a try. It works, but it is expensive. When the printing process is stable i will do some research to find a cheaper material.

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Jasmine wrote 6 months ago null point

Hello Mario, if you want to enter this project for The Hackaday Prize, login and use the 'submit to' under your project images on the left hand side. Any problems give me a shout.

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Mario Lukas wrote 6 months ago null point

Thanks, done.

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Mario Lukas wrote 6 months ago null point

@dandumit, @nmz787 Sorry i was at a Rock Festival during the last 5 days. I will post some more details during the next days.

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dandumit wrote 7 months ago null point

Very nice project ! I would like to use it to expose my PCB boards. Would you please give some more details regarding speed of mirror ? On logs you said that you are using an attiny 2313 to lower the speed. I have also some exposing units and I would like to try this.

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Mario Lukas wrote 6 months ago null point

Thank you. I will design the PCB Exposing Unit after the Makerfaire Hannover. The attiny2313 is used to regulate the mirror speed which currently is 55 rotations per second at 333 Hz scanrate.

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nmz787 wrote 7 months ago null point

I've been very interested in using a blu-ray writer optical sled, taking advantage of all the engineering money that went into the optics and beam shaping... I know the DOF is quite shallow, but I want to do micro-SLA (exposing photoresist with micron or sub-micron sized beam spots).... What do you think about that? Others have used a laser pointed into the ocular (eye piece) of a microscope, then tracing the laser by adjusting the microscope stage... but my thoughts are the beam shape degrades, and requires a microscope... with blu-ray optic and laser, you just would need another old CD/DVD rom to complete a 2 axis CNC laser.

Best regards!

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Mario Lukas wrote 6 months ago null point

The microscope solution should be possible, have a look at the following link: http://goo.gl/29oGWL
There was a talk at our Dorkbot meeting a few month ago. As i remember they used telescope or microscope optics.

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frank wrote 7 months ago null point

Nice. I've just started a similar project. I'm using a closed looped galvonometer as used in light shows to deflect the laser. It is placed about 1 meter away from the vat, and uses a lense that focus to a point at 1 meter. That way I get minimal distortion as the beam moves from left to right.

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x3n0x wrote 7 months ago null point

Just curious, have you approached the problem of varying focal length as you trace the arc from the polygon mirror? Laser printers use a specialized type of lens to insure the focus is consistent, allowing a consistent spot size over the entire sweep of the beam. Those funny curved lenses you see in the scanner housings you got the poly mirrors out of are what do the trick. The math is not trivial... You have to solve a complicated differential equation to generate a lens solution. This really becomes an issue if you want to use the device for PCB direct exposure without a mask. If you use a mask though, the laser simply becomes a light source, and the process proceeds like a normal photo etch process.

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Mario Lukas wrote 7 months ago null point

Thank you for your suggestion. Yes i know the problem of varying focal length. But the lens which you can find in laser printers is made for a infra red wave length. I think they absorb to much of the uv laser power, so they are not suitable. I am trying different approaches to solve it. It actually also works great without a lens. It's all a matter of resolution. But in the first step i have to get the process stable.

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x3n0x wrote 7 months ago null point

You are correct about the lenses! They are also plastic, so any substantial laser power will result in damage to the lens. The ones I looked at were not treated or coated in any way because of cost, and depending on the material might work OK for UV if the laser power is weak enough. I asked because I was looking at building a similar system, and was looking at some other solutions for scanning the laser that do not involve changing the focal length over the scan area. I was curious what you had done. Good luck with everything!

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Mario Lukas wrote 7 months ago null point

The main focus of the OpenExposer Project is on the little red box which should contain all electronic and optical parts. This box should be clampable to different modules. The 3D printer which i am building currently is only one of those clampable modules. For PCB etching i am planing to design a module which works like a laminator. The whole project is "work in progress". You can find some people who already did it with and without those lenses behind this link http://www.mikrocontroller.net/topic/306825#3645579 (in german only)

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RodolpheH wrote 7 months ago null point

For stereolithography, this kind of system isn't optimal but you can try to get it better than any others. However, you should know there is some patents on 3D printing using a laser projection system. I hope you won't get caught ;)

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Mario Lukas wrote 7 months ago null point

Thank you. I use this kind of system because it is a very cheap solution. And everybody with an old laser printer laying around is able to build it. Most of the patents ran out in the last years.

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Eric Evenchick wrote 7 months ago null point

What kind of laser does this use? I haven't worked with photolithography, but do you need specific laser power or wavelength to expose the resin?

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Mario Lukas wrote 7 months ago null point

At the moment i use a 405 nm laser diode with 80mw and it works great with the resin from Spot-A-Materials (spain). I will post some more pics soon. For PCB exposing you will need more power, for that usage i recommend a laser diode with up to 1w.

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Eric Evenchick wrote 7 months ago null point

Are those hard to get due to regulations on importing lasers (at least in the US)?

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Mario Lukas wrote 7 months ago null point

I bought mine on ebay. Laser diode and lens module (housing) separated. The driver board is also custom made. So i had no problem to get the parts (in germany).

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Mario Lukas wrote 7 months ago null point

By the way, laser protection glasses, or laser safety glasses, are an absolutely necessary part of the safety apparel!

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