An affordable Arduino controlled multipurpose laser exposing unit. Use it for SLA Printers, PCB Exposing, Laser Harp etc.
This project was created on 05/11/2014 and last updated 10 days ago.
I just solved the scattered light problem. Now i am working on a new protocol. I will switch to gcode. So it will be possible to use an existing host software . (e.g. pronterface).
Next week i will start to make the PCB Exposing (laminator like) attachment.
I am back from Hannover Maker Faire. Time to proceed with the project. Thank you to all visitors of my booth.
The copper plate seems to work good. I am fighting with some scattered light. I don't know where it comes from. The first build of the Exposer Box doesn't have problems with scattered light. I changed the laser position last week, maybe i have to rework or calibrate the laser mount. I will find out tomorrow how to fix it, because there are many things to prepare for the Hannover Makerfaire.
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.
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.
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.
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.
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.
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.
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.
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.
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!
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)
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 ;)
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.