Dual Machine - Laser/3D Printer

General discussion of laser machines

Dual Machine - Laser/3D Printer

Postby bdring » Wed Aug 04, 2010 5:25 pm

cupcake-cnc-final.jpg

I got a little excited about seeing all the 3D printers at the Detroit Maker Faire. I realized that I could probably adapt my laser to be able to work as a dual use machine.

I need to do a little more research, but I think the only new parts I would need would be the extruder head and the extruder controller. The rest of the parts are probably already in the laser. It all runs on G-Code with some special commands for the extruder. Several people have alread done this to their CNC mills. They are often called RepStraps. They are typically run though EMC2, but Mach3 could probably be adapted to work.

The concept is this: I would make a quick release 3d printer carriage that rides on the gantry just to the left of the current laser mirror/lens carriage. It would connect the the current carriage to provide X motion. It would be heavier, so the speed would be slower, but 3D printing does not require much speed. It would be disconnected and removed for laser work. It could even be stored on the gantry to the extreme left if you don't mind the reduced X travel. the left side would keep it out of the laser beam.

I think the only big modification to my machine would be in the Z axis. Right now it is not too stable in the X/Y axes while moving up or down. It relies on the straightness of the threaded shafts which are less than perfect. Has a visible wobble when moving. I think I will change to some sort of ridged support. I am thinking about a wide central v-rail system. It might still be powered by by the threaded shafts but they would not be able to move it.

Am I missing something? Is this a viable concept?

If I persue it, I'll probably start a separate buildlog for it.
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Re: Dual Machine - Laser/3D Printer

Postby lasersafe1 » Wed Aug 04, 2010 11:27 pm

Personally I would like to see a little more research into fusing of powders or liquid acrylic with a laser. The extruder outputs are improving, but a powder or the surface of a liquid could give much finer resolution. It was my understanding that all of this 3D stuff originated as a system of lasers converging at a certain point in a liquid acryilic to harden it. The object would then be lowered into the liquid one step at a time as the layer above it is hardened. This was probably 10 years ago when I first read about it. I do know there are UV hardener additives for liquid acrylic. We aren't likely to find anything for 10 micron light.
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Re: Dual Machine - Laser/3D Printer

Postby bdring » Thu Aug 05, 2010 1:52 am

Yes, I am surprised more people are not doing that. I had some parts done for me 20 years ago in SLA. They used a UV laser cured fluid and the process you described. The fluid was crazy expensive though. The latest state of the art is sintered powder like Shapeways is doing

I am very impressed with the fused deposition MakerBots though. The parts are good and strong. For less than $200 I think I can add it to my laser.
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Re: Dual Machine - Laser/3D Printer

Postby Tweakie » Thu Aug 05, 2010 6:01 am

This is my first attempt at using the process of 'Selective Laser Sintering' http://en.wikipedia.org/wiki/File:Selec ... ematic.jpg
This little bike was made in just two layers using a stacking frame system which was done just as a trial and the MKII 'Z2 lifting system' is now under construction.
For the sintering material I used cane sugar (which makes any parts that are made edible :D ) and inspiration came from the CandyFab project which has been running for some years now http://candyfab.org/.

Image

Image

This is the progress so far on the new Z2 lifting system.

Image

There are a dozen or more different methods for 'rapid prototyping' and I have just chosen this one for initial experimentation. It would be great if others chose a different method then we can all compare notes :D

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Re: Dual Machine - Laser/3D Printer

Postby lasersafe1 » Thu Aug 05, 2010 11:55 am

Sugar bike is so Cool! Wonder if powdered sugar would work for finer resolution?
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Re: Dual Machine - Laser/3D Printer

Postby bdring » Thu Aug 05, 2010 12:15 pm

I'll bet it smells a lot better than acrylic. I would love to see a video.
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Re: Dual Machine - Laser/3D Printer

Postby Tweakie » Thu Aug 05, 2010 12:38 pm

LS1,
Thanks for the suggestion, I need all the help I can get here. If it is what we call Icing Sugar, here in the UK, then it doesn't work too well - it just ignites, instantly - probably because I have to have the air assist at a low flow rate to prevent everything blowing away (perhaps an air knife will be the next project or Nitrogen gas assist ?). Obviously there are many materials to try (the commercial product is still very expensive) and I will gradually work my way through - microballoons (tiny glass spheres used for thickening GRP products) are tempting me at the moment. Who knows, I might discover a common product that works just fine :D .

Bart,
Spot-on, it smells just like a candy factory. When I complete the build jig I will make a video (but I doubt it will be very exciting to watch - unless it catches fire :lol: ).

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Re: Dual Machine - Laser/3D Printer

Postby lasersafe1 » Thu Aug 05, 2010 1:24 pm

Certainly a fine powder would kill the idea of any air assist. The flame issue could be solved by having the powdered sugar under vacuum or in a static volume of inert gas. (unless burning sugar produces oxygen). This design would need a moving XY table within a chamber that has a ZnSn window seal.

So what do we have? Solids that can become liquified momentarily so they stick. Liquids that are normally fluid but harden when heated.

What about a thick sugar solution that you have mixed in boiling water to make it super-saturated. This is the process normally used to make rock candy on a string. The laser would heat the surface of the liquid and locally boil off the water leaving behind a thin solid sugar. Let this layer drop with a Z axis and repeat.
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Re: Dual Machine - Laser/3D Printer

Postby Tweakie » Thu Aug 05, 2010 4:47 pm

Comment From Buildlog Author What about a thick sugar solution that you have mixed in boiling water to make it super-saturated. This is the process normally used to make rock candy on a string. The laser would heat the surface of the liquid and locally boil off the water leaving behind a thin solid sugar. Let this layer drop with a Z axis and repeat.


Thanks LS1,
This is, I think, one brilliant idea which I will just have to try. (when I have completed the system I have already started).

Please keep the ideas coming, I think Bart has started a good thread here - when we consider the diversity of experience / knowledge which can be combined in a forum everything is possible, even this ? http://www.thinglab.co.uk/printing_prod ... bCatID_=66

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Re: Dual Machine - Laser/3D Printer

Postby bdring » Thu Aug 05, 2010 5:00 pm

We used to make Rock Candy as kids. You supersaturate the solution by adding sugar to boiling water. As I understood it, when it cooled it became more saturated. We then added a seed crystal on a string and it grew from there.

So, who knows which way your idea may go. A CO2 laser is perfect for that idea, though, because it will not go past the surface of the water.

P.S. I did a blog article a while back on the RepRap powder project...still quite rough. We need to find the raw powder.

http://www.buildlog.net/blog/2010/06/d- ... sintering/
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