laser moleculare material phase state change to increase quality of prints

this is a little bit of some off the wall research I've been doing on my own to improve the quality of prints i make. I have until now been doing chemical experiments with acetone, which still require manual processing and post processing, and well 4-6 hours of recurring to even handle the post processed parts. the parts look well when dipped in acetone about 20 times, at a rate of 4 times a minute.

I have here something that is just being experimented on that looks really promising, if anything else, because the part is basically ready to go after it is done processing with laser. also laser power could in theory be increased enough to get rid of stringers, and still not melt or change the color of the large object. i already have videos of increased laser power drawing images onto white abs. so there is some fine tuning to do.

However, what i think is really cool is this experiment to use lasers to phase change the abs from a solid to a liquid long enough for gravity, or forced air to move or smooth out the liquid, and then have it instantly cool back down again is a better and faster alternative. my goal is to create parts without tool marks and z height effect of Cartesian printing.

here are my laser power settings. if the laser power settings are just right, the plastic should not change color. i will do a test in the next few weeks with white plastic and yellow plastic to determine the settings.

10mm/s at laser output of 10watts with .05mm wide pulses

laser molecular material phase state change on abs.

create parts without tool marks.

here is object before and after phase 1
before:


after:


here is a video of pass 1 process

phase 2 process i turned the object on its side to get the front with the laser, as the beek was in the way, and some parts were vertically flat, so no laser exposed. here is the part after 2nd pass. phase 2 was at 12 watts, and there was some areas of plastic that split, so next object i will try less power and maybe 2 passes at a particular angle.

here is that picture. some work needs to be done because the temp change caused some lines to split open rather than melt together. also some areas bled into each other too much.

second pass here:


also there is some residue on the plastic, so washing it may show a better part,

anyone interested in me doing some experiments on this further? cameras do not do or capture images detailed enough to show it justice. I'll work on capturing better images.

Edited 1 time(s). Last edit at 07/03/2011 07:10AM by jamesdanielv.

Have you thought about doing this layer by layer during the print?
It would take longer but you could focus the beam correctly.

... i had the idea to use fishing line (Nylon) or another material in form of a thin filament and fuse the solid filament to the surface without extruder heater ... simply touch with the tip of the filament the surface, melt the connecting point by laser, so it fuses to the surface, and then draw a fusing line as with the common FDM printing.

Stringing will be avoided by a short burst with higer energy, so the filamet can be retracted without a string.

With energies high enough you can use any wire or material you can fuse to the surface ...

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I've thought about several things, but mostly the amount of power and the angle of the beam to be 90deg that of the z axis. some experimenting and such. abs has a wide range of temp that it is liquid at, so focus does not need to be that exact over an area, just needs enough power to melt and cooling to cool properly especially if the part is less than 3 inches from my testing so far. it is important to ensure not much vaporization is going on as well, so weighing the part before and after with a gram scale will be important as well.

here is a better picture with using laser on one side of an idler.
it took a photo booth and 3 light sources to bring out what the detail change is. here is before and after. you can now see that my printer i used has a slight wobble. not really noticeable before. without the light sources on the object it looks professional

To be honest this is the first photo where it actually looks somewhat nicer afterwards. But maybe this is the flash, maybe try using a diffuse lightsource. (Desk lamp reflecting off paper works nice for macros...)

I wonder if the result could be improved if you align the laser path to the outline layers. If you always travel in one direction you will hit the layers with a different angle resulting in a different result. This may also a reason why the idler looks so much nicer than the tux...
Completely aligning it would be impossible to do without a 4 (+) axis robot though.

A compromise would be using the laser horizontal and using a elliptical robot.

jamesdanielv Wrote:
-------------------------------------------------------
> here is a better picture with using laser on one
> side of an idler.
> it took a photo booth and 3 light sources to bring
> out what the detail change is. here is before and
> after. you can now see that my printer i used has
> a slight wobble. not really noticeable before.
> without the light sources on the object it looks
> professional


Interesting concept.

I've noticed pretty much every single printer using standard threaded rod has a bit of wobble. Acme lead screws are the only thing I've seen so far that really helps the issue (assuming very small wobble)

Since you seem to be going this route because you didn't get good chemical results, did you try using vaporized acetone to smooth things out? Using a pressurized spray bottle or heating acetone to make vapor has produced very good results by comparison, and only requires a few minutes to completely re-harden. It was discussed in the following thread if you missed it. [forums.reprap.org]

Edited 2 time(s). Last edit at 07/06/2011 09:44AM by Andrew Diehl.

Quote

I've noticed pretty much every single printer using standard threaded rod has a bit of wobble.

Mendel doesn't wobble because the axis is constrained to follow the smooth rod and the threaded only has a bearing at one end so it free to wobble.

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[www.hydraraptor.blogspot.com]

I should have said the print "appears" to wobble. I think the poor tolerance of the threads makes for slightly uneven layer height which makes some layers slightly thicker than others. Maybe just a poor assumption on my part, but I will know next week when my acme screws are in.

"Since you seem to be going this route because you didn't get good chemical results, did you try using vaporized acetone to smooth things out? Using a pressurized spray bottle or heating acetone to make vapor has produced very good results by comparison, and only requires a few minutes to completely re-harden."

i had ok results using acetone , but the larger parts became incredibly soft. i hate dealing with flammables especially in vapor form. what i determined that smoothed the parts for the chemical was the liquid running down the sides of parts.
i have shop and electronics work space. I hate dealing with combustibles and gases.

I thought until a few days ago that the chemical method of acetone diluted in water was the way to go. FYI anyone looking for a container that can store acetone, look at an empty paint canister. less than 3$ in hardware store.

I am going to pursue this laser method further. this method takes less than 10 minutes, and parts are immediately usable afterward.

the recent image is of a part where the laser was 90deg rotated to the angle of the z layers. i will try 45deg next. going along the layers at the same angel causes open spots and does not seem to increase quality that much.

Edited 1 time(s). Last edit at 07/06/2011 03:53PM by jamesdanielv.