Three Layers of Liquids for Higher Quality Prints

[jstrack2]

I don't have a video to show since some glue attaching the solenoid to the object that goes up and down broke, but by testing some by hand not solenoid it appears that using a plastic sheet to act as a wall works. The surface waves formed on the dish soap (simulating the resin), which is sandwiched between the fresh and salt water, were massively reduced. I think with a proper setup they could be more or less eliminated.

[jstrack2]

Just to clarify the theta = arcsin(n1/n2) I mentioned is just internal reflection. So just like how if you shine the laser at an angle through the water to the surface and it is totally reflected instead of passing into the air this works the same way. If the energy can't be transmitted into the next liquid, it just forms a surface wave.

[rylangrayston]

Nice Work Jstrack2
It very valuable when people talk about ideas
but so much more value and questions come out when you actually hack one together and try it, which you have done
so I aplod you!
...

Anyway with all of this said I don't think that this issue is too big. Vibrations on the desk don't seem to really translate to vibrations at the resin when it is sandwiched between water and salt water (which is the reason for doing all of this). They are only generated by the temporary lowering then raising of the resin level. But these surface waves die after a couple seconds. So it is just an issue of making print times longer. Of course there may also be better ways to change the resin level or to have the surface waves energy dissipated faster that could help too. I will try doing a test later to see if the wall approach really helps things.

I completely agree, surface waves are not a big deal, in fact during many early prints i would constantly tap the printer to cause surface waves which HELPED the resin break over the printed wall.

Maybe if when I read the forum more I could find the answer, but what is the current thinking on how everything will be powered? Could everything run on a USB connection?

The Basic peachy printer is aiming to be very low power as far as 3d printers go, the hole thing will be powered of of one or 2 usb jacks ... a few hundred mA
I dont think it a big concern in the beginning stages of this hack, lets get this hack printing and if its valuable for printing ( i think it will be )
Then at that time we will know how much displacement we need, taking a bit of the guess work out of power requirements.

...
now my turn
if you look at the new software here:
http://software.peachyprinter.com/

run it and click setup printers --> setup Options
you will see a "use serial drip control" check box

Screenshot-6.jpg

This feature connects to an arduino telling it to move a servo ( that closes a valve ) when the dripper is going to fast.

Thats not exactly what you need but it will be pretty quick to change it to move a solenoid every layer... all the meat is there just have to change the events that trigger it.
I have put this feature request on the to do list so we will have an option to move a solenoid each layer in the future.
Of course if you dont want to wait for us to implement this you can alwase code it in yourself
as the sources are here:
https://github.com/PeachyPrinter/peachyprintertools

Again Great work Jstrack2
keep it up!

[jstrack2]

Thank you for the kind words Rylan!

The one problem with the surface waves formed in the resin when the resin is sandwiched in between fresh and saltwater is that it dissipates slower than when between salt water and air (although not way longer). However putting a sheet of plastic (or whatever material) in between the object that displaces water and the rest of the container prevents the surface waves (I think because of the total internal reflection effect I discussed). So yeah it isn't a problem.

Thanks for the update on the aim for the power requirements. I agree that making it work at first is most important. I think that this solenoid can be really low power though. If the fresh water had some salt in it to bring it closer to the resin density, but still a little below, then the apparent mass of the object that displaces liquid would be almost zero. That way the solenoid would need to exert very little force, perhaps well less than one newton. Adding a bit of salt to the fresh water (if using the 3 liquid method) would also be a good idea since the object being printed will have less force on it too.

Also if the power requirements for the solenoid are too high a battery or capacitor could store some energy temporarily since the solenoid is only active a small fraction of the time.

I have since read through the forum and there are a lot of great ideas! Unfortunately though I have not yet gone through the Peachy code. Thanks for the link. I will start doing this soon. I like the user interface, it's hard to beat the simplicity of a check box!