intresting bug we have found but yet to fix

[rylangrayston]

at 0:05 - 0:06 you can see the peachy printer drawing ( real time) in some water with florescent die in it.
Using long exposure photography and a script I wrote ( sequenceFromLayer.py) the peachy printer drew out all text in this video
Me and my Brother Nathan used to run our own media company and we love coming up with unique organic effects like this.

So any way the really interesting thing is the bug you can see. check out the wiggles in the R in FRIEND at 0:07 this seems to happen many times
- the last letter in customize 0:27
- the last letter in oporation 0:35
- the 8 at 1:03 and here is it is very interesting that the problem is intermittent for the 8!
- the F in FIT at 1.11

and more you get the point.



video can also be seen here http://www.peachyprinter.com/

If this happend during a print it would very likely fail at that point, or at the very least make a hole.

The gcode was created with cura
and the script called sequenceFromLayer.py can be found here https://github.com/Rylangrayston/gco...wTextTimeLapse

I wonder if the source of the bug is my script or cura or something

[quertz]

Hey Rylan,

I don't know where this bug comes from, but I've just realized, that this is a good method for measuring the amount of light delivered to each point!

You could very well use a setup like this using fluorescent material and long time exposure to reduce the seam of the prints.
In the text for example, you can see the starting point of each letter very strong.
Also sharp corners tend to receive more light than straight lines.

Especially with the new digital circuit that can do more than just turn the laser on and off you could make the print quality even better easily.

Greetings, quertz

[rylangrayston]

Quertz! I wish you had been in on the phone conversation between me and our software engineer James Townly today!
.
James is just starting to work on the printers abuility to accelerate and decelerate the mirrors movement.
To make that work we will be turning the laser power up and down with the speed of the laser dot. Acceleration is the feature we need to fix the bright corners and starting points, which are caused by the printers slew rate.
I was just saying to James how if we were to de focus the laser and do long exposures of say a 1 cm wide laser spot
then perhaps the light would be more in the cameras dynamic range, because right now the laser spot is a bit over exposed.

Your right This is a good way to test for even exposure. Its awesome that you had this valuable realization all on you own!
and since you did I bet you would be interested to watch this video to see how far we ran with the same realization.



There are lots more pics and a gif of one of the captures in Update #37
also you may notice that there are no bright corners the animated gif of the Julia vase in update #37, that is probably because
the printer was shining so far ( deap in to that box) that the mirrors didnt have to go very fast draw the picture. The slew rate of our mirrors will have a negligible effect
if we move slowly Hence why slowing down for corners is a good idea.

[mike_biddell]

Am I stating the obvious that slew rate(S) divided by laser power (P) shud ideally be a constant (K) to keep the exposure even.

S/P = K, where K is the exposure constant

If there is a high slew rate, the power must go up to keep K the same and if the slew rate is low the power should go down !!!!

All this pre-suppose that an even exposure is desirable.