Mount and Reservoir Discussion

[jontelling]

Nice informative reply Rylan. But as always I have more questions.

Do you plan (I'm sure you do) allow serial input to the peachy board? I ask as this would allow an arduino (are in my case as I had a bad habbit of blowing them an atmega chip) to bridge the gap between a PC (via wifi) or an SD card or even just tell the peachy that you added XXml to the build area of salt water.

[Toasterboy]

Yes, thanks for the great response. I'm really excited about the printer.

Are there any other I/O pins for output on the peachy board? It sounds like there is a drip sensor pin on the board ; wondering if there's another pin for output besides USB, or if the expectation for this hardware version is that the Peachy software would signal other (separate) devices (like a drip assembly) through other I/O mechanisms on the computer.

It seems like long term, the printer (or its successor) should have the capability to signal the zlevel rise directly rather than relying only on external passive decoupled drip + detection. Since the travel path of the laser for each layer is variable, to get optimal print speed it would benefit from being controlled by signal rather than depending on an external sensed rate. But I can certainly see where it makes sense to focus engineering on a whole list of other areas, like laser speed and accuracy, and variable laser focus and power output that need to be tackled first. It might be a bit silly to build a super accurate, super fast Z level control mechanism to support larger build areas if the laser speed / power needed requires minutes to cure each layer. =) Still, accurate, controlled z-level on smaller volume build areas is still useful and important.

>We have yet to Write a feature where you get N calibration points. ( Right now you just get 8.)
Can you comment on this further? 8 points for which calibration? for Z or for XY?

I picked up a used 300cc fuel injector on Ebay for really cheap. The math suggests that for the ~2'x2' container, @~40psi the injector should be held open about 80ms per pulse to get 0.33ML, the amount needed to raise 1 micron in this container. (roughly) Assuming that salt water flows similarly to gasoline, and the used injector is in more or less good condition, and the thing is actually accurate. That's a lot of assumptions. Will need to experiment and see if it's in the ballpark.

I also picked up a peristaltic pump. It's a bit hard to tell from the specs what the pulse size will be. Anyway, I can play with both ideas. What size pump are you playing with above?

I'm not going to attempt to run anything bigger than 2'x2' for now. That size is still manageable to build UV cage around for safety (not to mention it will be a while yet before you guys are ready to ship). And anyway, even if the injector can do the z-level rise at ~12.5 pulses per second as the napkin math suggests, the laser speed has a long way to go before it can cure that many layers per second (if it's even possible to go that fast).

What is the layer height you are using on your test prints? With surface tension and other effects, how would you say the printer is performing with respect to z-layer height?

[rylangrayston]

Yes, thanks for the great response. I'm really excited about the printer.

Are there any other I/O pins for output on the peachy board? It sounds like there is a drip sensor pin on the board ; wondering if there's another pin for output besides USB, or if the expectation for this hardware version is that the Peachy software would signal other (separate) devices (like a drip assembly) through other I/O mechanisms on the computer.

It seems like long term, the printer (or its successor) should have the capability to signal the zlevel rise directly rather than relying only on external passive decoupled drip + detection. Since the travel path of the laser for each layer is variable, to get optimal print speed it would benefit from being controlled by signal rather than depending on an external sensed rate. But I can certainly see where it makes sense to focus engineering on a whole list of other areas, like laser speed and accuracy, and variable laser focus and power output that need to be tackled first. It might be a bit silly to build a super accurate, super fast Z level control mechanism to support larger build areas if the laser speed / power needed requires minutes to cure each layer. =) Still, accurate, controlled z-level on smaller volume build areas is still useful and important.

>We have yet to Write a feature where you get N calibration points. ( Right now you just get 8.)
Can you comment on this further? 8 points for which calibration? for Z or for XY?

I picked up a used 300cc fuel injector on Ebay for really cheap. The math suggests that for the ~2'x2' container, @~40psi the injector should be held open about 80ms per pulse to get 0.33ML, the amount needed to raise 1 micron in this container. (roughly) Assuming that salt water flows similarly to gasoline, and the used injector is in more or less good condition, and the thing is actually accurate. That's a lot of assumptions. Will need to experiment and see if it's in the ballpark.

I also picked up a peristaltic pump. It's a bit hard to tell from the specs what the pulse size will be. Anyway, I can play with both ideas. What size pump are you playing with above?

I'm not going to attempt to run anything bigger than 2'x2' for now. That size is still manageable to build UV cage around for safety (not to mention it will be a while yet before you guys are ready to ship). And anyway, even if the injector can do the z-level rise at ~12.5 pulses per second as the napkin math suggests, the laser speed has a long way to go before it can cure that many layers per second (if it's even possible to go that fast).

What is the layer height you are using on your test prints? With surface tension and other effects, how would you say the printer is performing with respect to z-layer height?

There are about 8 extra io pins( i dont have the details memorized because we havent started using them yet)

a more direct Z height will definitively get implemented something like a g code to the micro that says goto this height travleing at this speed.

more on calibration..
We are working on a 3dmentional matrix of points that can be used to interpenetrate out all the non-linearities for all the places the laser can be in the build volume... but dam thats a wordy way to say it, and a year ago I wouldn't have understood what I just wrote.. so ill try to put it into an analogy too. This analogy by the way is actually how i prefer to think of it:

say you had a clear cube of Jellow and inside this cube of jelow was a bright red capital letter T.
To get the Red T in the clear block of jellow you cast the T first, then placed flopy red T in a cube and then poured clear jellow around it.
Great just one problem, The Upper Right tip of the T is sagging down, but the upper left side is bent towards you and also bent up.
What can you do to correct this.
what if you had put iron balls in the upper right and upper left parts of the T. Then you could use magnets pull on the balls just enugh to unwarp the
Saggy T. The balls would squish and warp the jellwo around them, Such that the T could become less saggy.
Now what if you had 100 magic balls that you could move magicaly in the jellow, then you could really straighten out that saggy T to perfection.

In this analogy above the magic balls are our calibration points. We get to magically move the balls because we have a mathematical representation ( a 3d matrix ) of the jello cube / build volume. The atoms of jellow are akin to every resolution point in our build volume, just like the position of each atom in affected by the balls near to it, we interpolate the position of every resolution point so that our calibration points affect the resolution points near them.

Currently we only have done the work to have 1 ball at each corner of the cube shaped build volume, so we only have 8 balls and there only in the corners.
This means currently we can only remove linear artifacts, for example we can correct for things like the entire T leaning, but we cant yet unwarp a specific part of the T. Some day we will do work to allow you to decide to have as many calibration points as you like, and when that day comes your printer could be much more accurate.

hope that analogy made thing better not worse

Glad to here of the progress on the injector pump idea already Toasterboy!
lets see whats next.., pump size.. We have been making our own pumps so now its time for my napkin math
Today I was printing in a 6 in diamter cylinder, and there are 206 pump rotations per mm so ....
6* 2.54 = 15.24 cm diameter
15.24/ 2 = 7.62 cm radius
7.62 * 7.62 = 58.06
58.06 * 3.14 = 182.32mL
182.23/2000 pumps per cm = .091 mL per pump rotation

The pump uses between 100 and 200 mA depending on speed which is controlled via votages between 3 and 20 volts.

as for how its doing in the z resolution. I think there is a recent post where I explained this in some detail... ill see if i can find it...
EDIT: found the posts with details about z resolution, there on the 3rd page of update 51 thread.. here is a link
http://3dprintboard.com/showthread.p...Printer!/page3


Great questions everyone, Im happy to answer them now while the community is still small, someday there may be thousands of people joining and posting, and Ill be glad to have all the help I can get from those of you who are here now learning about the peachy printer in detail before anyone else

[rylangrayston]

Nice informative reply Rylan. But as always I have more questions.

Do you plan (I'm sure you do) allow serial input to the peachy board? I ask as this would allow an arduino (are in my case as I had a bad habbit of blowing them an atmega chip) to bridge the gap between a PC (via wifi) or an SD card or even just tell the peachy that you added XXml to the build area of salt water.

along these lines here is what we were thinking ( but have not done yet)
use the extra IO pins to create ic2 and or SPI communication ports, so that an arduino can send and receive any message to the printer via the peachy circuit and so that
the peachy circuit could posibly control things like LCD screen, button panel etc.

What we do have working now is the peachy software sending commands thru a separate serial port, this is how we do our time lapses of prints an arduino is instructed to open the shutter while the laser drawing 1 layer. We also have send codes to the arduino to turn the peristaltic pump on and off, or whatever else we want.