Z axis calibration idea

[Aztecphoenix]

I purchased this digital caliper for $9.19 (now it is $11.59): http://www.ebay.com/itm/271477770522...84.m1439.l2649

I took it apart, removed an internal metal strip that added friction and put it back together. Now the caliper slides effortlessly, perfect for the float idea. I am real busy this week so I doubt I will get to it in the next few days, but I will relatively soon try to build a float just to prove the idea works. I am not a beta tester, so there will be no printer involved. I will just have water dripping, a container and the caliper with the float attached. After seeing it slide so easily I am convinced that I can make the physical caliper float system work. That just leaves the electronics side, but in my experience that is by far the easy part.

just remember to keep track of how much water displacement there is on the float, if it fluxuates it will throw off your measurements.

[rylangrayston]

Wow just read this hole thread

ALOT of great ideas here....

ill be bringing them up at a meeting soon

I loved the tone detection for the start and end of the print, so simple and uses just wire.

We have been making a fairly inexpensive capacities feed back thing for the peachy pro, ( closed loop galvos )
and im really curios to know it the capacitance's of the body's of water in the 2 reservoirs can inform us of there levels.
perhaps capacitance between the water and a laminated strip of tin foil on the side wall of the upper reservoirs.



I like the idea of closing the feed back loop with capacitance or pressure sensor chips, but still using drips as the very fine grain measure.
I wonder if we can leverage some leaver action to cause these chips to be 10 times more or 10 times less sensitive that they are naturally, if so that could make for a hack that works for both really big and really small printers, using the same chip.

@jstrack2 Im really looking forward to seeing some detailed results and pics of the 9 dollar caliper & float system, we have a pair of supper cheap calipers here at the hacker space if what your suggesting works
ill probably build one two

Peachy will alwase aim to make a supper affordable 3d printer but we also want to take a shot at making pro printers too ... so even solutions that cost a bit more can make it into a slightly different printer.
and of course modding the 100 dollar printer is what its all about!!

Great thinking everyone!!!

[Feign]

It occurs to me too that the Peachy already has a "signal out" on the board that goes to the drip sensor... If the software gets a constant tone on the drip sensor, would that effectively stop the count, or would it keep rising from fluctuations in the tone?

If the former, then the two-wire calibration might be something that the beta testers can try with the Peachys they already have... Just as long as they can disconnect the "tone out" line when they actually want to print.

[nka]

If you stick the two cables, the count upgrade by one only. Until you unstick them and stick them again.

You can try this, even without the Peachy. Just need the software.

[Feign]

Well, that's good news!

So yeah, pretty simple way to do an auto z-level calibration:

From Drip Sensor Out                                                                     To Microphone in
    |___________________________________________________________                                  |
         |                                                      |"tone line"                      |
         |___Drip count assembly___                             |                                 |
                                   |  -(top of the tank)-       |                                 |
                                   |                            |                                 |
                                   |       (1mm vertical spacing between tone line and gap)       |
                                   |_____________________ [Gap] __________________________________|

Not actually code of course, I just needed a way to keep the spaces in the formatting, to make this little wiring diagram make sense. Place it in the tank, make sure it's level, start dripping saline, after the level is above the sensor, look at the drip count and subtract 1 to get the number of drips per millimeter. Dry off the "sensor" and repeat in a different part of the tank as desired to get a good average.

If there were a piece of acrylic with exactly a millimeter spacing between three wire-sized gaps, that would make it even easier.

[jstrack2]

Thanks Rylan! Yeah I am excited to make it. Having such good accuracy and resolution will be great. I really like Mike Biddell and Nahoj's caliper and scale ideas.

What do you think about shining the laser up to hit the resin below the top of the liquid (the topic I started about using three layers). I think it is a pretty simple way to fully remove the ripples. I'm not sure how much of an issue they are, but it seems they must hurt the potential print quality some.

[jstrack2]

Good point Aztecphoenix. I was thinking about the same thing. The float will have to avoid having significant friction against the wall. This effect will likely be small, but more than the 0.02 mm resolution the caliper is capable of! (Which amazes me that is possible for nine dollars)

[rylangrayston]

Thanks Rylan! Yeah I am excited to make it. Having such good accuracy and resolution will be great. I really like Mike Biddell and Nahoj's caliper and scale ideas.

What do you think about shining the laser up to hit the resin below the top of the liquid (the topic I started about using three layers). I think it is a pretty simple way to fully remove the ripples. I'm not sure how much of an issue they are, but it seems they must hurt the potential print quality some.

Ill go have a look at it now...
mostly it hurts the speed at which we can print good looking things because we have to wait for the resin to flow over top.

[rylangrayston]

Well, that's good news!

So yeah, pretty simple way to do an auto z-level calibration:

From Drip Sensor Out                                                                     To Microphone in
    |___________________________________________________________                                  |
         |                                                      |"tone line"                      |
         |___Drip count assembly___                             |                                 |
                                   |  -(top of the tank)-       |                                 |
                                   |                            |                                 |
                                   |       (1mm vertical spacing between tone line and gap)       |
                                   |_____________________ [Gap] __________________________________|

Not actually code of course, I just needed a way to keep the spaces in the formatting, to make this little wiring diagram make sense. Place it in the tank, make sure it's level, start dripping saline, after the level is above the sensor, look at the drip count and subtract 1 to get the number of drips per millimeter. Dry off the "sensor" and repeat in a different part of the tank as desired to get a good average.

If there were a piece of acrylic with exactly a millimeter spacing between three wire-sized gaps, that would make it even easier.

multiple "tone Lines" at different heights ?
the code is avalible here:
https://github.com/PeachyPrinter/peachyprintertools
feel free to pull request once you have added this handy feature

In fact i could use this now! it would alow me to go to bed an hour earlier! as im currently waiting for a drip test to finish lol

[Feign]

Ah, sadly, I'm no coder. Though what I was getting at is that this mod might not even need a coding change, it's just a change in the physical wiring of the drip sensor.