Z axis calibration idea

[3dspider]

has anyone tried using an AD7745 Capacitance to digital converter with a flat speaker wire in place of the capacitor? If the ends of the wire were waterproofed, an AD7745 should be able to detect the minute changes in capacitance in the wire as the water level was raised/lowered. Datasheet available here

[Jukurpa]

Sorry if it has already be proposed before, but for a Z-axis calibration, couldn't we just print a predetermined shape, for example, a tube (which is the easiest with two sinus signals) for a know quantity of drops and then, measure the final print with a caliper (yes, maybe not everybody have a caliper, but at least, the poeple in the beta team).
So, for X drops, we've a tube of Y mm and then, we know the thickness of the layer added by a drop. These could be parameters for the slicer, or even be included in the Peachy Printer software.

And not knowing the Z-axis speed, I suppose there is no problem to print the tube at "full speed" for the X and Y axis, several passes on the same layer shouldn't cause any problem... I suppose.

[Chayat]

I think that's the very basic method, you'll be assuming a perfectly walled build tank and perfect drip uniformity. I think the things that are being discussed assume that calibration has already been done.

[Jukurpa]

Yes, I understand it's the very basic method, but the one with the less impact on the final cost of the printer.
And even if the tank is perfectly build, the use of two sinus signals leads more to a "cone" than a tube in fact.
That aws only my two cents, even if it must be obvious for most of the beta testers

[Aztecphoenix]

I have been experimenting with a home built variable capacitor the past few days and have made a discovery, my initial worries about the varience of salt in the water has turned out to be the least of our worries for a reliable means of determining Z height, the difference in water temperature as well as disolved solids in the water have a huge effect on the capacitors feed back I have however begun work on a work arround, an additional sensor array that is to be used to factor in all the veriables and constantly automatically calibrate the capacitor.

I am trying to design this whole system on a budget as well as trying to design the parts in such a way that it is possible to laser cut many of the pieces however, the final system is going to require a microprocessor and possibly some software for calibration, therein lays the problem, building the prototype isn't that much of a problem yet (I still have a little bit of research to do) but my programming skills are nearly non-existant, so I am comming to the forum to see if there is anyone interested in assisting on the software side of things, so far it looks like the build my be around $50 to build (but like I said, there is still a little more work to be done) I may also require some help with the electronics side for the final circuit.

anyone willing to lend a hand please let me know and we will see what we can do

[rylangrayston]

I have been experimenting with a home built variable capacitor the past few days and have made a discovery, my initial worries about the varience of salt in the water has turned out to be the least of our worries for a reliable means of determining Z height, the difference in water temperature as well as disolved solids in the water have a huge effect on the capacitors feed back I have however begun work on a work arround, an additional sensor array that is to be used to factor in all the veriables and constantly automatically calibrate the capacitor.

I am trying to design this whole system on a budget as well as trying to design the parts in such a way that it is possible to laser cut many of the pieces however, the final system is going to require a microprocessor and possibly some software for calibration, therein lays the problem, building the prototype isn't that much of a problem yet (I still have a little bit of research to do) but my programming skills are nearly non-existant, so I am comming to the forum to see if there is anyone interested in assisting on the software side of things, so far it looks like the build my be around $50 to build (but like I said, there is still a little more work to be done) I may also require some help with the electronics side for the final circuit.

anyone willing to lend a hand please let me know and we will see what we can do

Hey Aztecphoenix
It may be a little while before we get to it, but we will likely write software right in to the peachy driver/ printing interface that is meant to detect capacitive feed back.
The testing we have done here at peachy confirms most of what you said about capacitive feed back. We havent Graphed temperatures affect and im really curious to know more about that.
Since your actualy doing this, it might be good to start a new thread to document your work in. If you can be very descriptive (vids and pics of what you have set up ) Ill be more able to get involved.
There is also this Thread on the topic of Capacitive feed back, and there you can see that colehard has made some progress on this as well.
http://3dprintboard.com/showthread.p...gt-freq-gt-mic