Z axis calibration idea

[jstrack2]

Or actually just using a scale and swapping out the load cell when an especially large or small print is desired, but leaving every else might be easier. The rest of the circuitry shouldn't need to be replaced.

I really want to see a high accuracy measurement system used because I think that the prints could be super awesome.

[Feign]

To a point, the higher resolution the better, but I mentioned a possible problem earlier that I'll elaborate on.

Because of the top-surface nature of the printing, there will always be ripples in the fluid under your measurement device. Not just from the dripping action of the top tank into the lower one, but also from natural ground and air vibrations. A small amount of the time, when you get to within a single drop of a change in the sensor's measuring, the ripples can cause the sensor to 'flicker' between one position and another. Because there's not a more complex input than a single on/off signal, this flickering might drive the software to think that the print has gone up several layers in one drop.

While it's possible to filter this flickering out, it would require a much more complex circuit than what most are suggesting in this thread.

[jstrack2]

I don't know that this is true for some of the methods suggested. For a method using a float small ripples are unlikely to lead to very much movement at all in the float. Ripples can certainly screw up the print, but I don't think that they will cause very much movement of the float. The weighing method should be totally unaffected. Obviously the drop counting method is also unaffected.

Also the direct z-axis measurement methods do not need anywhere near single drop precision. If the drop counting and Kalman filter is used in conjunction with some relatively accurate measurement method then the Peachy will already have single drop resolution. I suppose if single drop accuracy is required then this would be an issue, but I don't think that kind of accuracy it needed for measurements. The whole printer would need to work a lot better to do that. A 25 cm x 20 cm wide container would add just 1 micron per drop. How many people would complain if the print ended up a couple microns or so too short/tall?

[Anuvin]

For a $100 printer? A few microns is no big deal.

[Feign]

For a $100 printer? A few microns is no big deal.

True, and I suppose this is something that a lot of us in this thread have lost sight of.

Still, it's fun to daydream about taking a $100 printer and making it into a top-tier machine through addons and mods.

[jstrack2]

My point is though that if a pretty good accuracy method is used (like a good scale or caliper) at least from the z-axis measurement side of things you will have top-tier machine print abilities. It will have a micron or so resolution (as far as measurements are concerned, not saying in practice for the final print), and roughly 0.1 mm accuracy (or better!). This means that the final print might be off 0.05 mm or so in total height, but the details would be single micron (again if the rest of the printer were up to this). For reference bacteria are generally 1.1 to 1.5 microns wide and 2 to 5 microns long. So this is really small!

I don't know of many applications were using the cured resin is okay, but being 0.05 mm off is not.

[Aztecphoenix]

True, and I suppose this is something that a lot of us in this thread have lost sight of.

Still, it's fun to daydream about taking a $100 printer and making it into a top-tier machine through addons and mods.

We haven't lost sight of it but I think it's safe to assume that the majority of us are makersnd as such we live for the challenge of taking something and putting our own spin on it to make it better.

the only people who are hurt buy this are those who want to make money by forcing us to buy upgrades every year. LONG LIVE OPEN SOURCE!!!!!

[Anuvin]

I don't mean to discourage this work, because I think that while it may be overkill, it is still awesome. But a few microns is not a big deal, really.

[jstrack2]

I don't mean to discourage this work, because I think that while it may be overkill, it is still awesome. But a few microns is not a big deal, really.

Haha yeah that's what I meant. The ~1 micron resolution made possible by the drips will exceed what the human eye could ever see without a microscope or something. An accuracy of 0.1 mm or (or better!) is plenty. If more is desired then a couple dollar more caliper or maybe also a scale could do 0.02 mm haha! But yeah 0.02 mm accuracy measurements are definitely not needed (even 0.1 mm is pushing it a bit).

[jstrack2]

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.