Z axis calibration idea

[EthanSpitz]

Would it be possible to use a jewlery scale to find the weight of the upper container, to calculate the volume in stead of meassuring the level in the lower container? You get pretty cheap ones with 0.1g accuracy.....

I actually really like this idea....

[jstrack2]

I think the main problem with a jewelry scale is that they generally can't hold much mass (at least the cheaper ones). For example if you had a 1 kg max scale the build volume would be significantly less than 10x10x10 cm. Also the container would need to have totally vertical walls. If it doesn't then things could get way more complicated.

[EthanSpitz]

I don't understand what the problem is here. It will take some work to make a simple, cheap and reliable design, but what is so inherently bad about something floating up the side?

I think the problem is going to be the reliability/accuracy

[EthanSpitz]

I think the main problem with a jewelry scale is that they generally can't hold much mass (at least the cheaper ones). For example if you had a 1 kg max scale the build volume would be significantly less than 10x10x10 cm. Also the container would need to have totally vertical walls. If it doesn't then things could get way more complicated.

how does it work with drips right now and height? Doesn't it need to know the shape of the container anyway?

[jstrack2]

Why would it not be accurate? Calipers have extremely good accuracy. I saw on ebay one for only 9 dollars that had 0.02mm accuracy. The one posted was cheaper and had 0.1mm accuracy. Resistors will not achieve that. Plus calipers are much more reliable than using resistance.

[Feign]

Would it be possible to use a jewlery scale to find the weight of the upper container, to calculate the volume in stead of meassuring the level in the lower container? You get pretty cheap ones with 0.1g accuracy.....

Now that's actually a pretty great idea. In fact, if you use equal-sized containers for both the top and bottom, then you can use almost all of the ideas in this thread to find the height without any chance of the mechanism coming in contact with the resin. It would also help with the problem of the optical mouse and digital caliper ideas accidentally registering ripples as layer movement.

[jstrack2]

how does it work with drips right now and height? Doesn't it need to know the shape of the container anyway?

Yeah you are right. Scratch that point. Still the mass issue exists, but if that can be overcome real cheaply then I think that it could definitely work.

[Nahoj]

There are a lot of different jewlery scales at aliexpress.com.

[jstrack2]

Maybe a scale with less accuracy (like one gram) could hold more. This would still be real accurate and would be simple.

[jstrack2]

For example if the container was just 10 x 10 cm wide then 1 g (~1 cm^3 of the salt water) would add just .1 mm of height. If the container is wider then the accuracy will be even greater. That's like the caliper. The scale has to fit the size of the container which is a drawback since the scale will have to connect to the microcontroller. Work will have to be done to get each different scale size to communicate with the microcontroller properly.

Of course with the caliper it is limited in height (maybe 150 mm), but the other two dimensions could be unlimited in size.