New bed level probe idea (Page 1 of 2)

So, does Marlin only look at it during the first level, or would this trigger during a mid-print curling/lift?

Some of the delta guys who were talking about that idea were toying around with using a accelerometer.  Basically they are trying to log the moment the hotend touches the bed and using it in tap mode to log the point it touches.  Will know once they get back if it works but it will be nice to not have the hotend able to move.

Well there certainly isn't an official version. We need to port the Solidoodle to the latest marlin. Maybe this is an excuse to do it.

The $800 printer whose bed never needs to be leveled, a feature none of the other $1000+ assembled printers has.  It's worth doing the R&D.  If the code is there, it's a matter of mechanical implementation using the existing Z stop.  With the homing switch on the nozzle, no one would have to mess with the Z tab either.  Even better if the new probing extruder mounts into the existing X carriage in the same holes, making it an easy upgrade.

So who is going to add a Z probe first, Solidoodle or someone here?

A servo to swing the probe out of the way. Or a solenoid to raise and lower it.

hahah.. no I didn't. I have now. I read the thread and then forgot there was a video at the start. The built in idea looks pretty clever, but how would that impact on print accuracy having that much movement possible in the print head?

A micro servo to move a locking bar into position maybe

Time for me to shut up and watch the engineers and makers do what they do best.

http://www.youtube.com/watch?v=x8eqSQNAyro

The support for the servo is already in place. I'm sure a solenoid would be equally as easy.

The trouble with that approach is that it doesn't take into account things like the hot end expanding/shifting. I like the idea of using the hotend as the probe, because you're measuring exactly what you want to know.

You can try - but a hotend is not homogenous. You can model it decently with thermal coefficients, but you can't calculate it absolutely.

Wow, you guys are taking it too far. Thermal expansion on the nozzle?

Servo problem is easy, the probe would have an hardstop on the down position. Servo is commanded farther than that but can only reach the (known) distance of the hardstop. Probe is at a reliable distance and retractable.

What I am curious about is how well this works once Marlin has the data about the z axis. Think about it, the Z axis would be going up and down constantly during the print....alot. Is this supposed to go on for every layer? For every move? Better build an anti-backlash Z rod setup for the stock machine while we are at it.

I have a better idea: Put 4 servo motors under the bed attached to leveling screws. Use the data to level the bed using the servos (I am thinking they would have to continuous rotation with rotary encoder).

I actually started updating the Solidoodle Firmware to the latest Marlin the other night, specifically because of Alex Borro's bed levelling.

And IanJohnson, think outside the square Using an E3D, you have an electrical connection from Tip to nozzle assuming it isn't carbonised to hell and back. I'm playing with using a small copper square from some copper tape, with the 3 squares earthed together and then run back to ground. Then I'm using the signal side to connected to the top housing of the extruder.

Voila - Contact switch using the extruder itself. Beats the hell out of calculating the offset like Alex describes

Anyway - will post up the updated 'solidoodle' firmware tomorrow - Just wanna finish playing with one thing first.