[Idea] Easy way of adding in auto bed leveling.

So i have an idea based on part that the hot end is a conductive metal that can transfer a charge.
Essentially the servo will have a rod with an attached flat piece of metal that swings under the hot end/nozzle that is free floating enough that it is hovering both over the bed a bit and under the hot end/nozzle.
When the extruder comes down, the flat metal will come into contact with the bed first and since it's free floating, it will stay on the bed while the hot end/nozzle comes into contact with it effectively sandwiching the flat metal between the bed and hot end/nozzle and complete a circuit.

This would, in theory, give a better way of auto bed leveling in that the z-probe is stiff and flat enough that it can have the hot end/nozzle act as the z-probe itself in the exact spot of where it is probing.

Anyone think that this would work?

Edit:
Maybe this would have been better posted in the mechanical forum...

Edited 1 time(s). Last edit at 07/07/2015 01:34PM by alatnet.

Let´s hope the nozzle tip is always clean and not covered with filament...
-Olaf

this would be done before heating up the nozzle as when i print i've always adjusted my bed leveling with the nozzle off and the bed on.
but it may vary between people.

EDIT:
well, there is another way by having two plates that come in contact with each other.
by having two plates, one negative and one positive, sandwiched inbetween, that could account for nozzles with filament residue.

Edited 1 time(s). Last edit at 07/07/2015 03:08PM by alatnet.

The problem with the filament sticking out is not only the electrical isolation. With the two plate approach you would solve that. But the problem also is that the filament would trigger (in the two plate approach) a bit "higher". The two plates would not been pressed together when the nozzle hits them but when the filament hits them. The Filament that sticks out of the nozzle might be much more than 0.1 mm thick. So the result of the measurement would basically be worthless.

A possible solution might be to use the "Z-Probe" not only for bed leveling, but also to prevent the filament from leaking through the nozzle. If you can change the design in a way so that the "plate" could be pushed to the nozzle then that would be a good thing. It would make sure that the nozzle is clean and no filament sticks out, thereby solving the problem for bed leveling. And it would also an alternative to retraction to prevent filament to be spilled at placed we don't want it.

I don't know if that is possible to do or if it would work out. So if you find a way to do it you will need to test it to find out if it is a good Idea.

while there's that problem, a fix could be that there's a probe that takes the place of the hot end.

This could make it so that there's less parts and can have the probe be adjustable.
it would just take one printed part to attach the plate and probe and have the probe be adjustable to the level of the hot end/nozzle.

[edited]

I briefly ran my printer with that enabled, and I really didn't like the continuous moving of the Z axis.

Now, let's separate ABL for Delta printers from ABL for Cartesian printers like Prusa/Mendel.

On a Delta, I get it. Maybe... I haven't actually ran it on a delta yet.

But on my Prusa i3, it makes the printer run so much slower that I can't believe anyone would want to use that on anything larger than a hockey puck print.

Personally, my money and energy is going to be spent on a better, flatter bed, rather than ABL. Which in the end, is what we should be focused on anyway, build a better machine not build a better bandaid.

Cheers,
Mark

Edited 1 time(s). Last edit at 07/08/2015 12:54AM by thetazzbot.

Mark, have you read the_digital_dentist's Instructable? I think you'd like his style.

And yeah, ABL is usually used on Deltas, partly because they're so damn hard to level the normal way.

Quote
thetazzbot
[edited]

I briefly ran my printer with that enabled, and I really didn't like the continuous moving of the Z axis.

Now, let's separate ABL for Delta printers from ABL for Cartesian printers like Prusa/Mendel.

On a Delta, I get it. Maybe... I haven't actually ran it on a delta yet.

But on my Prusa i3, it makes the printer run so much slower that I can't believe anyone would want to use that on anything larger than a hockey puck print.

Personally, my money and energy is going to be spent on a better, flatter bed, rather than ABL. Which in the end, is what we should be focused on anyway, build a better machine not build a better bandaid.

Cheers,
Mark

On a delta, you have the advantage of a fixed bed and you shouldn't need ABL (or Automatic Bed Compensation to give its proper name). OTOH auto delta calibration can save a lot of time.

If ABL on your Prusa makes printing very slow, then I think either there is a firmware problem, or you are asking the ABL to compensate for very large errors, or you have the maximum Z speed set very low. I use ABL on my Ormerod when doing large prints, and it doesn't slow down the print at all. OTOH it does increase wear on the Z screw. As you say, it's better to get the bed as flat as level as possible, and use ABL to compensate for small errors only, or not to use ABL at all if you can manage without it.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Personally, i dont see significant benefit in this approach considering the amount of weight that would be carried by the y carriage to enable it. If you want to see a more refined version of what you are talking about take a look at the lulzbot mini, which seems to have implemented this quite successfully with the use of a preheating cycle and a very large wipe area. Alternately you could take a look at something like the printrbot setup with metal proximity sensors. The drawback of the printrbot setup being of course, that you have to carry the sensor around and you must have a metal print bed.
If there is some advantage to your system that i am missing please let me know! I would like to learn more.