Corexy bed sensor concept. Possible?
March 02, 2017 03:25AM
I'm considering a corexy bed leveling concept and I'm curious if my idea is feasible. I'd like to auto level the bed for real, not via compensation. Rather than cantilever the bed, I'd like the 4 corners to ride on 4 lead screws. I'll use 4 piezo sensors at the corners, or one atop the hotend. Ideally I'd have a script or macro that moves the hot end to each corner, and raises that corner till the sensor is tripped, before moving to a different corner and repeating. Is this possible? I'd obviously need the breakout board for enough motors, but thoughts?
Re: Corexy bed sensor concept. Possible?
March 02, 2017 03:30AM
This is already planned for a future version of RRF for Duet WiFi and Duet Ethernet.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Corexy bed sensor concept. Possible?
March 02, 2017 11:08AM
I'd go for 3 lead screws then. 4 screws always influence each other.
Question is: will you get more accuracy during the print with 4 (3) individual motors? I'd try to figure out a separate z-lift drive for adjustment only ( servo ?) and use only one stepper for all leadscrews.
Re: Corexy bed sensor concept. Possible?
March 02, 2017 01:23PM
Quote
o_lampe
I'd go for 3 lead screws then. 4 screws always influence each other.
Question is: will you get more accuracy during the print with 4 (3) individual motors? I'd try to figure out a separate z-lift drive for adjustment only ( servo ?) and use only one stepper for all leadscrews.

I plan to support 2, 3 and 4 motors. With a very large bed moving in the Z axis, some flexing is inevitable, so 4 screws makes sense for such a machine. For more normal-sized 3D printers, 3 screws is undoubtedly better.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Corexy bed sensor concept. Possible?
March 02, 2017 03:24PM
I'd say that you probably only need 2 motors.

Use 3 pivot points, but you only need to adjust two of them to get everything leveled.
Re: Corexy bed sensor concept. Possible?
March 02, 2017 07:18PM
I am looking forward to this feature! I use a printer that has two Z motors, currently in parallel. I like maso's idea of pivoting around a point, but this requires two SEPARATE motors for just levelling, to move the whole bed up and down you still need another one\set.
My motor configuration is two motors are sitting in the middle of each side of the bed (two sides). Bed is machined cast aluminum and is quite flat, but initially you have to manually tram the motors to keep the bed parallel to the nozzle travel plane. It would be awesome to have this feature!
I use RADDS electronics and volunteer to beta-test, if you need any testers.
I have access to various Z-bed sensors: inductive probe, capacitive probe, mechanical endstop, BL-Touch and am working on my take on an analogue IR sensor. Bed size is 300mm x 300mm (1ft x 1ft actually).
Re: Corexy bed sensor concept. Possible?
March 03, 2017 09:07AM
You can configure the Duet to use two separate drivers for two motors. This is how I have my Corey configured.
Re: Corexy bed sensor concept. Possible?
March 03, 2017 01:17PM
I would suggest having adjustment limits. For instance you need to decide which corner is low or high and limit how far you will go to correct the level. You do not want to find your printer bed jammed at an angle because you had a positioning problem.
Re: Corexy bed sensor concept. Possible?
March 03, 2017 01:26PM
Quote
BuildAThing
I would suggest having adjustment limits. For instance you need to decide which corner is low or high and limit how far you will go to correct the level. You do not want to find your printer bed jammed at an angle because you had a positioning problem.

That's a good suggestion.



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

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