DC42, Bed leveling request

Hello DC.

I have extended my bed Y axis to take a 280 long bed. I have a few different bits of glass (IKEA mirrors) which have some inconsistencies. I didn't need to use the setbed utility before, but now it's really hard to get the bed mechanically level. Setbed works great to get round this, however, I was wondering if it would be possible to have to effects of setbed diminish over a number of layers so the top of the print is physically flat. In theory it would work, but in software I wouldn't know where to start.

Obviously, for those with a bent X axis plate, they would need to keep it throughout the print.

I think this would be good for everyone who uses it. What do you think?

Thanks.

That's an interesting idea. I intend to add 9 and 16 point bed levelling when I get time, and I will look at implementing your suggestion at the same time.

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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].

Thanks DC.

you're the man!

An interesting idea I had to add to this.

If we somehow used slic3r/firmware combination, we could print a raft that would start on the unlevel bed. But by the time it's finished we'd have a level surface to start the print on.

In this way, the change wouldn't need to be very gradual, we could make it as extreme as we want because only the raft would get mucked up.

Maybe if we had an M command where we could tell the firmware by what Z (i.e. 2 or 3mm) we want the print level by, and set the raft to print slightly higher than that.

If you didn't want to use a raft you'd just set the Z value to something much higher i.e 50mm, so the change would be gradual.

I've also previously thought about using the raft to print a throwaway level bed, but never got around to playing with the idea - my idea was to try cobble something together in Cura using a plugin, but never got around to it.

I'm in 2 minds as to whether this should be a slicer or a firmware feature - both viewpoints have their merits.

Edited 1 time(s). Last edit at 03/31/2015 04:58PM by pandionx.

Shadow.

I had not thought about a raft for this, however the use of a raft may not be ideal, but it would ensure that the print is parallel from top to bottom.

I think we are only talking about a +/-.2mm difference, anymore than that, the bed should need mechanical leveling.

Pandionx.

That too is an interesting idea, however I feel as it is the printer that is at fault, it would be better to have a software solution embedded in the printer as opposed to the slicer.

For example, multiple build plates with different surface variables could be used without the need to re-slice a model for each build plate.

I will eventually have numbered build plates and corresponding setbed files on the SD card.

Quote
Yella3D
Shadow.

I had not thought about a raft for this, however the use of a raft may not be ideal, but it would ensure that the print is parallel from top to bottom.

I think we are only talking about a +/-.2mm difference, anymore than that, the bed should need mechanical leveling.

Pandionx.

That too is an interesting idea, however I feel as it is the printer that is at fault, it would be better to have a software solution embedded in the printer as opposed to the slicer.

For example, multiple build plates with different surface variables could be used without the need to re-slice a model for each build plate.

I will eventually have numbered build plates and corresponding setbed files on the SD card.

No need to slice for different beds. The idea would be to lay down a rectangular plate on the bed that has a very thick first layer (maybe 0.5mm), and around 50% infill. Set the Z zero height for the lowest part of the bed. On the lowest part the nozzle will thus be printing exactly 0.5mm above the bed and so will print correctly. When the nozzle is printing over a higher part of the bed, the nozzle is lower than the set layer height, which will result in the plastic spreading sideways - i.e. a thicker than intended extrusion width. But with 50% infill there will still be room for the plastic down to half the layer height (at which point the extrusion width will be double and the infill thus becomes 100%). You then have a rather messy looking rectangle - but it has a perfectly level top. You can then lay down your raft support structure on that rectangle, and then build your part on top of the raft.

Dave

Yup, I was also thinking along the lines of what DMould said.

I actually agree with your viewpoint of the printer needing to compensate for it's own mistake. But since my day-to-day area of expertise is distributed enterprise architecture rather than embedded controllers, making firmware changes on the Ormerod for this appealed less to me than writing a Python plugin script

So the main benefit of having it in the slicer, would be
a) the amount of effort involved (at least for me, I'm pretty sure DC or ZPL can build it into the firmware in roughly the same time one of us would need to build the Cura plugin )
b) the system would work even on printers that don't have firmware support for this in (all of them currently), and
c) one would not need to do a firmware upgrade to test it.