Lokbuild vs IR sensor

has anyone had problems with that combination? With the tests I did today there's a big variation between activation height based on the probe being on orage or the black/white lettering in the middle. My bed mesh on Duet literally had a hole in the middle where the lettering is.

I considered covering everything with some white paper and then after calibrating account for the paper thickness, but I am sure someone smarter than me found that problem before and may have a better idea

Is Lokbuild a transparent material, with the lettering on the underneath? if so, then unfortunately it's inevitable that the lettering will affect the trigger height. The reason is that you get an IR reflection from the top surface and another one from the bottom surface. The strength of the reflection from the bottom surface will depend on the colour of the lettering, which means that the ratio of the strengths of the top and bottom reflections changes, and that is what causes the trigger height to change. With transparent bed surfaces, I recommend using a black backing underneath, to minimise the reflection from the back surface.

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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].

Quote
dc42
Is Lokbuild a transparent material, with the lettering on the underneath? if so, then unfortunately it's inevitable that the lettering will affect the trigger height. The reason is that you get an IR reflection from the top surface and another one from the bottom surface. The strength of the reflection from the bottom surface will depend on the colour of the lettering, which means that the ratio of the strengths of the top and bottom reflections changes, and that is what causes the trigger height to change. With transparent bed surfaces, I recommend using a black backing underneath, to minimise the reflection from the back surface.

No, it's bright orange with black and white lettering in the middle. It's exactly this one on amazon [smile.amazon.com]

In that case, the best suggestions I can offer are either to put a sheet of paper on top when you do mesh probing as you suggest, or use a mesh that is only 4 points in the Y direction so as to avoid the lettering. Recent versions of RepRapFirmware allow you to choose a different grid spacing for X and Y, so you could still use a smaller X spacing.

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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].

Quote
dc42
In that case, the best suggestions I can offer are either to put a sheet of paper on top when you do mesh probing as you suggest, or use a mesh that is only 4 points in the Y direction so as to avoid the lettering. Recent versions of RepRapFirmware allow you to choose a different grid spacing for X and Y, so you could still use a smaller X spacing.

Yeah I will try that paper thing. Idea for the future: be able to define a 'no go' area for the mesh so I could tell it to avoid the middle but do it around.

Thanks DC!