Paper under Kapton tape for bed levelling on Huxley Duo

I have assembled my RepRapPro Huxley Duo kit, and am at the 'bed leveling' stage. It seems that the instructions for any machine with Duet electronics are now all in one place - this would be great, except they appear to just be the Ormerod instructions, and so all data is for the Ormerod, and the machine is always referred to as an Ormerod. This has resulted in me not realising that trying to send my Huxley Duo to X/Y200 will result in crashes, and having crashed my machine multiple times.

The biggest issue however, is the bed levelling. The page frequently mentions some kind of paper under the kapton tape in the corners for the IR sensor, but I can't find anything about paper in the Huxley Duo instructions (which is where the instructions about kapton-taping the bed are). I've been using a slip of paper and putting it roughly on the bed under the sensor, but this is obviously not very accurate. I then tried putting paper under the kapton tape, but it sometimes didn't register, resulting in the hot end crashing into the bed, and often pushing the two Z motors out of alignment.

What's the deal with the paper? What should I use, and where?

Thanks,
Archie

Hi Archie,

With any luck, Ian from RRP support will reply on Monday. Meanwhile, I suggest you read and adapt the Ormerod bed assembly instructions, which tell you to put squares of white paper under the Kapton tape close to the corners of the bed. If the sensor crashes into the bed when you do this, then the sensor may be mounted too high compared to the nozzle.

Alternatively, you could buy my differential IR sensor, which doesn't need white targets. See [miscsolutions.wordpress.com] for details. It has different fixing centres from the RRP one, so you would need to print a modified mount for it first.

To print without getting the sensor working, home X and Y but not Z. Heat the bed and hot end to operating temperature, command the nozzle to the centre of the bed, then lower it until it just grips a sheet of paper between the nozzle and the bed. Then send G92 Z0 to define that as Z=0. Raise the head a few mm, then print - making sure that the gcode file you print doesn't have a G28 command near the start.

Edited 1 time(s). Last edit at 10/11/2015 10:58AM by dc42.

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

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

I ended up sticking a few extra M3 nuts in between the acrylic piece and the sensor board - I think it wasn't parallel with the nozzle, so kept missing the paper under the tape (possibly my mistake!). My machine is now happily printing the calibration part.

It would be good if the Huxley's instructions were modified to include this paper bit though!

Hi Archie

You shouldn't need the paper on the corners for a Huxley. The sensor should work fine on the aluminium itself. The reason it's on the Ormerod and Mendel beds is because they have glass on the bed, and the probe gives a false reading as it sees through the glass. Make sure you use the Huxley SD Image, which should have the bed size set up for the Huxley, so the bed compensation points are correct.

Sorry about the lack of specific instructions for the Huxley. I though I had de-Ormerod-ed the instructions, to make it less specific, but I think the instructions do refer to the Ormerod more than they should, still. They are due for a re-write, when I have time.

Ian
RepRapPro tech support

Hmmm, that's strange. The only reason I even thought about putting paper on the bed was because it didn't stop when leveling and was pushing the bed downwards. Well, it's working now, so I'll just leave it alone I think!