Mounting dc42's Mini height sensor board
Posted by Treito
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Re: Mounting dc42's Mini height sensor board November 13, 2016 08:38AM |
Quote
dc42
I recommend aiming for 1.5mm. Below 1mm there is a risk of the sensor contacting blobs or curl-up on the print, and above 2mm there is a risk that the sensor will not trigger.
Good advice on playing it safe, just want to note that 2,5mm never failed on my two machines, both with 4mm glass directly on the PCB heater, even think I could raise that a bit with mat black under the glass but should not be needed
What a difference your Sensor made, thank you!
Erik
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Re: Mounting dc42's Mini height sensor board March 10, 2017 08:23PM |
Just wanted to say how pleased I am with your height sensor.
No other sensor was compact enough to easily mount anywhere near the hot-end with my fan duct in place.
Also, I like printing on glass.
To measure the standard deviation of the height measurements from the sensor, I tweaked Marlin so that G30 would output the trigger height to 3 decimal places (1 micron resolution). I turned on my printer and made 46 measurements with G30 and got an s.d. of 1.4 microns. I noticed a trend in the data, presumably due to temperature drift somewhere in the system (probably the steppers warming up my crappy M5 threaded rods so the trigger point appeared to get lower with time). So I did another 34 measurements and the s.d. was 0.8 microns, but still with a small trend, so the device is way more accurate than I was expecting.
I used a permanent marker pen to blacken the red heated bed pcb under the probe areas, and 3 mm glass which had a thin layer of UHU glue stick on it, as I would normally use for a print.
The only (minor) issue I had was that initially I mounted the sensor so that the bottom of the board was 1.5 mm above the tip of the nozzle, as recommended. The problem was this meant I reduced my build area from 200x200 to 200x185, to avoid the board colliding with the bulldog clips holding the glass down.
I commonly use the full 200x200, so this was a problem.
I am not sure how other people deal with this, but I used my hot-air rework station to tweak the angle of the outer led to increase the trigger height by ~0.5 mm out to 3.3 mm. This meant I could mount the board so it would clear the clips (which rise 2.65 mm above the glass), and still leave the nozzle tip 0.4 mm above the bed when the sensor triggers.
It seems to me that scaling the spacing of the optical components a little (x 1.3 say) to achieve a slightly greater trigger height would be beneficial if/when you do v1.3. There is a little spare room still on the current 24 mm wide board to do this, but I think it would be worth it even if the board had to be a bit wider, since I don't think the width would be a constraint for most installations.
Thanks again for a great sensor,
Kit
Edited 1 time(s). Last edit at 03/10/2017 08:28PM by spinorkit.
No other sensor was compact enough to easily mount anywhere near the hot-end with my fan duct in place.
Also, I like printing on glass.
To measure the standard deviation of the height measurements from the sensor, I tweaked Marlin so that G30 would output the trigger height to 3 decimal places (1 micron resolution). I turned on my printer and made 46 measurements with G30 and got an s.d. of 1.4 microns. I noticed a trend in the data, presumably due to temperature drift somewhere in the system (probably the steppers warming up my crappy M5 threaded rods so the trigger point appeared to get lower with time). So I did another 34 measurements and the s.d. was 0.8 microns, but still with a small trend, so the device is way more accurate than I was expecting.
I used a permanent marker pen to blacken the red heated bed pcb under the probe areas, and 3 mm glass which had a thin layer of UHU glue stick on it, as I would normally use for a print.
The only (minor) issue I had was that initially I mounted the sensor so that the bottom of the board was 1.5 mm above the tip of the nozzle, as recommended. The problem was this meant I reduced my build area from 200x200 to 200x185, to avoid the board colliding with the bulldog clips holding the glass down.
I commonly use the full 200x200, so this was a problem.
I am not sure how other people deal with this, but I used my hot-air rework station to tweak the angle of the outer led to increase the trigger height by ~0.5 mm out to 3.3 mm. This meant I could mount the board so it would clear the clips (which rise 2.65 mm above the glass), and still leave the nozzle tip 0.4 mm above the bed when the sensor triggers.
It seems to me that scaling the spacing of the optical components a little (x 1.3 say) to achieve a slightly greater trigger height would be beneficial if/when you do v1.3. There is a little spare room still on the current 24 mm wide board to do this, but I think it would be worth it even if the board had to be a bit wider, since I don't think the width would be a constraint for most installations.
Thanks again for a great sensor,
Kit
Edited 1 time(s). Last edit at 03/10/2017 08:28PM by spinorkit.
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Re: Mounting dc42's Mini height sensor board March 11, 2017 02:24AM |
I'm glad you like the sensor!
Ormerod users mostly use Swiss clips (= frameless photo mount clips) instead of bulldog clips to hold the glass down. The ones on my Ormerod protrude about 1mm above the glass.
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].
Ormerod users mostly use Swiss clips (= frameless photo mount clips) instead of bulldog clips to hold the glass down. The ones on my Ormerod protrude about 1mm above the glass.
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].
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Re: Mounting dc42's Mini height sensor board March 11, 2017 10:59AM |
Quote
spinorkit
To fix this I bolted a 16x16mm aluminium channel extrusion diagonally under my heated bed and I use lots of medium size bulldog clips to hold the corners of the glass down. This gives me one warp-free diagonal.
The extrusion means I can't get swiss clips anywhere near the corners.
Thanks again,
Kit
I modified the bulldog clips, cut one side, rounded the edges so not to damage the kapton and made a simple tool for mounting the clips
Erik
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