Mounting Hot End Board V2

Hi,
I'm in the process of upgrading the Z probe to dc42's differential sensor.

First off, the LED sensor clearly works. I can home X ok.
But I'm having difficulty getting the Z probe to be non-zero above the Kapton + glass bed.

It's the dual version sensor wired for one extruder, and I've used the modified one-piece heatsink/fan duct.
I'm using 0.78r-dc42 on a green Ormerod 1, with daveK's Al X axis and bed support.

With the hotend off the bed in the +X position, and the sensor still over the bed, I can see from the web interface that
with Z = -0.3 the Z probe is 462, so that suggests a mounting problem, or the relationship between
the position of the nozzle and the IR board.

Does anyone have any experiences like this?
Or any suggestions before I start tweaking and reprinting the heatsink duct?

DaveS

Hi DaveS, I think either your board is mounted too high above the nozzle, or one or more of the phototransistor and IR LEDs has got bent away from its correct orientation. On the board you will find I have written the distance between the edge of the board and the glass at which the output changes from 465 to 535. It will be around 3mm. That is measured using plain glass, but it should be almost the same for Kapton on glass. So I suggest you measure the distance between the board edge and the bed when you get the 465 reading. If it is over about 2.5mm then you need to mount the board lower down on the hot end. If it is less than about 2mm then check for bent IR LEDs or a bent phototransistor.

The edge of the board should be 1 to 2mm higher than the tip of the nozzle.

Hope this helps - David

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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 David, it was the specific numbers that I needed.

It looks like I have a host of problems, all of my own making

The nozzle to edge of the PCB is more like 4mm,
and the edge is not parallel to the plane of the bed.
The extra mounting hole I made in the Heatsink is too low, so the nozzle is lower too...
One of the sides of the mounting hole/slot on the X-carriage for the hot end had cracked,
so that bolt wasn't holding the hot end down...
...
Well at least it's a checklist for future upgraders

I'll check the location of the mounting holes in the unmodified heatsink duct and print a new one.

DaveS

Quote
gnarly
The nozzle to edge of the PCB is more like 4mm..

Should look something like this, the fanduct on the picture is johneato's mod of the original and compatible with David's probe

Quote
johneato
..I wanted to control the air flow to the nozzles to be able to provide cooling to PLA but not to ABS..

Control air to the nozzles:
[forums.reprap.org]





Erik

Thanks Erik, great pictures.

I've printed a new two part duct which seems to work ok now
..except it's lacking the cable management...

Now the Z probe is changing exactly 1.00 mm above the bed

I'll try the one piece duct again in a while, when I've printed some other fixes and upgrades.

DaveS

Let me know if you think the mounting points for the board on the one piece duct need to be lowered.

I'll look at adding cable tie points to the modified two-piece design.

Edited 1 time(s). Last edit at 09/21/2014 11:40AM by dc42.

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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].

Hi, i hapen to have the same problem, the mounting is to hi, there is only 0.3mm clearance. When the head has some oozing left, than it cannot detect zero position.
I would love to have the one piece duct modified to have the mounting about 1mm lower.

Pavel

My board triggered a bit too low until I gently bent the IR sensors - a small adjustment results in a fairly large change to the trigger height.

Dave

Before bending the IR diodes or phototransistor, I recommend checking the height of the board above the tip of the nozzle. First make sure there is no plastic stuck to the bottom of the nozzle. Then the bottom edge of the board should be between 1mm and 2mm above the tip of the nozzle.

Also check that the board is perpendicular to the bed in both dimensions.

I attach an STL of the 1-piece duct with the board mounted 1mm lower.

---

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].