Anyone interested in a differential IR Z probe for deltas?

I am considering adapting my dual IR beam Z probe sensor to work on the Mini Kossel and other deltas. It would be based on my design for the Ormerod (see [miscsolutions.wordpress.com]), but shorter so as to fit under the effector plate of a Mini Kossel. I would probably leave off the thermostatic fan control, because the hot end fan of the MK is quieter than the one on the Ormerod.

Would there be any interest from Delta printer owners in such a probe?

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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].

Dave

Yes please but able to mount to the side as well if poss my hotend is only about 12-15mm below the effector plate.

Doug

I am definitely interested Dave, as you know.

Size is going to be the key thing, I am using a version of AndyCarts CPIIIs sprung effector, and there is limited space to fit one. I had this crazy idea, which probably isn't feasible due to noise or interference, but is it possible to separate the sensor part from the main PCB? You could then have a tiny PCB mounted on the bottom of the effector with just the sensors, and then mount the main PCB on the top with a short cable connecting the two.

Just an idea.

Regards,

Les

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Pointy
I am definitely interested Dave, as you know.

Size is going to be the key thing, I am using a version of AndyCarts CPIIIs sprung effector, and there is limited space to fit one. I had this crazy idea, which probably isn't feasible due to noise or interference, but is it possible to separate the sensor part from the main PCB? You could then have a tiny PCB mounted on the bottom of the effector with just the sensors, and then mount the main PCB on the top with a short cable connecting the two.

Just an idea.

Regards,

Les

Or have the board waisted so that it could fit on one corner of the effector (Narrow part) Maybe that would work.

Doug

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Pointy
I am definitely interested Dave, as you know.

Size is going to be the key thing, I am using a version of AndyCarts CPIIIs sprung effector, and there is limited space to fit one. I had this crazy idea, which probably isn't feasible due to noise or interference, but is it possible to separate the sensor part from the main PCB? You could then have a tiny PCB mounted on the bottom of the effector with just the sensors, and then mount the main PCB on the top with a short cable connecting the two.

Just an idea.

Regards,

Les

Les, how much depth is there between the bottom of the effector plate and the tip of the nozzle on your build? I'm wondering whether a very basic sensor without illumination and the other hot end connectors would fit.

Splitting it into 2 parts would be possible, but would make assembly more difficult and increase the build cost.

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dougal1957
Or have the board waisted so that it could fit on one corner of the effector (Narrow part) Maybe that would work.

That would be possible, but the problem is that to make it economical to produce these sensors, I need them to fit as many different printer designs as possible. So the waist would have to be very long.

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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].

Could be interesting, we are looking at using pressure sensors on the backside of the wooden plate of the (square) bed for our Kossel. But your design coukd be an alternative if we fail :-)

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I am aware that some people use FSRs under the bed supports, but I was under the impression that this was not so easy when a heated bed is used. I presume this is because of the extra weight of a heated bed and/or temperature sensitivity of the FSRs.

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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].

I would be interested in fitting them to my Cherry Pi builds. I've built around 20 so far and it fairly steady. Not huge volumes I know but since moving to my new all metal hotend I've had to ditch the Z probe effector. Typically Rich Cattell has just re-surfaced with a new version of his auto calibration firmware. It would all depend on cost however!

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dc42
I am aware that some people use FSRs under the bed supports, but I was under the impression that this was not so easy when a heated bed is used. I presume this is because of the extra weight of a heated bed and/or temperature sensitivity of the FSRs.

JohnSL developed a standalone FSR board with three analog FSR inputs and a simple digital output. His board has signal averaging on each FSR channel, which overcomes many of the problems and auto-calibrates for the bed weight. As far as the main controller board is concerned, it sees the board as a mechanical endstop on the Z-Min pin.

If you wire the three FSR's in parallel, JohnSL's code will also run on an Adafruit Trinket or Trinket Pro. Of course, you do not get the handy debugging LEDs for each FSR channel that show which one(s) triggered the endstop signal.....

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dc42
I am aware that some people use FSRs under the bed supports, but I was under the impression that this was not so easy when a heated bed is used. I presume this is because of the extra weight of a heated bed and/or temperature sensitivity of the FSRs.

Because they seem to put sensors under the bed ... Not under the wooden panel that reduces greatly the effect of temperature. In the end the sensors are to be used before warming the bed, so they should just not be damaged during prioting by a hot bed. ... Or so we believe.

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----- Making the world smarter @ www.xetal.eu
----- Helping entrepreneurs @ www.fralke.com

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dc42
Les, how much depth is there between the bottom of the effector plate and the tip of the nozzle on your build?.

I have 8mm from the bottom side of the effector to the tip of the nozzle.

Regards,

Les

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Pointy

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dc42
Les, how much depth is there between the bottom of the effector plate and the tip of the nozzle on your build?.

I have 8mm from the bottom side of the effector to the tip of the nozzle.

Regards,

Les

Yes mine would be the same (Or possibly a little more when my E3D Volcano hot end arrives).

Doug

Dave

Just measure the spacing between the narrowest gap on the rods and if you could get the width of the board down to 15-16mm then it would fit.

The latest design of Andy's Cherry pi uses stainless ball's on the end of the rods held in tension by a spectraline/spring arrangement which is actually very effective and easy to implement.

This means that the probe would need to sit between the narrow part of the rods and I agree that all it should need is the endstop signals and no need for fan/thermistor cableing.

I'm all in favour of the KISS principle here.

Les you may have to modify the effector design slightly to add a mounting plate on one of the corner's to take whatever dave comes up with (It would need to have provision to move the probe up or down to suit the hotend as well)

Dave if you need anyone to beta test just give me a shout my printer should be up and running in about a week or so.

Doug

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dougal1957
Les you may have to modify the effector design slightly to add a mounting plate on one of the corner's to take whatever dave comes up with (It would need to have provision to move the probe up or down to suit the hotend as well)

Yes, as soon as Dave has a design I can model it in sketchup and add some mounts.

Regards,

Les

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Pointy's Things
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Definitely!

The problem I am up against with designing an IR probe suitable for a wide range of delta printers is that the height of the effector plate above the nozzle varies so much. On the Mini Kossel, the complete IR probe and electronics would for comfortably below the effector plate. On some other printers there is too little space there, so the board would need a very narrow waist that fits in the effector cutout between a pair of parallel rods, with the sensors below and the rest of the electronics and connectors above. But there is no standard height at which to put that waist.

I'm thinking of resurrecting an earlier idea I had, which is to use a solenoid-activated mechanical probe. The solenoid I have in mind weighs 12g. It can be mounted above the effector in all cases, and the probe extended downwards as necessary for different printers. Sensing contact of the probe with the bed could be done either using an optical pickup to detect when the probe has been pushed in a certain amount, or by using a cheap microcontroller (e.g. attiny45) to sense the change in inductance.

I would provide two output options:

1. Stepped analog output compatible with my Ormerod differential IR sensor. This provides an indication of when the trigger point is approaching, to allow the firmware to reduce the speed.

2. Digital output emulating a normally-closed microswitch that opens when the probe is triggered, for use with Marlin and similar firmware.

I would probably design the board to require +12V, 12V ground, output, and signal ground wires. The 12V and 12V ground wires are typically already available from the hot end cooling fan (provided it is wired to a permanent 12V supply), and the output and signal ground wires are present already on the Mini Kossel kit with mechanical Z probe.

I could also provide the option of terminating all the hot end wires on the board as I do on my Ormerod board, with or without thermostatic control of the fan.

How does this sound?

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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
The problem I am up against with designing an IR probe suitable for a wide range of delta printers is that the height of the effector plate above the nozzle varies so much. On the Mini Kossel, the complete IR probe and electronics would for comfortably below the effector plate. On some other printers there is too little space there, so the board would need a very narrow waist that fits in the effector cutout between a pair of parallel rods, with the sensors below and the rest of the electronics and connectors above. But there is no standard height at which to put that waist.

I'm thinking of resurrecting an earlier idea I had, which is to use a solenoid-activated mechanical probe. The solenoid I have in mind weighs 12g. It can be mounted above the effector in all cases, and the probe extended downwards as necessary for different printers. Sensing contact of the probe with the bed could be done either using an optical pickup to detect when the probe has been pushed in a certain amount, or by using a cheap microcontroller (e.g. attiny45) to sense the change in inductance.

I would provide two output options:

1. Stepped analog output compatible with my Ormerod differential IR sensor. This provides an indication of when the trigger point is approaching, to allow the firmware to reduce the speed.

Dave this solutions sounds ideal to me.

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dc42
2. Digital output emulating a normally-closed microswitch that opens when the probe is triggered, for use with Marlin and similar firmware.

This is also a good idea could you maybe do both on the same board but have them link selectable (maybe with a solder bridge link This would then be a one board fits all scenario)

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dc42
I would probably design the board to require +12V, 12V ground, output, and signal ground wires. The 12V and 12V ground wires are typically already available from the hot end cooling fan (provided it is wired to a permanent 12V supply), and the output and signal ground wires are present already on the Mini Kossel kit with mechanical Z probe.

I could also provide the option of terminating all the hot end wires on the board as I do on my Ormerod board, with or without thermostatic control of the fan.

Yes Please This would make wiring a breeze as long as the sockets/plugs you use are readily available (Or even supply them with the board at additional cost)

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dc42
How does this sound?

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dougal1957

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dc42
I would probably design the board to require +12V, 12V ground, output, and signal ground wires. The 12V and 12V ground wires are typically already available from the hot end cooling fan (provided it is wired to a permanent 12V supply), and the output and signal ground wires are present already on the Mini Kossel kit with mechanical Z probe.

I could also provide the option of terminating all the hot end wires on the board as I do on my Ormerod board, with or without thermostatic control of the fan.

Yes Please This would make wiring a breeze as long as the sockets/plugs you use are readily available (Or even supply them with the board at additional cost)

The connectors I use are Molex KK series, which are widely available. Unlike some other connectors used on hot ends, it is not difficult to remove the crimp pins from the housings after they are inserted. When I supply Ormerod hot end boards, I include the mating connector shells and crimp pins too. However, the customer still needs to connect the wires from the hot end loom, for which I recommend a crimp tool.

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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

Quote
dougal1957

Quote
dc42
I would probably design the board to require +12V, 12V ground, output, and signal ground wires. The 12V and 12V ground wires are typically already available from the hot end cooling fan (provided it is wired to a permanent 12V supply), and the output and signal ground wires are present already on the Mini Kossel kit with mechanical Z probe.

I could also provide the option of terminating all the hot end wires on the board as I do on my Ormerod board, with or without thermostatic control of the fan.

Yes Please This would make wiring a breeze as long as the sockets/plugs you use are readily available (Or even supply them with the board at additional cost)

The connectors I use are Molex KK series, which are widely available. Unlike some other connectors used on hot ends, it is not difficult to remove the crimp pins from the housings after they are inserted. When I supply Ormerod hot end boards, I include the mating connector shells and crimp pins too. However, the customer still needs to connect the wires from the hot end loom, for which I recommend a crimp tool.

Good news Dave I can cope with KK's easily and already have a crimp tool for them so not a problem What I would like to see if possible is that we could use a simple 4 wire loom back to the controller and have a 12V tap from the Sensor board to feed the Hotend fan if possible Either use a 4 way + a 2 way connector or else a single 6 way one.

Just ideas.

Doug

Dave

Any progress/news?

Doug

I would be interested in one. I have a MakersGeek All Metal Delta, which has a very short hotend < 2" long.

I was considering building an optical sensor using an Adafruit Trinket 5 vdc with a single IR diode and phototransistor. The whole thing should be very light so as not to give the hotend too much mass.

I have a Smoothieboard, so the 5 vdc would be compatible with the z minimum input.

What cost range are you thinking?

Chuck

I have done some preliminary design work on the board, and the size is coming out at 25mm wide by 20mm high. The bottom edge of the board needs to be between 1mm and 2mm above the nozzle. So the minimum space needed will be about 20mm height between the tip of the nozzle and the underside of the effector. I may be able to reduce this by a couple of mm if I use a smaller connector than the Molex KK.

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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
I have done some preliminary design work on the board, and the size is coming out at 25mm wide by 20mm high. The bottom edge of the board needs to be between 1mm and 2mm above the nozzle. So the minimum space needed will be about 20mm height between the tip of the nozzle and the underside of the effector. I may be able to reduce this by a couple of mm if I use a smaller connector than the Molex KK.

Dave

Think I would stick with the Molex KK 2mm shouldn't make to much difference to be honest and as I replied in the 7factor thread I can increase my space below the effector tho at the cost of a loss of 15mm height (not to fussed at that as I have 515 Z height anyway).

Doug

Dave,

The size would be good for me, I still need to get a Z probe for my printer.

Let me know when you have a prototype and how much money you need.

Chuck

I now have 4 working pre-production boards, but they are all spoken for. I have enough PCBs left to assemble another 6, and I will order the components for them shortly. Prices (in GBP) including shipping and VAT where applicable will be 38.50 to UK, 46.60 to EU, 38.83 to Europe when VAT does not need to be charged, and 39.86 to anywhere else. To order a board, send me a PM with your PayPal email address, country, and VAT number if claiming the EU VAT-free price.

Please note: for maximum flexibility, I intend to ship the 3-pin connector separately, i.e. not soldered on. You will have a choice of which side of the board to solder the connector on, or to solder flying leads directly to the board instead, or to solder on a different connector e.g. right angle. So you will need at least some soldering skills. If/when standard ways of mounting the board on various printer heads have been developed, then I will offer the boards with connectors already soldered on.

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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].

Can you post the schematic? I would like to build one my self.

Maybe the source files as well, but schematic would be fine. (I have access to pcb machine.)

Schematic is at [github.com].

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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].

Does it have to be the same ir diodes? They seems hard to get.

The IR LEDs were chosen carefully to have a narrow beam angle.

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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].

I have shipped the first few boards. Fitting instructions are here [miscsolutions.wordpress.com].

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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].