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Updating Ormerod 1 with RRP 4-wire modulated proximity probe

Posted by droftarts 
Updating Ormerod 1 with RRP 4-wire modulated proximity probe
September 23, 2014 10:28AM
A customer writes:
Quote

What's the advantage of the new modulated proximity probe, as supplied with the Ormerod 2? Can I update my Ormerod 1 with the new probe?

I replied:

The infra-red Z/Bed probe is now differential, meaning that readings are taken with the IR LED on and then subtracted from readings with it off. This gives much less interference from ambient light and it is more accurate.

Yes, you can fit it on an Ormerod 1. You will need 3 parts:

1 x 4-wire proximity sensor PCB (available from RRP)
1 x 4-wire proximity sensor wiring loom (available from RRP, or modify existing loom)
1 x x-carriage (this has been updated to accommodate the probe, and you can print it yourself)

The probe and loom are available directly from RepRapPro. They are not listed on our webshop yet, but should be soon. Email us directly on info@reprappro.com if you can't find it in [reprappro.com] or [reprappro.com]

There is no way to wire up the 4-wire probe with the existing 3-wire loom. However, you can modify your existing wiring loom, by adding an extra wire to the loom, to use the 4-wire probe correctly. This extra wire allows the IR LED in the sensor to be turned on and off, so it is able to sense the background level of Infra Red. Cut a length of wire (for example, yellow) the same length as the blue wire, and feed it through the loom sheathing. Fit a 1800-T crimp on each end, and replace the single crimp on the Duet end of the blue wire. At the proximity sensor board, the wiring order is blue/black/yellow/red. Remove the blue, black and red wires from the 3-way housing, and put them back in a 4-way housing in this order. At the Duet end, put the yellow and blue wires on the Duet end in a two-way crimp housing. In firmware version 0.78 (recommended) and later, the blue wire goes on the 6th pin from the right on the bottom row, and the yellow wire goes on the 5th. This wiring colour scheme is NOT the same as the shipping 4-wire loom, so BE CAREFUL!

Once you have assembled the parts:

1. Download, print and fit the new x-carriage: [github.com]

2. Fit the 4-wire probe and wiring loom: [reprappro.com] . See the wiring diagram at the top of that page to confirm position of wires.

3. Make sure you update your firmware to 0.78c (currently the latest version), update your SD card with the latest files from 'SD-image-Ormerod-1'. Copy any custom settings from your old config.g into the new one.

4. In sys/config.g on the SD card, change the line 'M558 P1' to 'M558 P2'. This enables the modulated (4-wire) probe, otherwise it works in non-modulating (3-wire, as used in Ormerod 1) mode. When you send a G31 command, you should get a reading something like:
>>>G31
SENDING:G31
245 (318)
The first figure is the modulated reading, which is what the firmware uses. The second reading is the response including ambient IR, and is the reading you would get without the modulated probe. You can switch between the two modes using M558 P1 and M558 P2 to compare.

5. In sys/homex.g and sys/homeall.g on the SD card, remove the ';' in front of ';M558 P2'. The X axis homing uses the 4-wire probe in 3-wire mode, as the response is faster (it doesn't have to do the modulation calculation and smoothing). It then needs to be set back to 4-wire mode afterwards. The edited homex.g will look something like this:
G91
G1 Z5 F200
G90
M558 P1 ; uncomment this line for Ormerod 1 upgraded with 4-wire probe
G1 X-240 F2000 S1
G92 X0
G1 X3 F200
G1 X-30 S1
G92 X0
M558 P2
G91
G1 Z-5 F200
G90
The edited homeall.g will look something like this:
G91
G1 Z5 F200
G90
M558 P1 ; uncomment this line for Ormerod 1 upgraded with 4-wire probe
G1 X-240 F2000 S1
G92 X0
G1 X3 F200
G1 X-30 S1
G92 X0
M558 P2 ; uncomment this line for Ormerod 1 upgraded with 4-wire probe
G1 X60 F2000
G92 Y0
G1 Y250 F2000 S1
G92 Y200
G1 Y197 F200
G1 Y250 S1
G92 Y200
G1 Y0 F2000
G30
G1 Z5 F200
G1 X0 Y0
G1 Z0

A little more detail about how the sensor works: The sensor (the small black component on the board) is split into two parts; an Infra Red LED, and a receiver that measures the amount of returned IR light. There are four wires going to the probe: 3.3V (green), trigger (blue), ground (yellow), signal (red). The trigger wire turns the Infrared LED on and off (to modulate the reading, to take account of background infrared), and the signal wire is the reading from the sensor.

I hope that helps.

Ian
RepRapPro tech support
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
September 23, 2014 01:09PM
I'd like to point out when Ian uses the term "differential" in the above, this is not in the same sense that I use when I refer to my "differential LED height sensor board" (as in [forums.reprap.org]).

The RepRapPro 4-wire proximity sensor board measures the difference between the IR readings when the infrared LED is on and when it is off. This greatly reduces the sensitivity of the reading to ambient light. It doesn't entirely eliminate it, because the IR sensor is not linear. Some time ago I hacked the standard IR sensor to add modulation, in the same way that the RRP 4-wire sensor now does - see [forums.reprap.org]. The sensitivity to ambient light was reduced by a factor of 14.5. Later (see [forums.reprap.org]) I reduced the sensitivity to ambient IR by an additional factor of 2 by adding an extra resistor. RRP's design doesn't appear to include the extra resistor.

My hot end board uses TWO infrared leds (instead of just one) and one phototransistor. It measures the response from the phototransistor with each LED on in turn, and with both LEDs off. The two LEDs are geometrically arranged to give maximum response from the phototransistor at slightly different heights. The height at which they give equal response is the calibration height. An on-board microcontrollor tell the Duet whether the sensor is a long way from the bed, approaching trigger height, at or below trigger height, or that there is too much ambient IR to get a reliable indication.

IMO the RRP 4-wire sensor is a big improvement over the original in that it is less sensitive to external IR (from incandescent light or bright sunlight), probably by a factor of about 15. However, it is still sensitive to the reflectivity of the surface, so you need to use it over white targets. My hot end board (see [miscsolutions.wordpress.com]) is even less sensitive to external IR, but more importantly, it is much less sensitive to the reflectivity of the surface. So there is no need to use white targets - which means that you can use it anywhere on the bed, and even on bare glass if that's what you print on. And of course my board includes other features, such as fan control, along with LEDs to indicate whether the hot end heater is powered and whether trigger height has been reached. In fairness to RRP, these improvements could be considered non-essential, and therefore the increased parts cost would be hard to justify on a basic 3D printer kit.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 12, 2015 01:21PM
Hi guys, i have DCs firmware and the current web interface that goes with it.. was wondering how the bed leveling works with the new probe as the values i get are a ton lower with the modulated probe. i did everything else, am just wondering how people now do the bed leveling?
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 12, 2015 04:08PM
AFAIR the modulated probe is deliberately less sensitive than the original one. This has two advantages. First, it is less prone to saturating due to background IR. Second, you can calibrate it at a lower Z height, which increases the precision. So you need to find the height at which it gives you a reading around 500 or 600.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 12, 2015 08:38PM
hmm. then i think i have a problem. my probe gives me a reading of somewhere around 247 at z:0... i checked the wiring, it seems to be on the nose but im open to the idea i stuffed something up somewhere..
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 03:16AM
Things to check:

1. Look along the X axis. Is the print head level, or is it sagging? If it is sagging, the sensor head will be higher above the bed.

2. Is the black IR sensor head at the bottom of the sensor board square to the board, or have the legs got bent?

3. When the nozzle is touching the bed, how high above the bed is the bottom edge of the sensor board? AFAIR it should be around 1.5mm.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 06:58AM
the probe is definately higher than 1.5mm its about .5cm. but that seems no lower than the old head? i would imagine 1.5mm wouldn't give it an awful lot of clearance.. it was a little off kilter but changing that didn't really help the scenario
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 08:29AM
5mm is WAY too high. 1.5mm is plenty of clearance, even 1mm is enough. But aim for 2mm if you prefer.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 08:48AM
hmm. how the hell would i change that clearance then? i could just drop the IR probe down a little by only using the 1 screw rather than the 2 its using the whole hot end sits perfectly verticle as it is now
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 10:08AM
HAHA nevermind. turns out i put the nozzle mount in upside down... move along, nothing to see here.
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
February 13, 2015 02:13PM
that being said. it still cant give me a reliable bed level.
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 06, 2015 06:29AM
Hello, I've bought the updated RepRap IR sensor board.

When I printed off the new X-carriage from the link above it became apparent that there are two problems...

1) The bearing mount is at 90o to the original. I've machined it to mount it orientated correctly - leading to...

2) The bearing is too far away from the X rib.

Doh!

I have an Ormerod 1, is this new part for the Ormerod 2?

Does anyone know if there is a modified X-carriage for the new IR sensor, or do I even need it?

Many thanks in advance.


Ormerod 1
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 06, 2015 10:51AM
Quote
Mr_Bodge_It
Hello, I've bought the updated RepRap IR sensor board.

When I printed off the new X-carriage from the link above it became apparent that there are two problems...

1) The bearing mount is at 90o to the original. I've machined it to mount it orientated correctly - leading to...

2) The bearing is too far away from the X rib.

Doh!

Yes that look a bit strange, I think its supposed to run the bearing under the x-axis-plate (on lower edge of)




Quote

Does anyone know if there is a modified X-carriage for the new IR sensor, or do I even need it?

the only difference I can see is 2mm added to total length in the X+ direction



Erik
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 06, 2015 12:13PM
Quote
ormerod168

Quote

Yes that look a bit strange, I think its supposed to run the bearing under the x-axis-plate (on lower edge of)

[attachment 50556 ormerod1_x-carriage_diff1.JPG]

Ah, mine doesn't look that pretty - there was some infill printed at the point where the bearing should be housed.

I shall give it another go and update my progress.

Many thanks for your time Erik
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 10, 2015 12:28PM
Sorry, that seems to be a version that the designer was messing around with that's been updated to the repository a few days ago. I'll get this change reverted. For now, you can get the production version here: [github.com]
Direct link to file: [github.com]

Ian
RepRapPro tech support
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 10, 2015 01:17PM
Quote
droftarts
Sorry, that seems to be a version that the designer was messing around with that's been updated to the repository a few days ago. I'll get this change reverted. For now, you can get the production version here: [github.com]
Direct link to file: [github.com]

Ian
RepRapPro tech support

Ian When are you likely to get more Duet's in stock I Need one to help test the CoreXY functionality in DC42's firmware fork?

Doug

(I Have emailed Sales with same question)
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 11, 2015 06:50AM
Actually, the new x-carriage with the bearing underneath the x-axis-plate will work fine. It is going to be changed in production, and will be in the next revision of the Ormerod.

Doug: Bit off topic?! We're waiting for new boards from China. They should be arriving early next week.

Ian
RepRapPro tech support
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 11, 2015 08:11AM
Quote
dougal1957
Ian When are you likely to get more Duet's in stock I Need one to help test the CoreXY functionality in DC42's firmware fork?

Have you tried Think3DPrint3D to see if they have any in stock? Their price for a Duet was a few pounds less than RRP last time I looked. OTOH their boards come with screw terminals unless things have changed recently, and I prefer the Molex connectors on the RRP boards.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
March 11, 2015 08:35AM
Quote
dc42
Quote
dougal1957
Ian When are you likely to get more Duet's in stock I Need one to help test the CoreXY functionality in DC42's firmware fork?

Have you tried Think3DPrint3D to see if they have any in stock? Their price for a Duet was a few pounds less than RRP last time I looked. OTOH their boards come with screw terminals unless things have changed recently, and I prefer the Molex connectors on the RRP boards.

Dave that was the point of the Q as I prefer the molex connectors as well
Re: Updating Ormerod 1 with RRP 4-wire modulated proximity probe
April 25, 2015 04:14AM
Little question on the side. What if i keep using the old 3-wire probe on the shield? RRP only shows the 4-wire on the sheme.
There are more things missing in the manual, "The following connections remain to the Duet: Z motor, Y motor, Y endstop, heatbed power and thermistor."
No more x-motor in this version?
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