Adding Multi extruder support - howto

There have been a couple of post in different threads about how to add multi extruder support to the Ormerod - mechanics and electronics.
Let's see if we can collect the information and experience in this thread.

My opinion is: if you can assemble the Ormerod and are not afraid of dealing with g-codes and m-codes, then you can also add multi extruder support to your own Ormerod.

dc42 made a good buying list in another thread: [forums.reprap.org]

Quote
dc42
..... having gone through this myself and not got it quite right first time, this is what I think you need:

1. Two Ormerod hot end kits, [reprappro.com]. I am assuming that you want to keep your existing single-nozzle hot end as a backup, and perhaps for single-nozzle mixing extruder experiments. In fact two hot end kits provide more than you need, you will have a heatsink and fan left over, but it is slightly cheaper than buying one hot end kit and the extra parts.

2. One Duet X4 expansion board, [www.think3dprint3d.com].

3. One Ormerod extruder kit. I haven't found this on the RepRapPro shop, but I expect Sally can give you a price.

4. One Ormerod hot end loom (unless you make it up yourself). I haven't found this on the RepRapPro shop either.

5. For the 2-nozzle heatsink block, there are a few possibilities. You can ask DaveK if he can quote you a price for a copy of the 2-nozzle heatsink block that he made for me, and use it with the modified nozzle mount I published here [github.com]. Or you can bolt two standard heatsink blocks together at the back of the hot end, with what were the nozzle mounting screws in one of them drilled out and tapped for the nozzles.

I'll post a photo when I have finished assembling it.

I definitely agree with him, that you should keep your single hot-end intact and build a completely new dual one.
Here are some photos from my setup:

I made an extended enclosure for the Duet and its expansion board.


This is how the motor is connected to the extension-board. The connector at the board-end of the standard cable has to be changed to a 2x2-type. With the right type, you don't need to change the crimped pins. I did not damage my board, even though I tried almost every combination




The same goes for the hot-end cable - 2x3 connector. Yellow and white wires are for the heating cartridge. Green and blue are for the Thermistor.



I got a longer nozzle-mount made (unfortunately in stainlass steel - should have been aluminium). With two nozzles heated, I could safely touch the nozzle-mount-bar, so no need to upgrade the fan and heat-sink. I'll post some pictures from a thermal camera later. Only one nozzle is mounted, because I broke the wires off a heating cartridge. Be careful not to bend those too many times - they break very easily.



For the power-supply, I replaced the supplied power-cable with 2.5mm^2 cables (AWG13) and just split them into two - one for the Duet and one for the extension-board. I think the original PSU should be able to support one extra extruder. I use a bigger PSU, because of an upgrade to the bed-heating.


Making a nozzle-mount bar yourself should be possible with a simple drill-press and a bit of tapping. It doesn't have to be overly accurate, as you will have to adjust and calibrate the Ormerod. 8x8mm aluminium bars can be found on Ebay.

I have probably left a ton of details out. Please ask questions.

Best regards,

Carsten

Edited 1 time(s). Last edit at 07/10/2014 03:39AM by colsenfoto.

Hi Carsten

Nice work! Our development machine has the two boards very similarly mounted; we didn't even print a new enclosure, just made a bigger laser cut piece of acrylic. However, I should point out that any production version of the dual head Ormerod may look quite different, and we may end up changing any number of parts, eg Duet housing, x-carriage, nozzle-mount, cooling block etc. But the basic hot end kit shouldn't change. Just trying to give you a sense of what we're doing, without giving too much away!

The metal machined parts of the Ormerod are in the Ormerod repository on github: [github.com] . The drawing of the current, single-nozzle cooling block (aka heatsink block) is called 'heatsink_block.PDF', so you can use this to get the dimensions right for any extended block.

Ian
RepRapPro tech support

edit: Ormerod repository updated with machined parts, added reference.

Edited 2 time(s). Last edit at 07/10/2014 11:21AM by droftarts.

This is my sketch for the 3-nozzle-mount-block:



I found the original one in the SolidWorks files in the Ormerod-master repository. Its called: "narrow-heatsink"

I considered mounting the X4 next to the Duet like that, but I didn't like the idea of having such a tall enclosure, or cables going to the top of it. So I've taken bobtidey's enclosure design here [forums.reprap.org] and adapted it to accommodate the Duet and X4 boards back-to-back.



I will attach the cables to the X4 first, using the screw terminals to keep the profile low, then fit the X4 to the enclosure component side down. Then I will fit the Duet on top of it in the usual way.

Normally, connecting the Z probe wires would be a problem with this arrangement, because one or two of them would be connected to the expansion connector on the X4, so a low-profile mounting would be needed or the X4 stood off further from the base of the enclosure. However, I already epoxied an extra 3-way header to the bottom of my Duet board for the Z probe to reduce noise pickup from the switching regulator, so that won't be a problem for me.

---

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
colsenfoto
This is my sketch for the 3-nozzle-mount-block:

I don't have a decent sketch of my 2-nozzle heatsink block, but here is a photo of it, partially assembled.



Compared to the standard heatsink block, it's wider (46mm) and the two M3 tapped nozzle mount screw holes are moved outward to be 40mm apart. In place of one M5 tapped nozzle mounting hole in the centre, it has two of them 15mm 14mm apart.

Edited 1 time(s). Last edit at 07/10/2014 11:44AM 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].

One issue I have found with the dual nozzle hot end is that when used with my hot end board and the modified heatsink duct with mounting points for it, the sensor components are uncomfortably close to one of the heater blocks. So I've added a dual nozzle option to the OpenScad model file for the modified heatsink duct in [github.com]. Enabling this option increases the height of the mounting points by 2.5mm. I've partially compensated for this by adding a dual nozzle option to the insulating plate, which reduces the depth of the pillars by 1.75mm.

I've printed en enclosure to hold the X4 and Duet boards back-to back:



The X4 board fits face-down on the inner mounting pillars, and the Duet face-up on the outer ones.

Edited 1 time(s). Last edit at 07/11/2014 06:06PM 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].

I've completed my dual nozzle hot end. Here are some pictures. The extra circuit board at the right hand end one of the prototype PCBs for my differential LED board. I could have used the standard 6-pin hot end connector instead, but I prefer the Molex connectors, so I used that PCB with as a convenient mounting for the 3 connectors. It would also allow me to add a LED for the second heater.

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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].

Nice, I think I will be following in your footsteps pretty soon. It will be interesting to see if the cooling system can cope with 3 heads.

Looking great, @dc42. Definately a much more finished solution than mine

I guess you have modified the hotend-mounting piece on the x-runner. I have been thinking about a way to also adjust the hotend in the Y-direction to align the nozzles perfectly with the x-axis.

One thing to be aware of is that the wires for the thermistors should not touch the heater-blocks. At printing temperatures they will melt right through the insulation. For those who want to play safe, you can use thin silicone insulated wire. It's available in a lot of RC-stores. Otherwice you can use PFTE insulated wires. Both are rated to about 200C, but won't be damaged untill the temperature is much much higher.

:-) Carsten

So i will need soon a pcb from dc42......

Quote
colsenfoto
I guess you have modified the hotend-mounting piece on the x-runner.

All I have done is to produce a wider nozzle mount with holes for two Bowden tubes and wider fixing centres. See [github.com].

Quote
colsenfoto
I have been thinking about a way to also adjust the hotend in the Y-direction to align the nozzles perfectly with the x-axis.

I was just going to calibrate the Y offset of the nozzles as well as the X offset, if the misalignment is enough to be significant.

Quote
colsenfoto
One thing to be aware of is that the wires for the thermistors should not touch the heater-blocks. At printing temperatures they will melt right through the insulation.

Good point! I have some heat resistance sleeving, and I'll use some over the PVC thermistor wires that run close to the heater blocks.

Edited 2 time(s). Last edit at 07/12/2014 05:55PM 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].

Another user, @dmould, posted this link to hybbyking - everything you would ever need in silicone-wires: [www.hobbyking.com]

See his good points in this post: [forums.reprap.org]

Yesterday I finished connecting the second extruder and hot and looms to the X4, and today I finished installing the Duet and X4 in the new box:



A few points came to light:

1. The mounting pillars for the X4 and Duet boards in my adaptation of Bob's design are not very strong. I didn't dare use ordinary machine screws in them, so I purchased some self-tapping screws to use instead. Even so, it would be preferable to modify the design to put a solid rectangular fillet between the mounting pillars and the walls of the box, for extra strength.

2. Although I thought increased the depth between the Duet mounting points and the lid by 0.5mm, I can't fit the lid. The box needs to be at least 2mm deeper. I've modified the design to increase the depth by 2.5mm.

3. The cutouts for the Ethernet, SD card and USB connector are usable but a little too high. I've moved them by 1mm.

4. I had to buy some 6mm M4 countersunk screws to fit the box to the Y extrusion.

I have the second extruder working and selectable using the T2 command. I'm about to swap the hot end for the dual nozzle version.

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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 David,

Are the points you noticed included in the scad file on gitub? This is a great design and I will make the mounting pillars for the X4 and Duet boards stronger, assuming I can understand what to change.

Paul

---

appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

Quote
colsenfoto
Another user, @dmould, posted this link to hybbyking - everything you would ever need in silicone-wires: [www.hobbyking.com]

See his good points in this post: [forums.reprap.org]

If you are in the UK or Europe, be sure to switch to the appropriate warehouse before ordering from HobbyKing (and you can also change the currency). Anything ordered from the "Global" warehouse ships from Hong Kong and takes weeks to arrive and may incur a customs charge. Orders from the UK warehouse arrive on my desk within 2 days (I'm in the UK). Also always choose the "PayPal" checkout option - their default card merchant is a Hong Kong company that can take a day to approve your purchase (and it won't ship until payment is approved). Not only that, but the default card merchant imposes a transaction fee, which PayPal does not. You can pay by card via PayPal - you don't need a PayPal account.

All the above I have learned the hard way!

The silicon wire is marked "200 deg C", but I'm pretty sure it will survive ABS hotend temperatures, which are a bit higher. Needs testing to be sure though.

Dave
(#106)

Edited 1 time(s). Last edit at 07/14/2014 11:37AM by dmould.

Quote
appjaws1
Hi David,

Are the points you noticed included in the scad file on gitub? This is a great design and I will make the mounting pillars for the X4 and Duet boards stronger, assuming I can understand what to change.

Paul

As of 1 minute ago, yes. The pillars are generated in module mountingStands, which in turn calls module mountingStand.

Edited 2 time(s). Last edit at 07/14/2014 11:53AM 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].

@dmould, both silicone wires and PFTE wires survive a hot soldering iron, which is typically around 400C.....tested many times....Normal cables will let out the smoke :-)

Temperature specifications for cables are typically given for a 10 year expected lifetime at that temperature - before the cable have to be replaced.

:-) Carsten

Quote
colsenfoto
@dmould, both silicone wires and PFTE wires survive a hot soldering iron, which is typically around 400C.....tested many times....Normal cables will let out the smoke :-)

Temperature specifications for cables are typically given for a 10 year expected lifetime at that temperature - before the cable have to be replaced.

:-) Carsten

Thanks - that's what I thought. Silicone insulation is a heck of a lot more flexible than PTFE (or any other insulation I've come across except cotton). The fine-stranded silicone wires are as flexible as string!

Dave
(#106)

I finished building the dual nozzle system yesterday.



There is a mechanical issue, which is that the cables to the main hot end board can snag on the secondary board used to connect the hot end loom to the second heater. I shall cut the bottom off the second board and mount it lower down.

I modified the web interface to support two hot end heaters and display the positions of as many extruders as the firmware reports. I then ran into firmware problems. There was a bug that meant that you had to set both the active and standby temperatures of each hot end heater at the same time. If you only set one of them, the other got set to an undefined value (in practice, it always seemed to be something low enough to turn the heater off). The PID parameters were unsuitable. I had noticed that the ones RRP switched to in 0.78 (which I adopted in my 0.78a) resulted in significant overshoot and oscillation, but this became so bad as to be unusable when I tried to set standby temperatures of about 150C on the dual nozzle head. So I reverted to the PID parameters I had been using with 0.65e, but even those didn't work very well, even with only one heater turned on. It was as if the cartridge heaters in the dual nozzle head were much more powerful than the one in the single nozzle head, which is the original heater from the kit. Has the specification of the heater changed, I wonder? Another problem was that the M0 or M1 command at the end of a gcode file didn't turn the hot end heaters off, it only put them on standby. This is no good when the standby temperature is around 150C.

So after fixing these and a few other issues, I released firmware 0.78c-dc42 (see [github.com]).

I am now at the state where I have done a successful print with each nozzle, with the other nozzle set to a standby temperature of 150C which I hope is high enough to prevent it snagging on the print. Now I just have to do a print that uses both nozzles!

---

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].

Congratulations @dc42

I have had the same feeling, that there is a significant overshoot. Also my temperatures flicker a lot, but that could also be due to electrical noise picked up by the non-shielded cables. It's not big enough of a problem to hunt it down now, though.

:-) Carsten

Quote
dc42
I am now at the state where I have done a successful print with each nozzle, with the other nozzle set to a standby temperature of 150C which I hope is high enough to prevent it snagging on the print.

After changing filaments, I usually turn the extruder by hand to feed through the new filament, and switch off the heater after extruding a bit of the new stuff. I then continue to extrude by hand (also with frequent retractions) as the nozzle cools until I feel a very marked resistance. (It's an attempt to get out all remains of the old filament so I don't get the odd few sporadic streaks of the old colour on the print - not sure how well it works). I have noticed that the increase in resistance occurs as the indicated temperature is decreasing past 170 deg C, and by 150 deg C it's pretty solid, so if you are using ABS you may need to increase your standby temperature a bit if the idea it to keep any seepage soft enough to deform easily over any bumps.

Dave
(#106)

This is a post, I have been looking forward to be able to make for a long time. There has been some discussions, whether the heatsink and fan can handle multiple hotends.

This is my three nozzles heated to 250C!



The short conclusion: The heatsink and fan handles the job very nice
The heatsink is around 40C. The metal-bar is around 55C in the middle, raising to about 70C at the ends. Please note, that this is a stainless steel bar, which have absolutely horrible heat-conduction properties. I would expect the temperature to be pretty even across an aluminium bar.

I had to cover the metal-sufaces with sanded capton tape to get a dull surface. Otherwise the camera will measure whatever IR-light is reflected from the surroundings. Therefore be careful not to conclude anything on the non-covered metal parts.

I have attached the complete output-file from the camera. The software can be downloaded at: [www.testouk.com]

Best regards,

Carsten

Edited 1 time(s). Last edit at 07/15/2014 03:04PM by colsenfoto.

Carsten, thanks for the report and evidence. It's good to know that the standard fan and heatsink can handle additional nozzles.

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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 modified the board that holds the connectors for the second nozzle, so that the cables to the first board don't snag on it.



Now I have come up against a number of problems in slic3r. Specifically:

* slic3r 1.1.6 assumes that in a 2-nozzle system, the extruders at called T0 and T1. But RepRapPro call them T1 and T2. I haven't found any configuration option to change this. I have to use an editor to search-and-replace all T1 by T2, and then all T0 by T1.

* slic3r has no concept of operating and standby temperatures. It doesn't generate G10 commands, it generates M109 commands, and it commands both nozzles to the same temperature. These M109 commands seem to turn the other nozzle off completely. I have to edit the start of the gcode file it produces, replacing all the M190 commands by G10 commands.

* It was suggested to me that I set the skirt height to 999 to allow for tool changeover. However, even if a layer (or all the remaining layers) use only one colour, it prints the skirt in the other colour (and only the other colour). This makes layer change extremely slow, because of the heating/cooling time. So this isn't viable. Tool change is so slow that it really needs to be minimized.

* When generating a 2-nozzle gcode file, to command a change in layer temperature, slic3r generates M104 commands with an extra T parameter. The Duet firmware ignores this parameter, so only one of the extruders gets its temperature reset to the new temperature. Again, I have to edit the temperature change gcode in the file.

I'm still trying to get my first 2-colour print to work.

---

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 came around the T0/T1 extruder problem by defining three extruders in Slic3r. Number 2 was used for perimeters and number 3 for infill. these translated to T1 and T2 commands in the gcode-file. Number one was just a dummy for getting the T-codes right. Unfortunately I never got the time to actually do a real 2-color test print.

Somehow I get a couple of options for the filament settings in the pull-down boxes at the right side of the screen. I have an idea about making a couple of filament config-files and then see if I can choose among them. Otherwise it's a mess with those different temperature-commands

Well, the folks at Reprap manages to get a two-color print so we must be close.....

:-) Carsten

Ian, can you share your setup and setting for the 2 colour print you published a picture of. How did you overcome the problems that dc42 experienced?

I think Carsten's idea of defining 3 nozzles is the main answer.

Still waiting for parts for my 2 nozzle ormerod.

Paul

---

appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

I've written a sed script to process the output from slic3r into a form that the Ormerod accepts. I attach the script and a Windows batch file to run it. Adjust the paths in the batch file to suit your system. Also adjust the standby temperatures in the G10 commands in the script if you want to use anything other than the 140C that I use.

Only run the script once on a gcode file. I haven't yet worked out how to get sed to leave the file alone if it already contains T2 commands.

Sed can be downloaded via [gnuwin32.sourceforge.net].

Edited 1 time(s). Last edit at 07/16/2014 04:24AM 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].

I've noticed that the temperature readings from nozzle 2 vary over a range of about 1C when it is at a steady working temperature, and the LED on my connector board shows correspondingly large fluctuations in heater power. When nozzle 2 is cold, the temperature reading fluctuates by several degC. This is despite the 32-reading averaging filter used in my 0.78c firmware. In contrast, the nozzle 1 temperature fluctuates by only 0.1C once it has stabilised.

A quick glance at the Duet X4 schematic revealed a likely reason. On the main Duet board, the ground sides of the thermistors and the filter capacitors are connected to analog ground (VSSA). Unfortunately, on the X4 board, standard ground is used instead. The ground pin on the expansion connector is a long way from the SAM3X processor and I know from previous investigation with an oscilloscope that it is noisy. The negative side of the 12V supply input provides another ground path, with even more noise on it.

So I think I'll bypass the X4 board for reading the temperatures. I already epoxied a 3-way header on the bottom of my Duet board for connecting the Z probe. It's a shame I didn't make it a 4-way header, then it would already have the 2 spare pins I need for a thermistor.

I'm going to suggest to RepRapPro that they add extra connectors on the new revision of the Duet for additional thermistors.

Edited 1 time(s). Last edit at 07/16/2014 04:50AM 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].

Success! My first 2-colour print (a purple 2001-style monolith on a white base).



Edited 1 time(s). Last edit at 07/16/2014 05:33AM 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].

Looks great, well done, can't wait
Paul

---

appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1