Upgrading the Rambo (mod)

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Upgrading the Rambo (mod)

Postby enggmaug » Wed Mar 12, 2014 3:29 am

In order to upgrade the Rostock max with an E3D Kraken quad extruder, I am exploring the possibilities to use the extension connectors on the Rambo to drive 4 extruders, 4 hot ends, and read 4 hot ends thermistors.

I did some progress so far, and will log my activities and my plans in this thread so that if someone spots a mistake I'm doing, I can be warned before I do it. :roll:

First of all, I want to be as close as possible to the original design. I am not electrical or electronics engineer, and I want to take as little risks as possible. I learned electronics in college , and used to be electronics technician, but that was in my previous life… long time ago... Let's say I know the basics, and luckily, have the required tools.

So, about the project with the Rambo, I read the schematics, to make sure I am not loosing time, and I won't find I miss one pin in the end. :mrgreen:
What I saw is :

ABOUT STEPPER DRIVERS :
There are 3 stepper driver extensions. I will only use the first 2 of them. They will interface with stepper drivers using 3 signals : Direction, Step, and Enable. That means that the current regulation has to be manually done on the stepper driver, and that the microstep value has to be hard coded. Most stepper driver modules that we can find on the shelves have embedded manual current regulation tuning potentiometer.
Image
I just need to add microstep value selection with jumpers on 2 signals per driver. Not too difficult. :roll:

ABOUT THERMISTOR INPUTS :
There are 4 thermistor inputs on-board. One is for the bed, so I just need to add one more. I will copy the design of the existing thermistors, and interface it to a signal on the ANALOG Extension connector. On that connector I already strapped Thermistor3 to signal PK0 in order to make sure I can use this one. It works well, I can read temp on PK0, so PK0 will be used for Thermistor 4.
Image
Image

ABOUT HOT-END HEATERS :
:idea: If you look at the schematic, FAN0 driver is made exactly the same as HEAT0, HEAT1 and HEAT_BED drivers.
Image
I will re-use it for HEAT2, and instead, use FAN1 and FAN2 for fans. They have a different design, and cannot be used to heat up a hot end. That means that I keep 2 fan drivers, one of them being FAN2 instead of FAN0, and I just need to add one more heater driver.
So, the last heater just needs a pwm output, and I will re-use the design of the Rambo to add a heater resistor driver on it.
Best option seems to be either PE3 on the PWM extension connector, or PL3 on the SPI connector because they are both unused signals. SPI connector is used by the LCD, so it will be PE3.

WHAT NEEDS TO BE DONE :
- I will make a board that will connect to ANALOG Extension, PWM Extension, and STEPPERS Extension, a bit alike the LCD board.That board will host connectors to plug in the steppers, heater and thermistor. That board will also host 2 "on the shelf" stepper drivers, and the exact copy of the Rambo design for adding one Thermistor Input and one heater output. 8-)
- I will modify the firmware to change FAN0 from a fan to a heater, and replace FAN0 by FAN2. For now, I just need to understand how SeeMeCNC modified the firmware code to enable FAN0 when you print, no matter what… so that I can remove that feature. I will modify it also to configure the additional hardware in pins.h. Not too hard. 8-)
- I must try to estimate whether I can use the onboard 12V, or if I must use, and regulate one more output from the PSU. Now, I have 5Amps fuses on board, but I may need to change them to 10Amps fuses. I have these in stock, it would not be a problem.

What do you guys think ? Is it crazy stupid :?: :?: :?:

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Re: Upgrading the Rambo (mod)

Postby Captain Starfish » Wed Mar 12, 2014 4:08 am

I like the way you're headed with it.

Off the top of my head, if I were trying to extend the RAMBO, I'd probably try and run a daughterboard from a SPI port on the RAMBO which had its own software, drivers, thermistor (actually I'd go thermocouple) inputs and PWM drives. RAMBO firmware updates could interpret G-Code and just pass any instructions onto a modified RAMBO firmware loop sitting on the daughterboard for separate processing.

But if the RAMBO has the I/Os free and there's no major rework involved in accessing them, your plan on the surface seems sound.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Thu Mar 13, 2014 2:34 am

I should receive stepper driver modules today... I'll be able to test the stepper extensions soon !!

Does anyone have an advice on how to measure exactly and easily the distance between connectors in order to adapt my card design for a perfect fir onto the Rambo 1.2 ?


If I could avoid removing the card, that would help me.

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Re: Upgrading the Rambo (mod)

Postby Captain Starfish » Thu Mar 13, 2014 3:04 am

1. Get some plasticene. Roll it out flat on a bit of cardboard and build up protrusions roughly where the connectors are. Cover with a sheet of cling film. Press onto the board, check that the indentations are all there for the connectors you want. Repeat as required until you have a good impression. Keep it cool so it stays super stiff (ie return to fridge between goes) and then just measure off with a vernier OR use an ink stamp and sheet of paper.

~or~

2. Can you lay hands on a PCB layout or drill guide file? Perhaps the RAMBO manufacturers would send you one if you explained why you wanted it and asked nicely?

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Thu Mar 13, 2014 6:03 am

Nice, I don't know what is plasticene yet, but I understand the principle.

About asking Ultimachine, I can try... but my first atempt to get some information from them was unsuccessful... I gat no reply.

Maybe they are working on a version of Rambo with more in/outs, or maybe they don't have time to reply every single email asking for help... they probably prefer to focus on customers actually having troubles, rather than on customers looking for troubles, who try to mod the card.

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Re: Upgrading the Rambo (mod)

Postby Eaglezsoar » Thu Mar 13, 2014 7:30 am

enggmaug wrote:Nice, I don't know what is plasticene yet, but I understand the principle.

About asking Ultimachine, I can try... but my first atempt to get some information from them was unsuccessful... I gat no reply.

Maybe they are working on a version of Rambo with more in/outs, or maybe they don't have time to reply every single email asking for help... they probably prefer to focus on customers actually having troubles, rather than on customers looking for troubles, who try to mod the card.


The card is open source and they do provide schematics but I don't think they are going to give anyone access to their drill files.
They would be fools to do that because it would enable or at least help someone to produce the card easily.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Fri Mar 14, 2014 2:19 pm

I finished the schematics.

If some experienced electronics wizards want to have a look and give me feedback, that would be terrific.

As you can see, I have been very inspired by the Rambo schematics, and chose the exact same components, except for the stepper driver modules, I chose the Polulu A4988.

Cheers :)

EDIT > I did not see how to attach a file directly here in the first place...
Thank you McHackney for pointing that out to me.
Attachments
RamboExtension.pdf
(48.34 KiB) Downloaded 284 times
Last edited by enggmaug on Fri Mar 14, 2014 5:20 pm, edited 1 time in total.

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Re: Upgrading the Rambo (mod)

Postby mhackney » Fri Mar 14, 2014 3:13 pm

I was going to take a look but the page had a russian dating video on it. I won't trust downloading files from sites like that. Perhaps you could post it here.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Fri Mar 14, 2014 5:21 pm

Ok, I found how to... I attached the file directly to my previous post.

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Re: Upgrading the Rambo (mod)

Postby mhackney » Sat Mar 15, 2014 10:07 am

Thanks. I took a look and it looks good to me. Are you going to use a protoboard or make a PCB for this?

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Sat Mar 15, 2014 11:06 am

Good question...

I'm heading toward a 2 Layers PCB, but I'm still not sure.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Mon Mar 17, 2014 6:49 am

I found the card's silk in Github...
That will help me to place the connectors on the PCB, and design the shape for my extension.

Do you guys have an idea on where to find the references for the connectors on the card ?

I found the steppers and power connectors, using the reference from connectors section of the Ultimachine Website, I searched on Molex Website for the matching connectors.
I still miss Thermistor connectors, and the connectors matching the extension ones on the card.
The extension connectors are very basic 2.54mm connectors, but I am not used to buying components, and I don't know the exact term for searching them. Mouser has thousands references, and I'm kind of lost... if someone is willing to help, that would be great... :D

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Re: Upgrading the Rambo (mod)

Postby Eaglezsoar » Mon Mar 17, 2014 10:21 am

enggmaug wrote:I found the card's silk in Github...
That will help me to place the connectors on the PCB, and design the shape for my extension.

Do you guys have an idea on where to find the references for the connectors on the card ?

I found the steppers and power connectors, using the reference from connectors section of the Ultimachine Website, I searched on Molex Website for the matching connectors.
I still miss Thermistor connectors, and the connectors matching the extension ones on the card.
The extension connectors are very basic 2.54mm connectors, but I am not used to buying components, and I don't know the exact term for searching them. Mouser has thousands references, and I'm kind of lost... if someone is willing to help, that would be great... :D

The 2.54mm connectors are called headers and you can find them as just the pins or with plastic shrouds.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Mon Mar 17, 2014 11:46 am

:D Thank you !!!!!

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Wed Mar 26, 2014 4:30 am

Ok, I finished routing the extension.

I oppened a Github project, but I'm gonna wait a bit before uploading my files.

I wrote an email to Ultimachine to tell them about my project, and ask them about licencing. The fact is that I mostly copied their design, and I used their silk to position my connectors.
So I want to know how should I reference their name, and if they don't mind me releasing it.

I mean, their card is open source, so I don't think they would mind, but it is mainly about being polite. Above that, I have no experience with open source software and what you should legally do , and how, when you reuse someone's design... especially there are different open source licences out there.

I have 2 questions for you guys, in case you happen to know :
- GitHub asks me what licence do I wanna use for my project. Do I have restrictions on the kind of licence I can use, when I use the work from another open source project ? I am totally a noob at this point.
- What do you expect to find in an open source hardware project ? Gerber files, or source files, or PDFs ? Maybe all of them ?

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Re: Upgrading the Rambo (mod)

Postby mhackney » Wed Mar 26, 2014 7:56 am

Usually you pass on the same OS license the originating work used. That is usually stated in the license file with the original work. UM will likely get back to you on that.

Gerber files are fine for folks wanting to make the parts. PDFs are convenient to see what's there if you don't have the ability to open Gerber files. Source files are up to you!

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Tue Apr 01, 2014 8:07 am

I did not have any reply from ultimachine.

I put everything online, and will send them another email about licensing.

I did not make the pdf yet, but I put my design files, and Gerber online.

I am still waiting for the components to arrive, they were shipped over one week ago, but Fedex does not feel like delivering.

As soon as I receive them, I'll check the pads size, make the PCB, and then, of course take pics for you guys. Can't wait.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Tue Apr 01, 2014 11:40 am

Sorry,
I forgot the Github Link ...

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Re: Upgrading the Rambo (mod)

Postby teoman » Sat Nov 01, 2014 1:07 pm

enggmaug wrote:There are 3 stepper driver extensions. I will only use the first 2 of them. They will interface with stepper drivers using 3 signals : Direction, Step, and Enable.


If you are running out of pins, you can use the same enable pin for all of your motors. IF not used they will be enabled and they may get a little hot, but that would not be a sigificant problem.
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Re: Upgrading the Rambo (mod)

Postby Highcooley » Fri Nov 21, 2014 8:47 pm

Kraken is installed and dual extrusion is working.
Next will be extruder 3 and 4. However, can somebody point out which pins have to be selected for the Rambo? Following the pin assignment list on the RAMBO developer wiki, heater 3 should be pin2. However, in pins.h, 2 is already assigned for Temp_1_Pin. Or do I have to set it to 15 as is the PCINT pin number? This is all a bit confusing.

I would like to use the following pinout configuration:
Heater 3 PWM2
Heater 4 PWM5

Thermistor 3 A7
Thermistor 4 A6

Motor 3 MX1
Motor 4 MX2

Thanks!

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Sat Nov 22, 2014 2:27 am

As I recall, numbers for temp pins, and PWM pins can be the same, repetier knows you are assigning a PWM or temp pin...
But I might have a bad memory on this.

I still did not manage to build the extension. I think the design is mature, but I can't find time.

If someone can get it to work, I would be glad to know.

Actually, on my rostock, I got the kraken installed. I can get Extrudder 1 or 2 to work, but I am not satisfied with the results I get when both are running.

For now, I need to change my magnet arms mod to a tricklaser carbon arms, because of the extra weight and constraints the kraken gives me will all the hoses and bowdens moving around : the magnets happen to fail in holding the platform, sometimes.

But if someone has some advice in how to get good results in multihead printing with the kraken, I'll take them.

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Re: Upgrading the Rambo (mod)

Postby Highcooley » Sat Nov 22, 2014 5:31 am

Ah, here we go. Not exactly intuitive, but as long as repetier knows its Pins, all is good :)

Honestly, I didn't have a glance at your design yet. Since I have a Rambo 1.0, I need two additional PWMs anyway (I use the spare one on the Rambo to control the cooling pump). But I'll give it a go when I find the time. Maybe I can easily upgrade your design with an additional PWM.

With working dual extrusion I mean, that I can print with either of the two heads without scratching the print with the other so far. So no experience with actual dual head action. That's all on my to-do list.

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Re: Upgrading the Rambo (mod)

Postby Highcooley » Mon Nov 24, 2014 9:45 am

I just had a look at your extension board and I have to say, it looks very impressive. Cudos on that!

First I though I could work with it to easily create one for the 1.0 version of the Rambo. However, the pins seem to have a completely different layout on your board compared to mine. So I pretty much would have to start from scratch. Compared to the time this will take to properly layout the board as well as the cost to produce a prototype just for myself, I will probably go for a hacked prototype board instead for my needs. As it seems, there are not many 1.0 owners around who also want to add a Kraken to their printer anyway.

Keep up the good work! I hope you'll find the time to finish this project.

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Re: Upgrading the Rambo (mod)

Postby enggmaug » Tue Nov 25, 2014 2:18 am

Thank you.

I'll try my best to finish it... but I'm not too sure of when that would be...

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Re: Upgrading the Rambo (mod)

Postby Highcooley » Sat Dec 27, 2014 7:38 pm

I just implemented another solution for getting additional extruders for RAMBO. The solution is called Extrudrboard and is an original extension for the Printrboard controller. It's currently on sale on different online shops. So if anybody is interested, I'd recommend to hurry up, since I don't know if the board will be discontinued soon.

Anyways, the board is a straight forward two extruder solution with a 6pin Molex connector for the 12V supply (in case someone still happens to have the 6 pin connector of his PC PSU uncut for his heated bed) and a 14pin connector to attach to the controller.

Image

Of course, the wiring is a bit complicated, since RAMBO has dedicated connectors for each signal type. But these sources helped to find unused RAMBO pins and attach them to the 14pin ribbon cable:
http://www.printrbottalk.com/forum/viewtopic.php?f=15&t=4931#p32317
http://reprapelectro.com/wp-content/uploads/2014/09/RAMBo-1.1B-User-Manual.pdf
http://www.3dxmy.com/wp-content/uploads/2013/11/20131128170736_38355.png

In my case, I used the following RAMBO pins (I do own an old RAMBO 1.0e which doesn't have the dedicated FAN2 driver):
Motor MX 1 & 2 (except for PA01, which is double used with the y max endstop. I used PL3 instead, since SPI Ext 2 is normally not used by the SD card reader)
Heaters PWM Ext 4 (FAN 2) & 5
Sensors Analog Ext 3 & 4

This way I even ended up with T3 on the RAMBO unused which could be utilised for a heated chamber.


The hardware itself works splendid. However, I have to warn you as until today, Repetier 0.91 has still two hiccups if set to 4 extruders. The problems are documented here and the issues have been reported to Marcus from Repetier:
http://forum.e3d-online.com/viewtopic.php?f=8&t=24&p=1899#p1899


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