ID3 hotend and thermocoupel upgrade

[EvilFz1]

hey guys, looking for some assistance. I had shorted something on my board a while back having to do with the hotend, but was wanting to upgrade it to get more heat out of her anyways.
I got the inDimension3 hotend and have seen over 700F degrees with just hooking the same power to the dual resisitors in this kit. swapped the fuse with no luck, and i thought i might be able to switch the heat0 to the heat1 and it might work, but no luck there either... the bed is fine, when i turn it on its red led turns on on the Rambo, but not the hotend led on the Rambo when i ask for it to supply heat.
i think i can just pull the power leads from the board that supply the hotends power and send it thru a potentiometer before it goes to the hotend, and just toggle the trim pot manually as an anolog temp control?
second thing is when supplying more heat requires a sensor that can handle it so im now using a thermocouple signal into the thermistor signal that the Rambo can read.
i have the olimex - MOD-TC-MK2 module, with a k type thermocouple, but don't really know to much about this.
mechanically this thing mounted up with just a few extra pieces of hardware from home depot or whatever, and i got a m5x.8 tap to thread a capnut that the ptfe tube now rests, so that part wasn't to ridiculous, but the remainder is just a touch over my head not to ask a question. thanks

[EvilFz1]

this is the board and the link shows firmware and stuff pins assingments but still might enjoy some assistance!
i know i have to give 3.3 to pin1 and ground pin2. pin 5 and 6 are data lines, SCL and SDA that form the I2C line, from what i know from a short reply from oilmex support.

[dtgriscom]

i think i can just pull the power leads from the board that supply the hotends power and send it thru a potentiometer before it goes to the hotend, and just toggle the trim pot manually as an anolog temp control?

You'd need a potentiometer that can handle as much power as the hotend (which is what: 40 Watts?). That's going to cost a bundle. You can get a cylindrical power resistor with a sliding clamp in the middle, which functions as a pot, is much harder to adjust on-the-fly, and is a lot cheaper.

I'm dubious, though.


Dan

[Captain Starfish]

Firstly, to the heater output: No.

There's a reason we use the electronics. All sorts of things can affect the temperature, so the electronics and firmware monitor the hotend temp and switch power to the heater on and off to keep it close to the target temp.

If you don't use those smarts and just run a pot between power and the heater:
1. No point in having a thermocouple, all it will do is show you how wildly and horribly your head temp is fluctuating.
2. Your print jobs will be utter, utter crap. Guaranteed.

If a simple pot was enough, don't you think all the printer manufacturers might have opted to use the cheaper, simpler solution?

If it isn't the fuse, next guess would be that the driver MOSFET for the heater has released its magic smoke. They are not hard to replace. Download the RAMBO schematics, find the driver chip's part number, look it up from the manufacturer (you might even luck out and be able to order a free sample or two) or grab it from Mouser, Digikey, rscomponents or element13. Unsolder the old one, solder on the new one, just be careful of static and chances are it'll be working fine from then on.

If that's not your scene, you can also look at using an independent PID temperature controller. Which will have its own thermocouple inputs anyway.

Part 2: I2C thermocouple board
If you're going to fix the channel on the RAMBO and want to hook this puppy up, that's all you need. SDA, SCL, power and ground. You'll need to have a play in the Arduino firmware to select the appropriate temperature input AND the correct I2C address for the thermocouple driver, which should be in the datasheet for it.

Thanks for posting that pic, by the way, if it's that simple I may get one myself when it (inevitably) comes time to replace the crappy thermistor in the hot end at the moment.

[EvilFz1]

alright so I got a new Rambo, its getting power and I have this I2C with the +/- from the thermocouple into the blue connector, and I have 3.3 going into pin1 along with its - to pin2 (on the 10pin connector) just rubber banded for now... these two white leads are from T0 on the Rambo, I need to connect with pin5 (SCL) and pin6 (SDA), but how do I know which goes in 5 and which goes into 6?

secondly, here ( https://www.olimex.com/Products/Modules ... e-hardware ) towards the middle right, there are 2 software demos, I d/l olimexino 328 and got a few files and these intructions:

Instructions for the Olimexino-328 with MOD-TC
- Connect the MOD-TC to your Olimexino;
- Copy the MAX6675 foder to your arduino libraries folder
- Run the Arduino environment
- Open the example sketch from File/Examples/MAX6675/olimexino_tc_serial
and upload it to the board's memory. When It's done uploading, open the
Serial Monitor and you should see the current temperature in C and F
continuously updated.
If you'd like the updates to be faster/slower, change the parameter
of the delay() function at the end of loop(), which is currently "1000"
(1 second).

so I have to open the repetier file in arduino but where do I make the change there?

this isn't as simple of an upgrade as I thought...

[Captain Starfish]

I went through this process last week and some bad news for you I'm afraid.

You cannot extend thermocouple wires with normal wires like we did for the steppers etc - it creates another junction and stops the thermocouple driver from picking up the information. You /could/ use a second and third thermocouple (which have different alloys for each of the two wires) to extend it, thus keeping the junctions from the extending wires from similar to similar metal all the way to the thermocouple driver, however, this arrangement becomes extremely susceptible to noise. So you need that olimex board on the effector platform.

The Repetier firmware mostly has it organised to read the MAX temp chips but not quite. You'll need to solder out to some pins on the extension board for the LCD to get the I2C signal out and even then you need to grab a pin which the Arduino environment doesn't know about to select the thermocouple on the bus. Blah blah blah, it's not trivial and some coding mods are required to the Repetier firmware which aren't really helped by the Olimex examples and are all to do with jumping out of the Arduino head space and into AVR-GCC port/pin bashing.

Confused yet? I was. But don't worry, because just extending the clock line - even when it was shielded - from the I2C bus up to the effector head locked up the RAMBo and LCD. De-solder, it works again. Re-solder, it locks up.

Short version? Chuck the Olimex board in the bin or save it for another project, it's incompatible with the protocols and distances involved on an RMax.

I'm in the process of putting an AD597 thermocouple amplifier onto the effector platform and running its analogue output down to the RAMBo on my off hours, in the thermocouple upgrade thread. I'll post more results as I get along but suspect this will be a much better fit to the layout of the Max.

[EvilFz1]

that's the adafruit board I looked at? knew I shoulda got that one... and i seen ur thread nosing around, i'll just stay tuned to that one, thanks

[EvilFz1]

this might also redirect others, http://forum.seemecnc.com/viewtopic.php ... 7&start=10
it helps to read thru others comments first, but I missed it till earlier...