@dragonn

We are working on a bio-printer, so we only need to heat up the cell solutions to a maximum of 80deg but we also need to be able to cool it (ideally to about 4deg).

@dc42

Just an update, you are legitimately and objectively awesome. We got it to work!

Just to try to help people in the future who have this same problem, in your config file, make sure to set the axis mins and max, otherwise it won't be able to move in the direction where the mins and max aren't defined.

We also set our X axis offset at 50 as a test, but the first print sometimes the X axis won't do the offset, but after redoing the same print file, the X axis offset will work so I think it has to do with the same problem. Will report back with an update

@Danal:

Also, to your original question, there is no "recompile". Using the above, just change an html or js file in the editor, save it, refresh the browser.

When all your mods are finished, you may wish to compress and zip up YOUR version and put it on your Duet. You don't have to… it runs fine from a local PC file system. If you wish to put it on a duet, you can:

1. Follow the build scripts, which only run on Linux (not even a Mac!!). Then upload the resulting zip via DWC's standard upload.

2. Do the rough equivalent of the build scripts by hand. That is, compress and zip and gzip things. Personally, I'd skip all the minifiy stuff if I was the only person using it. Again, upload via DWC.

3. Don't even compress or anything, just load your files "as is" to the Duet SD. If you do this, there is one quirk to know about: If Duet sees a given file, say "reprap.htm" and the gzipped version of that same file, say "reprap.htm.gz", it will use the .gz. The easiest way round this is to put the SD card in a PC/Mac and completely clean out the /www directory, then put your files in /www.

Any of these three will work fine. I've done them all and verified that they work.

Dude, I can't believe how helpful this is!! You're amazing!! Thank you so much, this is exactly what I am looking for.

The way our project is set up, we don't have physical access to all our gear (duet, rpi, etc) during the week since it stays in the boss-man's office, so that's why I spend all week asking questions, so when we meet in our weekly meeting we are ready and raring to go lol.

This is such a great few posts, thanks again!

@dc42

Thanks for your help!

Just to updated, we haven't done the cooling portion yet but we wanted to let you know about the DC regulator you recommended.

So when we heat up to say 40degC, the peltier only receives anywhere from 7V to 10V, so it's not like it is receiving the full 24V. Because of this we haven't used the peltier yet. Just to let you know

@dc42

So for a test, we set our temp for 35degC and the peltier will heat up and maintain that temp assuming we cool the other side enough.

So heating is good. But would you be able to point us to the function that is controlling the heating process?

I ask this because we would like to modify it to be able to COOL instead of just heat.

For example, if we set the temp to cool to 10degC (with current temp at 25degC), the temperature sensor actually shows that the peltier tries to cool by a degree or half a degree but then it will shoot up rather crazily.

So I am thinking:

if (desiredTemp < currentTemp)
// Send a control voltage to DPDT relay to send current one direction
// Do cooling function (might need to swap some increment/decrements in existing code)
else
// Stop the control voltage to DPDT relay to have current go the other direction
// Regular Heat.cpp functionality

So basically if we want to heat, then the normal heat function occurs. But if we want to cool, then we select our COOl function.

So I guess the question is where do we find the heat function to edit this?

@dc42

Just an update, you are legitimately and objectively awesome. We got it to work!

Just to try to help people in the future who have this same problem, in your config file, make sure to set the axis mins and max, otherwise it won't be able to move in the direction where the mins and max aren't defined.

We also set our X axis offset at 50 as a test, but the first print sometimes the X axis won't do the offset, but after redoing the same print file, the X axis offset will work so I think it has to do with the same problem. Will report back with an update

To explain our process for a tool change:

We have dual extruders (in our case actually syringes) but both extruders are connected by a rack system that works as a see-saw.

So, when we do a tool change, we need a macro that will (1.) offset distance between the two syringes and (2.) activate the U-axis motor.

The U-axis motor will be connected to the see-saw/rack system that will rotate to lift one syringe and lower the syringe that will be printing.

See here: https://imgur.com/a/ZSWwyqb

The U-axis will rotate one direction to lift one syringe, and then when the other tool change occurs, it needs to rotate the opposite direction to lift the other syringe.

So...this is just to explain our reasoning.

@dc42 We did not home it first. Our printer technically isn't assembled yet so we are trying to do as much as we can before that.

EDIT:

edited out

@dragonn

Thank you! The regulator will come in tonight so I will update you tomorrow.

@dragonn

I was not aware of this tbh. Thank you for info!

I honestly thought the the regulator would go inbetween the heater outputs and the peltier, like in series between the two.

I want to make sure I understand, so I drew a picture to clarify.

https://imgur.com/a/fRSyRrN

Does the negative output of the regulator go anywhere? (see X)

Does the Vin of the heater output go anywhere? (see X)

@dc42

Thanks for the info!

I bought this DC/DC regulator and will update you when it gets in

https://www.amazon.com/Nextrox-Converter-Regulator-Step-Down/dp/B00BWKXTUU/ref=sr_1_1_sspa?ie=UTF8&qid=1524780116&sr=8-1-spons&keywords=24v+buck+regulator+12V&psc=1

@dc42

If we measure the resistance of the peltier (let's just say it is 10kOhms), and then we take a 10kOhm resistor and put it in series with the peltier, voltage divider means that the voltage across the peltier should be half (12V).

Is this viable? Assuming we can find a resistor that can handle up to 6A?

@dc42

Ahhh this sounds like it may be the reason, thank you for pointing this out! We will experiment...

Our Duet Ethernet is hooked up to a 24V 350W power supply, so as I understand it, that means the extruder heaters/motors/bed heater are all running off this 24V, which is why we chose 24V motors and heaters.

But we want to take your suggestion and run the heaters at 12V instead. Is this something we can change internally (in the firmware or config file) or do we have to swap our 24V power supply with a 12V power supply in order to accomplish this?

The closest thing I can find is this:

M307 V12

source: http://reprap.org/wiki/G-code#M307:_Set_or_report_heating_process_parameters

"Vnnn VIN supply voltage at which the A parameter was calibrated (RepRapFirmware 1.20 and later). This allows the PID controller to compensate for changes in supply voltage. A value of zero disables compensation for changes in supply voltage. "