Thermocoupler Question (v1 vs v2)

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
haylcron
Posts: 14
Joined: Mon Apr 04, 2016 2:30 pm

Thermocoupler Question (v1 vs v2)

Postby haylcron » Sun Mar 05, 2017 6:55 am

Per my other post, I have a feeling I'll be buying a thermocoupler soon. The page says to get the correct version for my printer, but I'm not sure which that is - let me explain.

I have a v1 printer from the kickstarter. I replaced the hotend with the v2 when it was released but I did not change out the thermocoupler. If I need to replace mine, do I order a v1 or a v2? Feels like a silly question to ask, but I just want to be 100% sure.

Jetguy
Posts: 1037
Joined: Tue Mar 22, 2016 1:40 am

Re: Thermocoupler Question (v1 vs v2)

Postby Jetguy » Sun Mar 05, 2017 7:16 am

A thermocouple is a thermocouple. Yes, the new style is all about wiring protection and installation, but the entire point of using a thermocouple is they are accurate to within 3C of any 2 of the same type (K type refers to the type of metal wire used Alumel and Chromel is K).

If there is a claimed difference, that is a problem and is bogus.

Now yes, I understand why Raise 3D would like the new version, it's much harder to damage during install and less user complaints and replacements. But again, a thermocouple in and of itself is the one of the simplest sensors known to human kind. It's 2 specific metal wires, welded together at the sensing end to form a junction. The details about the ones we use is that there is a hollow stainless tube, and the thermocouple junction is mounted inside using a heat conductive but electrically insulating adhesive so that the thermocouple can measure the heat but not short out to the heater block. Why is that electrical insulation so important? Because the junction generates microvolts signal (tiny fractions of a volt). This is why a special instrument amplifier is used (AKA thermocouple amp) to read that microvolt differential signal between the 2 wires- and yet NOT pick up or amplify the typical RFI/EMI common mode noise picked up by everything electrical surrounding the thermocouple wires and junction.

So what the difference in again, is really all about the total package surrounding the actual thermocouple.
Both the OLD and NEW are the same electrically. What is different is how the wires exit the tube that slides into the heater block, and makes that 90 bend upwards to go through the central block. The early ones used fiberglass braided insulation on the wire (technically, the new ones still do- just you cannot see it) and then heatshrink on the end of the tube and up the wires all the way up to the screw terminals at the head breakout. The new versions have a spring (mechanically there to provide strain relief and limit bend radius) and there is braided metal wire shielding on the new ones.

I have 3 Raise 3D printers, N1, N2, and now brand new N2Plus.
Only the N2plus has the new version of thermocouple (the big spring style with the shielded wire). All are running V2 hotends and the older 2 machines have the original as shipped thermocouples. All are within 3 degrees C of each other, actually closer to within 1 C as measured with an external thermocouple contact probe and external meter.

haylcron
Posts: 14
Joined: Mon Apr 04, 2016 2:30 pm

Re: Thermocoupler Question (v1 vs v2)

Postby haylcron » Sun Mar 05, 2017 5:01 pm

Well, that answered my question AND educated me on the principles of a thermocouple. Thanks for the thorough reply!

User avatar
Vicky@Raise3D
Posts: 1621
Joined: Fri Mar 25, 2016 3:54 am

Re: Thermocoupler Question (v1 vs v2)

Postby Vicky@Raise3D » Mon Mar 20, 2017 11:46 am

haylcron wrote:Per my other post, I have a feeling I'll be buying a thermocoupler soon. The page says to get the correct version for my printer, but I'm not sure which that is - let me explain.

I have a v1 printer from the kickstarter. I replaced the hotend with the v2 when it was released but I did not change out the thermocoupler. If I need to replace mine, do I order a v1 or a v2? Feels like a silly question to ask, but I just want to be 100% sure.


If you were using the V1 thermocouples on your printer and want to replace to be V2, please leave message when you carry out the purchase that yours is V1. We recommend to add a 224 monolithic capacitor when using V2 thermcouple on V1 extruder board. The temperature will be more stable.


Return to “Hardware”

Who is online

Users browsing this forum: socke and 2 guests