Polarity on E0 Heat?

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wepollock
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Polarity on E0 Heat?

Postby wepollock » Thu Mar 29, 2018 12:45 am

Just noticing that in the documentation on the two pin connector it states that "polarity matters"
The wires that go up to the duet are Black and Red and fit into the wago connector; which then leads to E0


On Duet E0 heater (per the legend);
Black is attached to PWM_VIN (yellow/black)
Red is attached to VIN (yellow)

I would think that the heating element would not care about polarity.
This is confirmed on the Duet Documentation


Your hotend heaters should be connected here. From left to right, the connectors are E1 and E0.

Polarity does not matter for hotend heaters.



(the PWM on the legend is a bit interesting, Is there a signal?; grounding through the effector board?; is this just to ease assembly?)

------------------------------------------

The reason I am asking these questions is that I using my rostock MAX V2 as a testbed.
I want to be in a position for any work I do on the Rostock V2 to transfer over to the Artemis. Currently, I am playing around with a hotter element on the Rostock Max and new materials.

It would be better to have two of the same machines; production and lab.

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Re: Polarity Question.

Postby wepollock » Sat Mar 31, 2018 10:33 am

Just looking at the Artemis assembly instructions (and wiring) vs the Duet Board wiring.

I think (and I could be wrong here) that 12v positive (rather than ground) is running from E0 Heater - to the SE300 effector board.

After typing this I found that;

The Duet switches the fans' connections to ground so you may be able to connect each fan's positive side to the appropriate voltage and its negative side to the appropriate pin on the Duet.

Is this correct, and is that how the heater is being switched on and off? The ground is being toggled?

A concurrent projects;

I am putting a Titan Aero on my Rostock Max V2 - If I am going to do that I want to standardize connectors-connections
I am going to build my own board so I could swap out effectors based on application
It might just be more effective to put Duet on the Rostock Max 3, purchase another Artemis, or just rewire the Artemis. I don't really want to rewire the printer because it's good to be on the same standard for upgrade purposes.

This is also going to be a complexity for anyone putting an E3d on the Artemis. If you wanted to do that I would take the spare probe wires, and the led wires and use those for positive on the fans. (and or nix the led). Then you would lose ability to use the nice Seemecnc effector.

I don't see much advantage to the E3d hotend in and of itself vs the Seemecnc hotend.

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Re: Polarity on E0 Heat?

Postby geneb » Sat Mar 31, 2018 11:58 am

dc42 would know better, but I think that it's due to the MOSFETs used - they switch the ground side, not the hot side.

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wepollock
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Re: Polarity on E0 Heat?

Postby wepollock » Sat Mar 31, 2018 2:46 pm

G.

Yep.. that is what I am thinking... that all the circuits (fan, hot end, bed) are toggled on/off through the negative side. This in turn allows the positive voltage of the heating circuit E0 to stay on.. Each fan then can have a single wire connection to the duet board (negative connection), with the circuit completed through heating circuit E0 positive. (using positive always on, available at any time to complete a circuit).

This sort of explains why the Artemis documentation states that polarity matters for E0.. (its really that E0 is being used in the effector circuit board as positive always on).

The wiring, as is, very much complicates anyone wanting to connect a "third party" hot end. If you wire a "third party" hot end directly into the E0 heat cables, you then have to wire fans for positive using some of the "pre wired probe cables" Not that this is difficult. However you are locking yourself out of the Seemecnc ecosystem unless you build a custom board to retain compatibility..

If Rambo works the same way, build a single perf board using 10, 4, and 2 pin connectors. My printers would then be standardized to connectors, not to hot ends; not to effector type; this way I can retain different setups in different hot ends.

When I answer those two questions I find out if I can swap effectors (hot ends) between printers, using a custom interface board. I think I have the Molex connectors identified. It might be easier to purchase another artemis, just build a board to the existing wiring plan for my existing inventory of hot ends.

I had Molex work to identify the connectors in use. They are quite expensive because nobody would just buy a singleton. Folks are not going to buy the crimp tools .. A 3d printer is only 2x the price of a molex crimp tool!

And another (but less pressing) question; has anyone ultrasonically welded a 3d print? And also "Damn it Kirk, I am a retired business person not an engineer). As a kid, heathkits were fun and what goes around comes around.

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Re: Polarity on E0 Heat?

Postby wepollock » Mon Apr 02, 2018 10:44 pm

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By dc42 Today 00:22
Administrator · 9,421 comments
All heaters and fans are negative-side switched on the Duet (as on other electronics). So if the heaters and fans use a common voltage (e.g. all 12V) then you can have a common positive wire feeding them all.

You can take that common positive wire from the E0 heater terminal block, but be careful: on older Duet PCB revisions, the E0 polarity is incorrectly marked on the underside of the PCB. The positive terminal of the E0 and E1 heater connectors is the one furthest away from the motor connectors.

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Re: Polarity on E0 Heat?

Postby wepollock » Fri Apr 06, 2018 5:21 pm

What exactly is the SE300 circuit board doing for me? I know that the circuit board will eventually be used for probing and other features.
Essentially, and for now, there are 16 pins in total with only 6 meaningful wires. Why?

Do I really want to build a patch board or just rewire the duet using spare cables. If I was going to rewire I would just go end to end with the fan wires (4 wires total) and I would go end to end with the thermistor (2 wires) and I would go end to end with the heater wires (2 wires). Then I would be losing compatibility with the SE300. And that was the idea of the patch board. The idea of the patch board is to retain continuity with future ideas from seemecnc. The other way around is to rewire the duet board and then patch to the seemecnc hotend.

I was watching the E3d idea at the reprap forum to build a "framework" with the details up to the end user. I guess the approach depends on your customer and your market more than anything. The E3d framework is definitely going to be a lab machine for me, I enjoy learning and jiggering-bodging more than printing frankly.

The cabling I would definitely do differently, the extruder I am using is a titan geared - and it can be used - limited to speed @12v (I have a bondtech to test in the background, and I have a titan Areo with a small stepper built in, using a geared extruder justifies a move to 24v. @24v why not just replace the effector. 24v is on order. I will figure out what works best for me. Essentially, I am using the machine I intend to leave in a solid state as a lab machine. Even experimenting, these changes plus the printer itself costs less and provides more value than ultimaker or a host of other machines.

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Re: Polarity on E0 Heat?

Postby wepollock » Sat Apr 07, 2018 10:22 am

So here is the plan.. I connect the original effector cables to the top pins, I can patch a homemade se300 effector cable to the Seemecnc Se300 hotend,

The board connects (branches out) to a two pin header for a thermistor - a two pin header for always on fan - a two pin header for cooling fan.
The phoenix connector gets connected onto the positive and minus rail, positive goes to the fans via red, negative gets pulled from the effector cable.
A phoenix connector then goes out to the hotend. (so I harvesting positive from heater e0). I am waiting on the phoenix connectors.

Advantage is I don't have to rewire the machine, I retain compatibility with the original hotends, and I can use whatever hot end I want to.

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