Hot End Cable Connector

[LukeH]

Hello All,

I’m new here.

Actual Question:

My current question for the group (and there may be a few) is about effector cabling: I’ve been toying with the idea, since I’m using magnetic ends on the rods of my in-build Delta, of having a few different effectors with different setups (a whole effector/hotend reserved for printing PEEK, or hotend with different parts cooling solutions and nozzle setups, for example). Obviously I’m going to need some way of quickly connecting and disconnecting the hot end cabling. Originally I was thinking of using a connector block on the effector, with JST connectors for most things (fans, thermistors, z-probe, etc.), and screw terminals for the heater cartridge, but digging through my cable bin, I find I have lots of basically obsolete cables (parallel printer cables, RS232 cables, VGA cables, CAT5 Ethernet, etc.) and was thinking that maybe I could use one of those for a truly modular connection. No, I’m not saying I plan to run a 70W heater cartridge over CAT5, but using a 24V PSU, the heater would be drawing about 3A, so if I distributed that over a bunch of pins in a more substantial cable...?

Background: 

I am currently designing/building a large Delta-style printer from scratch, with the plan to use it to prototype some musical instruments (and because I don’t yet own a large Delta printer). This is a home project for personal use.

I’m basing it off the Kossel design. Plan is to limit the print area to the constraints of the frame, so that I can simply enclose the print volume with doors on the uprights. I’m also moving the electronics to a separate outside box, so I can heat the enclosure, so I can experiment with some exotic materials that I can’t currently print on my existing machines. The frame, which is in assembly, has vertical members 1300mm long, and the horizontal members are 550mm, and I’m using 500mm mag-ball rods (I based the whole design around the rods, because that’s what I had). I should have a print volume 400mm diameter (because I’m staying within the boundaries of the frame), and about 600mm high. The frame is constructed of 40mm x 20mm rectangular hollow section aluminium (because that’s what I had in the workshop already, and I’m trying to keep costs as low as I can)

I’m going to be  (mostly - see below) running a Volcano hotend, with a 0.6mm or 0.8mm nozzle, precision piezo Z-probe, BMG in a “flying” arrangement. Because I’m trying to make it light and fast, I’m hoping that 48mm NEMA 17 steppers will be sufficient, but I’m going to be running a Duet 2 Wifi (with TMC2660 drivers), so I’ll have plenty of reserve current capacity to move to longer steppers, or even NEMA 23’s should I have to (although that would increase inertia at the stepper, making it potentially slower). 

Thanks for any advice or ideas.

[TobyCWood]

Theres a kickstarter campaign on right now which may be exactly what you are looking for...

https://www.kickstarter.com/projects/printermods/xchange-v10-hot-swap-tool-changing-for-every-3d-printer?ref=discovery&term=3D%20Printer

[James Fackert]

RJ-45 or the 10 pin version are remarkably capable... 300 volts, 3 amps each contact. They can terminate to metric spacing flat cable, so you don't need to use Cat 5, and ribbon is a lot more flexible. There is no cheaper, more reliable, more easily terminated, gold plated connector in existence. And there are 4 and 6 pin versions too for your breakouts.

so I would not rule it out.

The flat cable systems on printers like the artillery or the Artist are also pretty interesting. paralleling lines in the higher current heater is an easy solution. Just remember that the contact rating and heat removal are connected. adequate heat dissipation through conduction to larger circuit board pads is important if you are pushing connector current ratings.

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[FlowBot3D]

Luke,

As you are already using the duet2 board, why not also use their excellent smart effector? It integrates all the connections down to just 2 plugs and has the inbuilt touch sensor for leveling, fan connectors for the hotend and the parts cooling, and lighting directed towards the parts so you can clearly see the first layer going down. 
It's also designed for use with the magball arms. On my deltas I can swap between print heads in a matter of seconds. It even comes with the different head sink needed for use with e3d hotends, or you can get an inexpensive adapter for mosquito hotends from 713maker.

https://www.duet3d.com/DeltaSmartEffector

[LukeH]

I like the connectors, but being a delta effector, and being only held on by 6 magnets, I don’t actually need the mechanical quick release mechanism. I suspect it would just be unnecessary weight.

Good system for something like a coreXY though - I could imagine building a SnapMaker-like system, where I could remove the hotend, and replace it with a laser, or an engraver or something.

[LukeH]

I think I’ll stick with round cables, rather than flat, since flat cables are flexible in one direction, but not in the other, and the cable will need to flex in all three directions on a delta printer.

RJ-45 though is a good idea, and I’ll look in to it some more.

[LukeH]

I really like the Smart effector and I am sort of torn between going down this easy, but expensive route, or doing some of the engineering myself and saving some (well actually quite a bit of) money. I was also keen to try the precision piezo probe because if it works as advertised I can use it on other (non-Delta) printers as well. To be honest, I initially didn’t even plan to use the Duet board - I was going to go cheap and go down the BigTreeTech SKR 1.4 route with TMC 2209, but then I decided I wanted the option of using NEMA23’s if I needed to in the future (or just to experiment), so I would need TMC5160 or similar and do Marlin 2 (Which also has a pretty good Delta autocalibration system now), but I’ve had a couple of SKR 1.4 failures recently, and I wanted something more reliable. While the Duet 3 would be overkill, the Duet 2 would do everything I needed.

Do you know if you can switch the smart effector around and have the balls on the rods and the magnets on the effector/carriages?

[LukeH]

After some research, I’ve decided, for no other reason than because I haven’t tried it before, to go with under bed piezo sensors for my  z-probe solution. This will allow me to take advantage of the fixed bed in the delta, while keeping the probe outside of the heated build volume (and reducing some of the wiring to the effector).

I’m was thinking that I would still mount the bed on levelling screws, and put the piezo discs between screws and the bed itself. Time to fire up Shapr3D (which I have been experimenting with as an alternative to Fusion), and design up some mounts...