Question regarding duel endstops?

Hi

I finished my mpcnc primo build and couldn’t be happier, I love it. Works great already cutting, but I am still working on calibration and squaring. I am using the SKR Pro 1.2 for my board works great. I connected the motors in series, but now I am trying to connect duel endstops, but I getting confused on how to connect the motors, because motor wires are too short to connect without extension, so I am working on extensions for the motors to connect each one directly to the driver. So I am wondering do I need to make any changes to the firmware on the board to make sure that (extruder=0), or is it already set?
Sorry for the long post and thank you so much in advance.

I posted a picture for the build.Uploading: IMG_20201215_172402.jpg…

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Typically you need to update the firmware when going from ‘serial’ to ‘dual end stop’ setups. You will find the current releases here, and I assume you need this version: V1CNC_SkrPro_Dual_2209-2.0.7.2-src.zip. If you didn’t purchase Ryan’s dual end stop wiring kit, it is essentially six conductor extension cables with male Dupont connectors on one end and female connectors on the other. It eliminates a lot of soldering.

Note there are debates on the forum about the benefits of dual end stops. You can accomplish nearly the same tasks on a serial setup using some sort of hard stop that you can push the axes against. So if you have a working serial setup, you could just enjoy it for some time before tearing your wiring apart.

To answer your question more directly, extruders are set to 0 for both ‘serial’ and ‘dual end stop versions’, but there are other differences. If you care to see the differences, you can run a comparison between the configuration.h and configuration_adv.h of both versions. Currently I’m using meld to do my comparisons, but there are a ton of other diff-like tools on the net for text-based file comparison.

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Thanks for the quick answer. It looks like I only got the series wiring extension and didn’t realize it. Not a problem I usually do wiring by taping and heat shrinking the joints. So from what your saying even if I didn’t update the firmware I should be able to have each motor connected to a driver independently and they will run? ( X2 = E0 ) on the board. Because I tried that wiring with the current firmware and didn’t work motors wont run! So I thought I needed the duel firmware to run each motor individually and have xmin,xmax,ymin and ymax show up when running M119 code. Regarding the duel debate on the forums I get the point of not really needing them, but I need the machine to be as precise as possible and repetitive, plus a peace of mind for when hitting the home button by mistake. Thank you so much for the help and support.

If you bought the serial wiring harness, the skr is probably flashed with serial firmware.

It is easy to flash the skr and you don’t need to install any software. Download the zip Robert pointed you to and rename the firmware to firmware.bin and put it on the sd card in the skr.

Ok I got the cables extended to where I need them, and I reflashed the board with the duel firmware and it’s working!! The problem is for some reason my steppers started making a bozzing sound after moving and it won’t go away unless I unhook the USB from my computer then plugging it back again. Also, still making the same sound after moving!!?! And yeah still trying to figure out a way to mount the endstops as they are a bit tall to fit under the trucks and I figured the have them fixed rather than moving with the axis. Thank you so much for the help you guys are great.

They always buzz when they are enabled.

I took the extensions I made out and connected the motors directly to the board with no extensions and the sound is gone ! No more buzzing!? After close attention I realized that the extension cables and the cables I used for the endstops are a different gauge ( smaller ) then the ones on the motors and they where causing over heating in the connection and making the motors buzz. So I will try to find a similar or larger gauge to remake the extensions, or would anyone recommend CAT 6 cables as extensions and how I would go upon wiring them? Thanks again.

Cat 6 solid core can fatigue with the constant movements. I think Barry uses cat cable of some kind, but it is stranded and he doubles them up, so one pair per wire.

I see. So I don’t think cat 6 is a good solution. Would you guys think it’s a good idea to cut 20 gauge wires from a salvage PC power supply to soldier and make extensions for my stepper motors. A picture for the wires.

don’t know if you went ahead with this or not, but 22awg is what you should be using, obviously anything lower will work too. Spools of 22awg wire are super cheap on amazon (and probably even cheaper elsewhere). i wired my entire machine with 24awg the first go 'round – before reading more on the subject and ended up feeling the need to safe-guard my investments. i re-wired the entire machine with 22awg. I don’t like to hear things like “it should be fine”, or “what’s the worst that could happen?” i just know, for me, I’d rather drop coin on the right wire than burnt out steppers.

i read up on this a bit, and i believe there is a cat 6 spec that uses 23awg iirc, which is close enough to the 22awg. from what i could find it looked like i would’ve had to go with already-crimped patch cables(stranded) because all the spools of that spec looked like they were solid-core. but that raises an interesting question… i believe standard cat 5, and most of the cat 6 cables i’ve seen all actually use 24awg, so really it seems like if you’re doubling them up anyway cat 5 would work fine (as long as it was stranded). no matter how i rolled it when i was pricing out parts for my machine, straight up spools of wire were the safest, most cost-effective route.

You don’t burn out the steppers unless you send way too much current. What could happen is that you get voltage drop in the wires. If you used 30ga, for example, you might lose a few V over a long distance. Then you would find that as the motors speed up, they will actually lose torque and skip steps. Or, at the extreme, the wires will heat up and melt. If that happened, you could short a coil and it wouldn’t moved. It wouldn’t be good, but that would have to be an extreme case.

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i wasn’t aware of the full extent of what could happen, but even that is scary enough for me to double and triple check every box :stuck_out_tongue:

The melting would be an extremely small wire.

it’s possible i’m entirely too paranoid about these things

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