Rewiring jeffeb3's low rider

My build is pretty old, and my thread is pretty long with me kind of figuring things out. This thread will be specifically about the work I’m doing now, so I can stop (hopefully) worrying about poor wiring and just cut some more stuff. Things I would like to add to this build:

  • Get my mini rambo on it. I’ve had this for a while, waiting. It’s time to put in on my LR. No more potentiometers!
  • Get an on/off switch on the mini rambo, but not the v1pi.
  • Get Marlin on there. I’m ready to say goodbye to grbl, at least for a while and the mini rambo should be great.
  • Get my Router Relay installed on the side. This will let me power on/off the guy. I suppose I could use the PID. I might actually do that. Hmmm. Either way, we are bringing back M3/M5!
  • Box up the pi, and controller with a fan. I don’t think I need a filter.
  • Install captive wire connections. I had ruined a couple jobs with the duponts failing. Not sure why, but I like these JST-XT or whatever. The only problem is, the male pins are all through hole soldering, so I can’t easily do wiring or connect cable to cable.
  • Wire the steppers at the controller. This is related to the JST connectors, but I had an idea for simplifying the serial wiring and I want to try it out.

Unfortunately, the LR is down until I at least finish the wiring, so it’s table saw, drill press, and 3D printing for the time being.

Here’s what I’m thinking:

[attachment file=72765]

The small board in the middle is a 5V power supply for the pi.

There is a voltage and current meter in the left panel.

I am thinking that I want 12V to go to the current meter first, then the 5V PSU, and only have the switch for the mini rambo. That will give me an “oh shit” switch, but I can leave the pi on when I’m laying testing things out on v1pi.

Here’s a pic of the panel I printed today:

[attachment file=72766]


I wish I understood this more? what is the purpose of the pi and where did you get the solder in board for the wires?

Hey Josh,

In systems that use the parallel port and software, computation is done on a computer and signals are sent for the motors… but the parallel port can’t push enough current to drive motors. Also, it would fry your motherboard… so a driver board is used. They’re just amplifiers… They take the small signal from the parallel port and make the same signal, but with enough current to drive the motors.

That’s MASSIVELY oversimplified, but decently accurate.

In systems that use USB and arduino boards, there’s a middle man… the arduino board. The problem is that USB isn’t meant for timing. It’s meant for pushing data to and fro. CNC work needs precise timing. So, software pushes gcode down to the arduino board, it does the math to make the needed signals, the arduino boards sometimes have amplifiers on them, and the pulses get sent to the motors.

From the standpoint of a CNC guy, the arduino is annoying. I have kickass software that drives everything, I don’t need the arduino, but oh well. 3D printer folks are used to them, and so that’s how a lot of folks do it. Go with what you know, it’s really all about the job getting done at the end of the day.

That’s a barebones explanation that didn’t cover microstepping or opto isolation. Hopefully it made sense?


So is the pi a wifi antennae cutting out the sd card? Or is he running something like Estlcam on the pi to write gcode?

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Josh - I suspect he using the v1pi image and running either Octoprint or cncjs.

Heffe - On my lowrider, I ended up putting terminal boards like yours on the y-plates for the connections to the steppers - while it added a connection, it allowed me to 1) reuse steppers where the integral wiring was too short (I didn’t have to solder an extension) and 2) change the wiring from series to parallel and back to series when I was trying to set up dual XZ (x is my long belted side). Side note, I still see some benefit of dual X, but I haven’t gone back to it; I’ll probably try again when I convert my LR to LR2.

I like the clean look of your front panel. Where are you putting the 12V power supply?

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The pi will run v1pi (I have to use my own medicine), which let’s me run jobs and run the setup a few feet away. I will not be attaching an LCD.

The solder board is the one with the stepper wires attached? It’s a piece of perf board, and I’m not totally happy with it ATM. I will have some more details when my PCBs arrive :).

I’m not running estlcam on the pi (although I use it in Linux using wine). You could also use bcnc, but I have a linux laptop for all that, and I send the files to cnc.js when I’m ready to cut them. So it’s basically like the sdcard.

The mini rambo is a good solution to have integrated steppers and the real time of the arduino. Marlin and grbl are both very good at extending any computer to be able to run a CNC. I’m not sure where the love of parallel comes from. Have you seen klipper? It’s Python doing the advanced stuff and a very cool protocol for sending timed commands (over usb) to a dumber arduino. The arduino can then interface with the driver boards and jist step at the right time, so it can step a lot faster without all the gcode to movement math. I haven’t tried it yet, but I really enjoyed reading the protocol information. It’s very clever.

I’m not sure what I’ll do on the far side. I need two motors to connect to their extension wires and I want to get rid of the dupont. Screw teinalsight work there, but the Z motor wires aren’t very long… I meed something that’s 4 pin for connection cable to cable that has some captivity.

I was thinking I’ll either strap it to the bottom or let it drag on the floor. :). It depends on where my AC ends up.

I mounted my power supply to one of the table legs, then it just has a long power wire that gets pulled back and forth.

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I like that idea, I think ill do the same on mine. Right now mine is attached to the Y plate dangling with rope.

I got a package in the mail with a board I designed to make serial wiring and captive connectors easier.

I wired it up and it’s not perfect, but I think it’ll be good:

Each motor has the spot to wire up two motors in serial, so I just solder jumped the ones I’m not using. I plan on using the E0 driver for Z2. Not sure if that will matter at all yet.

I also added a spot for a fan but there JST-XH plug is in the way. It will work like this, if I need it to.

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Thats awesome, I have been working on an adapter board to simplify my build’s also but plan on using phoenix spring terminals and some amphenol connectors that can carry both motor and limit switches. Still waiting on some data from my vendor to finalize the designs and proto the board.

Ill post soon when I get them in.

Those amphenol plugs are pricey though, right? I guess you’ll only have to buy them once.

Yeah they tend to be a little costly, I may be going a bit overboard on this but I would rather spend a little extra money and time to simplify my wiring, I also like to challenge myself with each new project. I have the board designs done and going to run some quick bench tests on some 24awg S/FTP cat 8 that I have, Math says it should hold the load and with the shielded twisted pair should keep noise to a minimum.

So before I make the run on a few boards im going to try out this cable beforehand and may switch things up a bit.


I’ve been playing with these connectors lately. They’re a little big, but have worked great for other projects:




Those are interesting. But they just have the pigtails on the end? How do you connect them to things like the steppers? Or do you just find them long enough to replace the entire cable?

I think I am going to build a second set of boards using this S/FTP cable to pass 4 signal wires and motor over one connector, Bench test looks promising we will see if the real word supports this. Board design will also support signal routing jumpers so I can pick which motor cable the limit switch is tied to. Board design will support shield mounting for the RAMBO 1.4.

Since I have started all 3 builds at this point having this one solution for all 3 machines will be nice , it should clean up and simplify wiring which tends to be the part I spend the most time on anyways.

By no means will this be the most economical solution but the trade off should be worth it if it works.


My plan for my MPCNC Hefty rebuild is to use stranded UTP Ethernet wire for anything that moves around and solid core for anything that’s stationary, with appropriate jacks and plugs where needed. I have a case for the Arduino/RAMPS setup that uses those aviation connectors and I might put them on at that end. Molex at the terminations for the stepper hardnesses and the connection on the RAMPS. Braided cable covers and potentially buying for disassembly cheap tape measures to run in them, though I do have cable chains available for the X/Y wiring.

I have seen where others have done the same but noise and using both wires of a twisted pair for a motor pole seem to be common topics, I hope to use a single conductor for one motor pole to use the other 4 wires for other purposes. 24 and 23 awg should support the motor current of the nema 17 motors, I will see if this is a practical real world solution, I also plan on using some phoenix spring terminals for the motor terminations to make it more of a tooless install.

I have to place a 5 board min so I will end up with 5 sets, a main board and 6 motor boards per set if anyone has interest is playing with this idea and sourcing some parts themselfs.

Well, I have put this off long enough. Instead of fixing bugs in sandify, I’ve spent the last week or so on the LR wiring and I’m happy to say, “It’s ALIVE!”.

[attachment file=77687]

Close up of the control box:

[attachment file=77686]

It’s got the basic parts for me. I have a back panel designed, but not printed, and I am thinking of CNCing a plexiglass front panel, but I have a BB one already sized, so I might just screw that on for now. It’s attached to the LR using a french cleat, which is pretty bulky in this application, but it’s super strong and I can easily just pull it off if I want to work on it.

I wired each Z motor to it’s own driver on the mini Rambo. That seems to be working fine. But I haven’t done any cuttin yet.

I ended up using a JST-SM 2.54 on each motor, to connect to a 4 wire extension cable. Then I used JST-XH to my custom PCB, which connects to the rambo.

The vac I have is one of these canister dust collectors, and has a 2.5" input hose. I need to figure out a way to attach that to the LR instead of this 1 1/8" one I’m using now. That should reduce the noise and the dust.

One of the first things I’ll be cutting is the flat parts for the LR v2. You never know when you’ll need them.

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