Upgraded 3018 Pro using MGN15H Linear Rails and a 500w Spindle

I stopped by Jaycar today and bought 5 meters of their AWG 22 spec, shielded, flexible microphone cable.

I realised that the cable is actually good for 4A when used with stepper motors as there are 2 wires per winding (AWG 22 = 2A per wire).

I also found a number of CNC suppliers selling an apparently identical spec cable for use with stepper motors, so that sealed the deal.

This stuff is really nice and seems perfect for use in cable chains.


4 Core Screened Professional Microphone Cable - Sold per metre - Sold per metre | Jaycar Electronics

 

Hmm, I’m not running them over 2A per phase so I should be fine. By my calculations these wires are good for about 2.2A each based on the number of conductors.

 

@Alex Chambers I double checked with a local CNC supplier that uses this spec cabling for their 3A NEMA23 steppers, and they advise that the cable is good for up to 3A per wire at a distance of 5.5m. Apparently they have tested it at up to 7A peaks without issues, but unsurprisingly don't recommend it.

Seems reasonable to me.

 

My first new stepper cable came out great! And my Z Axis now works! I just need to make the X and Y cables now. The XLR connectors pair perfectly with this cable - I guess I shouldn't be surprised seeing as it's sold as Microphone cable!

 

Hehe, dude, just get some OFC speaker wire from Selby Acoustics. Their “Ugly” brand cable is excellent and really good value for money.

https://www.selby.com.au/cables/speaker-cable/pre-cut-bulk-lengths.html

PS, I’m guessing you are in Australia?

 

lol, I’m not an audio-phool, but when you spend $12k AUD on your speakers (many years ago before those little money suckers, we call kids, arrived on the scene), $60 for a roll of decent OFC cables seems cheap.

 

I made an X axis cable cable and ran into an odd issue. I must have made a config error somewhere as it energises correctly, but then won’t move.

Same result on the Y axis - X and Y use the same model motors. I double checked my wiring and it’s definitely correct and even matches with my old cables. I checked every connection with my multimeter and everything has continuity and minimal resistance.

I might move on to the limit switches and come back to it.

 

None at all, however you can hear the initial energise sound and it does hold position.

 

Quite low, in fact identical to what I ran with regular GRBL.

Code:

axes:
  shared_stepper_disable_pin: I2SO.0
  x:
    steps_per_mm: 400.00
    max_rate_mm_per_min: 1500.000
    acceleration_mm_per_sec2: 1000.000
    max_travel_mm: 278.000
    soft_limits: true
    homing:
      cycle: 2
      allow_single_axis: true
      positive_direction: false
      mpos_mm: 0.000
      feed_mm_per_min: 100.000
      seek_mm_per_min: 1000.000
      settle_ms: 250
      seek_scaler: 1.100
      feed_scaler: 1.100

    motor0:
      limit_neg_pin: gpio.36
      limit_pos_pin: NO_PIN
      hard_limits: true
      pulloff_mm: 1.000
      stepstick:
        step_pin: I2SO.1
        direction_pin: I2SO.2:low

My working Z axis for comparison:

Code:

z:
    steps_per_mm: 406.00
    max_rate_mm_per_min: 2500.000
    acceleration_mm_per_sec2: 1000.000
    max_travel_mm: 100.000
    soft_limits: true
    homing:
      cycle: 1
      allow_single_axis: true
      positive_direction: false
      mpos_mm: 0.000
      feed_mm_per_min: 100.000
      seek_mm_per_min: 1000.000
      settle_ms: 250
      seek_scaler: 1.100
      feed_scaler: 1.100

    motor0:
      limit_neg_pin: gpio.34
      hard_limits: false
      pulloff_mm: 1.000
      stepstick:
        step_pin: I2SO.3
        direction_pin: I2SO.4

 

It was a config issue, as soon as I connected my X limit switch, it started working.

 

Today I finished writing up the stepper motors and started working on the limit switches.

Unfortunately, I ran into a couple of issues.

1/ the inductive limit switches I was planning to use need 12v-24v and my board only supplies 5v. I can get around this by supplying power separate from the board. It’ll be a bit of a pain, but not a big deal.

2/ the mini XLR jacks suck to work on and I melted two of them before giving up in frustration. I was a bit surprised as the sockets where not an issue at all.

I think I’m going to switch to GX12’s or GX16’s for the limit switches.

in the mean time, I ripped out the mini XLR sockets and just wired my limit switches direct to the board with my old cables.

And then my lovely wife requested my presence to assist with Sunday arvo chores. So I haven’t had a chance to test anything.

 

I ducked out to the garage for some quick testing after dinner, and I’m finally getting all the settings working correctly in FluidNC.

https://youtube.com/shorts/4u-4MBUV964?si=XEUG2YZXrY5ZShh8

 

Looking good!

Mine weren’t clean either, but taking them apart and cleaning them in isopropyl alcoho, and then lubricating with a dry lubricant does the trick.

I prefer to use SuperLube grease on my linear bearings, but that seems to attract dust and crap into them.

 

You could just print an insert in ABS and drop that inside a 65mm aluminum mount.

 

Ah that sucks. hey, do you have a build topic? I'd like to follow your exploits as Im always keen to see how others solve challenges.

PS, I don't mind if you just want to post updates in this topic.

 

Honestly, im not sure.

Btw, my comment wasn't intended to be a "get off my lawn" - I just wondered if I was missing any interesting updates.

PS, ordering the wrong bits is a right of passage! I've lost count of the parts I've mistakenly ordered!

 

Awesome.

My "extras" just go into a box of parts I'll prolly need for something ... one day.

Good stuff. No worries, it's been a lot of fun tinkering in the world of CNC. I did the same thing with 3D printing - I started with the cheapest printer I could find and learnt from there. The below printer started life as an AnyCubic MegaZero v1 that I got on sale for $170 Aussie Micro-Peso's.



Here's the underside: