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
If I understand what you said above correctly I think you have got that wrong. Although there are two wires to each stepper motor coil they are part of one circuit. The same current flows in both wires - along one wire, through the stepper motor coil and the along the other wire. Alex.
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!
A thing of beauty. It stands to reason it's a nice cable for this because I'm the guy that uses Ethernet cable for speakers. I either twist 8 into 4, then into 2 per speaker for the PA. Or 8 into 4 for the long run outside to our party/workshop area's stereo pair. The wires' colour-coding helps me remember who's who.
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?
It's too late for me... save yourself man! lol Besides, when it is time to set the gear up for reals, my friends know to bring their own good cabling. I just bring nice, heavy black boxes, and the best music
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.
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
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
A wipe with tissue showed the parts weren't clean of grit etc. And disassembly showed they weren't as square and flat as they could be either. Work continues..
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.
Yes, dry lube might be the go. Next stage is making a spindle clamp. Being the only weirdo who would keep using a 42mm "775" motor in an upgraded setup; I have to make it myself. Besides, I know how to engrave well with that motor so I don't want to change too much at once and take out engraving.
Quite likely, however more than a few of the mounts I've looked at don't share the 70mm x 20mm bolt centres with this 'sliding block', necessitating an adapter plate. Which I'll avoid if I can, keeping the angle of the dangle as short as possible and all. Besides this'll merely be iteration zero of the new machine... And it'll have to make some more money before it gets too much more honey
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.
I was just going to put some updates here but if you think it's a better idea I'll start a new one. I didn't think it'll be comprehensive, so I thought by adding some bits to yours it just adds a variation, seeing as your build was my inspo. Despite me continually ordering the wrong bits, l'll see how I go remembering to take pics
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!
Not taken that way at all And it's a good suggestion. Instead of counting my badly ordered bits, I might just weigh them all up at the end lol. I'll drop you a link when I set up a new topic.. and thanks again for your excellent write-up here )
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:
