A few simple wiring questions for DIY build

Machine: DIY
Board: LaserBoard
Firmware: I have a new board and I’m using whatever it came with

Hi everyone,

I’m building a DIY 80w laser, primarily using OpenBuilds hardware. Nearly done building out the frame and just getting into wiring, and I think I’ve already made a little mistake… I wired in the X-axis limit switches NO, and from searching around here it looks like NC is expected. I’ve already sort of embedded those wires and it’s a bit of a pain to fix, but easier now than later if it’s necessary. I saw you can switch via software by adding ! to the end of the lines in the config file…
So my first question is, is it better to rewire NC or is it all the same if I just change the software config? And if I keep them NO and change the config file, should I wire all of the other limit switches the same and correct via config, or should I wire the rest NC (not sure if mixing would create problems).

Second question concerns the SD card slot and finding an extension for it with a panel face mount… I’ve had no luck trying to find one besides custom 3D printed ones. Can anyone recommend one that works well?

Thanks in advance for any help.

Yes, you can easily invert the switch logic in your config file as you describe. It is adjustable per switch/ pin on the board.

I believe that NC is more tolerant to electrical noise and is safer in case a wire gets cut/ disconnected and try to use it when I can. You should also twist your switch wire pairs together for noise immunity.

The official response will be to not use an SD extender as it can damage the SD slot on the board, and probably also some concerns about noise. That said, I am sure people do, but I am also not sure about finding a panel mount one off the shelf.

A generic SD Extender looks like this, and then you make a little holder to attach it to a panel using 3D Printing/ Laser Cutting/ Hot Glue, whatever your preference:

And again, official stance is don’t do it :slight_smile:

Thanks for the quick reply, Ray. Interesting about noise… what sort of issues would that cause? I would assume random triggering? I’m using some 2-conductor wire that I’m not sure is twisted, however it’s buried along the inside of the extruded aluminum and I’d think that might provide some protection if I ground it properly. Would you agree?

That’s funny… almost every customized layout I’ve seen on youtube is doing this. Honestly at this point I don’t think I’ll really need it… originally I was thinking I’d have the laser in a different room from the computer and would have to transfer jobs via SD card, but I found a better spot for it and can run USB. Thought I’d run the extension to the panel anyway for easy access, but if it’s a bad move I’ll just leave it off.


Remember, I live in the world of the what if within the what if (synonym: engineering). Ideally everything works. Do what you can in advance. If you have problems then we look at potential improvements.


Another quick question, as I’m going thru the docs concerning firmware/config files on the memory card, it all seems to imply that I should already have one. I didn’t receive one with my board… should I have? I see where the files are available to make a replacement card myself, are there any specific requirements for the SD card itself?

The memory card is typically in a small plastic case in the bubble wrapped pouch that contains the board and C3D Sticker. I have seen people misplace it, probably more often than I would like.

Max 32gb and format it FAT32, at least a reasonable brand would be good, not some generic junk.

that’s unfortunate… I must have thrown it away. Maybe you should consider putting it in a small envelope or something that makes it harder to miss? I don’t recall there even being bubble wrap, just an anti-static pouch, but I’ve unwrapped so many overwrapped things in the past month I really couldn’t say… kinda sad I missed the sticker, too… I like stickers…
Thanks for the specs, I’ll add that to the list.

Sorry if this has already been asked somewhere, but I just want to make sure I don’t make a wrong assumption here. In the board diagram I found here it shows the on-board stepper connections as B2 B1 A1 A2. Is that B- B+ A+ A- or B+ B- A- A+? Thanks :slight_smile:

I don’t think the nomenclature actually matters. Identify the coil pairs of the motor. Plug them in. Try commanding the motor to turn. If it buzzes and doesn’t move, flip a pair.

Fair enough… I should have power wired up soon (waiting for parts again) and will give it a go. Have my motors and stepper drivers all wired now, and finishing up limit switches today…