CNC at home - what would I need?

guitargeek62

GSPBASSES said:

@guitargeek62 Let’s get back on topic, if you decide CNC it’s not the way to go have look at my post https://thefretboard.co.uk/discussion/230913/how-to-build#latest. Relatively easy to build not terribly expensive, they are very accurate. I think they are safer than hand routing. I am in the middle of writing a post on how easy it is to modify jigs for a pin router and how I go about it. In that post there is also a link to a post I wrote a while ago how to turn a paper plane's into a jigs for a pin router, then the making of the guitar.

Thanks Graham, I only used hand-held and table routers when I'd built guitars previously, but I definitely see the sense (and safety!) in a pin router setup. I'll follow your thread with interest, and I suspect this is the way I'll end up going - in part because I'm not actually sure that I want to cut out* too many of the hand-worked steps of any build!



*no pun intended

guitargeek62

Looking into this a bit more, I suspect something like this approach is what I'd end up with:

https://www.projectguitar.com/articles/workshop_and_tools_47_47/a-small-cnc-machine-for-luthiery-part-1-r8/

As previously stated, I don't want to lose too much of the hands-on aspects of builds, so most of the benefits for me would be around inlay and fretting/fingerboards. If I increase in output my any meaningful way then I could rethink, but there's no point in investing and setting up in factory-level equipment for a handful of builds a year. However, a small CNC for simpler jobs makes more sense, and lets me learn and apply the basics that could then scale as needed

m_c

guitargeek62 said:

Looking into this a bit more, I suspect something like this approach is what I'd end up with:

https://www.projectguitar.com/articles/workshop_and_tools_47_47/a-small-cnc-machine-for-luthiery-part-1-r8/

As previously stated, I don't want to lose too much of the hands-on aspects of builds, so most of the benefits for me would be around inlay and fretting/fingerboards. If I increase in output my any meaningful way then I could rethink, but there's no point in investing and setting up in factory-level equipment for a handful of builds a year. However, a small CNC for simpler jobs makes more sense, and lets me learn and apply the basics that could then scale as needed

Unless you want to do a lot of tinkering to keep it working, I would very strongly advise against that style of machine.
 I do have a 6040 sized one, but I bought it for a very specific purpose that didn't involve machining anything (I used it as a base for a digitizer/CMM, so pretty much all the electronics got ditched, and the mechanics got a fair bit of modification).

To give an idea of how bad a machine they are, I could measure over 0.5mm flex at the spindle nose, just with moderate hand pressure. That will translate to producing a resonating/chattering mess under load. Under light loads, like engraving, that's not likely to be an issue, but will likely limit cutting speeds to ensure a good finish.
They can still produce OK bits, but you need to know the limitations, and check a few mechanical issues (biggest issue is the ballscrew thrust bearing setup is likely horrendous, so you can't adjust endfloat/backlash out).

If you do buy one, make sure you get what's usually marked the 'Z' version. The 'T' version uses acme/trapezoidal leadscrews, which will quickly result in backlash due to nut wear, and just won't perform as well as ballscrews. You're still likely to have some backlash in the ballscrew version, as they typically use cheap rolled ballscrews, but it should be more consistent and lower than a leadscrew.
You'd probably also want to get the watercooled spindle version, as it's far quieter, and will run slower with more torque than the basic DC spindled version.
You'll also want to go over every electrical connection, to make sure they're crimped correctly. Mine came with quite a few badly crimped connectors, which if the wires came out with it running, would likely result in the relevant stepper driver dying, which in turn would mean a complete new control board, as they use a single integrated board.


As I mentioned in a previous post, if you just want to try CNC without too much of an outlay, you'd be hard pushed to beat one of the self-assembly kits like - VEVOR CNC Machine 3018 3 Axis CNC Router With Offline Controller Milling Machine For Wood PVCs PCBs | VEVOR UK
£129 should get you a little functioning machine, that will let you learn about the process, and hopefully machine a few bits, before it falls apart (seriously though, these little machines will usually run for a while without nay major issues, as long as you don't try doing anything stupid with them, and keep an eye on them for mechanical issues).
For those wondering what software this kind of machine runs, it's likely GRBL. Not something I'd personally recommend for a larger machine, but it does the job. There's a few different PC based apps that will work with it, if you don't want to rely on the offline controller.

guitargeek62

@m_c thanks, I'll take a look. To be clear, I wasn't linking to that site in regards to any specific machine they use there, just that it was an interesting read and gave me something more to think about with my plans


(Well, day-dreaming at this point!)