View Full Version : Small CNC for guitar inlay work - general thoughts

29-01-2018, 02:07 PM
Small self-build CNC machine for guitar inlay work Ė General thoughts

Three of the questions Iíve been asking myself about why I want to build a small CNC machine:

1. My hands no longer give me the level of control I need to cut fine inlays in Mother-of-Pearl etc, and their associated housings in a variety of hardwoods
2. I get some of the MoP inlays cut commercially at present which is expensive
3. Some inlays require me to make a pattern for a homemade pantograph using 8x (size) patterns and 1mm cutters in a dremel fixed to a home made pantograph Ė this is time consuming at best.
This also requires a reversed pattern to cut the housings with the pantograph too

Took me quite a while to admit to the first point, the second point is simply one of cost. MoP and other shell inlay blanks are quite cheap and offer a greater range of sizes which in turn offers more flexibility in the designs I can use. Point three shows that I can currently cut inlays and housing but the process is drawn out in having to make enlarged patterns to cut out shapes.

What materials do I work with:
Inlays Ė normally in a shell of some sort, bone, resins, various hardwoods, rarely metal (brass or aluminium)
Inlay housings Ė normally cut into various hardwoods
Sizes: logo typically 38 x 18mm to 45 x 21mm. Headstock veneers upto 200 x 75mm. Rosettes 90mm upto 140mm diameter either as complete circles or partial arcs.
Cutting depths for inlays typically 1.3 Ė 1.7mm, for the hardwoods 1.5 - 2.5mm max, for softwoods (soundboards) 2mm max.
Rosettes are currently cut with a Dremel on an adjustable radial arm which rotates about a fixed pivot at the centre of the soundhole.

So Iím looking to build a small CNC with X, Y and Z movements covering a working area approximately 250 x 150mm (minimum) and a working height of upto 30mm. Cutter sizes Iím guessing will be between 0.4 Ė 3.0mm in general with a max of 5.0mm.

Initial thoughts are towards a fixed gantry machine, itís axles being screw driven in X, Y and Z.
Base frame and gantry built from aluminium (mix of extrusion and bar/plate). Working platen aluminium.

These are general thoughts at present. Iím a complete newbie with regard to CNC so guidance from the forum members will be appreciated in all aspects of the design. Iím guessing that some will favour the fixed gantry others will opt for a travelling gantryÖ

I have some image examples of typical simple inlays Iíve made with the pantograph/Dremel and a commercially made logo.


29-01-2018, 03:31 PM
Hi and welcome.

I'll add some thoughts:

If you are "only" looking to cut inlays (and I assume the corresponding pockets) then you don't need a massive machine for this kind of work and this may be one of the rare use cases for the cheap 6040 machines (I think there's is also a 3020). You will have to be "honest" with yourself, as hogging out guitar bodies and necks (whilst it can be done) won't be a quick or easy experience on the cheap machines and a self build route would be better in that case, and there are a bunch of build threads on here you can look to for inspiration/guidance.

Things to look for on the 6040 style machines:

I haven't looked for a while but round supported rails is a minimum and if they are doing linear guide rails go for those instead. Do not buy a machine with unsupported round rails.
Look for a machine with a water cooled spindle, rather than air or one you can upgrade to a water cooled spindle - they are much quieter.
Be prepared to upgrade the cabling and control board, drivers etc. this is one area the costs are kept down and especially when it comes to grounding/shielding and where problems usually occur.
Also be prepared to have to do a bit of maintenance to get everything aligned and travelling smoothly.
Unless you can ensure the seller is providing a "proper" licence of MACH3, be prepared to spend extra getting that also (or go Linux if you are OK with software and running that OS).

Hope that helps and I'm sure others will chime in with other advice (you'll likely be goaded into to building a machine weighing 6 tonnes and built from granite ;) ).



29-01-2018, 04:28 PM
A common fact is that people start out by buying/building a machine to suit their immediate needs, and then realise that they can do so much more now that they have that capability. Or, at least, they could do more if only the machine were just a little bigger/stronger/more accurate/faster...

A friend bought a Chinese machine (fortunately, one of the better ones) to "just" do some engraved lettering on the products he makes. Then he realised that those products could be made better/cheaper/easier/faster by incorporating the router into the build process. Then he found that he could start making items for sale that he just could not do before.

Chris above points out more ambitious uses of a CNC router in guitar making; it might be worth looking at the whole of the process to see if that points towards a different target machine or design for home building. Within reason, a big machine can do small jobs as well, but a small machine is always a small machine.

29-01-2018, 05:08 PM
Chris / Neale, Thanks for your thoughts.

I know Chris is into solid body Telecaster guitars and having built similar using a hand router to cut pick-up slots, cable channels etc I can see where he's coming from on this. I build acoustic hollow bodied guitars (though I have hand carved front and back plates on a 17" archtop jazz guitar (https://milsomguitars.weebly.com/archtop.html)), so my need to carve out large quantities of material doesn't really exist.
I initially started looking at the Chinese 3020 / 3040 machines on *bay before I joined this group. What put me off was the comments high lighted again by Chris about how good/bad these machines can be. Then after joining I started reading some of the re-build threads on the Chinese machines...
Clive S pointed me towards Wal and seeing his self build in action made me think more about going on the self build route.

I'm currently researching materials (ali extrusions, lead screws, bearings, motors... etc) No money commited yet!!

Thanks again your points are noted and perhaps I will look again at the Chinese machines in a more informed light but I think the 6040 will be beyond my current budget especially if I have to factor in replacements before I really get going.


29-01-2018, 10:09 PM
Thanks again your points are noted and perhaps I will look again at the Chinese machines in a more informed light but I think the 6040 will be beyond my current budget especially if I have to factor in replacements before I really get going.


Francis Don't even entertain the Chinese machines they are just hassle waiting to bite you. Like Clive mentioned these small cutters require rock solid machine and the chinese machines are just not strong enough and soon go sloppy.

Either DIY build or save and buy better machine.

01-02-2018, 09:21 AM
Transferred from my Hi from Hereford thread:

Hi folks, I've been doing a few things: looking at commercial desktop machines and how they go together, looking at build threads and how they evolve, looking at some of the rebuild of the Chinese stuff and doing some parts costing. Initially looked at linear bearings and tracks for the Y & Z axii, motors, lead screws etc., even though I'm looking at a quite small machine the cost is rising sharply. Sharply enough for me to look as supported rails rather than linear bearings/tracks. Not looked at the electronics yet. All part of the learning process, I need to take more time. I was hoping to get this project going quite quickly but I think it will be a few months before I pull all the bits together ready for assembly.

I'll put some of my drawings up for discussion over the next few days to see if my thinking is in the right direction. Still looking at a fixed gantry with moving bed. Twin support rails under the bed (Y) and across the X axis and paired rails on the Z axis...

Not decided yet on the type (diameter or pitch) of lead screw for each axis but decided not to use toothed belt drives.