cnc build at home for templates and necks

[simon1138]

Hello

I have tried to read about cnc machines on various websites and got nowhere. Please could I get some advice from you experienced people on building a cnc machine and making one of adequate size to cut templates from 10mm (max) and possibly the backs of guitar necks. I have not tried making a neck yet and shaping is something I dread. 

I have some experience with electronics and programming. I can learn those things when I need to. I am more concerned with overall size of machine and size/type of motors. I have a katsu palm router and I see similar things used as the cutting tool. I have experience with arduino from my HNC electronics course.

What would be the maximum size of the machine (approx) if i just wanted to make basic body and neck templates?

Thanks

Simon

[curtisa]

14 hours ago, simon1138 said:

What would be the maximum size of the machine (approx) if i just wanted to make basic body and neck templates?

As big as the biggest part you want to machine in one go, plus some overhang, plus whatever 'dead' dimensions the machine itself can't use due to the moving parts having to fit within the maximum travel requirements of your machined part.

Say the longest thing you want to machine is a Strat neck. The neck itself might be somewhere around 700mm long. You're also going to need some extra length of travel for the cutter to move around the longest parts of the neck (the tip of the headstock and the area around the highest fret), so maybe allow another 20mm at each end. You might also need to allow some extra to fit clamps, screws or whatever in order to hold the part down to the table as it's being machined, so maybe add another 20mm at each end, The total machine travel required to comfortably machine the neck is therefore 700mm + (2x 20mm) + (2x 20mm) = 780mm. The machine itself needs more physical size to allow all those moving parts to fit within the 780mm of travel which will depend a bit on how the machine is built, but maybe allow another 80-120mm at each end. Overall the machine will probably be over a metre long to fit that Strat neck in.

Doing the same estimates for a Strat body you're going to want a machine capable of travelling about 400mm at its widest, plus the excess for the machine itself, so maybe something about 550-600mm wide?

Generally the size of the machine itself is secondary unless you are really strapped for space. It's more about what the maximum machining area is available to you underneath the cutter. That's also ignoring all the new skills, knowledge and practicalities required to make the jump into CNC - at times the learning curve may well be brutally steep. And expensive.

I found the The Guerilla Guide to CNC Machining handy when I first got started in CNC. It's more geared towards making resin casting moulds for hobby robotics, but the basic principles it detailed were fairly easy to understand and translatable to machining other stuff (ie, guitars made from wood).

Edit: duh. Can't do math properly today

[Prostheta]

I agree.

The way I would look at it is from the size of spindle you want to work with. A small Makita RP0700C clone (which I guess that Katsu is?) is about as small as you want to go, bearing in mind that these routers are not intended for long working duty and have very inaccurate (lots of runout) single-locking collets. I would imagine that any machine other than something slightly overbuilt would end up with accuracy in the half-millimeter range, with it being a fight to hit tenths, which is what I regard as a reasonable point of accuracy.

This raises the issue of expectation; if you're aiming to produce templates that represent parts that need to fit together, there will likely still be a bit of finessing from off the machine. For perimeters, pickup cavities, bridge hole locations, etc. you can accept a little slop in most cases. Errors from tolerances compound very quickly, and necks easily don't fit bodies they were made for.

Perhaps look into a DC spindle that can be controlled better by software. At best the Katsu/Makita palm router can be switched via a relay from software, but not the speed. DC spindles tend to have better locking mechanisms and lower runout than laminate trimmers as well, plus are quieter.