Official Luthiers Forum!

I have a K2...it's a cool little machine for home use. you won't set the world on fire with blazing speed, but it is certainly capable. It's repeatable to within about .001 or maybe a hair more....so it's plenty fine for inlay, fret slotting, etc. Operations like neck carving are benefited greatly by higher horsepower spindles. You can do it with the smaller router based machines, but you have to be pretty "strategeric".

In general, I would recommend learning CAD first. If you can't draw something, you sure as heck aren't going to cut it! It's not for everyone, and never underestimate the effectiveness of a nice manual jig!

I wasn't crazy about the shopbot...their repeatability numbers weren't that great and the machine I would have bought would have had steppers. The K2 runs using Mach III controller software, which runs off of standard G-Code (standard CNC controller language).

Here's the machine I have..

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http://www.PeakeGuitars.com

You have to be very careful going with repeatability numbers from router manufacturers. VERY few of them will tell the truth, and usually only when pressed. Those few are not in the sub 50K range. It's a lot like '1200W (at the amp) computer speakers' (instead of RMS) or '1000 horsepower' (but not at the wheels). The only way to get a straight answer out of the router guys is to say 'I want it in writing that it'll hold those numbers and that you'll buy it back if it doesn't'.

Haas says 0.005" for repeatability on their router (a higher end machine), and Thermwood won't guarantee 0.005" on any machine under 80-100K if you ask them to back it up in writing. Those are companies serving customers who will nail them to the wall if they make up numbers. These are both machines that are leagues ahead of the low end stuff in both components and rigidity.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Thanks for the information.

I talked with K2 and asked if I could use my Flashcut as post/controller and they said they could set the machine up for that.
I understand Shopbot does not run off industry Gcode and Gcode can be converted but just to clarify is the Shopbot Post/controller not interchangeable with say Mach or Flashcut.



Thanks,
Mike Fleck

I've measured different parts as they come off the machine....the accuracy of my K2 is on the order of 2 or 3 thou, but the repeatability is very good, probably on the order of about .001.

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http://www.PeakeGuitars.com

Shopbot uses their own proprietary controller & code. You'd need to re-post all your cutting files. Mach is nice, but it's not a slam dunk IMO - one piece of SW trying to cover too many applications. Shopbot was very reliable for me for 6 years.

I haven't seen the Buddy in person, but I like the fixed bridge design. It looks a lot sturdier than the K2. K2's gantry looks really light.

If size is an issue the K2 will take up half the room.

I recall hearing back in the day that a lathe was the only machine capable of reproducing itself.
Also recall hearing that a hand scraper can produce a flatter surface than the most precision surface grinder built today.
It seems that the very first "precision" machine tool had to be produced by the human mind and hand.
I suppose this goes back to the stone age but if you think about it, todays high precision machine had to evolve from some where.
Nelson

I heard you can build a lathe with a mill but you can't build a mill with a lathe

I should have said how we get to a jig boring machine! Making something really flat, truly square, and true to length are the fundamental problems we had to overcome. If you rub three pieces of glass against one another long enough they all converge to flat. There are a couple 'rock and stick' ways to make things truly square, though they're not as elegant as the glass thing. Getting something true to length is a tricky one, but we can use certain properties of physics to measure lengths very accurately.

The problem I was addressing with using one machine (where these variables of flatness, squareness, and accuracy are fixed) to make another is that the second machine can at best be expected to inherit the properties of the first and most likely will inherit less than that. The process of making the next machine will have its own margins of error, and those will be added onto the flaws inherent in the first machine and that can only be turned back by reintroducing accuracy (ie: if I lapped my Fadal's table enough I could get it as flat as the table on a precision grinder)

Not very on topic, but this stuff is really interesting (well, at least to me and one other person here I think )

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Accuracy and repeatability of slide positioning is very important and especially for inlay.
Another machine accuracy element that is not often discussed is geometric alignment.
Perpendicularity of all three (or more) axes to each other is very important. Also the straightness
of travel within an axis is important.