Fret cutting jig

[johnosb]

Probably over kill but....

I tried using a rule and marking knife for fretboards but couldn't seem to get them accurately marked/cut so I resorted to preslotted and radiused fretboards for my first two guitars. The two I'm currently building have 'non standard' scale lengths so I'm obliged to make my own but was seeking more accuracy than I knew I could achieve by hand. I searched the internet but couldn't find anything so came up with the following by ripping off the CNC guys.
Basically, it's an X axis gantry riding on skate bearings on 25mm square section ally tubing driven by an 8mm longthread mounted in skate bearings. A handle on the end moves the gantry 1.25mm per revolution and I extended the threaded rod through the handle to attach a drill for rapid transit. I used a digital linear encoder to provide absolute position with 0.02mm precision (about $40 off EBay) so I didn't have to worry about backlash. To keep the saw parallel to the cut I mounted a couple of rare earth magnets. Just knocked off my first and it looks like it's within 0.1mm or so accurate between each fret (digital vernier) and I can't see any error with a ruler between fret zero and 21.
After having spent a couple of hours sanding the radius, I realised that it would be simple to modify it to carry a router as per Martin Taylor's post below.

Os

[charangohabsburg]

Brilliant!

[Kim]

Well that's just too clever...your banned..



As Markus said, brilliant!!

Cheers

Kim

[martintaylor]

Makes my jig look prehistoric! Would love to see how the saw is mounted.

[Henk H]

Nice jig ! However thusfar I couln't find a reasonably priced digital linear encoder. What brand do you use and /or where did you find it ?

[johnosb]

Thanks guys,

I was sure I'd get a bollocking for using a sledgehammer on a walnut!

Makes my jig look prehistoric! Would love to see how the saw is mounted.

The saw is held vertical by the RE magnets. I had to spend a bit of time getting it squared up and it's not too hard if you go easy with the pull saw. I found 4 or 5 easy strokes did the job. A couple of rough bits where the saw kicked a smidge but always on the edge so disappeared when radiused. I did another today and no probs, just slowed down a bit and stopped using the saw the way the old man taught me!

Nice jig ! However thusfar I couln't find a reasonably priced digital linear encoder. What brand do you use and /or where did you find it ?

Ebay. A bloke in SA is flogging them. 500mm travel was a bit over $40 - just checked EBay for a link for you and it was actually $48 including postage. Try this http://www.ebay.com.au/itm/DRO-Digital- ... 51a6a45353

It's sold as 600mm but it measures 500mm due to the 100mm encoder case. Pretty impressed, metric and imperial (in thou and fractions), relative measurements too and it seems accurate enough.

Modified the jig for radiusing today a la' Martin. Bloody ripper. I'm a bit under 1/4mm thinner at one end so I might have to shim the base up a bit one end apart from that, 5 to 10 minutes with the router and I'll run through a couple of grits to finish it off. I reckon less than half hour all up - bucket load better than the couple of hours of sweat and toil doing it by hand - thanks Martin!

Os

[martintaylor]

Looks really good. I must say, I didn't invent the concept, just copied someone else's idea but glad it is cutting down time. It certainly has for me.

[johnosb]

Looks really good. I must say, I didn't invent the concept, just copied someone else's idea but glad it is cutting down time. It certainly has for me.

Even so it's a great idea and major time saver bonus that I can add it to the slotting jig without too much hassle. Always nice to have a multipurpose jig.

[johnosb]

Ah sorry Henk, just realised that you're in Holland and the dude in SA only ships to Oz. I just did a search on Ebay and found this in the US which looks like much the same sort of jigger:

http://www.ebay.com.au/itm/24-Digital-R ... 20caabaefc

Might even work out cheaper considering the cost shipping from here especially given the state of the US dollar.

Os

[nnickusa]

John,
If you tell us that you've both tapered the rails, and adjusted each side of the bearing form to allow for a tapered fretboard radius--compound--I, for one, will never read another of your posts. You clever fellas just piss me off!

I happen to Neanderthal my way thru, tho I'm trying to become more sophisticated.........

[Kamusur]

John,
If you tell us that you've both tapered the rails, and adjusted each side of the bearing form to allow for a tapered fretboard radius--compound--I, for one, will never read another of your posts. You clever fellas just piss me off!

I happen to Neanderthal my way thru, tho I'm trying to become more sophisticated.........

Just cause we use hand tools surely that's no reason to call us Neanderthals
And trying to get my head round the maths/physics part of the tapered rails idea
Seriously, great jig though.

Steve

[nnickusa]

Yeah, really nice bit of kit.

Steve, I refer only to myself

[johnosb]

John,
If you tell us that you've both tapered the rails, and adjusted each side of the bearing form to allow for a tapered fretboard radius--compound--I, for one, will never read another of your posts. You clever fellas just piss me off!

Not smart enough to solve that one but happy to rip off anybody that does!

[nnickusa]

OK, I'll keep looking at your stuff.....

[Kamusur]

Nick its ok I have a mono brow.

Steve

[nnickusa]

HAH

[timbuck]

I really like that set up...it's accurate, just one step away from CNC..and can handle any scale

[EricDownunder]

I like that thing; do you mind if I copy your idea and build one for myself?

[johnosb]

I like that thing; do you mind if I copy your idea and build one for myself?

Go fer it, any improvements should be posted back but..

[Bill Hodge]

One sweet unit for sure!