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F hole cutting jigs
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Author:  jason c [ Tue Feb 16, 2010 4:42 pm ]
Post subject:  F hole cutting jigs

I wanted to get some ideas from you guys on how to cut F holes (I could use a coping saw but I'm planing on making more than one). I like Benedetto's pin router set up but I have no pin router nor will I have the ducats for one soon. I'd like to see any jigs you guys have come up with.
Jason

Author:  Dave Stewart [ Tue Feb 16, 2010 4:56 pm ]
Post subject:  Re: F hole cutting jigs

No jig...I use a scroll saw (use a wine cork under for support). Lots of ways to skin this cat, from a knife (traditional violinmakers technique) up to pin router (which I may yet try... my old Ryobi radial arm has a high speed collet to work as a pin router but I've never tried it).

Author:  WudWerkr [ Tue Feb 16, 2010 4:59 pm ]
Post subject:  Re: F hole cutting jigs

Use a scroll saw and small files myself . seems to work pretty good . Never even considered a router for that duh

Author:  Howard Klepper [ Tue Feb 16, 2010 5:14 pm ]
Post subject:  Re: F hole cutting jigs

Your drill press is a pin router, albeit a slow one with excessive runout.

Or use a hand guided router with a top mounted template. Or table router with either top or bottom mounted template (and either an end or shaft bearing flush cutter). Easier to get the template level if mounted to the bottom of the arched top.

Author:  jason c [ Tue Feb 16, 2010 6:21 pm ]
Post subject:  Re: F hole cutting jigs

Aaah the drill press! duh Would a down cut bit work at those rpm's? My drill press only goes up to something around 3200 rpm.

Author:  Dave Stewart [ Tue Feb 16, 2010 7:04 pm ]
Post subject:  Re: F hole cutting jigs

I've often thought (even made a few sketches) a dremil held in a fixture and clamped to a drillpress spindle (like a mortising fixture) could be the basis of a poor man's pin router! (I'd want a higher bit speed than a drillpress.)
Maybe someone'll give it a shot.

Author:  Barry Daniels [ Tue Feb 16, 2010 7:09 pm ]
Post subject:  Re: F hole cutting jigs

I set the top bottom side up in my Benedetto style carving cradle to hold it steady. Lay a piece of 3/4" MDF on top with the oversize f-hole template cut into it. Then a full size router with top bearing to follow the template.

Author:  WaddyThomson [ Wed Feb 17, 2010 11:21 am ]
Post subject:  Re: F hole cutting jigs

I have used router bits in a drill press, and it works, but it isn't pretty. they just aren't fast enough. I have also used them in my radial arm saw, 3450 rpm, and it works, but the results are similar. Lots of bad edges. I don't know if I'd try it on anything as soft as spruce. Seems like you'd get a lot of fiber tear out, possibly.

Author:  jason c [ Wed Feb 17, 2010 8:19 pm ]
Post subject:  Re: F hole cutting jigs

I was looking at Daniel Slaman's website and I think I like his jig. It looks a lot like Benedetto's clamping cauls but with the F holes cut out and then I think he uses a top bearing pattern bit. I might try making something along those lines but out of some kind of clear plastic so I can see what's going on.

Author:  GordoninNM [ Thu Feb 18, 2010 11:24 am ]
Post subject:  Re: F hole cutting jigs

Here's how I do it,

Make an accurate line drawing on stiff file folder material, and cut cleanly to the line. I use a scalpel for this. Trace pattern onto template material, 3/8" MDF in this case. Be sure to make the outer profile over sized by the thickness of your binding material.

Attachment:
template640.jpg


Cut template with drill press, jigsaw, files, etc. If you overcut, bondo and rework it. Get this first one righteous! it will pay off later. next make a copy of this first one with a router and template following bit. This will ensure that the sides are cut perfectly square to the face plane. If you're happy with it, make a few extras, you'll be glad to have them later. Using a pair of these templates, squared and matched, you can build a template to cut both sides in one setup. My f-hole template is pretty much straight outta the Benedetto playbook.

Attachment:
fjig640.jpg


I cut from the bottom up using a router table with a long 1/4" spiral bit with the shaft of the bit protruding above the tabletop to ride the rim of the cutout like a bearing. I use grease to keep it from burning or digging in. Voila, a 1/4" pattern follower. A 1/2" template following bit is too big for my F-holes. When cutting, I clear out the middle first, leaving the delicate edges alone, then make a careful climb cut to final cut the perimeter in the delicate spruce. Final cut is to clean up the sharp inner corners with a skewed carving chisel.

Not that tough to do, but go slowly because thin spruce tops disintegrate quickly if treated roughly.

Attachment:
fhole800.jpg


Good luck,
Gordo

Author:  stereoandy78 [ Thu Feb 18, 2010 6:05 pm ]
Post subject:  Re: F hole cutting jigs

I was terrified the first time I cut mine using a coping saw. Ended up working very well. Clean up with your knife afterwards and perhaps a sanding stick and you'll be good. I like the feeling that comes with tackling those types of things using hand tools.

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