Official Luthiers Forum!

Does anyone have a good source for the "fly cutter" type circle cutters ? there is a few ebay , anywheres from $7 each to about $ 20 . I am always nervous about buying a tool without some prior knowledge of quality . thanks jody

Jody - I just use the General - brand cheapo fly cutter that came from wherever ... the Borg? I don't know. The thing scares me to death because it looks so imbalanced, but I just make sure that everything is nice and tight, and it works fine - better than my Dremel on it's S-M base, I now think.

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Jim Kirby
kirby@udel.edu

I have a couple of Generals also. Only use these in a drill press !! Use them at the slowest speed!!! Make sure your work is secure and keep your hands out of the way!!!!
The tool supplier I bought them from has replacement cutters. I had a machineist grind the cutters so now I have a .063" and a .043" for .060" and .040" purflings. When using these to cut out the sound hole, cut half way thru, flip the sound board and complete the cut.

Steve

Also, sharpen the blade! Out of the box it's not really as sharp as it should be. Also, for the thicknesses that we are cutting, it's very easy to put it into the drill press, apply downward pressure, and spin it slowly by hand. Just a little slower than by power, and way less scary!

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

I've used flycutters for cutting circles in all sorts of things - some of which I won't admit here I would recommend getting a General or other decent tool - stay away from the cheap ones, they'll just be more trouble than they're worth.

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Steve Smith
"Music is what feelings sound like"

I'm scared to use a fly cutter... my drill press will only go to 600 rpm at the lowest and I am not sure if that's slow enough. So you guys use those to cut rosettes? I think I would much rather use my drill press than the wells/krinol jig because (not saying that the wells jig were poorly designed or anything) due to the design of my laminate trimmer, when the jig is used as intended I can't see where the bit is at so I don't have an accurate way of sizing the cut.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Cut a test sample first.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

[quote=]"Tai Fu: So you guys use those to cut rosettes?[/quote]

I use a Wells/Karol type jig to rout for the rosette tiles first. After the body of the rosette is done I use the fly cutter for the purflings and to cut the sound hole. I've standardized the size of my rosettes. I use a lay up board made from MDF with a standard channel cut in it to set up the router and to size the body (tiles or rings) of the rosette.

Steve

Woodcraft has one that takes double cutters, so you have better balance.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

To me a fly cutter is a tool of last resort, when you can't come up with any other way to do the job. I hate them, and have avoided using them for the last 20 or so years. They are the only tool in the shop that spooks me, other than those old wobble dado blades. I just don't like depending on the friction of a set screw to prevent pieces of steel from being launched at my face. Also it is so easy to be concentrating on the action of the cutter and lose track of the arm that is extending another inch or more past. If you are careful and run at slow speeds they are not a big danger, but keep Murphy's law in mind. I think that their continued use is a holdover from earlier days when there were fewer options for rosette cutting.

Along with the trial cuts mentioned above, careful use of a caliper will allow you make precise adjustments without needing to see your bit when the tool is in place. In conjunction with the caliper, I also like to use a fractional construction calculator to quickly figure the radius or add the various widths together.

If you must use one, I really like Douglas' idea of hand-turning it. Might want to unplug the drill press first.

I don't use it to cut rosettes. I'm pretty much with Brook, I don't use mine for anything routinely. I used them in hand drills for years before I had a drill press although I wouldn't recommend using them that way. So far, I cut my rosette and everything around the sound hole with a Wells-Karol jig.

Tai Fu, perhaps you can modify your laminate trimmer so you can see the bit easier?

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Steve Smith
"Music is what feelings sound like"

I forgot to add that I did a little mod to mine, I replaced the center pilot drill bit with a piece of 1/4" brass rod. The rosette area has a pre-drilled hole, and is centered over an index hole in the table for the drill press. Not the actual table, but a panel that is set over top of it. this ensures that the holes are aligned correctly.

It very important that the table be set perfectly square to the axis of the drill press, otherwise one side of the circle cut will be lower than the other.

To cut the soundhole by hand turning, I give it about 6 turns of modest pressure on one side, then flip the top and give it about 6 turns from the back side. This keeps the hole cut nice and clean.

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

I have a Greven rosette cutter, which for the most part I love...I do use a cheap ($11) fly cutter for cutting out the soundhole though...I took the Greven idea and used it with the fly cutter - a 1/4" ID bushing in an MDF table clamped to the drill press table...and, I set the fly cutter where I want it (3 7/8") and epoxied it there...it won't ever move! I have had great luck using it like this...very stable and balance is not a problem if the speed is around 300-600 RPMS...

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http://www.presnallguitars.com

Heh, I said they scared me, but they aren't THAT bad. My drill press goes down to 320, so that's a little better than 600. I do find that I get a nice clean cut if I keep my cutter sharp, and there is the benefit that you can see the cutting action, which you can't with the Dremel+Stew-Mac jig, where chips pile up around the cutter. After getting used to the fly cutter, I don't think I'd go back to Dremel now.

I like the idea of putting in a brass rod instead of the drill bit.

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Jim Kirby
kirby@udel.edu

I have one like this but I have not yet tried it.
This type of circle cutter is not really expensive:
http://www.dick.biz/dick/product/716163/detail.jsf

As mentioned above. Single arm General, substitute a 1/4" metal dowel pin for the drill bit, embed a bushing in the backup board, and I do it as the last step after the rosette is leveled and top thickness established. RPM 2-300 and I usually go all the way through from the top. Very slowly. That has not been a problem so far if the knife is sharp. In the picture below only the lower bout is clamped but I now usually put a strip of wood across the upper bout and clamp that too to make it more stable. I've done about 30 guitars this way with no "misadventures" yet. In all the excitement it's easy to forget to tighten the lock on your drill press table after you set everything up. Scared the hell out of me first time it happened but the bushing held.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I have seen it work well. Ken Franklin makes some of the nicest rosettes I have seen and he uses a fly circle cutter for the whole process. He custom grinds different knives for different size purflings etc. YMMV but with Ken it comes out perfectly. Actually Ken could probably do it with a pocket knife but it does work well.
Link

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Cut to size.....Beat to fit.....Paint to match.

I have one, and will not use it again if I can avoid it. In fact, if some one wants it, I will sell it to you (cheaper than you can buy it at SM). I do not like the way it cuts "angled" grooves. This could be overcome by machining the cutter. I do not like that thing flying arround at 600 rpm. Maybe the double would be better. And most of all, watch out if it catches going that last thousandth through the wood (when cutting rosette wheels). Can turn it into tooth picks.

After that, I bought the rosette base for my Bosch Colt from Rod.

Mike

Mike,
I might be interested. I PM ed you.
Link

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Cut to size.....Beat to fit.....Paint to match.

Thats the best advice (no power) that Ive seen with this tool. I want to build a simple plexi- face/body shield that may be free standing, just to have in front of me for peace of mind with the drill press. Anything big like a spade bit bothers me.
Here is a hand held jobber from a classical site.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Ok, I just took my General Circle cutter, and wacked off the metal round thing(I surmised it was the same model with the clumsy round thing added) , so it is a square hole all the way through the horizontal shaft (as pictured above), and my gramil 1/4 inch blades fit into it nicely , the set screw goes all the way in, (grinding 3/16 inch off the tool steel shaft would not be fun.)

All I need to do is make up a handle, and tap it into the shaft.

You can get an Ibenez blade for like $5.00. This seems to be a simple /quiet way to do the sound hole cutter thing. It could even be a purfling cutter but you would have to make or buy a small steel blade to clear it out, but those binding channel cleaners may work for that also, I will give it a try and do pics and an update!

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Just an update, I am using the General circle cutter with a 1/4 gremil blade in it, and just cut out a nice rosette from spalted maple burl, had no problem, got a nice straight cut, on the wrong side of the wood, but its a nice straight clean wall.

I did not even add a handle, just a larger bottom washer, and a few minutes, no noise or dust!
I also notice that LMI has some of those 'perfling' cutter blanks, and even spacers, if you don't want to grind away for 1/2 hour....

http://www.lmii.com/CartTwo/thirdproduc ... tte+Cutter

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

wells/KRINOL ... I will have to add that to the list of misspellings of my last name, cause thats DEFINITELY a new one !!!!

BTW.. no offense taken, I'm still


If you want, with the Karol jig, you can always use a dial caliper to measure between the pin and bit .. accurate to as close as you caliper can measure ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

That's what I do - works great. I recommend you right the numbers down instead of doing it in your head. Fortunately it only required a slight design mod.

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Steve Smith
"Music is what feelings sound like"