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Hello All,

I'm trying to decide between different tools for cutting the rosette channels for a steel string guitar. I don't have a tool for it now so I'm starting from scratch. I've done this procedure only a few times over the past several years, with a manual tool or a friend's ginormous drill press with flywheel cutter. I now have a medium size drill press that could handle a flywheel cutter but that seems a bit (ouch, sharp pun) scary to me. I'm wondering what the different advantages/disadvantages are for Stew Mac type circle cutter, Wells/Karol cutter, using Dremel vs. Laminate trimmer; LMI manual circle cutter, LMI drill press (Greven) cutter. Any thoughts you have on the matter are much appreciated!

Thanks,
Vivian

I use one of these: http://www.bing.com/images/search?q=cir ... ORM=IDFRIR except mine will cut up to 7 inches in diameter, not 5.5.

It's cheap.

You don't need a huge drill press.

I use various high speed steel cutters that I have ground to different thicknesses, down to 1/32nd of an inch. They're cheap too.

It will cut any rosette, you can see what you are doing as you do it, and can make infinitely variable adjustments on the fly.

It will also cut out the hole.

I replaced the drill in the middle with a 1/4 inch steel rod that fits in a bearing that I install in the middle of the soundhole-to-be while I'm rosetting to keep everything centered and to prevent wear on the soft wood.

Here's a link to a photo album, you can see it in action:
http://www.facebook.com/media/set/?set= ... 4209cb309b

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Old growth, shmold growth!

I got the Stew-Mac set years ago. Router and circle cutter set. They work good. The markings can be off and tightning is critical. Go slow and don't take off too much at a time. Also, sliding the whole thing around on the top can scratch the top up. So leave enough top for final sanding. I have a piece of MDF with the peg hole in it, and then lay the top on it, and it works great. I taped the air hose and power cord together so its one unit too.

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Jason Moe
LaCrosse WI 54601

I added a digital verner caliper to my Stewmac/Dremel set up. I've been very happily using this for quite a while now. It's dead-on accurate to 0.001" (relative moves, of course, not absolute) but it's easy to set up an accurate absolute using a piece of scrap wood before using it on the soundboard under construction. Here's a full-on shot of it:



I showed it off in a thread on OLF here when I first made it.

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I still use a popsicle stick to score the inside and outside diameters of the channel. Then I use a router with a circle guide to get the rest. When the bit is close to the scored line it comes off nice and clean.

If you do use the fly cutter, you don't need to operate it full speed. Mount it in the drill press for ease of use and orientation, but lower it into position and spin it by hand. It only takes a few turns to cut as deep as is needed for a rosette.

If you are clearing the channel with a chisel, you can score a few more lines in the trough to determine the correct and consistent depth to clear out.

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For safety and accuracy and ease of use, Dave F's setup is hard to beat. And it is the one that I use FWIW.

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I copied this Charles Fox design after taking his course in 2003. It has performed flawlessly since.

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Well .. you all know what one I use .. I like it because it uses a router, not a dremel, so much more accurate. You can micro adjust the size by a couple thou at a time, to get a tight fit. Mine are all made from UHMW plastic, so they glide on the top, and htey also hold thereade parts snug, for years. I built a new one a couple years back, and its still tight to turn - I dont bother locking it once I adjust for size, because it never moves (in fact, I have only one lock knob, to keep the whole adjust mechanism in one spot on the rods). And like Todd, says, for making a lot of different rosettes and sizes, it works great. Its easy to mod if you need even more flexiblility .. I needed to get it to cut a 2 3/8 hole on a harp arm soundhole ... so I drilled one extra hole to allow a nylon locknut to countersink into a mating piece, and then it adjusted far enough in and I was there.

I used a dremel and base once for acoustic guitar one, then designed and built the Karol jig. Sylvan saw it and then put a step by step how to make it on the web.

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

This is a Foredom attached to a micro fence. I can adjust both height and radius in 1/1000's and the rods have stop collars which can be used for repeatability. The whole thing is kinda overkill given how simple a dremel on a stick is, but it is cool. Cons would be cost.

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I run mine at 500 RPM, you actually can't run it much faster.

It cuts clean and precise with no fuzzies, and will do any circle based rosette you can think of.

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Old growth, shmold growth!

well, I tried the circle cutter in the drill press, I totaly didnt like an unbalanced object with removable parts, made in some foriegn country where quality does not seem to be a concern, , spinning at 500 rpm right in front of my face...... so I borrowed the plan Mario Proux was sharing over on the MIMF awhile back . it is simple. all one needs is a small piece of 3/8 plexiglass or lexan approximatly 5"x8" . using a hole saw drill about a 1" hole for the cutiing bit to pass through the ( I used a mill end) plexi off to one side . locate a trim router center of the hole and mark drill and counter sink holes to line up with the holes in your router , after removing the base that came with it. then install the router to the acryllic plate with your cutting bit on it . turn it over, using a micrometer , mark the radius center to the outside of your cutting bit , then drill a pin hole for the out side of your rosette. a 1/8 drill bit works nice for this, then you can use the bit for your pin. then you need to mark and drill another pin hole for the inside diameter of your rosette, again allowing for the diameter of the drill bit, this time measuring from the inside of it. then before cutting the sound hole, drill a 1/8 hole in what will be the center of it . cut your inside and outside radius for your rosette, you can then clean the remaing wood in the channel with a chisel, or you can drill several more pin holes and use the router to clean out the rosette. You can then use the same fixture to cut out your sound hole. I ike this because one gets a constant depth of cut on all routed areas .if I can find mine tommorrow I will post a pic. or you may be able to search the archives for a drawing or pic. Jody

My circle cutter is made in the USA. It cost twice as much as the Chinese one (I paid about $30) but was still cheap enough, and it does an awesome job.

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Old growth, shmold growth!

Nice, where did you purchase the circle cutter? thanks jody

Here's my take on the Stew Mac. It was just going to be prototype for one made of plastic, but I got lazy.

Works great.

I used the Dremel StewMac for many years and it worked very well. The key is to find a Dremel that doesn't have much slop in the bearings. If you're lucky enough to find one, they work great. A couple of years ago, I bought Bishop Cochran's jig along with a Bosch Colt lam trimmer and it's a different level of precision. Also a more versatile tool in that I rout truss rod pockets and a few other tasks with the new setup.

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Jimmy Caldwell
http://www.caldwellguitars.com

This works really great.

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Francis Richer, Montréal
Les Guitares F&M Guitars

Francis - do you use a chisel to remove the wood between your scribed lines?

I bought it from a place called "Craftsman Supply Center".

You can buy the same one from woodcraft:
http://www.woodcraft.com/Product/200079 ... Large.aspx

I have no problem getting perfectly fit rosetteswith it, it is infinetly adjusteable.

This is the large one which can cut circles up to almost 8 inches in diameter. I replaced the drill bit inthe middle with a 1/4 inch steel shaft which fits into a bearing that keeps the cutter centered.
Here's a link to pictures of it in action:
http://www.facebook.com/media/set/?set= ... 4209cb309b

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Old growth, shmold growth!

Are there plans for the Wells Carol jig? I know Chris did a tutorial a way back, but I can't seem to find it!

My micro adjust is - how accurate can I move the sliding part and keep it there while I tighten the wing nut - D'OH! It works, but I agree with Todd - Micro is a MUST!

Steve

Steve, I was not able to find plans for the Wells-Karol Jig other than the ones I would have to pay for from Sylvan Wells' site.

Do a Youtube search for "making a precision router base" and Chris Paulick's three videos should show up. You may want/need to adjust some measurements slightly, especially if your proposed laminate trimmer is not a PC 7310 like Chris's.

I just watched and rewatched them while making notes until I had what I needed. I think mine cost me about $4; the UHMW was given to me by the local plastics shop, and the bolts I scrounged from stuff others threw away. Far and away the best time and money I have spent on guitar and jig making.

I did with a chisel, and also with a router. Using the circle cutter before the router prevent chip out and give a really nice clean cut.

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Francis Richer, Montréal
Les Guitares F&M Guitars

Just to offer another way........

We use a drill press rosett cutter.......... especially designed that has 4 adjustable knives ....... that are ground to custom size......... (Luthiertools which we sell)

We use laser cut templates to adjust the cutters on the fly as needed ..........

Anything unusual or different we cut with the laser...... (oval, rope, etc.)

Kevin

I just ground a HS steel cutter on my grinding wheel to .02 using my digital caliper.
Where would you get a router bit that small for a dremel or laminate trimmer setup?
I would imagine they'd be quite expensive and weak, and break pretty easy, too.

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Old growth, shmold growth!

I bought a trim / laminate router and it comes with 2 rods that screw in . I glued up a block from ebony to make a centering block and will post a pic when its done . I just happened to be doing exactly this when the post was started .

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