# How can I cut circle grooves with hand tools?



## DLK (Nov 26, 2014)

Using non-electric hand tools only.


I would like to cut a 2 or 2.5 inch diameter circle groove that leaves no center mark or a small mark. 
I also would like to cut small quarter circle grooves with radius as small as 3/4 inch and as large as 6 inch.
All with the same groove width say 1/8 or 3/16 wide. (Groove shape, vee, round, square does not mater.)

Wood for the quarter grooves must include 3 contrasting colors, I am thinking, purple heart, walnut, maple. (Maybe maple would be too difficult so I could be talked into other choices).

My only two ideas are:


build a scratch stock trammel, or 
have at it with carving chisels.

How would you do this?


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## terryR (Jan 30, 2012)

Don, you are way over my head here, but…

google string inlay tools,










LN and Veritas make a few. Honestly, I would probably start buying books and reading online for secrets to inlay.

Hope others have better advise!


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## Lazyman (Aug 8, 2014)

You could make or buy a beam compass with cutter knife and then use a chisel clean it out. I think that is how guitar makers put their rosettes around the hole guitar. You might look for guitar making tools.


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## DLK (Nov 26, 2014)

*Lazyman*: Beam compass I suppose is what I meant by a scratch stock trammel. But I like the idea of using a cutter knife. I wonder if I could use the slitter from a Stanley 55.

*TerryR*: That tool looks exactly what I had in mind


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## RandyinFlorida (Sep 27, 2012)

Prof,

You don't want to use power tools at all? A small trim router pivoted on a piece of stock temporarily applied using double sided tape (to prevent marring the surface). I saw something similar on Rough Cut on PBS just yesterday.


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## DLK (Nov 26, 2014)

I was not convinced I could cut such small circles with a trim router. The set of quarter circle have to be very very precise. But…. I may try it.


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## Tim457 (Jan 11, 2013)

Roy had an episode where he showed the carving of curved grooves, but I don't think it's available online anymore.
Basically he used a set of dividers that had a knife end to mark the curves then carved between them with a gouge.

Seems like the trim router would work too.

Don't worry too much about the maple. It's not as hard as purple heart.


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## brtech (May 26, 2010)

If power tools are really okay, then a Dremel would work great. Plenty of the right size bits. Pretty easy to rig up a circle guide, or you can buy one.


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## DLK (Nov 26, 2014)

I had not thought about a dermal. I have an antique one I could use. I'm not a hand tool snob. I was just hoping for a hand tool solution. Nice to learn new techniques.


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## brtech (May 26, 2010)

I thought of another idea, but I've never tried it. You have probably seen woodworkers like Paul Sellers make and use a "chisel plane". You could make one with the chisel held at an angle of twist to match the curve, with a beam to rotate around.


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## DLK (Nov 26, 2014)

> I thought of another idea, but I ve never tried it. You have probably seen woodworkers like Paul Sellers make and use a "chisel plane". You could make one with the chisel held at an angle of twist to match the curve, with a beam to rotate around.
> 
> - brtech


Or use a narrow router plane bit.

I've only got a about week to get this done. So I am beginning to lean towards the dermal idea or a shop made string inlay tool.

I have to edit a manuscript now. So latter…


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## TheFridge (May 1, 2014)

any bladed item would need knickers. At least to start. I think an electric router is your best bet.

I've had good luck with dremel and its router bits but not for somethings where both sides of the line mattered.


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## DLK (Nov 26, 2014)

Thanks *Fridge* more to think about.


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## Lazyman (Aug 8, 2014)

Even if you use a dremel, it might be a good ideal to score the inner and out circles with a knife to get nice, clean edges.


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## DLK (Nov 26, 2014)

Using ash, Oak, Purple heart now. Tried scoring the curve with dividers and then using a vee-carving tool. the grain of the ash made this to difficult. Will look at dremal router bits today. If that fails I think I'll just chop out the curve with a shallow gouge. By the way this is the first image of what I am trying to make:










The numbers indicate the the side lengths in multiples of (3/4) inches.

It is of course the curvy line I am struggling with. The plan I have is to cut a groove along the line and then inlay crushed copper.


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## terryR (Jan 30, 2012)

Looks challenging to me!

I still think a hand held string inlay tool is what you want. I have this straight line cutting tool from LN,










it's impossible to tell from the photo, but the blade is shaped such that it forms a groove when used. Like 2 knickers placed very very close together.

I'm certainly not close to an expert, but have seen a few videos of guys using a tool similar to the photos I've posted to form the groove, than tiny chisels to clean the waste. Even noticed the Veritas router plane accepts tiny blades for this purpose.

the cutter,










has two teeth bent north and one bent south to cut the groove.

Now…have I ever used this tool successfully to inlay string? no way! a bit of practice showed me I needed more information, not just practice.


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## terryR (Jan 30, 2012)

And, then again, youTube is full of router examples…


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## rwe2156 (May 7, 2014)

Did you all read the post? He said non electric tools. 
Don't see how an inlay tool won't work, either.

Can't think of any way to scribe a circle without making a center point in the wood.

You could scribe a line using circle patterns and chisel out the wast.
You could either make the patterns or adapt from various items like cans, jars, etc.

I would try to research it through marquety resources.

Or,

Maybe its time to build a Spring pole lathe?


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## Lazyman (Aug 8, 2014)

> Using ash, Oak, Purple heart now. Tried scoring the curve with dividers and then using a vee-carving tool. the grain of the ash made this to difficult. Will look at dremal router bits today. If that fails I think I ll just chop out the curve with a shallow gouge. By the way this is the first image of what I am trying to make:
> 
> The numbers indicate the the side lengths in multiples of (3/4) inches.
> 
> ...


Ah, a Fibonacci spiral. It might be hard to find or even make a trammel that could cut the radii for the first 2 sequences at least. Perhaps you can use a chip carving knife to cut along the line of the curve by hand. This way you are only cutting not removing as you cut to depth. Draw 2 curves representing the width you want for the inlay, score both to the depth you want and then clean out the area between the lines. If the width is at least 1/4" you should be able to do that with a very sharp chisel, bevel down. Just work very slowly and don't try to remove too much at a time. To make it easier to remove the waste, you might want to score another line or 2 between the outer lines to same depth. To get consistent depth, mark the depth on the tip of the knife with a sharpie.


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## DLK (Nov 26, 2014)

Yes, Fibonacci spiral. I has hoping for a 1/8 " groove. So this is my partially give up on the hand tool solution just to get it done. Use a router with a 1/8 straight bit and a circle jig to cut the the larger curves and cut the the two smallest by hand. OR star over and cut each square in two along the curve. glue every thing to a board then fill th gaps. (I wish I had thought of the latter first, but I am learning something I guess.)


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## brtech (May 26, 2010)

You can cut THAT with a template. Scale it for the bushing diameter, doublestick tape it down and route with a trim router.


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## DLK (Nov 26, 2014)

If I had or could buy bushings in town I would be doing that. I should have order them long ago.


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## brtech (May 26, 2010)

1/8" trim bits are not too common, but do you have one? You could make a bushing out of wood.


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## DLK (Nov 26, 2014)

I had no trouble getting a 1/8" straight bit.


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## DLK (Nov 26, 2014)

Here is how it came out.










Not perfect but I think close enough given that I wanted to stay off the edges to avoid blow out. I will clean it up a bit when it gets cooler.

Now I hope the "inlay" of crushed copper will go well, then it will be time to build a box under it. I am a little worried when this travels from our humid climate to the Argentina desert that it will all just fall apart. What can I do to prevent that?


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## Lazyman (Aug 8, 2014)

The end grain glue joints are probably the weakest points, especially since different types of wood might expand at different rates with humidity changes. Did you do anything to strengthen those joints? One thing you might consider is glueing a solid piece of wood or plywood to the underside of the lid to help stabilize and strengthen them. Some aromatic cedar might be nice or a thin piece of maple plywood? If you use solid wood instead of ply, make sure the grain runs at a 90° angle to the top.


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## DLK (Nov 26, 2014)

I don't recall if I can get maple plywood locally, but I may check the lumber yard. I do have 1/8th Oak ply though. I think I will float a plywood panel in the box top and bottom. The top to be recessed enough that I can drop and glue in the Fibonacci spiral. I was amazed at how strong the tite-bond II glue joints are. Once the pieces were glued up I planed them flat with a Stanley 5 1/2 and then smoothed with a 4 1/2. Box sides will be Pau amarelo (yellow heart).


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## Lazyman (Aug 8, 2014)

It may be fine, especially since it is not that wide but end grain glue joints are notoriously weak and are the most likely point of failure. The 1/8 oak ply glued to the underside should help considerably. For future reference, if you had cut a groove in the end grain joints so that you could have inserted a spline or cut a tongue and grove for example, that would have strengthen the joints considerably. Dowels or loose tenons are another way to strengthen end grain joints.

Looking forward to seeing inlay and the finished box.


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## DLK (Nov 26, 2014)

Tongue and grooving would have made it difficult to keep the sections exactly square. But yes splines would have been easy. (Or I could have resurrected the biscuit joiner.) I could run a grove around the the edge and insert plywood splines. But I think I will wait to get done with the inlay stage. I have filled the groove with a mix of copper and cooper mine tailings, because I could not separate them. I may have chosen too coarse a "sand". I will let that cure/harden 24 hours (although its 5 minute epoxy) before sanding. So it will be a day or so before I show the inlay.
(This forum/thread is becoming a blog. LOL)


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