Cutting S curves by hand

[Daniel Rode]

The saw bench I made this weekend has S curves on the feet. S curves, ogees and even standard curves and bows are commonly needed but I don't really know the correct way to cut and especially clean up these curves.

With machines, I often used a bandsaw (which I no longer own), MDF router templates and sanding.

Can anyone point me in the right direction on how to go about making smooth curves without power tools? Any tips or pointer to books or articles would be a big help.

[John RStegall]

Look at Paul Sellers site. He smooths curves using a sharp chisel, rasps, and a card scraper. See if you can look at his cane making video. He explained this very well when he was shaping the handle. It may only be available in his Masters woodworking series, but you can join for 15$ and cancel after one month.

[Prashun Patel]

Can't help you with the cutting; I'm a bandsaw user.

"...especially clean up these curves..."

Here's where the fun starts: spokeshaves and/or a rasp or even (in fact prefered) a small block plane on convex portions of the curve.

I find that these tools follow proper flow of the curve better than even a router - which will follow your pattern TOO perfectly (sanded divots and all).

[Jim Koepke]

If you want to make your own tool for doing this, use the SMC search box and look for > turning saw <. It is like a hand powered band saw.

http://www.google.com/search?sitesearch=www.sawmillcreek.org&q=turning+saw&submit.x=0&submit.y=0

Another method makes use of a curve is made by connection a lot of points. Draw the curve on the work piece. Then use a saw to make a series of cuts straight into the wood down to points along the curve. Do not go all the way to the drawn curve. Then remove the waste with a chisel or gouge. After this it is just a matter of fairing the curve(s) with spokeshaves, chisels, gouges or what ever is on hand.

jtk

[john zulu]

I would use a coping saw then clean up with a spokeshave. You can also use cabinet scrapers to clean it up or even files.
Do you have a picture of you S curve?

[Zach Dillinger]

I usually just waste away as much of the wood as I can with backsaws and panel saws, and then finish to the line with chisels, rasps and files. See the following pics:

294659294660294661

[Daniel Rode]

Zach, that's exactly the kind of stuff I want to do. No spokeshaves to clean up the edges?

My only rasp is a Nicholson half round from the home center. Working across the grain on white pine I was very concerned about blowing put the edges, so I set it down. Maybe it's my technique, maybe the tool? I really can't afford $100 for a hand made rasp.


I usually just waste away as much of the wood as I can with backsaws and panel saws, and then finish to the line with chisels, rasps and files.

[Pat Barry]

I usually just waste away as much of the wood as I can with backsaws and panel saws, and then finish to the line with chisels, rasps and files. See the following pics:

294660
Zach, it looks like you drilled holes for the two inside curves, is that right? That's probably the best way, especially for small radius's like that

[Jim Koepke]

Working across the grain on white pine I was very concerned about blowing put the edges

Tilt the rasp slightly upward. Don't let it exit the cut on the far side. Then do like wise working from the other side. It may produce a slight rounding effect. With care, this effect can be minimal.

jtk

[Zach Dillinger]

Zach, that's exactly the kind of stuff I want to do. No spokeshaves to clean up the edges?

My only rasp is a Nicholson half round from the home center. Working across the grain on white pine I was very concerned about blowing put the edges, so I set it down. Maybe it's my technique, maybe the tool? I really can't afford $100 for a hand made rasp.

I have spokeshaves but don't need them on pine. For walnut, I'd probably get one out. I've never spent the money for a high-end rasp as I've never felt the need. I have a NOS fine Nicholson that I scored from the grandson of a patternmaker that works absolutely perfectly, and cost me $5. You have to be very careful about blowing out the backside, true, if you want to maintain that perfect unseen look. I'm not terribly concerned about that in my work, and consequently there might be some blowout. Just follow Jim's advice and you'll be fine.


Zach, it looks like you drilled holes for the two inside curves, is that right? That's probably the best way, especially for small radius's like that

yes, Pat, I bored large holes for the tight radius areas near the center. It is easier to achieve a good shape that way.


Tilt the rasp slightly upward. Don't let it exit the cut on the far side. Then do like wise working from the other side. It may produce a slight rounding effect. With care, this effect can be minimal.

jtk

+1 to Jim's comments here. That is the way to do it.

[Steve Voigt]

My only rasp is a Nicholson half round from the home center. Working across the grain on white pine I was very concerned about blowing put the edges, so I set it down. Maybe it's my technique, maybe the tool? I really can't afford $100 for a hand made rasp.

I can't afford those rasps either. There are some good in-between options. You can get a half-round "vixen" file (an off-brand, probably) from yardstore.com for $12. Shipping was $10 IIRC. They work quite well. Another option is the mill-tooth files from LV for around $25-30, plus shipping, or wait for free shipping season.

About technique: If you rasp/file cross-grain, you will get spelching (blowout) and all your curves will be rounded and uneven when measured across the width. Instead, try drawfiling: move the file/rasp parallel to the grain, and concentrate on keeping it level. This will leave deep longitudinal lines in the wood. Once you get the hang of it, try adding just a bit of cross-grain motion to your draw-file stroke. This will take out the grooves and is a bit more aggressive. This technique is hard to do on the super-tight concave curves like the ones zach showed, but it will work great on anything from about a 1 1/2" radius or larger, and on any convex or flat surface.

You can also ease the edges before you rasp to control spelching.

[Mike Holbrook]

Bowsaw/turning saw 14 or 12" for tight turns, although I might drill like Zach did for something that small. Tools For Working Wood and Wood Joy are great sources for Turning saws. You can buy kits or finished saws. Drawknives are great for removing larger amounts of wood rapidly. Cutting surfaces that are not flat with a drawknife may require specific sharpening of the edge of the drawknife. Wood Joy makes a nice assortment of wood spokeshaves and offers a great deal on a very easy to make spokeshave kit too. Lee Valley makes some well regarded spokeshaves, scrapers/pull shave tools..Lee Valley and Highland Woodworking sell Japanese rasps/files/floats made by Iwasaki in many different sizes and shapes that are much less expensive than the custom rasps.

[Daniel Rode]

Terrific information! I need to come up with a curvy project to get some practice.

I had never heard of a turning saw before today. It's essentially a small bow saw, right? The blades look like long coping saw blades to me. Is it really much better than a coping saw?

[Jim Koepke]

Terrific information! I need to come up with a curvy project to get some practice.

I had never heard of a turning saw before today. It's essentially a small bow saw, right? The blades look like long coping saw blades to me. Is it really much better than a coping saw?

It can be as big or small as you like. The blade can be made out of band saw blades or you can purchase ready made blades.

A coping saw has a limited stroke. By the time you get it moving you're out of blade. A longer blade helps to get through the wood quicker.

BTW, I do not have a bow saw or turning saw. I like to let my band saw do that kind of work.

jtk

[Jessica Pierce-LaRose]

For smaller details, I like sharp chisels and gouges, paring across the grain (with the work piece backed up, perhaps the final lined scribed, to prevent blowout on the back.) In-cannel gouges are great for smoothing the insides of concave shapes.

[Daniel Rode]

I appreciate the advice. I don't own any gouges but it seems like a obvious fit. In-cannel would be a gouge beveled on the inside of the curve?


For smaller details, I like sharp chisels and gouges, paring across the grain (with the work piece backed up, perhaps the final lined scribed, to prevent blowout on the back.) In-cannel gouges are great for smoothing the insides of concave shapes.

[Jessica Pierce-LaRose]

I appreciate the advice. I don't own any gouges but it seems like a obvious fit. In-cannel would be a gouge beveled on the inside of the curve?

Yep. I like them for coping molding, too. They're a little easier for certain tasks, compared to carving style gouges with the bevel on the back, since you can judge vertical by the whole length of the blade, rather than trying to go by the bevel. Bob Rozaieski has written about liking them for this type of paring/scribing work (which is what drove me to try them) and has also written about their usefulness in working on cabriole legs. (Which is beyond me) Basically anytime you don't need to steer in and out of the cut like you would with carving, and really just want to continue that curved cut across the whole length of the piece, they can be useful. Which reminds me, I have a a few of those I bought used that I really need to hone up to working condition . . .

[Jessica Pierce-LaRose]

. . . Bob Rozaieski has written about liking them for this type of paring/scribing work (which is what drove me to try them) . . .

And here's Bob talking about them here on a couple of posts in this thread at SMC:

http://www.sawmillcreek.org/showthread.php?134731-Gouges&p=1365247#post1365247

http://www.sawmillcreek.org/showthread.php?134731-Gouges&p=1366364#post1366364