Having trouble cutting curves in 3" cherry

[Jeff Skory]

I'm following along with Bob Rozaieski's podcast (Logan Cabinet Shoppe) to build a Porringer tea table. I'm making mine out of cherry.

Currently I'm working on the legs (for the second time, but that's another story :o). These are cabriole legs. As such I need to cut out some curved sections.

I bought the 12" Gramercy bow saw from TFWW. This really isn't doing a very good job, and Joel mentioned in another thread that 3" wood is probably beyond what it should be used for.

Just to give you an idea, it can take 10 minutes or more to cut a 3-4" long curve.

So.....what tool is better suited for cutting curves in wood this thick?

(I have a band saw but I'm trying to build this particular table exclusively with hand tools)

Thanks,

Jeff

[Jonathan McCullough]

You could make a larger bow saw. If you're cutting a (mostly) horizontal curve, you could make a bunch of straight vertical cuts to the curve, then carefully pare out the "slivers" you created. The reason I like hand tools is that they're often quicker, more practical, and safer, and it may be heresy to say so here in this forum, but sometimes tailed tools are better for some applications, to say nothing of the satisfaction it gives you to quickly dispatch a piece of frustrating wood with a bit of electronic butchery . . . . . When you think about it, how far away are Roy Underhill's treadle lathe or treadle lathe-powered scroll saw, from those powered with a 1/2 hp motor?

[george wilson]

I used to make bow saw blades for the cabinet maker and the gunsmith's shops. The old original blades were tapered a LOT from the front edge to the back.

I'd punch teeth on a wide enough piece of spring steel .042" thick. Then,I'd shear the blade off. They were about 1/4" wide at the front,and about 3/8" wide at the rear end. Then,I freehand ground them until they were about .020" wide along the back edges.

This is how the original blades were done. It made the blades cut curves in heavy stock quite well. You can't buy them made that way any more.

Perhaps your blades don't have enough set in the teeth? Be warned,though,too much set makes a blade cut just terribly. Thus,the taper.

About the 1/2 h.p. powered tools mentioned above: The human body can only sustain about 1/10 h.p.. It can do bursts of about 1/2 h.p.. sounds like a very underpowered tool!! Keep them good and sharp!!

[Russell Sansom]

The 12" bow saw is way too small for what you're doing. I'm surprised you haven't broken every blade you've used. Or the saw. So...A bigger bow saw? Very easy to make one, even if the handles are eye bolts with slits hack-sawed into them for a blade.
Bottom line for a cabriole leg: you eventually have to whittle on grain whose direction inevitably changes. Spoke shave, draw knife, big chisel, block plane, rasp, scraper. Possibly all of the above. If you think of the cutting out as a prelude to shaping with sharp edges, perhaps your perspective will shift. Cutting out waste blocks with a straight saw works but you get a very messy surface that demands a drawknife at first.

[Bob Easton]

I'm following along with Bob Rozaieski's podcast (Logan Cabinet Shoppe) to build a Porringer tea table. I'm making mine out of cherry. ... I bought the 12" Gramercy bow saw from TFWW. This really isn't doing a very good job, and Joel mentioned in another thread that 3" wood is probably beyond what it should be used for.

Just to give you an idea, it can take 10 minutes or more to cut a 3-4" long curve.

Jeff

And there's something wrong with taking 10 minutes to do a cut? C'mon Jeff, be a man about this woodworking stuff. :)

Yes, 3 inches of cherry is a bit much for the Gramercy saw with 10tpi blade. I did a number of cuts (http://www.bob-easton.com/blog/?p=1194) with that exact setup in 3 inch Doug Fir. Each cut took slightly longer than 10 minutes. Yet, each was smooth enough to not need much cleanup. It's my experience that Cherry is only a bit harder than Doug Fir.

Your options are the ones already mentioned, a bigger bow saw ... or actually a more aggressive blade. But those are very hard to find for the radius of curves you want to do, unless you can persuade George Wilson to make one for you. In any case, DON'T try a bandsaw blade in a frame saw; the results will surely disappoint. ... or you could turn to the tailed demon sitting over in the corner of the shop.

If I were you, I would soldier on with the Gramercy saw. It is light and accurate, and only needs a Snickers Bar to keep you going.

[Robert Rozaieski]

Jeff,
I understand your frustration, but hang in there, I've been there. As has been previously mentioned, Joel's bowsaw (or any other commercially available turning saw that I'm aware of) really is not designed for 3" thick stock, but it will work (I did it, albeit it was poplar, not cherry). One problem with cutting stock this thick that I found was that the blades tended to dull quickly, presumably accelerated by the heat that is generated from such thick stock. I touched up the teeth on my blades (I have 2) a couple times while making the legs. Just use a tapered file and make 1 or two light passes on each tooth with the frame tensioned and held in a vise. It's not ideal as the blade will flex due to it being so thin, and these blades are really meant to be disposable, but it did improve things quite a bit for me. Just use a light touch so you don't bend the blade too much while filing, and file the most aggressive rake you can (0 degrees). It only took 1 or 2 file strokes on each tooth for me to make a big improvement in the saw's performance. Of course due to the size of these blades, you won't be able to do this forever, but it will make a big difference and it will extend the life of the blade at least until you finish the legs.

Another option is to saw a few vertical kerfs down to the pattern line with a backsaw and then use a narrow chisel and/or an incannel gouge to pare away the waste between the saw kerfs. You might be surprised by how fast this can be with a sharp incannel gouge.

I think for now, unless you want to make your own blade, we are out of luck for a good commercially available blade for building a longer turning saw. The longer turning saw blades that I'm aware of (24" and 28" that I know of) are all about 9 TPI, which is really no better than the Grammercy blades, they're just longer. And as Bob mentions above, band saw blades are really a poor choice for a hand saw (I've tried). You really need a blade that is longer AND has fewer teeth per inch AND that is filed properly for a hand saw for stock this thick. I don't know of any blades like this that are currently available on the retail market.

[Tom Kelley2]

Long time lurker here, but first post. I asked this same question a couple of years ago at the Hay shop in Williamsburg. They cut cabriole legs roughly with a regular straight panel saw and then do more shaping with spoke shaves and rasps. This approach was based an archeological evidence (a partially finished leg that was found). They told me that we all see cabriole legs cut with bandsaws and assume we should take that approach with hand tools. However, that doesn't seem to be how it was done. George Wilson would probably have more insight on this.

[Lowell Smith]

I used to make bow saw blades for the cabinet maker and the gunsmith's shops. The old original blades were tapered a LOT from the front edge to the back.

I'd punch teeth on a wide enough piece of spring steel .042" thick. Then,I'd shear the blade off. They were about 1/4" wide at the front,and about 3/8" wide at the rear end. Then,I freehand ground them until they were about .020" wide along the back edges.


This is very interesting. Did you also vary the tpi? If teeth of height 1/2 the blade width are assumed,
I estimate you cut 7-tpi to 5-tpi along the blade. Am I close?

[John Coloccia]

Long time lurker here, but first post. I asked this same question a couple of years ago at the Hay shop in Williamsburg. They cut cabriole legs roughly with a regular straight panel saw and then do more shaping with spoke shaves and rasps. This approach was based an archeological evidence (a partially finished leg that was found). They told me that we all see cabriole legs cut with bandsaws and assume we should take that approach with hand tools. However, that doesn't seem to be how it was done. George Wilson would probably have more insight on this.

That's exactly my first thought when I saw the post. If I were to do this entirely by hand, I would make rough cuts with a panel saw....heck, I'd probably just use my Pony "rough cuttin' " saw (I forget what it's called, but I use it to roughly break down boards quickly). Then I'd attack it with my ibex planes, maybe a spoke shave, and rasps....maybe some chisels and gouges where appropriate. If that seems like a ridiculous amount of work, your irons may not be sharp and your rasp might be innefective. With sharp iron and good rasps, you can remove a LOT of material very very very quickly, and very accurately.

All that said, if you really want to try cutting it out, rub the sides of your blade with some parrafin. It won't make it cut any faster, but it'll sure be a whole lot easier. I use parrafin on all my planes and saws now. Don't try beeswax as a substitute, like I did. It'll get gummy. The parrafin is like gliding on ice :D

In my own shop, I would surely bandsaw it out. I usually turn to the hand tools when I feel they'll be faster or better, or if the equivalent machine operation is just too dangerous for my tastes. I guess that'd make me a "Sunday neander".

[Robert Rozaieski]

Just to be clear, the straight sections of the legs were cut with a standard rip saw. The only use of the turning saw was the sharp curves at the ankle, the back of the knee and the top of the knee. All relatively short cuts. The turning saw was not used to cut the entire profile, as one would do with a band saw.

[george wilson]

Lowell.you are correct,but I can't recall the exact number of TPI.

The old cabinet makers often used a small hatchet to assist carving legs. Also used on gunstocks. Practical craftsmen found ways to do work the quickest,most cost effective way.

The old English furniture restoration person I have mentioned before,kept a small hatchet in his shop. It was kept just as sharp as any other woodworking tool he used.

[Jeff Skory]

Thanks for the feedback on this guys. Bob, I'll try sharpening one of the two blades I have left. I broke one yesterday (snapped the little pegs off). And if this doesn't work maybe I'll go the series of cuts followed by chisel route. I'll practice on a scrap piece first.

John, thanks for the warning on beeswax. I had actually been planning on buying some. Currently I'm just using Johnson's paste wax which is ok but I've felt that there had to be something better.

And to answer one of the other comments - drawknives, spokeshaves, and rasps are part of the process. I just need to get the big pieces out of the way.

As always, (even with 10-15 minute 3" cuts) I'm still having a blast when I'm in my workshop. :D

[Dave Anderson NH]

Along the lines of Bob Rozaieski's suggest, use a draw knife. Pencil in heavy lines giving the shape (and a margin for error) on at least 2 sides of the leg. Make a stop cut with a hand saw on the front corner just at the ankle and one on the back side corner behind the knee. Now waste the gross amount of stock away with a drawknife. Redraw the pencil lines defining the taper of the leg from knee down to the ankle, put in your stop cuts with the saw again and waste away the big stuff as before. I've watched Mack Headley at the Hay Shop at Williamsburg do cabriole legs this way and it is amazing how quickly you can get rid of the majority of the waste. While I couldn't do it that quickly, I watched him do the job faster than a band saw could do it.

[Robert Rozaieski]

Thanks for the feedback on this guys. Bob, I'll try sharpening one of the two blades I have left. I broke one yesterday (snapped the little pegs off).

Jeff,

This makes me think two things about what is happening:
You are forcing the saw and not letting it do the work. The blade should not be under so much strain that the pegs are forced to break under normal sawing pressure. Don't try to force the saw through the cut faster than it can make the cut. If it seems like it is bogging down and cutting slow, it needs to be sharpened or replaced. Which leads me to...
The blade is dull, which leads to #1. Trying to saw with a dull blade is an exercise in frustration. You end up putting too much pressure on the blade, which leads to increased friction, which builds up heat in the blade, which causes the blade to break. And if it doesn't break, the heat generated can be enough to take the temper out of those little teeth, causing them to dull even more. Stop and feel the blade. If it's too hot to touch, then you are trying to force the cut, which means the blade is dull. Check the teeth, do the points grab the skin in the palm of your hand firmly when you move the blade across a flattened hand or does the blade just slide over your skin? If it slides, even a little, it's definitely too dull.
Honestly, I think it only took me a minute or two to make each of the tight curves that I did in my legs with the turning saw. Again, I was using poplar, but still, 10 minutes to make those short cuts, even in cherry, seems excessive to me. I'm betting that the blade is just not sharp enough to saw effeciently.

Try sharpening it up and I'm sure things will improve. Just a couple of strokes on each tooth should take care of it, no jointing required. But be aware of how the saw is cutting. When it starts to slow down again, sharpen it again. These teeth are small and thin so they aren't going to stay sharp that long in stock this thick, especially since they've already gone dull. If they got too hot, you may have taken the temper out of them as well, which will cause them to dull even faster.

I think a common problem with these saws is that we try to push them too fast. These blades are so thin that they heat up very quickly when they are pushed beyond their tolerance. Think of it as equivalent to bluing a chisel or plane iron from grinding too aggressively. Once the steel hits that critical temperature, all of its edge holding ability is basically lost. In steel as thin and narrow as the Grammercy turning saw blades, which are basically long coping saw blades, this build of heat can happen very quickly, especially in 3" thick hardwood. Really, we're pushing these blades beyond what they were designed for so we need to ease up on them a bit.

Remember, the first step to solving any problem in this craft is to sharpen your tools :D. That fixes the problem probably 95% of the time.

[george wilson]

I'll bet you aren't pushing them as fast as a bandsaw!!

[Jeff Skory]

Jeff,

This makes me think two things about what is happening:......

Bob, I think you're absolutely right on the blades being dull. And yes, on the blade that broke I was not only pushing too hard but had tightened the saw too much. Luckily the blade broke and not the saw.

Until this thread I had never thought about sharpening those little tiny teeth. But why not, they're saws like any other saw. I'll be giving that a try later tonight.

Dave, using a drawknife to remove big blocks of wood is another possibility, however it might get tricky trying to do the deeper curves at the ankle and knee.

And George, of course my arm is pistoning at bandsaw speeds. That's why I was getting so overheated after 10 minutes of sawing. :D

[Jeff Skory]

Thought I would give you an update on my progress.

Tried sharpening the 10 TPI blade a couple of times. Helped for a very short time (couple of minutes), but it they really just aren't made for this job. Doesn't help that it needs to act both in crosscut and rip modes as you turn the corner.

Anyway, got fed up with it and started making closely spaces crosscuts in the tight curves and broke them out with a chisel. Left a really ugly surface of 1/4" tall slats sticking out. Couldn't get the chisel in any better due to the tightness of the curves.

Knocked down the ugly surface with a rough rasp and then I found my magic tool!! I bought an old wooden H.Cheetham spokeshave (9" long with a 2" blade). Combined with my shavehorse this little baby can really hog out some wood and it even leaves a nice shiny surface to boot!

I would definitely like to invest in a few more. A larger one (to have a more comfortable grip while hogging), and a smaller one that would be able to able to be used on the inside curve such as the ankle.

I have another question about the shaving bench but I'll start a new thread for that one.

[Pam Niedermayer]

My standard curve-cutting method is exactly what you came up with: saw perpendicular to the line, break it out with a chisel, smooth with a spokeshave. It works every time.

Pam

[Jeff Skory]

Pam, what type of spokeshave do you use to get into the tight curves?

[Pam Niedermayer]

Very tight curves, too tight to be handled by a 6" skinny boxwood shave, have to be sawed, usually with my flush cut or fret cutting Japanese saw. It's really more like shearing. Sometimes a knife, again Japanese, is needed, with which I shave holding it with two hands. Big caveat: I'll do most anything to avoid tight curves, so I haven't done a lot of this.

Pam

[Robert Rozaieski]

Tried sharpening the 10 TPI blade a couple of times. Helped for a very short time (couple of minutes)

Yeah, this makes me think they got too hot and drew the temper. Once the steel gets too hot, they lose the ability to hold an edge. This can easily happen with these thin blades just from friction alone if they're pushed too hard. I did it with one of mine some time ago. Taught me to slow down and not force the saw. But like you said, these blades aren't really meant for stock this thick.

Another option, if you have one, is a gouge. An outcannel carving gouge will work, but an incannel paring gouge is even better. A sharp gouge will work really fast for those tight inside curves and you'd have to do minimal cleanup. Skip ahead to the episode on doing the aprons to see what I mean. The same gouge I used for the cove cut on the aprons could be used to pare the tight inside curves of the leg and do it very effeciently. I used it later on as well to blend the curve of the knee block into the back of the leg. If nothing else, it's an excuse to get a new tool :D.

[george wilson]

Are you sure that those blades aren't too soft to begin with ? Try a file on a brand new one. They might make those bow saw blades soft so they won't break so readily.

[Jeff Skory]

George, I would try that experiment but I need to order some new blades first.

Bob, I need to watch the rest of the leg podcast anyway to find out what to do after shaping the two outside edges, so I'll also watch the future videos to find out about the incannel gouge. And yes, then I'll probably order one. :D

Damn, this table is costing me a fortune! I'll have to end up putting a velvet rope around it.