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Sawing within a plane with a japanese saw?

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Forum topic by Damien Pollet posted 06-11-2011 08:28 PM 1562 views 0 times favorited 11 replies Add to Favorites Watch
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Damien Pollet

73 posts in 1295 days


06-11-2011 08:28 PM

Topic tags/keywords: question japanese saw sawing

Hi fellow LJs,

I’m having difficulties getting flat cuts with my ryoba (japanese saw with rip teeth on one side and crosscut on the other). I stay within the lines pretty well, but the cuts seem to tend to curve to one side. Once finished, the sawed faces are hollow by more than a kerf wide, to the point where thin slivers of wood can detach from the middle of the kerf when I saw from both sides. So now I have 2mm or so of wood to plane away before I get a flat face.

This was while resawing a 70×38mm section of beech into thinner stock, but I had similar issues when just ripping it: cuts from opposite faces would not stay within one plane, and the kerf would deviate from the line on the face that is away from me.

I’m not sure if this is a technique issue or if my saw has some kind of drift. Any suggestions? How to detect / fix it when that happens? How to not have it happen in the first place? Do I need to stone my saw’s teeth ?

Thanks in advance :)


11 replies so far

View Gene Howe's profile (online now)

Gene Howe

5763 posts in 2114 days


#1 posted 06-11-2011 09:39 PM

Technique? When resawing, I put the work in a work mate and get it as low as possible. Then I straddle the work and try to pull as straight up as possible. I still have to plane it. I’ve tried re sawing horizontally while holding the work in the bench vise. I can’t do it.
It is possible that your teeth are incorrectly set. I wouldn’t mess with attempting to correct them. As far as I’m concerned, that’s a job for someone with more expertise than me.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View Gregn's profile

Gregn

1642 posts in 1669 days


#2 posted 06-11-2011 09:55 PM

First I’ll ask if this happens using other hand saws? If it doesn’t then my suggestion won’t help, but if this is a problem with your other hand saws as well keeping the cut square. Having had problems myself making a square cuts with hand saws, I learned a little trick. Try re-positioning your body so that your dominate eye is in the line of sight with the cut. I didn’t believe this could make a difference until I put a patch over my less dominate eye and then made my cut, man what a difference it made in my cuts. I took the patch off and tried it again using my dominate eye in the line of site with the cut and noticed it made a difference. Your eye wants to naturally keep the saw level. So if your right handed your right eye will be the dominate eye, and when you use your left eye it will want to naturally keep the saw level with the left eye causing your cut to be unsquare.

-- I don't make mistakes, I have great learning lessons, Greg

View tenontim's profile

tenontim

2131 posts in 2429 days


#3 posted 06-11-2011 11:27 PM

I think these saws are more for rough work. I had the same problem trying to use a ryoba for cutting tenons. I switched to a rip saw with a back. In fact all of my Japanese saws have backs on them. It helps keep the cut true.

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Loren

7715 posts in 2333 days


#4 posted 06-11-2011 11:34 PM

Ryobas are made for versatility, not precision.

You may be asking too much of a saw without a back as well. You
can get single-edged Japan rip-saws without the back. If you
look at Toshio Odate’s book you’ll get an idea of the variety of
different types. The ones used for sawing boards from trees are
just enormous and wide, for example.

Once you get the saw halfway down in the kerf, it’s going to follow
the kerf above it. A saw with a back saws a straighter kerf to
start, so one solution is to use a Japan saw with a back to start
the cut and use a no-back saw to finish it.

I use a bowsaw for larger cuts. The bowsaw solves many problems
with the blade supported at both ends.

-- http://lawoodworking.com

View Damien Pollet's profile

Damien Pollet

73 posts in 1295 days


#5 posted 06-12-2011 03:16 PM

Thanks all for your advice!

This ryoba is my first and only saw, so indeed I took it for versatility. The crosscut teeth are sometimes a problem during long rips, but it was not the case here. I don’t expect to fit tenons or dovetails directly out of this saw, and I don’t really care about the planing work afterwards, but 2mm hollows are a bit much (that means I lose up to 6mm of material instead of 2 or 3 if I was getting flat kerfs)

I think I’m really not handling it in line, like Gregn suggests, or maybe I’m putting too much pressure on the teeth; unfortunately I can’t try other saws for now. I’ll certainly get or make a bowsaw someday, and get a nice rip-only japanese saw as well, but first I’d like to make sure I’m actually getting the nominal precision out of this saw. What’s the point buying fancy tools if I’m misusing them :)

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Damien Pollet

73 posts in 1295 days


#6 posted 06-12-2011 04:56 PM

This particular cut was resawing a 1m long, 75×38mm section piece of beech kitchen countertop, to end up with two 75×18mm halves (which will end up actually being 15 or 16mm thick after planing). I clamped it vertically and sawed from both sides, pulling the saw at varying angles, mostly at 30-45 degrees to the vertical, sometimes nearly vertical to start the kerf between the lines.

I have a similar cut to make soon (I actually only resawed half the length of that 1m long piece), so I’ll try sighting into the kerf while I saw, maybe clamping some straightedge to the wood to check for alignment as well… hopefully this goes better :)

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Damien Pollet

73 posts in 1295 days


#7 posted 06-13-2011 11:53 AM

I marked the cut with a veritas marking gauge, the single-cutter version of their new dual one. In previous cuts I would run the saw along the gauge marks to make a 2-3mm deep start of a kerf, on both faces, but not this time. I did saw between my lines anyway, so it’s not really the problem. The saw makes a curved cut inside the wood, so the sawed faces end up concave in places. At one point it deviated a bit from the lines, maybe I didn’t completely fix that and this is what started the problem…

View Lee Barker's profile

Lee Barker

2169 posts in 1535 days


#8 posted 06-14-2011 05:20 PM

My brother-in-law, who was a metal worker, taught me to be light-handed when using a hacksaw. I get straighter cuts and approach the cut with the expectation that I’ll be patient.

I have found the practice to apply to all my Japanese saws as well. Light touch, let the teeth do the work.

I don’t mean this as a solution to to Damien’s quandary (very well described, by the way) but just wanted to insert it into the general discussion of technique. (I really like the dominant eye practice. Is there an easy way to ascertain which one is dominant?)

My hunch is that the condition of the saw is the main culprit here.

The good news is that a discarded Japanese saw blade makes nifty scrapers.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Damien Pollet's profile

Damien Pollet

73 posts in 1295 days


#9 posted 06-17-2011 04:09 PM

The saw is new (it cut through just a few meters of that beech since I bought it) but you’re right, it’s possible that I’m pushing it too much as well. Next cut I’ll do the complete zen approach, deeply scoring kerfs along the cut, sawing with a light touch and sighting down the blade, promised.

My dovetail exercise was done in oak resawed like that, and while that was a 10cm deep cut, I don’t remember having such deviation problems, so there is hope :)

View hObOmOnk's profile

hObOmOnk

1381 posts in 2813 days


#10 posted 06-17-2011 04:21 PM

You cut “to the line” not “in the line.”
—- 40+ years experience with Japanese woodworking tools.

-- 温故知新

View drewnahant's profile

drewnahant

222 posts in 1774 days


#11 posted 06-17-2011 06:29 PM

Lee, and anyone else interrested, I have a little technique to identify your dominant eye from learning archery. Not everyone has the same dominant eye as their dominant hand ( im left eye dominant and right handed, I have to shoot lefty to sight properly without winking), so you do need to test, though if you consistently try to use your other eye, it eventually becomes the dominant eye, you just suffer until that happens.

Look at an object about 100 ft away, then raise your thumb in front of you at arm’s length to block it. choose quickly based only on instinct, because each eye will want to align your thumb on a different line to the object, and if you think too much you will see both, and you cannot decide which one is right. hold your thumb in place, and close one eye at a time to see which one you were aligned to. your non-dominant eye will not line up.

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