Saw sharpening/deep ripping technique

[bugbear]

Since the need for large teeth (and the consequent large gullets) is sawdust removal, does that imply that the set should not be increased in proportion with the increase in tooth size?

Indeed, the less set, the less sawdust to remove.

BugBear

 

[profchris]

I've just been reading online about filing the saw with the file at 45 degrees to the vertical. This gives the same rip profile, but the gullets are far deeper (opposite sides on alternating teeth). In theory they remove more sawdust.

I might just resharpen, trying this out. It can't hurt, and I still have around 1/3 of the board to go.

Long term I think I'll redo this saw at 2.5 tpi. Most of my resawing (and I don't do a lot) is 3-6 inch widths, and 2.5 tpi should still be good for that.

 

[JohnPW]

How about removing every other teeth?

 

[bugbear]

How about removing every other teeth?

Since his saw is currently 5 TPI, and he's talking about 2.5 TPI, I think that's what he's proposing.

BugBear

 

[D_W]

Hopefully the teeth that are already on the saw don't have too much set.

 

[D_W]

Many years ago I knew an antique restorer who sawed his own veneers using a frame saw. I've only a dim memory of it, but I'm sure his wasn't the type of frame saw in Bugbear's avatar, instead of one cross bar it had two, one at each end so the frame formed a long rectangle. He held it flat, i.e. horizontal, and used two hands to saw, with the workpiece vertical so that the saw frame passed down over the

Like this ?
http://www.blackburntools.com/new-tools ... index.html

Looks quite an easy thing to make.

Yes, you can make one out of junk if you have the spring steel. On a four foot saw, the steel must be substantial or the cut will wander due to the weight of the saw.

Anything shorter than four feet isn't worth making.

I made one out of scrap and filed teeth in, it's on YouTube if you search "fast hand saw frame saw". I've gotten better/faster with it since. It's a workout, and so was filing in the teeth.

 

[bugbear]

Anything shorter than four feet isn't worth making.

That makes sense - in a 12" workpiece cutting at 45 deg, you've around 17" in the cut, leaving 31" for a stroke with a bit of room.

BugBear

 

[profchris]

In spite of all your help I wasn't making progress, so I put this aside to research and think. But I've found my problem!

I first sharpened the saw at its original rake, assuming that would be about right. The teeth had a rake of around 25 degrees. Yes, the saw cut, but it gently persuaded the wood to depart, at best. Slow and tiring.

Today I roughly resharpened to a rake of just under 0 degrees and, hurrah, I'm powering through (or at least, cutting four or five times as fast). I'll easily finish the job in another half hour or so.

The difference is really dramatic, even though I can tell the sawdust is impeding the cutting. But the three facet method (Custard I think) makes this manageable.

Thank you all. If anyone else is deep ripping by hand, near zero rake is what you need unless your plan is to develop a Popeye bicep.

 

[bugbear]

The teeth had a rake of around 25 degrees.

Oops!

BugBear

 

[Blevins]

That's an interesting one about the 0 rake. I've just filed a 2 1/4 inch rip at 10 degrees rake, and it's pretty good cutting, but now that you've said that, the next resharpen I'll reduce the rake a bit. I'd tried 4 degrees on a smaller rip saw a while ago and found it a bit tricky to get moving, but I reckon that was partly due to bad saw technique.

 

[profchris]

I'd tried 4 degrees on a smaller rip saw a while ago and found it a bit tricky to get moving, but I reckon that was partly due to bad saw technique.

My rake is 0 degrees plus or minus a bit (did it freehand).

For resawing plates you need to cut a kerf with some other saw first, so there is no problem getting the rip saw started.

 

[Trafalgar]

Don't bear down on the saw on its return stroke. This will save you from some of the dulling, but this operation is tough on a saw. Just keep going until it's done; nothing is going to make it appreciably easier except using a resaw bandsaw.

 

[D_W]

That's an interesting one about the 0 rake. I've just filed a 2 1/4 inch rip at 10 degrees rake, and it's pretty good cutting, but now that you've said that, the next resharpen I'll reduce the rake a bit. I'd tried 4 degrees on a smaller rip saw a while ago and found it a bit tricky to get moving, but I reckon that was partly due to bad saw technique.

If you start resawing things that are 6" of cut, or even 4, you'll find that you need a more aggressive saw than you did just ripping 4/4 to 8/4 type stuff.

Still, if you get certain types of wood that have good grip, it will be rough going and you may need to start the cut with another saw and then do most of your sawing severing the straws on the diagonal rather than cutting straight across. For things like cherry (and whatever the equivalent may be over there) I haven't seen a lot of speed difference either way (cutting 45 degrees to the end grain vs. straight across it).

Big teeth and little rake are a good start. It's still physical work no matter what, but if you need exercise, it will give you some.