Saw Plate Tensioning

[Pedder]

I don't believe in saw tensioning with a hamer, but there are long threads on the australian and the Uk forum:

http://www.ukworkshop.co.uk/forums/panel...96004.html

Take some popcorn and softdrink of your choice.

Cheers
Pedder

[Anji12305]

How long is this saw, in relation to your arm?

My only saw that 'whips' like this is a coarse D7 rip saw that I use one handed. Sharp, properly set and straight, it whips at the toe when I get up a head of steam.

My two handed D23 doesn't do this; so i suspect my elbow comes out at the 'bottom' of the stroke, and puts the plate in an arc as I return to the 'top' of the stroke.

When i slow down, reduce the angle of attack and loosen my grip, the whip stops.

I mainly use my shorter saws these days, and they don't have this problem, hence my suspicion that the length is too much for me to track straight.

Any chance you can post a video of this, as it happens?

[Admiral]

Thanks to all for their reply, I'll look into all the suggestions.

[C. in Indy]

The forum-link from Pedder is amazing...    I think if Lost Art Press decided to produce a definitive volume on "Tensioning", it would finally mentally bust their editors.

Saw rattle is something I haven't totally figured out, but it does vary saw by saw in my shop, given pretty similar saws.

I will admit I haven't formally tensioned my saws.   Some of them I just worked "straight" by rolling them against varied-diameter wood rolling pins and PVC tubings.   This got them to where I'm OK using them, especially the tiny crosscut Atkins which I can't find anything better than.   But -- many of them would not withstand the legendary "test of quality" of arcing a blade to have the toe touch the heel, and having it recover to a straight shape again.   Only my most pristine saws satisfy that test.   Maybe that's a sign of perfect tension?

[JimReed@Tallahassee]

Vibration is a harmonic and is probably the result of even friction. Saw set could be the culprit. "Sticky" saw plate could be the culprit. Try some wax.

I found your comment, "my others don't do this" interesting. I have found the same phenomenon with handplanes. Sometimes a plane works wonky on a particular operation or on a particular piece of wood. If I cannot diagnose it quickly, I just reach for another plane. Same with handsaws. If one does not please me, I just get another. As you have discovered, having additional tools to throw at the job is handy.

[WoodTinker]

First off I do not consider myself in anyway shape or form to be an expert.

Wouldn't the saw being straight suggest that the tension is good?

Having seen Ron Herman at WIA a couple years ago demonstrating how to re-tension a handsaw with an anvil and a round flat headed portion of a ball peen hammer. I can't remember the spacing of the hammer taps, but is done to both sides of the saw near the saw teeth (but not on). The teeth hang a little off the anvil. The hammer would hit the same place on the anvil with the same force while moving the saw after each tap. The anvil also needs to have rebound.

I vaguely remember a comment saying that adding tension will straighten a handsaw.

Also that rolling the tip left and right may release tension and adding and re-adding tension is not a good thing.

[Admiral]

First off I do not consider myself in anyway shape or form to be an expert.

Wouldn't the saw being straight suggest that the tension is good?

Straightening and tensioning are two different things, from what I've read.  I've taken bows out of saws by hammer and anvil smithing, actually gotten pretty good at it, and this involves compression of the steel on convex side of the bow in the plate.  Thing is this saw was not bowed, it was straight as an arrow when I got it; while others I've straightened (but not tensioned) don't "flap" at the toe.

I'm going to try and remove set from the first 4 or 5 inches of the toe and see how that works; I'm pretty certain of my sawing technique so I'm eliminating that from the calculus.

---

I don't believe in saw tensioning with a hamer, but there are long threads on the australian and the Uk forum:

http://www.ukworkshop.co.uk/forums/panel...96004.html

Take some popcorn and softdrink of your choice.

Cheers
Pedder

Thanks for the link, interesting discussion but the upshot is that the theory and practice of tensioning seems to be more a black art, known only to saw-smithys.....  


I've got to pull out some of my lesser saw finds and start experimenting, sometimes trial and error is the only way.  I'd really like to have spoken to a Disston smithy who did this for a living, again, more of an art is involved here that is likely passed down through experience.

[Mike Brady]

Here is the hammer-tension process being used on a large circular mill saw: 
https://www.youtube.com/watch?v=Wg0HGnWAU_g


Don't try this at home
.

[C. in Indy]

I had to chuckle today... rescuing a nice old Disston crosscut saw.
The blade had a gentle curve in it, but no distinct kinks.
Sometimes I've had them straighten out a tad just by removing rust.  This one didn't.  But I went ahead and did some filing, to get more uniform teeth.  It helped a little, but still there was a curve in the blade.  Then I decided the middle bunch of teeth just had too much set in them, from the past life.  I *gently* set up my metal vise with some soft-ish aluminum and brass scrap plates.  I went down the whole toothline and squeezed it just a little.

After all this, the plate has uniformly set teeth, and *no* curve.  Really a lucky turn-out for me.  I think the over-set teeth were really exerting some local tensioning.

Chris

[hbmcc]

Nice rescue of an old discussion, too! 

I read Smalzer's Tensioning article a few years ago and scribbled a column note that it was too much voodoo for me and went back to my pull saws. However, those have issues too. Price of sharpening is the big one; in this case, replacing. In Japan they may respect legacy tools, but no one does in the USA. 

I've been mentally designing a western saw conversion to a "pull" format. No video, please.