Nope. Stiffness is primarily in blade thickness, so one can look for that. This is why circular saws exist.

My experience is if the blade isn't cutting perfectly on each set of the teeth it will run off to one side, even in chain saws with a substantial support bar backing the chain. Also, if the guide on the saw is worn that can allow the blade to rotate, a vexing problem.

A spine is limited in thickness to the kerf - they make non-kerf blades, the thick ones I mentioned, which means the whole blade is a spine.

I see what you mean. Before I suggested this, someone suggested that I add a frame around the blade like a coping saw but I don't want to put the increased mass on the blade. I already tried the reciprotools metal file on the blade and the increased mass and intertia makes the saw unusable (and in my experience, practically dangerous).

I'm just trying to get straight rip cuts. Maybe if I clamp down a straight edge and go slowly I can get close?

Quote (m899nyc)

I'm just trying to get straight rip cuts.

You need a circular saw. A sawzall is a demolition tool - not a construction tool.

A friend's brother considered his chain saw a construction tool.
His results were pretty good.

http://aws.org/mwf/attachments/83/79983/farm_code_...

Is there room in the saw's collet/gripping device for two blades side by side?
Probably/might have to flatten out or grind the tooth "set" on the mating sides.
A couple of tack welds on the blade backs would get the sammich closer to 8X stiffness.

Have you tried Milwaukee 48-00-1600 ?

nah, you just need more practice ! (Smile, I am probably as clumsy as you are !? ... "straight" is a relative term ... most of my cuts are ... "gay" ?)

another day in paradise, or is paradise one day closer ?

Straight cuts require straight control, which is rather difficult with something that's reciprocating that much mass. A circular saw tends to stay in its kerf because the width of the blade resists turning. Alternately, one might use a long bladed jigsaw with a mechanical cutting guide; the jigsaw also reciprocates, but it's pushing a much tinier mass and therefore bucks less.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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Is there room in the saw's collet/gripping device for two blades side by side?
Probably/might have to flatten out or grind the tooth "set" on the mating sides.
A couple of tack welds on the blade backs would get the sammich closer to 8X stiffness.

Have you tried Milwaukee 48-00-1600 ?

Great ideas! I'm going to give this one a shot. This is part of a project with my Dad and I. We're going to restore an old aluminum housed Milwaukee sawzall, polish it up,put new bearings in, etc. as a tribute to my grandfather/his construction company (his original Sawzall was stolen years ago). Maybe have his name and company engraved on the housing with a picture. If I could get this tuned up to do something special like make straight rip cuts it would be pretty cool.

nah, you just need more practice ! (Smile, I am probably as clumsy as you are !?

Haha! I'm pretty hard to beat when it comes to clumsy. :)

Alternately, one might use a long bladed jigsaw with a mechanical cutting guide; the jigsaw also reciprocates, but it's pushing a much tinier mass and therefore bucks less.

Not a bad idea. I should be able to fab one up to fit in a Sawzall chuck.

A friend's brother considered his chain saw a construction tool.
His results were pretty good.

You know I see stuff like this:

http://www.bigfootsaws.com/bigfootproduct/head-cut...

and I really want to try it, maybe just on some 2x4s but something inside keeps telling me it's a kickpack incident waiting to happen. Am I wrong here?

Rigidity of the blade has little effect on straightness of the cut. That is controlled mainly by position control of the saw. Normally only the tips of the cutting teeth contact the material being cut and the blade will cut in whatever direction it is pushed or guided. A wide blade, like with a hand saw, will be guided by the kerf, somewhat, but only after the kerf is established.

Sawzalls are not designed to make particularly straight cuts. They are designed to make free-form cuts. If you want to make straight cuts with them then use the widest blade possible and a guide fence to control saw position.

Other factors that control cut straightness are operator skill, uniformity of blade teeth and sharpness and uniformity of the material being cut. Until you understand how a blade cuts you cannot develop the skill to control it. Note that Sawzall blades are not straight. The tip of the blade is canted forward, so that as it strokes up, the cutting teeth progress forward in the cut.

use fine pitch teeth, cleaner cut

Rigidity of the blade has little effect on straightness of the cut. That is controlled mainly by position control of the saw. Normally only the tips of the cutting teeth contact the material being cut and the blade will cut in whatever direction it is pushed or guided. A wide blade, like with a hand saw, will be guided by the kerf, somewhat, but only after the kerf is established.

Sawzalls are not designed to make particularly straight cuts. They are designed to make free-form cuts. If you want to make straight cuts with them then use the widest blade possible and a guide fence to control saw position.

Other factors that control cut straightness are operator skill, uniformity of blade teeth and sharpness and uniformity of the material being cut. Until you understand how a blade cuts you cannot develop the skill to control it. Note that Sawzall blades are not straight. The tip of the blade is canted forward, so that as it strokes up, the cutting teeth progress forward in the cut.

Thanks for your reply. Do you mean clamping down a fence for the foot to follow along or a fence for the blade to follow?

If the kerf is going to guide the blade then nothing would prevent one from starting a kerf with a marking knife or chisel the way the old cabinet makers did to guide their handsaws.

Do you know where they sell wider Sawzall blades?

In the future, I would recommend posting in forum1528: Engineers with Hobbies.

In the future, I would recommend posting in forum1528: Engineers with Hobbies: Engineers with Hobbies.

Sorry about that.

To clarify, by wider I mean the depth of the blade behind the teeth. Blades 0.75" or 1" are pretty common. But if you use a fence to guide the foot of the saw (not the blade, as that is not practical), then blade width does not really matter any longer. It just becomes more likely that the fence and the blade kerf do not align with each other. If the blade teeth are not set wider than than the blade, the cut will likely not be straight. This is because the kerf will be in contact will the blade and will tend to push the blade slightly to one side. This causes the blade to cut slightly to that side, and therefore the kerf will move to that side and push the blade more to that side. You cannot steer a blade where the kerf is not wider than the blade.

This happens with band saw blades when they get dull. The side set of the teeth gets worn away and the blade will no longer cut in a straight line.

CP above is on the correct track with the comment about controlling the saw. I would add however that the easy way to control the saw is to clamp a straight edge to the stock being cut and let that guide the foot of the saw. That is how you get truly accurate cuts with any handheld power saw whether its a circular saw, jigsaw, or otherwise. I also wouldn't doubt that a creative mind could build a Sawzall rail attachment similar to a panel saw. Here's a few commercially sold versions for circular saws.
https://www.thedailygardener.com/best-circular-saw...

m899nyc, a common attachment for handheld circular saws to allow cutting larger beams is a mini chainsaw attachment that replaces the circular blade.
https://homefixated.com/beam-cutting-tools-sword-s...