I don't get why all plane irons aren't laminated?

[Richard T]

I think it is to do with the low angle of the BU iron. Just by its lower angle it is much less likely to chatter than a BD at its steeper frog angle.
Even though (Jacob wrote) "the EP angle being the same in each". - you can pare with a chisel BU no probs but you'd have a game trying to pair with one BD .... at least I would ... couldn't hold it. And the plane has more trouble holding it too. A BU iron has its flat side drawn into the wood, pulling it tightly against the inside of the plane sole, like any sided blade pulls in. The BD is apt to bounce.
I guess this is why there has always been the greater need for extra support for a BD; be it a thicker iron, a cap iron, a lever cap etc; regardless of what possible extra benefits such upward curve on the secondary iron may have been found to have since.

Huh? Huh? Etc..

 

[Jacob]

...BU blades are always heavy and firmly held down so they don't need the extra hold-down effect of the cap iron.

Not so. My Stanley and Record block planes (#110, #0120) are bevel up, and have irons as thin as, or thinner than, my bevel down planes from the same makers. I.e. less than 2mm thick.

Cheers, Vann.

Oh yes except for block planes! :roll:
But IMHO they are hopeless for full width normal planing and are used for trim, small stuff etc. so don't count.
No doubt someone will say differently!

 

[bugbear]

In the context of a thread that wandered off into entirely hypothetical plane components, I see no reason to have assumed that block planes "don't count"

BugBear

 

[bridger]

two things here. bevel up planes like block planes can be supported by the frog a lot closer to the edge which lends them stiffness. they almost always are bedded at lower angles than bevel down planes which means that the body of the blade is closer to being in line with the cutting force.