Lamination on old Moulding Plane Irons

[paulc]

Hello,

I have a few old hollow and rounds I'm restoring and there are some cracks in the steel maybe 15mm from the cutting edge.

I want to grind past the cracks and reshape the cutting edge.

How far down does the laminated tool steel go on these irons ? Does it cover the entire rectangular head of the iron?

I don't want to grind past the hardened steel and be left with soft iron for the cutting edge.

Thanks, Paul

 

[Jacob]

Do the cracks interfere with the plane in use? If not then I'd leave them alone. Restoration often gets very over done.
You can probably tell where the hard laminated steel ends by looking at the edge. Usually covers most of the rectangular bit of the blade.

 

[Adam W.]

15mm seems a lot to take off a moulding plane iron, are you sure that the cracks are not just the end of the laminated section.

 

[cowtown_eric]

99% of the time trying to reshape the cutting edge is a fools errand, one simply laps and hones the flat side of the blade..a crack 15mm from the end may be a "hard steel" laminating error, and if lapping the flat side yields a good cut, let sleeping dogs lie

 

[--Tom--]

Got a pic of the iron? If fairly simple I could harden you a blank next time I’m heat treating something

 

[Adam W.]

99% of the time trying to reshape the cutting edge is a fools errand, one simply laps and hones the flat side of the blade..a crack 15mm from the end may be a "hard steel" laminating error, and if lapping the flat side yields a good cut, let sleeping dogs lie

Except, if you over do it and take too much off the back of the iron, you risk altering the taper of the iron, which could affect the holding power of the wedge.

The best way to re-establish the profile of the iron is to use engineers blue on the iron and draw the profile of the sole on the iron, using a scribe, with the iron fixed in place.

Larry Williams has a very comprehensive video on the Lie-Nielsen website, which describes the process in detail.

 

[cowtown_eric]

yu woiud have to work like an sob to hone more than a couple of thou off the back of an iron, and restore it to sharpness unless it's badly pitted.

Larry williams is welcome to hi own opinion

 

[cowtown_eric]

wearing off .001" off the back of the iron sharpened to 30 degree pitch (assuming a flat grind} has exactly zero (.000) effect on the edge, it's still 30 degrees. do the geometry.

Original grinding SHOULD have made all cutting eges co-planer with the all the cutting edges,so same logic applies there applies there.....UNLESS someone has tried to make it cut better, or the sole/boxing has worn, where a little honing can make it cut better, and yes I have done that in re-habbing panes back to utility

from his blog/fww/whatever
My question to him wasn't about shaping a molding iron, it was about honing an existing iron that didn't need reshaping. So far he still hasn't given an answer. I'd like to know if there is a different method for honing a molding plane iron. I know enough about going through the heat treating process to know that you don't end up with a sharp edge, it still has to be sharpened after tempering. If there is some practical way to get that edge that is different from what I stated, so I can end "up with a properly working molding plane." , let's hear it.

 

[Adam W.]

It's not that big a deal to sharpen the edge of a hollow or round iron properly. Just like most sharpening, it's as difficult as you want to make it.

If you wish to constantly lap the back, that's fine, but I bet Larry Williams knows more about it than you do.

 

[D_W]

wearing off .001" off the back of the iron sharpened to 30 degree pitch (assuming a flat grind} has exactly zero (.000) effect on the edge, it's still 30 degrees. do the geometry.

Original grinding SHOULD have made all cutting eges co-planer with the all the cutting edges,so same logic applies there applies there.....UNLESS someone has tried to make it cut better, or the sole/boxing has worn, where a little honing can make it cut better, and yes I have done that in re-habbing panes back to utility

from his blog/fww/whatever
My question to him wasn't about shaping a molding iron, it was about honing an existing iron that didn't need reshaping. So far he still hasn't given an answer. I'd like to know if there is a different method for honing a molding plane iron. I know enough about going through the heat treating process to know that you don't end up with a sharp edge, it still has to be sharpened after tempering. If there is some practical way to get that edge that is different from what I stated, so I can end "up with a properly working molding plane." , let's hear it.

it's pretty uncommon for a plane that was put aside for three digits of years not to go through additional shrink. It may or may not be enough to require reprofiling, but most of the older sets that I've gotten from england were in obvious use, but the profile on the iron is now a little wider than the wood.

Then, there's another shift of shrinking that occurs here in the states, though it's not drastic, it will result in bench planes (even really really old ones) getting a death grip on an iron or moulding planes getting tight on a wedge laterally.

When things are off kilter, rather than doing anything complicated, I would mark the blades as adam says, but then draw their temper, file them and reharden them. Larry warns about this, but he doesn't know how to shrink grain on steel and he overshoots on heating the iron (which is OK if you understand thermal cycling). Larry's suggestion is more or less only do that once.

it's far easier to file to a line than it is to grind or hone or have the equipment in the first place to grind profiles.

that's not really answering the original question - the plane would have to not function for me to consider anything with the iron beyond setting the profile and ignoring the crack hoping that I would be so lucky to ever get the edge close enough to it from work to worry about it.

Either that, or just make another blade copying the old one as a template.