Sharpening hollows and rounds

ttalma

ttalma

Well-known member
I just purchased a set of hollows and rounds with skewed blades. The bodies are in good shape but the blades are a little rough with some knicks on the thier edge and some surface rust.

I know how to clean the faces and remove the rust. But for the most part I will have to re grind thier edge, most about 1/16  and one about 1/8. What is the easiest way to do this?

I usually touch up the edges by hand and keep them sharp, so that It's never alot of work. If it were 1 or two blades I would do it this way, but I will have to do 12.

I recall seeing some sort of setup for a lathe, but can't rember where, or even if I am remebering correctly.


So basically what is the best way to regrind the edges? I don't mind doing the final honing by hand but I'd like a little faster way to do the main grinding.
 
I've successfully used a Dremel to regrind molding plane blades. There are grinding bits in various shapes and grits. Fast, easy and very little chance of overheating. I put the blade in my bench vise.
I know there are ways of marking the blade (?blueing) to see where to grind to, but I just eyeball it; trial and error, blade in and out of the plane etc.

Howard Steier
 
Tim - Typically, molding plane irons from the late 19th and early 20th centuries are a good bit softer than modern bench plane irons.  That means that you can often shape them with metal files.  Half-round mill bastard files in a few different sizes should do what you want - the convex side will allow you to shape the hollows, and the flat other side will let you shape the rounds.

I would recommend marking them out - you can do this with a magic marker.  Just color the back of the blade (the non-beveled side), insert it into the plane when dry, shim the blade to the front of the mouth with a wooden wedge made of softwood, and use a scratch awl to carefully scribe the profile onto the blade.

You can then get the profile close with a metal file, and finish up with slipstones (either waterstones, oilstones or ceramic files).

I would not recommend dry-grinding these blades unless you're really experienced at doing it.  It's really easy to draw the temper, and once you do, re-hardening and re-tempering to get a good balance between blade toughness and hardness can be a real bear.

Also be aware that you must relieve the profile for the planes to work well.  This is a bit hard to explain in words, but the bevel isn't just perpendicular to the sole of the plane - it follows the profile around on both hollows and rounds.
 
Tim,

I have not found David's shimming step neccessary.  The question I always ask myself is how closely (or should I ) match the profile of the sole.  There are two issues:

1) Folks who use these planes alot (and I'm not sure I'm one of them) often seem to have one side of the iron "cambered' or faded into the sole.  This allows you to blend surfaces I bit easier.  And it doesn't seem to effect the planes ability to "sink" a feature.  It's useful for modifying complex molded profiles.  I think I recommend the approach.  This would change what shape you grind.  Before you start grinding, you might want to have a close look at what you've got.  Chances are, this is how they were shaped by their last owner. 

2) The soles of yoru planes may be worn, especially at the wear, the portion of the sole you would use to mark your irons.  This may be the right time to restore the soles to their proper shapes and ensure their flatness (if you know what I mean).  If you find you open the mouths too much, you may find it helpful to epoxy or krazy glue a brass shim to the beveled side of the iron.  I've not done this because most of my planes seem to work okay as is.  I would think you'd want the shim to be custom trimmed to the entire length of the iron including it's tang.  Obviously, the wedge won't seat as deeply but it could be modified if it was a problem.

Adam 
 
Adam brings up a good point (and something I forgot to include).  It's essential when shaping an iron to the profile of a older or well-used plane to check to see that the leading edge of the mouth is in the same plane as the front sole.  If it's been chipped, or worn to the point that it's a few 32nds below the front sole, it may not be possible to scribe the iron - you may have to grind/hone the iron, place it back in the plane, check the work, and repeat. 

It's tedious, but I've used this procedure several times when I had a plane that I wanted to use but was unwilling to plane down and re-shape the sole (generally, these are 18th century British examples - they're too rare for tuning the sole).

This brings up a few other things to check for on a plane that you want to use - it's essential that the front and back sole not be twisted in relation to each other.  You can get away with a front and back sole that are slightly out of line in the vertical plane, but not in the horizontal.  Usually on a side-escapement molding plane were the throat is not cut all the way through to the blind side, the amount of twisting is fairly minor and can be corrected with a little careful planing/scraping.

On planes where the throat is cut through to the blind side (such as rabbet and dado planes), the freedom of movement often means that the twist is more severe - sometimes as much as 1/8".  If you're examining planes at a flea market, this is a go/no go buying criteria.  It's a matter of opinion, of course, but I don't buy dado or rabbet planes that are twisted more than about 1/32nd or so.  They're just too common to deal with the frustration of correcting twist and having one side of the plane have an unsupported sole after they're tuned.
 
Sorry to branch off a wee bit but the subject of reshaping the sole if needed reminded of my current restoration project. I just acquired a pair of snipe bills with boxwood boxing. The boxwood was chipped off the heel on one of the planes. I have a well dried boxwood limb and sucessfully matched a piece in place. Its fresh color begs to be changed to match the rest of the boxing. Has anyone ever dyed boxwood to match aged boxwood? Whats the best approach.
Thanks,
John
 
John - One thing to realize is that the grain of the boxing on a molding plane isn't oriented lengthwise to the plane.  Instead, it's generally angled downward so that the edge that's meant to ride against the work is largely end grain.  I mention this because one way to "tone down" new boxing is to saturate it with linseed oil (the "boiled" kind).  The linseed oil will absorbe much more strongly on the end grain surfaces and will result in final color that's fairly dark.  If you've oriented the new boxwood piece correctly, that end grain surface will match the existing fairly well once it's saturated with oil.

You can, of course, use aniline dyes to darken the new piece of boxwood and make it more yellow to match the existing, though that's a bit more complex than just coating the new boxing with linseed oil.
 
Thanks for the suggestion. I did take the effort to match the grain so it seems BLO should do the trick.
John
 
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