How I Flatten Chisels... What's the Catch?

**D.W.** · 7th April 2016, 12:26 AM

Originally Posted by bridger

I rust hunt. I have a soft spot for cast steel chisels, and when I find them for really cheap I tend to bring them home, regardless of condition (well, almost). some of them have come to me with cratered backs, nasty back bevels, all manner of radical flattening needed. I have tried lots of approaches from jigging a bench grinder to granite slabs and coarse abrasive sheets to hogging with an abrasive disk on a die grinder interspersed with sessions on a coarse diamond plate (works surprisingly well). most recently I picked up a sad sack makita flat top grinder missing all of it's attachments and having only the 1000 grit wheel. between that, a low speed bench grinder with a cbn wheel and a coarse diamond plate I flattened a batch of chisels. I found a 60 grit makita wheel for cheap online. I expected it to be used, but it was new in an opened box. anyway, it arrived yesterday. I haven't tried it yet, but if the performance of the 1000 grit wheel was any indication this should make flattening backs a pretty fast and accurate operation.

I saw a setup that a guy did- using the side of an abrasive cutoff disk for a metal cutting chopsaw sandwiched between a couple of nuts on a bolt chucked into his drill press spinning at the drill press's lowest speed. it didn't run particularly true, but at that speed you could compensate well enough to get by. when I saw it I thought I was seeing sure disaster, but he was getting passable results from it. if you have the drill press already and need to hog off the flats on some badly mistreated chisels it is probably the cheapest fastest solution.

I've been down that road, too, but now am at a point where I just don't know what to do with all of the tools, because all I want to do is actually have time to use them.

Having taken on a lot of junk, I figured out that if the methods I described earlier don't work (80 grit sandpaper or 100 grit loose diamonds to start, whatever is preferable), a 1" belt grinder with a hard steel platen can actually get the offending metal removed so that the sandpaper or diamonds can then create flatness.

But so much can be removed from a tool with those, that sometimes you find that once the pits are gone, you don't much like what's left because the shape has changed too much.

**bridger** · 7th April 2016, 04:28 AM

Originally Posted by D.W.

I've been down that road, too, but now am at a point where I just don't know what to do with all of the tools, because all I want to do is actually have time to use them.

I think I live in a sparser rust hunting environment than you. We're about the same age but have pretty different back stories. I have been a woodworker all my adult working life, which for me has meant doing a lot of house construction and a little finer work. the balance between new boutique premium / vintage restore fettle falls heavily on the vintage side. I need a good working set of tools and I enjoy the find/restore process. and yes, I do end up with an excess from time to time. a few have ended up on ebay but more have been given away.

Originally Posted by D.W.

Having taken on a lot of junk, I figured out that if the methods I described earlier don't work (80 grit sandpaper or 100 grit loose diamonds to start, whatever is preferable), a 1" belt grinder with a hard steel platen can actually get the offending metal removed so that the sandpaper or diamonds can then create flatness.

I seem to have a harder time controlling roll with the 1" belt sander than with a 2" sanding disk on a die grinder. the last round I used a CBN wheel at 1725rpm, very carefully. it worked well, but I think and hope that the flat top makita will be better yet.

Originally Posted by D.W.

But so much can be removed from a tool with those, that sometimes you find that once the pits are gone, you don't much like what's left because the shape has changed too much.

as long as the pits don't intersect the edge I'm happy to consider them patina. very few have come my way that cannot be made to work on those terms.

**D.W.** · 7th April 2016, 04:48 AM

Originally Posted by bridger

I think I live in a sparser rust hunting environment than you. We're about the same age but have pretty different back stories. I have been a woodworker all my adult working life, which for me has meant doing a lot of house construction and a little finer work. the balance between new boutique premium / vintage restore fettle falls heavily on the vintage side. I need a good working set of tools and I enjoy the find/restore process. and yes, I do end up with an excess from time to time. a few have ended up on ebay but more have been given away.

I seem to have a harder time controlling roll with the 1" belt sander than with a 2" sanding disk on a die grinder. the last round I used a CBN wheel at 1725rpm, very carefully. it worked well, but I think and hope that the flat top makita will be better yet.

as long as the pits don't intersect the edge I'm happy to consider them patina. very few have come my way that cannot be made to work on those terms.

Agree with the last part, they all still work in the end. When i started making planes, I was hell bent on picking up older planes with rusted irons and caps and bringing them back to life. I got one that was matieson (which I like quite a lot) and proceeded to work it on the belt grinder and by the time I had the pits out of it, one side was about 2/3rds as thick as the other. It wouldn't have been that much of a chore to bring the other side down to be equal (probably ten minutes), but I've since gone to trying to find either rust free or NOS.

My favorite paring chisels have pitting all over the backs in spots, but it's not at the edge, so they fit your description. I'm sure not going to try to get it out, it could be decades before I reach it, even though in some cases, it's only 3/4ths of an inch from the edge. It's intermittent with bright metal so it doesn't impede their use.

re: the makita, that's what Steve Knight used on his custom irons. They did need additional attention, but he was probably doing them on the quick as he didn't charge much for planes. I've heard good things about the machine, except that it does fling swarf, but that doesn't matter unless you're a TV demonstrator.

(as long as the belt on the grinder is tight, it's not too hard to keep the edge down on the platen - it just has to be introduced middle first and then the rest levered down onto the platen).

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