Help with Bowed Chisels

Not for the faint of heart

Bob Hackett

>I come across some pretty well abused chisels and one way I`ve dealt with bowing is to either place the chisel in a vice equiped with soft jaws and use my body weight and a a short length of pipe to bend the blade back or if it`s a thick blade then support the low points on 2 pieces of hardwood and then hit the high spot with a mallet or use your vice as a press with 3 pieces of wood if the chisel is short enough.

If the chisel in an old laminated one then support the hard steel area.If you don`t you may delaminate it,DAMHIKT.

Mainely,Bob

Re: Help with Bowed Chisels

Todd Hughes

>Again Why are we worrying about having the backs perfectly flat? Have you tried the chisels out now?. For that matter how did they work befor you started to flatten the backs?....Always curious about such stuff.... Todd

I agree with Todd....and other thoughts

Bryan in Broad Ripple, IN

>I agree with Todd. You don't need to flatten the entire back fo the chisel. When I rehab old chisels, as often as not, the backs are not flat. Usually, they are convex (front to back), which according to Leonard Lee, makes them unsuable. I, however, don't agree with Lee.

I think a perfectly flat back is a bit over-rated. Likewise, I think lapping the entire back of the chisel is a complete waste of time. Really, only the lower 1/2" to 1" of the blade back needs to be flat so that you can properly lap it during sharpening. Some even use less than 1/2".

If they are flat, this is, by all means best, but if not, having a concave back is better than convex because it's easier to flatten the the tip of the back. If it's convex, it's a bit trickier to flatten as it tends ot rock as you lap.

If I need to re-work the backs of my chisels that I'm re-habbing, I do the gross flattening with a belt sander chucked, upside down, in a vice. I then procede to my stones, or SS if necessary.

If I were to check to see whether my collection of rehabbed chisels had perfectly flat backs, less than 1 in 4 of mine would. However, I have reground, and lapped them so that ALL of them have the first 1" or so perfectly flat.

FWIW, They are all wonderful users.

-Bryan

Why?

Gerry Doll

>Todd,

Why? Because now when I try to pare or chop, the bevel tends to dig in on any deeper cuts. Like I said, I seriously messed these up by putting a substantial curve on the back. My own fault, now I'm looking for a fix.

Did I try to use the chisels new with the original grind marks on the back? No, because everything I had read in every mag, website, and book on WWing said that the back should be flattened before use.

Gerry

I agree with Bryan

Todd O. Cronkhite Maine Native in FL. Exile :~(

>When I first started learning to sharpen plane blades I knew not of flattening the backs first. Needless to say I was less than happy with the results. Once I learned that the backs had to be flattened to get them truly sharp it made a world of difference in my sharpening results. I used Scary Sharp at first, but soon discoved that it dubbed the side of my blades to un-acceptable levels so I switched to oilstones and have been very satisfied with them. I flatten all backs on cheap-o carborundum stones than polish them on my oil stones. I only flatten the first inch of the backs. I try to do less than that but find it difficult to hold the back flat on the stones when doing less than an inch. I will admit that I can't get my backs to look like mirrors with my stones like I did with scary sharp, more like a frosted mirror, but I'm satisfied none-the-less, and my edges aren't dubbed any.

Gerry, did you try to flatten the entire backs of these chisels? What kind/length of chisels are we talking here?

Todd O.

You'll like this

Gerry Doll

>Todd,

We're talking about a brand new, $75.00 box set of Lee Valley bevel edge chisels I bought before I had a clue as to what I was doing. That's why this is so painful.

The 1 1/2" through 1/2" show a significant bow, too big for my feeler gauge, but smaller than my little finger.

Gerry

thinking power tools aren't so bad after all

Re: all is not lost

les winter

>When you get a bow using Scary Sharp it may be that the glass was not supported on a flat hard unyielding surface. Glass is flexible and will not hold flat under back-honing pressure. I find the best way to make backs flat is 220 grit on a granite stone. LV sells small granite stones for 30 bucks or so. Works great.

Fold/tear a piece of 220 around 1 1/2" wide. Adhere with water. Take 20 strokes. Turn the paper the other way. Another 20. Throw out the paper. Get another piece. Repeat until you ave 1 inch flat. Then go to 500, 1000 and maybe 1500 or 2500.

Once you get the hang of it and get your backs polished, you will like the results.

If you want to use glass, put it on your table saw.

Good luck. This is a rite of passage. We've all screwed up chisels and plane blades. You can get it right.

regards

les

Re: Help with Bowed Chisels

Alan Hamilton

>Gerry,

After using waterstones for years and years, I got caught up in the "scary sharp" frenzy and gave it a try. I went back to waterstones immediately. Perhaps it was my poor technique, but when I SSed I dubbed the edge and the sides.

To remove several pounds of steel these days I have a rather odd system. I have a green stone--which I think is about a 220 grit--which for some reason doesn't seem to cut all that fast. So I now use my green stone with some SiC sprinkled on top. What can I say? It works. It cuts fast and easily.

Alan

What grit?

Gerry Doll

>I have the same situation. A HH 220 grit green stone which doesn't seem to cut very well anymore (possibly glazed with steel particles?) What grit SiC do you use?

Some disagreement

Adam Cherubini, NJ

>I'm not saying I'm right, but rather I'd just like to throw in my vote for flattening chisel backs since no one else mentioned it. I think its a good idea. But know this- flattening the back doesn't help solve the problem you mentioned (chopping). All chisels do that.

Yeah you can use a chisel with a non flat back. But can you sharpen it? And for how long?

I guess I'm a Leonard Lee devotee, but I think you need to return that chisel to a mating surface. Otherwise your are changing the shape at every honing. So I think you should flatten and polish the entire back. And I disagree with Todd O. (and maybe Todd H. as well) I don't think a dull gray back is good enough. I think you want a near mirror polish (just like Dunbar says- you should be able to count eyebrow hairs or whatever).

If you only hone 1", eventually you will have a bow in the other direction (which is not only hard to hone, but makes chopping very much harder too, imho). Its a one inch back bevel in the making.

I don't think your problem is so terrible, though. If you have to, (yikes) (whispering) put it on the side of the grinder. Just a light touch. Or use a belt sander. Its the convex back that's difficult to deal with. Or try the 80 grit drywall screen but don't apply too much downforce or you'll get deep scratches.

I reccommend going back to SS to repair this problem then using whatever you want after that. I would start with the 80 grit sanding screen then jump to 220 SiC paper. I've had better luck with 3M then just about anything else. I'd stick with the 220, changing paper often (after 20 minutes not 20 passes) until you have a nice uniform gray. I would use circular and other random motions to avoid any problems. From there, if you find the next finer grit makes discreet shiny spots toe and heel, I'd go back to the 220 and take them out. I'd repeat that way until the finer grits work the entire back. For final honing, try to avoid rubbing sideways as Dunbar says. Better to go forward and back as Lee says.

And yeah, to some extent this is your pennace. If it were me, I'd probably throw these chisels away or give them away. I'm only willing to do such work on antiques. But a few hours out of your life won't kill you. I think that's what it will take, though. A wide chisel may take 2 hours to fix.

I try not to discourage people or make up requirements (like squares must be dead square, or soles must be flat) especially where the requirement is onerous. But in this case, I think you'll never get or keep these chisels sharp and dull chisels really can hold you back.

So that's my vote anyway.

Adam

The Chisel Penitent

Gerry Doll

>Thanks to All. Appreciate the assistance.

But I still wonder how you prevent the excessive dubbing of the leading edge and sides that always seem to result from SS?

Gerry

The Chisel Penitent, looking for sack cloth to wear in the garage.

Excessive dubbing?

Adam Cherubini, NJ

>What excessive dubbing? First, I don't want sharp sides. How is SS any different from any other sharpening method?

Let's review:

You need hard, stiff something to mount the paper to. You probably should mount the paper so you don't get wrinkles. Is that your problem? I often only use a little water and 2 tiny quickgrip clamps, but sometimes the paper will still wrinkle. So I often hold it down with my free hand. Otherwise, contact Joel and ask for a few sheets of psa backed abrasive film in the grit you want. Or use a spray adhesive.

There should be no dubbing.

Adam

Re: Some disagreement

Todd O. Cronkhite Maine Native in FL. Exile :~(

>Adam,

I agree with you, dull gray is not good enough. I get mine ALMOST to the point of being able to count nose-hairs, but not quite. Yes, there is still minute scratches on my backs, but I don't think those minute scratches really effect the overall performance to that great of a degree. The last stone in my back flatting process is a extra fine black Arkansas. I tried going from there to my Translucent, but didn't see much of an improvement. Perhaps it is too big of a jump eh? I would like to be able to get them to the point of counting nosehairs tho, but am not willing to spend the excessive time to do that on a Translucent. Perhaps after the black stone I should go to a very fine sandpaper, say around 1200 grit eh.

When I used the Scary Sharp method I didn't use anything to adhere the sand-paper to the backing surface

which may, and probably did contribute to the dubbing problem. I also found SS to be quite expensive as a sheet of sandpaper didn't last very long, especially in the lower grits when doing the initial flattening.

Todd O.

Re: What grit?

Alan Hamilton

>Gerry,

Good question.

I just now ran (actually I hobbled) to my tool chest and looked. Yes, of course, the label had torn off.

Sorry. Once again I'm no help.

Alan

Re: Some disagreement

Mike McDaniel

>I also found SS to be quite expensive as a sheet of sandpaper didn't last very long, especially in the lower grits when doing the initial flattening.

Todd O.

And that ladies and gents is exactly why I don't use SS anymore. I restore old chisels. Probably over a hunnert a year. Paper can get real expensive. Tried water stones, but couldn't get the hang of 'em. If I get a chisel that needs a lot of flattening, I'll start with the belt sander. If it's just a little more then I want to do by hand, I use the side of the grinding wheel. After that it's carborundum,india,washita,translucent and then strop. The strop is where you really get the mirror effect. I don't use any grit or paste, just a thick piece of leather, glued to a 3X3X12 inch maple block.

Mike McDaniel

Adam brings up a good point....

Bryan in Broad Ripple, IN

>I would not flatten the back of a newly bought chisel if it came this way from the manufacturer. They should be flat from the factory, period. I realize however, that this is not the issue with the original post as the situation was user created.

FWIW, the chisels I use are almost exclusively vintage chisels which I rehab. If I were to flatten the entire back of some of these, It would take days, and consume much more of the chisel steel than I would really prefer (DAMHIKT). Besides, is it really necessary for the full 8" blade of my Swan firmers to be fully flattened and polished? I would challenge anybody to convince me that this would improve the performance of the chisels one bit.

Having said that, I am a proponent of preparing the chisles in the manner which best suits you work. If I did a ton of 4" deep mortising, I'd prepare the chisels accordingly.

As for flattening only 1 inch or so (actually, closer to 1.5" as I just measured)...I really don't need more of the back flat for my purposes. At the rate I consume chisels, this should last for a decade or longer. If I went through chisels much faster, I suspect that that I would not want to use vintage chisels as they would be too time consuming to properly prep. Also, I don't do much chopping deeper than 1 to 1.5 inches.

-Bryan

Loose grit and restoring chisels

Adam Cherubini, NJ

>Todd,

I've had similar experience with paper and asked my ringer here at work. As I recall the answer, when you first touch the paper, loose or poorly bonded grit gives a really aggressive cutting feel. After a few minutes or washing the paper with water or wiping it, that loose grit is gone and the paper feels less coarse. That feel is the real grit. And that grit should continue to cut for some time. I doesn't "wear out" after 20 strokes or 200. I was told one key is keeping the paper clean. Flushing it with water (from a spray bottle) then wiping it with a paper towel (as I do) may not do it. Try running the paper under a sink and see that improves things. Now the paper may not feel much diferent, but its life will be prolonged. Or so I was led to believe.

So in summation, the feeling I get (not necessarily the results) from the first strokes of SiC 220, is not 220, but rather 180* say. After 20 strokes, then its 220. So if you want that coarse feel, switch to a lower grit.

*Caveat- The grit size/particle size doesn't really change. We're just talking about our experience/feel.

One more piece of information I learned that might be helpful: Better papers, including the stuff Joel sells (no affiliation- and you can buy it elsewhere) have more uniform grit size, and the grit is bonded better to the film or paper.

Each individual must determine the value of the material- don't know if paper that's twice the price of other paper lasts twice as long- dunno.

==================

Like many of you, I restore old chisels and plane irons and find the process laborious. I bought a bench top belt sander, but don't much care for it. The belt seams aren't great. I tried a delta horizontal wet wheel and took it back (too slow). I don't like using the sides of grinders- its not safe and it doesn't work all that well. The best thing I've found for rough metal work is drywall screen and patience. I'm open to other suggestions. Is anyone using the LV thing for this purpose? Its not that my irons are so out of flat, it's that I may need to remove .005 from a 3"x3" area.

Adam

Help with chisel rehab

Bob Hackett

>I wasn`t at all pleased with belt sanders either.Perhaps after I hit the lottery I`ll pull the trigger on a Burr King and that will all change.;^)

I start on a large disc sander.Mine happens to be attached to an old cast iron Shopsmith.I remove any pitting/flatten the back and front by holding the chisel freehand with the socket/handle off the edge.I then square the sides to the back by using the table.

I work with mostly socket chisels and have found that Scotchbrite(or Beartex) pads on a 5" grinder work well to remove and blend the gorilla tracks(while leaving the maker`s mark) and smooth up the transition from blade to socket.After a maroon pad it`s off to a fine deburring wheel(like compressed scotchbrite in a bench grinder wheel form)and then the cosmetics are done and time to break out the sharpening stones.

It takes me longer to sharpen with the stones than it does to do the initial work,including rough flattening the back,even if the chisel is a rusty hammer beaten mess.

I know,I`m working on getting faster with the stones.

Mainely,Bob-Who`s last bottom feeding excursion netted 3 really rusty old socket chisels without handles.Two of these turned out to be T H Whiterby laminated(an 1 3/8" heavy framer and a 3/4" firmer).The third was an old heavy Butcher.$3 each-beep beep.

For those who don`t own a slick

Bob Hackett

>Slick backs are not dead flat.I`m talking real slicks now not the 2" framing "chisel slick" that you see on the `bay.

The old timers felt they needed some "rocker" in the back so you could adjust the depth of cut while it was in progress.This convex type of bow may also be useful for paring chisels under some conditions.

A chisel with a concave back will have a tendency to dive into the cut as more of the back registers to the work.Can`t think of anywhere,off hand,where this would be an advantage.

Those of you who only flatten the first 1-2" or so of the back are in good company(as long as the back is convex).Alot of the shipwright`s chisels I`ve seen are sharpened that way for the reasons I`ve just mentioned.

Mainely,Bob

PS

Bob Hackett

>You`d waste an awfull lot of metal completely flattening and polishing the back of a Japanese chisel. I hear they work just fine with that little bit of polished steel and that big hollow back.

MB

India Grits

Todd O. Cronkhite Maine Native in FL. Exile :~(

>After that it's carborundum,india,washita,translucent and then strop. -Mike McDaniel

boy here comes a dumb question, I'm almost ashamed to ask it it's so dumb, buuuuuuuuuuuut do india stones come in different grits? I've never paid them much mind so I really don't know for sure. I don't think they do, but thought I'd ask anyhow.

Bob, I can hear you you know. Please quit laughing now.

Todd O.