sharpening chisels

[invalid.address]

Hello,

I bought a wood chisels for fitting hinges to doors. Having hung doors in every room in the house, the chisel is now looking worse for wear. How do I sharpen it?

I have got an angle grinder, so I presume I could use a metal grinding disc but is this possible? Would I have to clamp the grinder to a work bench?

Would you recommend that I buy a desk-top grinder instead? Or since this was a cheap and cheerful chisel, are they supposed to be considered disposable?

How many times can a chisel be re sharpened? I presume they get slightly shorter each time you grind them?

Are there any web pages explaining sharpening technique? Do you have to grind a particular angle?

Thanks, Stephen.

[Bill]

In message , [e-mail] writes

An angle grinder is an interesting idea :-)

Take a read of

only time I nearly saw my dad cry was when my mother said " you were wrong you can use a chisel as a screwdriver, I just have". He remained remarkably calm!

[George]

I do it all the time on the "finer disk",bearing in mind I cannot for the life of me get a razor sharp edge using an oil stone.

:-)

[petek]

I inherited one of my Grandad's chisels via my Dad. Bevel edge, 1" wide. Blade length is about 1" ! Still good for chopping out old putty from window frames etc.

Pete

[Alan]

In message , [e-mail] wrote

Search for 'Scary Sharp' or 'Scary Sharp(TM)'

[Andy Dingley]

Many ways: various stones, or Scary Sharp (wet & dry stuck to glass, web search for it) is probably your best bet.

Don't use any sort of powered metalworking grinder to sharpen a chisel

- you'll overheat it and destroy the temper. If you were in a position to do this, you'd have other and better options available to you. Powered chisel grinders are too expensive, so go with the Scary Sharp.

[The Medway Handyman]

What about nicks in the edge? Can wet & dry paper remove enough metal? What grit?

[Cicero]

================================== Start with emery cloth on a flat surface. Hold the chisel vertically as if holding a pen and work it until the nicks are gone. Continue with the emery cloth at the normal sharpening angle until you've got a basic cutting edge and finish with wet & dry or standard oil stone. The emery cloth is a bit drastic but it does get rid of nicks and doesn't carry the risk of angle grinder treatment.

Cic.

[George]

Hmmm! my chisels havn't lost their tempred factor in the past three years of sharpening them on a grinder wheel but then again if you remember your school metalwork classes you always used a cooling process inbetween heated metal.

[The Medway Handyman]

Cheers - what grit emery cloth?

[Cicero]

================================== I use 'medium' emery cloth - no idea what grit that is. If it's too coarse you'll simply rip the grit off the paper without doing much work on the chisel.

Cic.

[Andy Dingley]

I'd suggest black wet & dry (silicon carbide grit) rather than emery cloth. Emery cloth has rather a stiff backing and is hard to stick down flat. For sharp edges you need flatness, otherwise the edge gets rounded off.

[Andy Dingley]

How do you know? Have you measured their hardness?

Which will cause cracking (too small to be visible) in high-carbon steels, such as chisels. This hasn't been a recommended practice for decades. When it was, back then "powered grinders" meant bench wheels rather than high speed angle grinders, and even then it was dubious (especially for woodworking tools). Bahco might survive (because of their alloy) but cheap Chinese from Lidl won't, even though these will take a better edge (those =A34 sets are actually pretty good).

Wood chisels (and plane irons) are _really_ sensitive to overheating during grinding, because of the narrow angles at the edge (minimal conduction cooling) and the high carbon content. Techniques that work fine on a Swiss Army Knife in 440 stainless will ruin even a simple chisel in short order.

Of course it's possible to use a powered grinder to sharpen chisels. A slow water-cooled grinder (and I've seen these for =A320) will do it fine. If you change the alloy away from a simple carbon steel then you can also make it resilient against heating and do it on a dry wheel. That's why so many modern plane irons trumpet that they're "tungsten vandium steel". This is a poor alloy for a plane iron and never takes a good edge, but it makes manufacturing quicker and cheaper on simple machines.

[NoSpam]

If you think you'll need to sharpen edged tools frequently it's worth looking at a wetstone grinder. I have one made by Tormek - it's great but pricey, there are probably cheaper versions around if you search for "wetstone grinder" in Google.

Dave

[Stuart B]

You could search around locally for tool sharpening places .One near me in Glasgow does chisels and plane bllades for £2 a time . You still need to hone them tho'

[mail]

Stephen Buy yourself a cheap offer two stone (coarse and fine) bench grinding wheel. Not an angle grinder! fill an old container with water and put nearby grind the blunt chisel first with the coarse then with the fine until it has a hollow concave profile between the tip (cutting edge) and the full sized part. Use the water every few seconds to keep the chisel cool. When you have a nice little hollow bit from the fine wheel and the cutting edge is straight and clean (no black burnt bits) transfer it to a diamond stone in water Old big ice cream carton or the like so that the stone is wet and clean. use a figure of 8 pattern on the diamond stone - cleanign it often in the water. Altnernate between the face which is resting on the two "points" resulting from the curved grind to turning it 180 and KEEP IT FLAT on the other non ground side. As you do this you will see a little rim of steel "filing" form where you are sharpening alternately on both sides of the chisel. Keep alternating until it just breaks off and then STOP. It should cut a piece of newspaper held in hand without effort Use the stone until the U has largely been ground away and then back to the grinding wheel and start again. The chisel will wear away with time but you would have to be pretty hard working if this is done properly to grind it all away in several years if not a lifetime! Chris

[Cicero]

================================== I suggested emery cloth (and also use it) for removing nicks before proceeding to more refined techniques and a final cutting edge. Any method that doesn't involve heating the blade will do and medium emery cloth is a cheap alternative for the DIYer without access to a wet grinding wheel.

Cic.

[Mark]

The same ones was being sold in Poundland last year, I bought a set to use as scrapers and then went back and bought another two sets when I realised how good they were. ( for the price)

-

[Stuart Noble]

There's a lot to be said for soft steel that sharpens easily on whatever happens to be lying around at the time

[Andy Dingley]

These are actually quite a hard steel, albeit somewhat brittle. They appear to be the same sort of low-alloy high-carbon steels that are so celebrated if they're pre-war and stamped with a Marples' cloverleaf (although not laminated).

The funny thing is that they're not desperately good at the use for which they're sold. I bought a set to hammer through plaster when sinking electrics (because I need _something_ for this sort of abuse). If correctly sharpened they're a useful bench chisel, but they're a bit on the brittle side for toolbag hackery.