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t121anf |
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t121anf World Chat Champion
Joined: 23 Feb 2007 Karma :
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MarJay |
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MarJay But it's British!
Joined: 15 Sep 2003 Karma :
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Pete. |
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Pete. Super Spammer
Joined: 22 Aug 2006 Karma :
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Posted: 21:39 - 29 Apr 2023 Post subject: |
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The little 150w bench grinder will sharpen your chisels but there are 2 other things to consider:
1, It will blunt pretty quickly, so buy a dressing tool.
2, Chisels when sharpened will lose their temper is you let the chisel edge go blue even once, so don't grind that chisel edge at too shallow an angle (60 degrees or more is OK) and dip it in water often.
If you don't follow 1, nothing will stop that chisel edge going soft. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good |
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 21:48 - 29 Apr 2023 Post subject: |
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I bought a bench grinder, then realised I should have bought a belt grinder.
I would sharpen a cold chisel with a file. Don't forget to dress the top too if it's looking like a badly hammered fencepost top so you don't learn about spalling the hard way. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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t121anf |
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t121anf World Chat Champion
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 22:50 - 29 Apr 2023 Post subject: |
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They are still hardened steel. Once hardened, the hotter the temper temperature, the softer the steel lands up. For tool steel, it'll be tempered at temperatures you'd bake a cake at. Get it hotter than that and you'll be making the steel softer.
I'm shit at metalwork and an engineer once told me that power tools don't do a job better, only faster. Hence why I use files a lot, then I can spot when I'm making a cock and balls of it before it gets unsaveable. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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MCN |
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MCN Super Spammer
Joined: 22 Jul 2015 Karma :
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Posted: 08:48 - 30 Apr 2023 Post subject: |
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I've used 'cold' chisels for years and anytime I tried to use a file to repair the edge it's been a time consuming phaph.
A big grinder with a quenching pot near it works perfectly. And the edge lasts as long as it did when new.
Once you have ground down a few mm though you will be into different material properties.
I can re harden and temper a chisel though.
As Stinkers said, grind off your mushrooms too.
And buy good chisels. You cannot make a sow's ear from a silk purse. ____________________ Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN. |
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Pete. |
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Pete. Super Spammer
Joined: 22 Aug 2006 Karma :
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Posted: 14:14 - 30 Apr 2023 Post subject: |
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t121anf wrote: | Thanks Marjay, the next step is 400w and double the cost so I’ll give the 150w a try.
Pete, does that apply to cold chisels or just woodwork chisels? Only taking cold here, I sharpen woodwork ones on a whetstone.
Stinkwheel, fortunately my chisels haven’t got to that point yet, good tip though. |
Cold chisel is named for 'cold cutting' so as above it's still hardened and tempered.
If you want to re-harden a chisel heat the tip with a blowtorch until it's hot enough so a mgnet won't stick to it then swish it around in a bucket of water right away, or even better, oil if you have it. Now get some emery and clean the faces shiny, then either put it in the oven at about 230degC or heat the shaft and watch the colour travel down to the tip. When the tip gets to straw colour stop the temper in water again. Don't let it get past golden-yellow.
It's easier to do than it sounds TBH and if you mess it up you'll know right away. If it's still soft you didn't harden it enough and if the tip breaks off you didn't temper it enough. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good |
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Robby |
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Robby Dirty Old Man
Joined: 16 May 2002 Karma :
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MCN |
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MCN Super Spammer
Joined: 22 Jul 2015 Karma :
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Posted: 14:27 - 30 Apr 2023 Post subject: |
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Hardening and tempering:
Heat in a hearth or with a blow torch until the top of the chisel is 'cherry-red'.
Cool it immediately in cold water. Cooling in oil will make a ton of thick smoke and might result in a bit of fire.
Clean off the blackened surface using emery cloth, wet and dry, sand paper etc. to a shiny finish. Heat the chisel again with a blow torch and watch the shiny surface change colour as the metal reaches each tempering stage.
It's a bit like a rainbow (but not ghey).
The heat creeps along the metal so it is easier to heat the shaft and watch the colour move up to the tip.
If you heat it up too quick you risk missing the temperature range and the tempering will not be correct.
For a cold chisel you want the tip to be at the straw colour.
Then dip in the water again to stop the tempering process.
You can phaph about with the sand paper to clean up, heat the whole thing up for a bit then drop it in oil. That will give the surface a burned oil finish which helps prevent corrosion for a while. ____________________ Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN. |
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MCN |
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MCN Super Spammer
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Pete. |
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Pete. Super Spammer
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Polarbear |
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Polarbear Super Spammer
Joined: 24 Feb 2007 Karma :
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Posted: 14:49 - 30 Apr 2023 Post subject: |
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If you use a rotary grinder to sharpen cold chisels. don't get them too hot or you'll fcuk up the heat treatment.
I have a cheap and nasty wet grindstone that does way better than my bench grinder.
https://cdn.aws.toolstation.com/images/141020-UK/800/30131.jpg
£60 from toolstation. Nothing special but way more versatile than a bog standard bench grinder. ____________________ Triumph Trophy Launch Edition |
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MCN |
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MCN Super Spammer
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t121anf |
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t121anf World Chat Champion
Joined: 23 Feb 2007 Karma :
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