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21st December 2012, 11:10 AM #1GOLD MEMBER
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Grinding a chisel - lose the steel temper?
I have acquired a Titan chisel that has collected some rust on the flat side near the cutting edge over a period of time. I have wire brushed the steel away, but the rust has left a small pockmark which will eventually show up on the chisel cutting edge, looking a bit like a gouge.
I understand the best way is to grind the steel flat past the rust pocket, and then rebuild the sloping face and cutting edge.
I have never put a chisel near a grinding wheel because of the heat generated, and the fear of losing the steel temper and hardness, and ruining the chisel forever.
Can anyone please advise the best way to go about this? I wish I had now paid more attention to the metallurgy subjects at TAFE all those years ago.regards,
Dengy
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21st December 2012 11:10 AM # ADSGoogle Adsense Advertisement
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21st December 2012, 12:35 PM #2
A photo would help as it depends how far from the cutting edge the pitting is.
But depending where it is you could grind the tip off past the pitting using a grinder, you could ignore it if is not to close to the bevel.
You could flatten the back depending on where the pit is or you could ignore it.
Search google or this forum for rehab a chisel to get you started.
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21st December 2012, 12:45 PM #3Retro Phrenologist
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Take it slowly, really slowly, and dip the blade in water frequently
OR
get yourself a wet grinder or a low speed grinder.____________________________________________________________
there are only 10 types of people in the world. Those that understand binary arithmetic and those that don't.
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7th January 2013, 07:43 AM #4
Very good grinding article IMHO ...
Old Street Tool, Inc. - Plane Articles - Tips on grinding plane irons and chisels
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7th January 2013, 08:25 AM #5GOLD MEMBER
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The Narex 1/2" skew chisels sold by Lee Valley are a real bargain for good steel.
For carving, I ground the bevels back from 25 to 20 degrees and did that by hand on stones. No biggie.
Less that 2 weeks later, I ordered pair #2. One of those, I have left as-is.
I used a grinder running at 3750 rpm to totally square off the end.
Then I used a belt sander to make a 10 degree bevel each side.
I did some oil stone work, then 1K and 4K water stones then honing on my strop.
I made myself a wonderful carver's stop chisel.
The grinding: take it real easy, one pass at a time. Wait. Relax.
I know it's as noisy as Hello.
If you can't touch the edge with your bare fingers = too fast and too hot.
I had a pot of cold snow but, I took my time and never shocked the metal.
Yes, you have to joint the tool beyond the damage.
Yes, you should paint the newly developing bevel edge with black felt marker
from time to time so that you can see your progress and where the metal is coming off.
That has shown me that, bevel down, I tend to lean on the RH side a little.
I have to make a conscious effort not to do that or I can turn any chisel into a skew.
All in all, I had a good time making that stop chisel.
Best wishes for your project!
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7th January 2013, 09:49 AM #6
The best way to grind a chisel fast and clean with the least chance of losing the temper is to dress the grinding wheel frequently. the difference you will notice in how the tool behaves at the grinder is HUGE. Just don't breathe the dust coming off the wheel as you skin it alive
The best dressing stick I have, was shown to me and made by a guy From Ace saw service in Braeside Melbourne, they take the diamond teeth of used concrete cutting saws and braze 3 or 4 to the end of a bolt head, you can then drill a hole in a stick and glue the bolt shaft in .
With this tool I flatten a grinding stone as it spins , or re shape stones ,usually the corner to get a radius, and do the same to grinding and cutting discs on the angle grinder when I am doing the delicate shaping of some of my home made router bits [ a section of file welded to some 1/2 inch bright rod, annealed then shaped ] or moulding plane irons.
I would inquire at your nearest saw service place to see if they can make you one up.
I have also used a bought single diamond in the end of a rod, it worked till the single stone which was tiny shot out one day . And also used the type with the metal disks that rotate when they are put to the wheel.
Rob
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7th January 2013, 10:09 AM #7GOLD MEMBER
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I bought this diamond dresser for $17 ( including postage) on eBay recently, delivered from the Illawarra region south of Sydney. Wish I had known about the potential danger of the dust that occurs during the dressing.
Abrasive wheel only needed a very light touch to get it truedregards,
Dengy
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7th January 2013, 04:27 PM #8
Grinding a chisel - lose the steel temper?
...I'll just make the other bits smaller.
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7th January 2013, 04:48 PM #9GOLD MEMBER
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Just go to eBay, do a search for "DIAMOND DRESSER , GRINDING WHEEL DRESSER", and there you have it, on a Buy it Now basis.
Before buying, have a look at the sellers feedback. Choose the seller with the highest +ve feedbackregards,
Dengy
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7th January 2013, 06:15 PM #10GOLD MEMBER
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I beg to disagree. My goal is a tool = carving sharp. That is quite different from woodworking sharp.
Wheel dressing will not allow me to shove a $75 gouge into a 3750rpm wheel just as hard as I can.
Dress, Schmess. The tool cooks. There's a whole lot left out of that explanation.
Dressed or undressed, if you go easy and don't let the friction boil your oil,
any stone at almost any speed, grooved rotten or not, will get the job done today.
If you need 1/4 wave from optical flat, there are cheaper ways to get there.
As a short note added in proof, I get no joy at all from wood carving unless my tools are
carving sharp. All the time. I can cheerfully admit that I've figured it out,
I can replicate my sharpening processes which make me content in my retirement.
Otherwise, you discover that I wear a very, very thin veneer of civilization.
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7th January 2013, 08:36 PM #11SENIOR MEMBER
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When grinding the chisel you will feel the heat being transferred into your finger tips. Also move the chisel across the wheel and do not just park it there. When you feel the heat stop sharpening for a couple of minutes and then recontinue. I personally do not like dipping into water as it encourages rust.
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8th January 2013, 08:57 AM #12
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8th January 2013, 09:36 AM #13
A 60 grit aluminium oxide wheel will cut fast and cool if kept dressed and not forced. A good way not to burn your tool when doing a major redress is to grind the cutting edge blunt past the defect. Now when you grind the bevel you don't have a thin edge that can very quickly build heat and burn.
Cheers, Bill
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8th January 2013, 02:09 PM #14
That is the best tip I ever got about using the grinder I think. Chris Pye gave essentially the same idea but re using only stones in a dvd on carving (chisels).
I'm not sure about the white wheel though. What is the next grit up from 60? I thought I got a sixty, but I couldn't get it spinning nicely for a year or so and now the label is off it.
There are no years of experience behind these observations, but i just went out again to try a few pieces.
I took this rubbish Chrome-Vanadium paint-can-opener (32mm) and flattened the bevel on the side of a grey wheel and a white one - both on the same grinder.
I would judge (roughly) that it took twice as many passes on the white to get the flat bevel, and it was definitely heating up faster on each pass. After three swishes on the white I wanted to dunk it in the jar ... but was only a little warm after six swishes on the grey wheel.
Again - I can't swear that it is a sixty. And I have no idea what the grey wheel is.
grind 002.jpg
Just putting it out there.
Paul.
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8th January 2013, 02:24 PM #15
Also - ID help please ...
Is this a Norton 3X wheel or something like that?
It is a light bluey-grey colour and feels a little bit soft and chalky like a waterstone.
Sounds like a ceramic when tapped.
The setup was on a termite-frazzled table put out for collection a good while back ... with a washing machine motor bolted alongside.
I tried using a 1400rpm motor, two belts and another double-pulley to gear down the speed (some time ago - trying to get a wet grinder happening) ... but it was still like travelling behind a F1 car on a wet track
Never thought of making a hand-turned affair ... but then I knew nothing about grinders back then.
grind 003.jpg grind 004.jpg grind 005.jpg
Cheers,
Paul
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