Sharpening tungsten carbide chisels and scraper blades

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FairweatherDave

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I have done a bit of reading around but not found anything helpful other than "diamond wheels" for a grinder. I don't have a bench grinder but do have an angle grinder and vice. Should I buy some sort of diamond disc? Advice welcome as it would be good to be able to sharpen my supply of various tungsten blades (they're not cheap and I've got a whole deck's worth of paint to do..... another thread coming :))
 
FairweatherDave said:
I have done a bit of reading around but not found anything helpful other than "diamond wheels" for a grinder. I don't have a bench grinder but do have an angle grinder and vice. Should I buy some sort of diamond disc? Advice welcome as it would be good to be able to sharpen my supply of various tungsten blades (they're not cheap and I've got a whole deck's worth of paint to do..... another thread coming :))
Click to expand...

I use a silicon carbide grinding wheel to sharpen by TC lathe tools. so may be look for a silicon carbide grinding discs or cup wheel for your angle grinder

https://www.google.co.za/search?q=g...igB#tbm=isch&q=silicon+carbide+grinding+discs
 
An angle grinder cannot put a precise edge on a chisel, and the speed and heat may wreck the chisel's ability to hold an 'edge'.


If you don't have a small bench wheel, then a whetstone from e.g. Axminster

http://www.axminster.co.uk/search/?q=whetstone&nR[visibility_search][=][0]=1&

is the next option, though the price may be as much as a decent wheel from Clarkes or Machine Mart.


The advantage of a whetstone is that you cannot overheat the metal, and you can round off the edges of the blades easily so that they don't dig into the paint/GRP. And really, they are pretty quick, and it is very satisfying.
 
When you say "diamond wheel" I'm guessing they're refering to a diamond lapping wheel. On your bench grinder the wheel will be mounted in a way that means you grind on the circumference. A diamond lapping wheel is mounted in such a way that you grind on the face of the wheel. We've got one here and if you like you can send me a sample blade to see what I can do.
 
FairweatherDave said:
I have done a bit of reading around but not found anything helpful other than "diamond wheels" for a grinder. I don't have a bench grinder but do have an angle grinder and vice. Should I buy some sort of diamond disc? Advice welcome as it would be good to be able to sharpen my supply of various tungsten blades (they're not cheap and I've got a whole deck's worth of paint to do..... another thread coming :))
Click to expand...

DO NOT use an angle grinder blade / disc for any thing other than cutting, applying side pressure with say a chisel can cause a conventional disc to shatter, a chap i knew had shrapnel in his arm
 
Thanks for the advice so far. Roger has got me searching. I take your point Sarabande. I have a whetstone but obviously it is not hard enough. Maybe I could use a mini diamond whetstone from Axminster. Really the blades are supposed to be disposable but I was thinking up to £15 for something to sharpen the blades I have would be good. Thanks for the kind offer Colhel. I am blunting the blades at a rate of two a day (maybe) and I want to rotate them so perhaps not practical. Please don't question my sanity about scraping off interdeck (probably 7 more sessions of 3hrs to go) :):) (the thread that will follow will explain)
 
sailorman said:
DO NOT use an angle grinder blade / disc for any thing other than cutting, applying side pressure with say a chisel can cause a conventional disc to shatter, a chap i knew had shrapnel in his arm
Click to expand...
Understand your point on side pressure and shattering, very aware of angle grinder dangers.....
 
I just did a google image search on diamond lapping wheels and it looks like some grind on the circumferance and possibly fit a bench grinder. I haven't looked into it further but maybe have a look yourself? :)
 
I find green carbide grinding drums in a Dremel are pretty good for carbide lathe tools etc.
Diamond sharpening tools are easy and cheap to get thee days.
W&D paper on a flat surface is good for sharpening a lot of things, I find it nice for the final polished edge.

If it's a Harris carbide scraper, you might find you can use blades from an electric planer cut in half? Cut them with a dremel.
Used ones are often good enough for paint scraping IMHO, esp. as I use the scraper with a hot air gun a lot.
 
The earlier suggestion to try to fit a grinding wheel or cup wheel onto an angle grinder is extremely dangerous. Don't even think about it.
A typical angle grinder can run at >10,000 rpm, far in excess of the safe speed fo a small grinding wheel.
The result would be severe.
 
Buy a cheap bench grinder with an adjustable rest, fit a green grit wheel and screw it to a block of wood that you can grip in a Workmate or clamp to a trestle.
 
Very happy to run away from the angle grinder idea. I like the idea of diamond whetstones but was initially put off by the price on the Axminster tools website. Has anyone gone for the ones on e bay at between say £16 and £30? That's much closer to my budget.
 
sailorman said:
DO NOT use an angle grinder blade / disc for any thing other than cutting, applying side pressure with say a chisel can cause a conventional disc to shatter, a chap i knew had shrapnel in his arm
Click to expand...

While I wouldn't for choice use an angle grinder for sharpening anything, it's not correct to say that side pressure is necessarily bad. Angle grinders are primarily used for preparing metal, and are normally used at an angle to the work, which puts side pressure onto the disc. The clue is in the name.
 
earlybird said:
The earlier suggestion to try to fit a grinding wheel or cup wheel onto an angle grinder is extremely dangerous. Don't even think about it.
A typical angle grinder can run at >10,000 rpm, far in excess of the safe speed fo a small grinding wheel.
The result would be severe.
Click to expand...
You can get grinding discs for angle grinders. They are much thicker than cutting discs.
Diamond grinding discs are quite cheap too.
For small tools I prefer something more subtle though.
 
Angle grinders can be fitted with all kinds of disks for use with metal and/or masonry. You can fit cutting disks or grinding disks. Cutting disks cannot take side loads but grinding disks can.

You can also fit sanding pads either flexible or rigid. and you can get silicon carbide sanding disks that will sharpen TC tools at a push.

SC is also used for cutting and polishing in the granite and marble work tops and the speed of a big angle grinder is much less than 10,000 rpm .more like 6000 rpm

I agree not to used a SC grinding wheel designed for a bench grinder on a small angle grinder but it would be ok on a big angle grinder at about 6000 rpm

semi-flexible-fibre-backed-silicon-carbide-discssemi-flexible-main.jpg


http://www.regentstoneproducts.com/...bide_pulsar-premium-silicon-carbide-cup-wheel

http://www.alldiamondtools.com/semi-flexiblefibrebackedsiliconcarbidediscs.html

I used a lot of Silicon carbide 36 grit sanding pads when I was removing all the paint from a ferro boat some years back.
 
What you are after is a straight and sharp edge with the corners rounded off so as to prevent damage.
What I use for plane irons and (wood) chisels is Wet or Dry Silicon Carbide paper. Get a thick piece of glass and lay it on a flat surface. Spray some cutting oil on it and then apply a half sheet of W&D onto it. The oil will hold it in place. Some more cutting oil on the paper and start whetting, applying more oil as necessary. Perhaps not as fast as the 'proper' way but no danger from over-heating, certainly much cheaper and definitely less dangerous to yourself or to your blades.
 
It was the suggestion of a cup grinding wheel in an angle grinder that bothered me. True, properly reinforced SC wheels intended for angle grinders are available, but, AFAIK, these are really for heavy duty rough grinding. I can't see them putting any sort of edge on a cutting tool or blade.
I've got a couple of Norton diamond stones, ie good ones. I've used them to try to restore my dulled Sandvik scraper. They improve it, but I can't get near the original factory sharpness.
 
Well thanks for all the thoughts. I did try and price up Parsifal's cheap bench grinder (about £18) but then a green grinding wheel I could only find one for £22 (axminster) so think I will try Puff's (and Iw395s) SC paper. I've got a good bit of toughened glass for a base. If anyone is interested the scraper is a BAHCO pull scraper (??451??) with a 62mm wide blade and the Bosch power chisel is a 190 E. The Interdeck is of course antislip and therefore gritty and blade blunting, on gelcoat.
 
earlybird said:
It was the suggestion of a cup grinding wheel in an angle grinder that bothered me. True, properly reinforced SC wheels intended for angle grinders are available, but, AFAIK, these are really for heavy duty rough grinding. I can't see them putting any sort of edge on a cutting tool or blade.
I've got a couple of Norton diamond stones, ie good ones. I've used them to try to restore my dulled Sandvik scraper. They improve it, but I can't get near the original factory sharpness.
Click to expand...
Thanks for that. I'm not too optimistic (and my BAHCO is a Sandvik) but my body is telling me sharper tools will be good:)
 
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