How To Grind A Blank With An Angle Grinder

[Chambers]

Ive asked over on BB without an answer.

Today I finished cutting out the shape of a blank, I then preceded to butcher the knife with an angle grinder, I got one side okay and the other was completely ruined. I dont have a bench belt sander that you can make a jig for just a hand belt sander, a disc bench grinder and an angle grinder. Could someone tell me the best way to grind the grind using one of these tools?

 

[Waldganger]

using the hand belt sander put it upside down in a vice or wedge between two bricks or similar so it is reasonably stable, then use it like a bench belt sander.

bench grinder and angle grinder are very rough tools, if you were to use either you would have to finish with files and sandpaper.

 

[nuggets]

try a `flapper disc` on your angle grinder !! But practice a bit on some scrap as your dominant hand -ie right or left handed will produce a better grind !!

 

[Chambers]

Fantastic, thanks for the speedy replies guys

 

[Landy_Dom]

2nd for the flapper disc - one that looks like a grinding disc, not a drum.

keep the revs up and apply very little pressure, keep it moving constantly and keep a visual check after every couple of strokes.

Dom.

 

[Chambers]

Ill give it a go with the upturned belt sander then if I muck that up again Ill get a flapper

 

[Culloch]

Might help to post some pics of what you have done so far, showing both sides of the blank. What size, style of knife, type of grind are you aiming for?

 

[ged]

Waldganger is right, and angle grinder is a very aggressive tool for work as fine as you need for making a knife, it's difficult to make the right sorts of cut and you can easily overheat the steel. I've used a speed controller on angle grinders for some work, that can reduce the energy input to the work, but you'd probably be able to get a bench mounted linisher as easily as a decent speed controller. Also it's possible to overheat an electric motor if it isn't spinning fast enough to keep a good flow of cooling air through it so you have to be careful with speed controllers.

Flap wheels may give a better finish than a disc but I'd still say it isn't really the right tool for the job because whatever you do with a wheel you're still cutting in an arc. I've probably got a dozen angle grinders, but if I were ever going to make a knife I would probably only use one for carving out very rough shapes.

A bench grinder is a lot like an angle grinder in most respects. Still pretty fierce, although it's a bit easier to control the cutting. You're usually working on the surface of a cylinder rather than on the face of a disc, so it's sometimes not too far from what you really want -- especially if it's a large diameter wheel.

 

[Chambers]

Sorry no pics as Ive destroyed the knife completely blunting it.

Would you guys recommend just going at it with a file then? Obviously itll take much longer but if its the better way its the way I'll go

 

[ged]

Sorry no pics as Ive destroyed the knife completely blunting it.

You might still be able to salvage it, but you'll probably need to be patient.

Would you guys recommend just going at it with a file then? Obviously itll take much longer but if its the better way its the way I'll go

You can do it with just hand filing but you will need to be patient. Quite a few people on this forum have posted photos of what they've done and a lot of it is really impressive. Here's an example:

http://www.bushcraftuk.com/forum/showthread.php?t=63487&p=769759#post769759

My feeling is that if you do it with hand tools before trying to use power tools you'll know a lot more about what you want from the power tools when the time comes to ask them for it. You'll still need to understand that hand-held power tools like grinders can produce several times more power than an Olympic athlete, and can do it continuously, so they need careful control if things aren't to get out of hand.

 

[Chambers]

Cool Ill get on with the file and see how it goes from there

 

[Ph34r]

Don't worry mate, think of it as a skills investment! I ruined about 2 blanks before I made a functioning knife - and even then it was not up to my desired standards. My advice would be to get a second cut metal file and hand grind the bevels. Use a piece of wood of any height (as long as it is flat) and then work out the distance you would need to place that piece of wood to produce the desired angle (for scandi 11 degrees per side). Clamp the metal down, attach your file to a strong dowel or other consitently shaped object, have the dowel running across your wood and file away!.

You can pick up the wood, dowel and second cut file from a decent DIY shop (don't bother with B&Q or Homebase - the quality of tools is shocking) for under a tenner.

Kind regards and best of luck,
Ph34r