Grinding blade stock flat?

J

jaymeister99

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Sep 14, 2010
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Any (low budget) ideas for flattening blade stock?

I've been running my 2x42 for too long on a 36 grit belt with a modified 12" platen. Its barely cutting it.

I had my first knife flat ground on a pro surface grinder at work. Got to get one! But that will have to wait until I got a few extra thousand to play with.

Any suggestions until then?
 
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This may sound obvious, but you can buy pre ground flat stock in various materials. The cost is a little more, but it would be cheaper than wasteing belts and the material will be in much better shape.
 
melsdad said:
This may sound obvious, but you can buy pre ground flat stock in various materials. The cost is a little more, but it would be cheaper than wasteing belts and the material will be in much better shape.
Click to expand...

I checked that out. A bit pricey and a bit of a limited selection of stock for anything precision ground. Got to be a way besides using a $2500+ surface grinder (or sweating on the 2x42 for an hour).:thumbup:
 
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Well there is always the TW90 with surface grinder attachment:p

All I do if I am working on non PG steel is cut it out to the shape I want, profile it, lay it out, and grind my bevels. Then I glue some heavy grit paper to some glass and start removing any thing that needs to be to get he blade flat. Once I have ground the blade out there isn't much left to be flattened of the original finish on the steel.

Its not the best or easiest way to do it, but it does work. I am looking into making a SG for my GIB or score a cheap working SG that fits in the space I have.
 
I do what Unky does. Once the bevels are ground there is usually less than 2 square inches of exposed flat left (I like high grinds). This small an area is not really a problem to deal with on backed sandpaper, as long as the original surface isn't too ugly.
A disk grinder is probably my next purchase but I'm getting along without it for now.
 
Something of a side question: I'm ginding off 440C from Alpha Knife Supply. Is this typically hard to grind flat? The first piece of 440C grinded flat fairly quickly. I got another piece I tried for over an hour. It still looks the same except for a slight shine to it.
 
I have no experience with 440C or anything from Alpha, all my steels have come through Knifemaker.ca except the last piece of O-1 because of the postal strike we had up here. I have yet to be not able to get anything not reasonably flat though with the method I mentioned.
 
unky_gumbi said:
I have no experience with 440C or anything from Alpha, all my steels have come through Knifemaker.ca except the last piece of O-1 because of the postal strike we had up here. I have yet to be not able to get anything not reasonably flat though with the method I mentioned.
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How long does it take to do that? What grit paper are you using?
 
I do all my grinding on a 2X72. I do not have a surface grinder. You can't work with worn out belts no matter how good the grinder is, If you can't do it on that 2X42 you won't do it on a $3000 machine. Frank
 
Frank Niro said:
I do all my grinding on a 2X72. I do not have a surface grinder. You can't work with worn out belts no matter how good the grinder is, If you can't do it on that 2X42 you won't do it on a $3000 machine. Frank
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The belts aren't worn out. 36 and 60 grit. The 36 has been used on two knives, the 60 is new.
 
Jay,
I haven't had any problems using my 2x42 to even the blades. I do it after I put the bevel on the blade, then put the blade on a strong magnet and push it agains the flat platen on the Craftsman. After I get it flat I will usually have to clen up my bevels again, but not much. Remember, it doesn't have to be precision, just has to look good to they eye.
Jason
 
Somethings not right. I'm starting to wonder if my grinding the other blade put a slight bow into my platen(?). The edges of the knife are clean and shiny, the middle has a slight shiny look but is still very rough. Take a look:

The first knife (I should say the knife I grinded just before this one) is on the bottom, the one I got problems with is on the top. Is this scale? But the other one had the same stuff, it came off (relatively) easy.

knifeflatgrinding.jpg
 
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jaymeister99 said:
Somethings not right. I'm starting to wonder if my grinding the other blade put a slight bow into my platen(?). The edges of the knife are clean and shiny, the middle has a slight shiny look but is still very rough. Take a look:

The first knife (I should say the knife I grinded just before this one) is on the bottom, the one I got problems with is on the top. Is this scale? But the other one had the same stuff, it came off (relatively) easy.

knifeflatgrinding.jpg
Click to expand...

work the other side of the blade , that will tell you if the problem is in the steel or your platen . You also need a new 36 grit belt probably .

and yes , that is mill scale from hot rolling .
 
jaymeister99 said:
How long does it take to do that? What grit paper are you using?
Click to expand...

It takes me about 45 minutes at the longest to flatten anything I have had with 150 grit wet dry and the glass. Most times it is about 20 minutes, but I would have already ground out my bevels when I do it so there isn't much left to take care of.
 
ONeill said:
work the other side of the blade , that will tell you if the problem is in the steel or your platen . You also need a new 36 grit belt probably .

and yes , that is mill scale from hot rolling .
Click to expand...

The other side looks pretty much the same. A 36 grit belt should grind through this without a problem right?
 
"Pickling" your barstock in regular vinegar overnight will make the mill scale much easier to grind away. A good deal of it will actually flake right off with a steel brush after being etched that way.

I second the notion of buying PG stock whenever possible. It's worth every penny.
 
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