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UncleBillyKnives
12-02-2010, 10:03 AM
I have been fixing, cleaning up and sharpening knives for friends over the last few months and a couple were Marbles with convex grinds. They get wicked sharp and it has got me thinking about trying one, but there is not a lot of "how to" info on the web. Only one video on YouTube and the way the guy does it is to flat grind at first and then to finish on the slack belt to blend and sharpen.

For the makers out there that do convex grinds, do you flat grind first and then switch over to the slack belt or do you grind the whole thing with a slack belt? Also, because there is no secondary bevel, I assume you would grind edge down so as not to cut the belt. This is how I sharpen the Marbles using an 800 grit cork belt full of polish. A few swipes and it was scary sharp.


Thanks for and info!

UncleBilly

Doug Lester
12-02-2010, 11:17 AM
The only convex grind that I do is on the secondary grind but if you wanted to do a convex grind all the way out to the spine, you could. It would give you a blade with plenty of strength behind it to stand up to chopping. Like just about everything in knife making, the geometry of a blade is a series of trade-offs. Remember to let the form follow funtion. I grind in all my final edges with the edge up and I've never had a blade cut into a belt.

Doug Lester

Todd Robbins
12-03-2010, 03:41 PM
I flat grind first, then convex, either just the edge or the entire bevel, depending on the intended use of the knife. I'm a wierdo I guess, but I grind one side edge up and the other side edge down, but always left to right, and I've never cut a belt either.

Cliff Fendley
12-04-2010, 08:08 AM
I flat grind before HT the blend it into the edge and make it convex after. Edge up before HT, edge down after. I was never shown how to convex grind so don't know if this is the best way or not but this has been what worked for me. There may be a better way, don't know.

UncleBillyKnives
12-04-2010, 11:43 AM
I flat grind before HT the blend it into the edge and make it convex after. Edge up before HT, edge down after. I was never shown how to convex grind so don't know if this is the best way or not but this has been what worked for me. There may be a better way, don't know.

Cliff,
This is the way I was thinking of doing it. Thanks for the feed back.

JDW
12-05-2010, 06:38 AM
Check out http://www.turleyknives.com/ he has a video on his site on convex grinding. He makes and awsome convex. The convex grinds that I have done were flat ground first then blend into a convex with the slack belt.