Sharpening a convex edge.

Tiiiiiiiim

Tiiiiiiiim

Joined
Jun 11, 2010
Messages
952
Hey folks. I was just wondering if there was a guide to sharpening a convex edge. I just got my chopper back from HT and started on the con-vexed edge. I got something that resembles an edge using a 120# belt but alas thats the finest belt my grinder will take. So i moved from the grinder to the bench and started using one of those tiny ezy-lap diamond rods. I THINK it slowly working.

Does anyone have any tips for sharpening a convex that i could try? I looked for a sharpening sticky and couldn't find one.

Thanks!

If it helps -
52517884.jpg

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How about a 120 or 220 wrapped around a file about 3/4" wide ? I expect you will have to decide if you are going to stay with a covex edge which is what I would recommend or a V edge. Frank
 
Hi Tim, i am on the Gold Coast Aus, I recognise u from ABF, you can buy finer belts here in Aus, I have 120, 220, 320,400 & 600 for big choppers these combined with a strop wil give you a razor edge.
Cheers Tracula.
 
Frank Niro said:
How about a 120 or 220 wrapped around a file about 3/4" wide ? I expect you will have to decide if you are going to stay with a covex edge which is what I would recommend or a V edge. Frank
Click to expand...

The only thing with using paper wrapped around something is it wears out really quick. Being a chopper I definitly want the strength of the convex edge.

tracula said:
Hi Tim, i am on the Gold Coast Aus, I recognise u from ABF, you can buy finer belts here in Aus, I have 120, 220, 320,400 & 600 for big choppers these combined with a strop wil give you a razor edge.
Cheers Tracula.
Click to expand...

Hi tracula. Yeah, but i have a 150mm wide grinder. Most places only sell 25-50mm belts.
 
No worries Tim, maybe try using all your old belts, try some scrap steel past your old belts to make them a bit finer, or it might be time for a different belt sander.
Cheers Tracula.
 
tracula said:
No worries Tim, maybe try using all your old belts, try some scrap steel past your old belts to make them a bit finer, or it might be time for a different belt sander.
Cheers Tracula.
Click to expand...

Yeah i have a really worn 120. I'll give that a go tomorrow. I will need to get a new grinder some time...but i can't afford it now. It's fine for other stuff, i can just use course stones after the 120#. It's just this chopper has a huge re curve and i only have that one round diamond stone.
 
I would suggest you get a 25X762mm belt sander or a 10 or 25mm hand held power file ( sort of a mini belt sander).
Try the Australian discount tool places like Just Tools Australia, Discount Tools, Sydney Power Tools,and the other tool suppliers.

Using a round diamond file will produce a poor edge. They are mainly for touching up an edge, and will wear out fast if used for much metal removal.

The sand paper and a stick of wood system is a good one, and should not be discounted. It will use up paper fast, but so will a small belt sander......and you can't ruin the edge by overheating it.

First, take the edge down to the final shape with your 120 grit belt sander. You probably have it too thick right now by the looks of the photo. Then when it is sharp on the 120 grit, switch to hand sanding with a 25mm block of wood and strips of abrasive paper. Use wet-or-dry type paper from the auto supply or a good hardware supply. Start with 220 grit, then 400. That should be fine for a chopper.
BTW, Lubricate the paper with water that has a teaspoon of baking/washing soda in it. This will make the paper work better and hold down the rust as you sand. Dry and oil after each session, as always.
 
If you want to do it by hand take a scrap piece of metal or a board and put a piece of mousepad or leather on it. Clip sandpaper on it and it'll do a great job of sharpening. The pad will give a bit to allow for convex sharpening.
 
+1 to what Will said. A mouse pad work great, but for a recurve lik that you may want to cut it into a 50mm wide strip to get inside the recurve section.

There are also lots of shapening tips in the maintenance subforum.


-Xander
 
bladsmth said:
I would suggest you get a 25X762mm belt sander or a 10 or 25mm hand held power file ( sort of a mini belt sander).
Try the Australian discount tool places like Just Tools Australia, Discount Tools, Sydney Power Tools,and the other tool suppliers.

Using a round diamond file will produce a poor edge. They are mainly for touching up an edge, and will wear out fast if used for much metal removal.

The sand paper and a stick of wood system is a good one, and should not be discounted. It will use up paper fast, but so will a small belt sander......and you can't ruin the edge by overheating it.

First, take the edge down to the final shape with your 120 grit belt sander. You probably have it too thick right now by the looks of the photo. Then when it is sharp on the 120 grit, switch to hand sanding with a 25mm block of wood and strips of abrasive paper. Use wet-or-dry type paper from the auto supply or a good hardware supply. Start with 220 grit, then 400. That should be fine for a chopper.
BTW, Lubricate the paper with water that has a teaspoon of baking/washing soda in it. This will make the paper work better and hold down the rust as you sand. Dry and oil after each session, as always.
Click to expand...

I'll have to say Stacy, the fact that you switch to Metric for advice rocks. But, shouldn't it be 5mL of baking/washing soda? :rolleyes: :D
Your advice, help is always appreciated. You are such a wealth of info.
 
fluidsteel said:
I'll have to say Stacy, the fact that you switch to Metric for advice rocks. But, shouldn't it be 5mL of baking/washing soda? :rolleyes: :D
Your advice, help is always appreciated. You are such a wealth of info.
Click to expand...

It's ok. We have teaspoons in Australia too ;)
 
For convexing recurves, I greatly recommend using a thick city phone book.

Let the loose (opening end) of the phone book roll over the lower pages, and it will cradle the recurved sections beautifully. I use this method for sharpening khukris, and haven't found a better one for larger convex choppers.


The mousepad works great for small stuff, but most mousepads commonly available aren't suitable anymore. I use a piece of 1/2" closed cell foam pad now, which works better for me than any mousepad I've found.
 
javand said:
For convexing recurves, I greatly recommend using a thick city phone book.

Let the loose (opening end) of the phone book roll over the lower pages, and it will cradle the recurved sections beautifully. I use this method for sharpening khukris, and haven't found a better one for larger convex choppers.


The mousepad works great for small stuff, but most mousepads commonly available aren't suitable anymore. I use a piece of 1/2" closed cell foam pad now, which works better for me than any mousepad I've found.
Click to expand...


Another interesting one. Thanks javand.
 
cbr900son said:
I wouldn't sharpen till you have the handle on and shaped.
Click to expand...

How come?

I want to sharpen it mostly before i sand the hole blade up so i can get any sharpening scratches out. I want To sand the whole blade up before putting the scales on because it's easier to get an even finish. I can always mask the blade up to avoid damage or cutting myself while attaching the scales.
 
Thanks for the help everyone. The edge was too thick so i thinned it down with a worn 120# and got a nice burr. I set up a bit of foam on my bench for sanding the convex/recurve.

This is what i ended up with for sharpening/sanding the re-curve and convex edge.
13154690.jpg
 
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