Bits Good vs. Worn

V

vcbvcbvcb

Joined
Aug 1, 2012
Messages
633
Thanks to you guys, I now know how to tell a worn Kelly Perfect form a good one. However, I'm stuck when there's no bevels to measure. I just bought this Blue Grass. The EBay description siad it was 7" long from poll to edge. It is actually 6 1/2". How can I tell how much the bit is worn back if I don't know the original length? With thie one I went on the angle of the heel and toe.

 
It looks fine...most worn heads look "stubby." When in doubt a vinegar soak will show the hamon line, or an easier way is to sharpen it with a file. If it's like butter, it might be out of steel. If it's hard to file you're good to go. That one looks fine as the proportions look good. I'd run it!
 
That's why I thought I might have goofed. The head looks stubbier in person that it did in the EBay photos. However, I took the pic I posted here and it's a pretty accurate representation of the head. It is dull, so I'll have at it this weekend. Based on the recommendations I got here, I bought Pferd files, a medium double cut, and a fine single cut. I already had course china freight files. This is the first time I've taken a file to an ax. I think I'll start with fine. Any suggestions? Is oil ever used with a file to lift the dust away?
 
Your suspicion is dead on. Now that I think of it, I've read on this forum to use sidewalk chalk. I'll give youtube a shot.
 
I've been grappling with the same question, and have just finished wire-brushing a Kelly double-bit. There's a distinct colour difference in the steel which I take as an indication of the hardening line and so amount of wear left. More than 2" each side in this case. Of course you can do that when you own the head but it isn't much work for a seller to do.
 
I have seen videos of guys unwilling to use a grinder to sharpen an ax because it's too fast and will hurt the temper, but they'll use a belt sander. I have both, the the belt sander is considerably slower than the grinder. Is it OK to use a belt sander in place of a file? I've also seen where guys dip the bit in cold water while using a belt sander.
 
vcbvcbvcb said:
Thanks to you guys, I now know how to tell a worn Kelly Perfect form a good one. However, I'm stuck when there's no bevels to measure. I just bought this Blue Grass. The EBay description siad it was 7" long from poll to edge. It is actually 6 1/2". How can I tell how much the bit is worn back if I don't know the original length? ...
Click to expand...

Bluegrass axes were reportedly made by Plumb (details in current thread about Plumb dating), and Plumbs were advertised as having 2" of heat-treated steel, so that axe probably has lots of life left.

Somebody who uses a belt sander for sharpening could give you some tips, I'd say cooling with water is a good idea.
 
vcbvcbvcb said:
I have seen videos of guys unwilling to use a grinder to sharpen an ax because it's too fast and will hurt the temper, but they'll use a belt sander. I have both, the the belt sander is considerably slower than the grinder. Is it OK to use a belt sander in place of a file? I've also seen where guys dip the bit in cold water while using a belt sander.
Click to expand...

I keep a water quench at hand when using a belt sander or grinder to profile. But I have found that new belts, specifically ceramic belts, and a light touch cause very little friction and heat. Old warn belts are a no no.
 
Among fine woodworking tool users, quenching is regarded as a no no as it produces micro cracks in the steel.

As for an angle grinder, I've had no trouble with one on a Kelly Australian head but did keep away from the edge by about 1/4". It's a heat dissipation problem closer.

IME ceramic sheet discs on something like a WorkSharp can cause problems at the edge but not belts. Again it's a matter of a lot of cutting in relation to the amount of free running.
 
The finest belt choices I can find are 120 grit ceramic to 240 grit aluminum oxide. An suggestions?
 
I''d say to start with the coarse files to get the bit bevels where they need to be, then proceed to fine. But be aware the cheap files may not bite that bit...Plumbs are usually very hard to file, so you may just end up having to use whatever file actually bites. I am sure new Pferds will work great.

Use the video tutorial from An Ax to Grind, and you'll be all set.

If you haven't done a head on the belt sander before I would start with a cheap or bad head, not the one you want to use. You can't really overdo it with a file, versus power tools which can cause big issues if you mess up. And yes, you can still ruin the temper at the thin edge with a belt sander, *especially* with finer grits.

Just clamp the head to a bench and use the files until the bit fits the gauge from the print version of An Ax to Grind (google it...it's available in a few places). Hone with stones and you'll have a razor sharp axe.
 
I'll start with files. The good news is that I've compared the specs. On a few belt sanders and I think mine is pretty slow, at about 1200 rpm.
 
You can belt sand it. As Quinton said, use sharp belts and you'll be surprised how much work you can get done without creating much heat at all. Keep the axe moving and if there isn't much work to be done, you'll likely never create enough heat to even burn yourself, let alone effect the temper. If you've got a lot of material to take down just go slow and use a light touch - if the steel can't burn you, you're miles from doing any damage.
 
File - coarse to fine. You can use oil if you like, but don't go over board with it.

Then you can use a puck to get some finer work in.

Then you can strop to get it real fine if you like.

No need for any sander, grinder, etc to sharpen. Worst idea ever. Keep it simple. Files, puck, strop if needed. Most of the time you can do what you need with files and puck. Grinder and sander are a short cut option that aren't needed IMO.
 
If one regularly uses a belt sander for sharpening tools, a variable speed model is best. Lower speeds reduce friction, and optimize performance.
 
You must log in or register to reply here.
Back
Top