Weird Sharpening Experience...Bad/Damaged Temper?

[SC T100]

So I set up a few of my axes that needed to be sharpened after some refurb work, and I got a nice setup to where I could apply good pressure with my files. I began working on my No-Name Double Bit and something odd started happening.

As I began getting into the bits (this one needed some serious profiling in some areas...more on that in a sec), I noticed the file would bite, begin removingmetal, but after two or three strokes it would sort of skip and the bit would end up gouged.

Pic here:


I know it's hard to see, but the darker cuts are to what I am referring. So then I looked at the file.


That large fleck is a piece of steel that seemed to be ripped out of the bit, would jam in the file, and then gouge the bit as I filed. So here's my question...what is the issue? Is it something I am doing? FYI this happened on a Nicholson file, as well as my dedicated Heller Nu-Cut files. Oddly enough...one of the four sharpening sides did this very little, while it occurred more often on the other three.

Or did someone kill the temper on the edge by using a grinder? I ask this because the grinds were pretty uneven side to side and top to bottom...it was rusty when I picked it up, so who knows.

Or, is it just a poor-quality axe head? I had offset ribs in the eye (two close on one side, two far apart on the other), so I assumed it was a decent axe. I finally got a nice edge on it, but haven't used it yet to see if it'll hold. I just wanted to see what some of the axe gurus thought.

FYI...this happened right after on my Cayuga double bit as well, but not nearly to the degree as the no-name. Any hints/tips/suggestions/clues?

 

[Alan G.]

Are you cleaning the files with a file card as you work? Looks like the file is just plugged up to me.

 

[SC T100]

Yes, definitely cleaning it as I go. It would happen again shortly thereafter.

 

[garry3]

Try going into it with a more heel to toe motion not just straight into the bit.

 

[Square_peg]

Hmmmm. Could be an uneven heat treat or temper damage caused by over heating. I've seen a few axes that acted this way. Try changing the both the speed and pressure on the file and see if that helps.

 

[SC T100]

Try going into it with a more heel to toe motion not just straight into the bit.

Hmmmm. Could be an uneven heat treat or temper damage caused by over heating. I've seen a few axes that acted this way. Try changing the both the speed and pressure on the file and see if that helps.

Thanks guys! I'm glad to hear it's at least happened to someone else. I'll give your suggestions a try.

 

[Bridger]

Do you file with a motion from left to right or right to left? I intuitively file from left to right, but I noticed I get a finer finish and experience less clogging with a right to left stroke. I think it has to do with what direction the file's teeth are slanted. You can notice a similar effect with double cut files. One motion will leave an even finish while the other leaves deep grooves that coincide with the tooth spacing. I finally figured this out after getting tired of carding my file every other stroke to prevent pinning.

 

[SC T100]

I file left to right as well. I will have to experiment with direction, pressure, and speed to see what works best to prevent the gouging. Thanks for the tips! I was also getting tired of carding/wiping the files with a shop towel every few strokes. I didn't have to do that as much with my other axes that are of known quality. I am still wondering if I have a poor axe head (I thought it could be a Kelly, but no way to tell), a poor example of a good axe, or a head that has had the temper damaged. I suppose once I use it I'll see if it holds an edge.

 

[applevalleyjoe]

Do you file with a motion from left to right or right to left? I intuitively file from left to right, but I noticed I get a finer finish and experience less clogging with a right to left stroke. I think it has to do with what direction the file's teeth are slanted. You can notice a similar effect with double cut files. One motion will leave an even finish while the other leaves deep grooves that coincide with the tooth spacing. I finally figured this out after getting tired of carding my file every other stroke to prevent pinning.

Good to know...I'm starting to resharpen 5 axe heads as we speak with a Nicholson Bastard file.

 

[SC T100]

So while pulling the handle off my Cayuga, I was still bothered by the thickness of the bits, and was still a bit surprised at their uneven grinds, similar to the no-name double bit that started this thread. So I experimented with the suggestions above and they really seemed to help. This time I had the axe head in a vice held higher (allowing for less pressure), and I varied the speed and stoke of the files. The gouging was noticeably lessened. I think I was simply overpowering the files and bits trying to remove too much metal at once. Additionally, as I got a little impatient last night I would accidentally begin adding more pressure and the gouging would happen again. I would then back off on the pressure and the files would cut cleanly again. Go figure...lesson learned.

So, the moral of the story is similar to a chef's knife...overpowering it leads to bad cuts, but letting the blade do the work is easier and cleaner, with better results. Same with files.....apply some pressure, but let the files do their job...slowly if necessary.

 

[the possum]

I briskly tap the tip of my file against the vice after every stroke or two, to knock the filings out of the teeth. If filings build up, stick together and start gouging your work piece, this is called galling. It's mainly an issue with softer steels, since the filings have to be soft enough to bend around & conform to the teeth and each other. But the same thing can happen with hard steel and clogged sharpening stones, so it's not always proof positive of the heat treat.

However, in your case, I'm guessing that bit is relatively soft. Maybe still hard enough to get some use out of- about like a lawn mower blade, perhaps? But the edges on my antique axes are so hard a file will barely bite on 'em, and it ruins the file faster than progress is made, so I use stones. So the fact that you can file away steel like that in first place says as much or more about the heat treatment, than the galling does.

 

[SC T100]

Thanks for the info! I need to check this again against my known vintage quality bits...it's been a while since I needed to hit them with a file!

 

[Square_peg]

Pretty much all vintage axes can be sharpened with a file - with few exceptions. The problem arises from the oxidation layer that forms on old axes (under the rust). That surface layer is harder than the underlying steel.

Work through the oxidation layer in one small area. Then work out from there with the file, raising the oxidation layer from below. It's much easier this way and you won't dull your file so easily. When your file clogs up, clean it with a file card.

 

[SC T100]

Pretty much all vintage axes can be sharpened with a file - with few exceptions. The problem arises from the oxidation layer that forms on old axes (under the rust). That surface layer is harder than the underlying steel.

Work through the oxidation layer in one small area. Then work out from there with the file, raising the oxidation layer from below. It's much easier this way and you won't dull your file so easily. When your file clogs up, clean it with a file card.

Yep...I touched up a few of my heads last night and on one of them, a no-name single bit that has a huge tempered area, I could hardly get the files to bite due to that super hard layer. I thought I had some super hard Forest Service axe until I got through that hard "skin" of oxidized steel. I actually have found that hand sanding those areas first, before using the files, will help the file bite easier and quicker too. My Plumb carpenter's hatchet, even though it has black paint, has surface rust underneath the paint, and it, too, had a hard layer that needed to be removed before the files would bite well.

 

[the possum]

While it can be done, I just don't like ruining a perfectly good file when a coarse stone does the work faster.

 

[SC T100]

Do you mean a true grinding wheel, like in An Ax to Grind? Or are you referring to a slab stone like you pick up a hardware store? I have a coarse/fine stone that I use once the bit profile has been set by the file, as I can't seem to remove material fast enough with the stone I have (it's a cheap stone, but I can't safely apply enough pressure to really remove metal at a significant rate. How do you use yours?

 

[the possum]

If I have a lot of metal to remove, like in restoring an antique or removing a big nick from the edge, I usually just use a bench grinder or my belt sander. I keep things cool with a bowl of water between passes and take it easy once it gets to the very edge. I don't like to use a file on steel that's over about 45 Rockwell, but will use 'em on steel in the lower to mid 50's Rockwell if the shape prevents me from using the grinder. Once things get to the upper 50's or 60, I'd rather not use a file at all, and do it entirely with hand stones if the grinder isn't an option. I have a big silicon carbide stone that's somewhere around 80-120 grit, and I lock the blade in a vice and use the stone like a file when the steel is that hard. An extra coarse diamond stone takes off metal pretty quickly, too. Once the geometry is established I start polishing it down with progressively finer sharpening stones until I'm satisfied.

My hatchet and one axe feel like they're around 56-57 Rockwell just by the way they work on my stones, one old double bit has a very hard edge that feels more like 59, and I have a scythe that I could swear is over 60- a file just skates across it.

 

[SC T100]

Thanks, I may give that a try too!

 

[Square_peg]

No hand powered abrasive can match the speed of a file for removing steel up into the high 50's RC. Of course powered abrasives can. And use of powered abrasives can be done safely just as the possum described. But for the inexperienced there's a real danger of ruining the temper of a tool with powered abrasives. On a fine axe I might remove some material back away from the edge with powered abrasives but would never hit the very edge except under continuous water flow. The thin metal at the very edge can heat up instantaneously under powered abrasives.

The edge of a fine axe is saved for the file. Then honed with stones.

 

[garry3]

So while pulling the handle off my Cayuga, I was still bothered by the thickness of the bits, and was still a bit surprised at their uneven grinds, similar to the no-name double bit that started this thread. So I experimented with the suggestions above and they really seemed to help. This time I had the axe head in a vice held higher (allowing for less pressure), and I varied the speed and stoke of the files. The gouging was noticeably lessened. I think I was simply overpowering the files and bits trying to remove too much metal at once. Additionally, as I got a little impatient last night I would accidentally begin adding more pressure and the gouging would happen again. I would then back off on the pressure and the files would cut cleanly again. Go figure...lesson learned.

So, the moral of the story is similar to a chef's knife...overpowering it leads to bad cuts, but letting the blade do the work is easier and cleaner, with better results. Same with files.....apply some pressure, but let the files do their job...slowly if necessary.

I have an old True American that I originally thought that some one had messed with the heat treat, it will wreck a good file. I was going to put it in an oven per recommendations on this forum, but I gave it my dry hard wood test and its good to go. There is no sign of it ever being heat treated after it left the factory or sharpened with a power tool. Its just that hard.