How to REALLY sharpen my Chip knives?!?

skinnyeddie · #1 10-19-2006, 10:55 PM

I have a Barton and Flex-cut. I stuck with chip-carving for awhile until I realized my knives were getting dull and I couldn't figure out how to get them really sharp, like when I first bought them. The quality of the chipping (I was still learning mode) began to suffer greatly and I lost interest.

I even purchased all the available "sharpening stuff" in a desperate attempt to restore my edge. Here's what I have: One of the big stones with oil, the expensive set of pink and white ceramic stones, a strop, and some of that yellow strop compound gunk that you rub on like a crayon.

Now, I have tried to follow the "hold it at ten degrees" instructions seen in the Barton and Pam's book. I am thinking maybe I am not doing it LONG enough as I saw somebody's post on here that said spend an HOUR on each ceramic stone...is that for real?!? If that's how long it takes, then no wonder I'm not getting anywhere...I spend maybe a minute or two at each attempt.

What do I need to do here, just chill in front of the TV for an hour using the stone?

Any help is appreciated because I really want to get back into chipping and use all this nice equipment I've purchased that's been sitting around in a storage box.

Help!!!

-Andy

Clifford_Parker · #2 10-20-2006, 12:28 AM

While an hour does seem a bit too much a minute or two is too little. Try the 30 - 5 technique.

30 strokes on each side
25 " "
20 " "
15 " "
continue till you reach zero.

Do this on each side of the stone and then give the blade 10 stokes each side on the strop.

SchreiberBike · #3 10-20-2006, 01:38 AM

I didn't really understand sharpening until I got a 30x magnifying lens (10x would probably work just as well) and started taking a really close look at the blade as I was sharpening. If you can look at your blade up close, you can see what the edge looks like when it's dull and you can imagine what it should look like when it gets sharp.

A rough surface will remove more material, but it will leave deep scratches. The idea is to use a relatively rough surface to get the shape of the blade where you want it, then go through finer and finer abrasive surfaces to polish off the scratches. Eventually, the planes of the blade will be visually flat, and the edge will be sharp, but even then it just means that the scratches are too small to detect with your eye.

I use "scary sharp" and shape with 80 grit (sometimes even 50 grit) and go through 120, 220, 400, 600, 1000 and 2000 grits for chisels and plane blades.

For a quick tuneup of a blade, I might just run it over the 1000, then 2000 girt a couple of times. Even if a blade is severely dull, (but undamaged) I can't imagine spending more than 20 minutes on it.

I don't need to look at the blade with the magnifying glass every time now, but I found that I was able to get a feeling for what was going on at the surface of the blade that way, and that guided my progression from grit to grit and from dull and misshapen to very scary sharp.

Hope that helps,

Irish · #4 10-20-2006, 04:45 AM

Hi Andy,

Most of us had a hard time learning how to sharpen. After a while it will become second nature to you.

You have three types of sharpening tools. The rough stones define your angle on the cutting edge, the fine stones define the edge and bring it to it's cutting point and the honing tools remove the tin edge and polish out the stone scratches.

If you already have your 10 to 12 degree angle established you don't need to return to the rough stones! Reworking the knife on the rough stones removes all the work you have already done in previous sharpening sessions.

Instead try going directly to your finest stone. This way you are reworking the cutting edge, not the cutting angle.

As you work the fine stone a thin sliver of metal will develop on the very tip of the cutting edge, this is the tin edge ... that tin edge is then removed by the strop. I finish my knives out on a sheet of newspaper as the last polishing step.

During one carving session I will hone my knive several times to keep the edge crisp.

Hope something here helps!

Susan

Hi_Ho_Sliver · #5 10-20-2006, 05:56 AM

I don't sharpen at 10 degrees on my chip knife, I lay it flat, much prefer it that way and it cuts smoother imo. I would be very surprised if you need a lot of sharpening on your blade? I wonder if you have been stropping right along as you have been chip carving? I carve maybe 10 minutes and then strop a few times etc. at the most I might put the blade on 800 and 1200 grit sandpaper and then back to the strop. I you have been attempting to sharpen I have a feeling you have rolled the edge...try laying the blade flat , put your index finger on the side of the blade, that way you can feel if its flat or not then do the same on the other side, and at the end of the stroke, "lift" the blade, don't roll it off the stone...that will round the edge as well. if worse comes to worse, send it to Rick ha ha...then get an old junk knife of some kind and practice with it.

sharpening that is!

skinnyeddie · #6 10-20-2006, 07:44 AM

Thanks folks. I had a feeling I was missing something fundamental. I think I will try getting the magnifying glass as suggested since I feel like I'm "flying blind" at this point. I have also ordered one of the Moor DVDs which I'm hoping will give me a good visual demo on sharpening.

It seems like a pretty simple concept, but the edge of my knife would currently suggest otherwise!

Thanks, I'll keep you posted on progress.

Andy

Just Carving · #7 10-20-2006, 08:54 AM

All of what's been said is good. But I've learned that it is better to hone/strop the tool first, and then see if it cuts through the end grain of a piece of basswood. If it does, then it's good. If not, then I take out the scary sharp paper, and sharpen the tool. An exception to this would be if I know the tool is chipped or broken. Then I go to the coarser paper, and rework the tool while holding it's original bevel as best as I can. However, I have found that laying the tool flat while sharpening does yield a thinner tool thereby making it easier to cut through the wood. But the downside is the tool is thinner, and thereby more fragile--making it more susceptible to breakage during use if the tool is used improperly.

skinnyeddie · #8 10-20-2006, 11:13 AM

What is the "scary sharp paper"? Some kind of superfine grade sandpaper I assume...

Just Carving · #9 10-20-2006, 11:37 AM

"Scary sharp paper" means various grits of wet n dry sandpaper or emery paper--starting with 100-120 and working your way up to 2000. If I make a tool, I grind the profile of the tool to the shape I want. Then starting with 100 or 120 grit, I sand back and forth 20 strokes at a time, holding the tool at the desired angle, and periodically checking the line (see below) until the metal is smooth, i.e. the paper isn't really doing much. Then I move on to 200 or 240 grit. Same thing. Then I move on to 400 grit. Then 800 grit. Then 1000 grit. The tool should be almost mirror finished by now. Then I polish it with 2000 grit. BTW--you can buy the paper at any hardware store or auto parts store. The higher grits are usually easier found at the auto parts stores where the body work supplies can be found. You don't necessarily need to go to 1000 or 2000 grit, but the tool looks nicer, and slides through the wood a little easier.

All along this process, I am checking the edge of the tool for a thin white line--which is an indicator of a dull edge. To see the white line, turn the tool's cutting edge up under a light, and slowly pivot the tool until you see a reflection of the light on the edge of the blade. Once I see the white line begin to diminish, and/or disappear in spots, I pay more attention to how I am applying pressure to the tool. If I have a white line on the edge at one side of the tool, I apply a little more presure to that side until the edge is gone or the line is the same thickness all the way across the tool. I continue until the white line is gone, and the tool is sharp. Then I hone it. Then I get a box of band-aids!

If you want to try this method, take an old non-serrated knife--like a kitchen paring knife, and give it a shot. You might not need to start with 120 grit all the time. If there is an edge, start at 400 grit--and see what happens. If it seems like it is taking forever--more than 10-20 minutes or so, to see some good results, then go back to 240 grit until you see some results. Then continue on to the 400 grit, 800 grit, and so on. If you're successful, you'll have a nice back-up carving knife--might even become your favorite.

Wes Leitch · #10 11-03-2006, 09:31 PM

Dennis Moor's Chip Carver's Workbook has a very good explaination of how to sharpen chip carving knives. Dennis sells ceramic stones for sharpening at Chipping Away. I don't know where else to get them. You could go to a hardware store, but getting the right grit could be impossible. I use the 8000 grit ceramic stone when the strop isn't good enough anymore and it gets the knife back to razor sharpness in about 30 seconds.