Thursday, August 31, 2006

Sharp woodworking tools.

If you are into Woodworking, wood turning or woodcarving, having sharp tools is a must. The tools that you buy are almost always useless out of the store; you need to remove the factory's grind marks on back and bevel, and polish the back and the bevel appropriately.

Wood chisels that you buy at the Home Depot or Lowes are low-quality, and some hard work is required to make them somewhat useful. Even the most expensive carving chisels bought in the best stores require at least some leather stropping with polishing compound to be truly sharp.

The edge of woodworking cutting tools (especially carving) requires stropping often during the work, and sharpening periodically when needed; knowing how to sharpen a blade is not an option for anybody that wants to use a blade for woodworking. If you don't do it, you will always think that using a chisel is too hard for you and you will give up. A sharp blade cuts cleanly and well and it is a pleasure to use. A dull blade is useless.

I have been interested in sharpening techniques for years now, and I experimented and practiced with water & oil stones, sandpaper, high speed grinders, low-speed grinders, flat grinders and curved grinders. It takes time to learn what a sharp blade is, and even longer to finally be able to create one.

Like all fields of engineering, it's both an art and a science, even with expensive equipment the difference between a sharp blade and an "almost" sharp one is in the artistry and experience of the sharpener. That said, with a bit of practice, anybody can do it.

What "sharp blade" means, depends on the application. If you are splitting logs, you don't need a very sharp blade; actually Wood Splitter's Mauls are not sharp at all. They only need to get between the fibers of the wood and push it out, splitting, and not cutting. A sharp blade tends to "catch" the grain, not splitting the log. A maul breaks the log along the grain of the wood.

On the other side of the spectrum, when you carve wood with chisels, you need a razor sharp blade. When I say "razor sharp" I am not making an hyperbole! I actually mean it. You should be able to shave with a carving chisel, if you wanted to. I test my carving chisels on the hair on the back of my hand. I consider a carving chisel sharp when I can cleanly shave hair off it with the blade (don't try this at home).

Turning chisels are a different beast. They need to be sharp, but they also need to be very strong given that they see a lot of wood very quickly. For this reason, turning tools are not something that you would define "razor sharp". The bevel is too steep to cut hair, but is still sharp because it needs to cut cleanly and quickly.

If you are interested in an in-depth description of various tools, what sharp means for each tool and how to sharpen them by hand, I strongly suggest a book titled The Complete Guide to Sharpening, written by Leonard Lee. The book is a bible, and if you are interested in sharp tools, it's a must have.

Unfortunately sharpening by hand is a very time consuming process, and when the time to be in the shop is little, you don't want to spend most of it making your tools sharp and no have any time to actually use them (I've done it). For this reason my personal quest has been to obtain highly sharp tools as quickly as possible.

The first attempt was with high-speed grinder, such as the cheap models that you buy at the Home Depot. If you buy one, throw away the gray wheel that comes with it. It's worthless. Buy a white or pink one. Even having done that, I realized soon that these were not very useful except, perhaps, to sharpen lown-mower blades or quickly touch up turning tools.

The second step was to try with the water stone approach. Years ago I purchased a few Japanese water stones and honing guides. The results were awesome. With practice I was able bring cabinet chisels to a near-mirror polish with razor-sharp edges. The problem here is that it would take hours of hard and tedious work to go from a store bought chisel to a precision cutting instrument. Who has time for that? Not me.

My third step was to buy a Tormek slow-speed grinder. Awesome machine, at the time it was the top of the line. You can buy all sort of additional attachments and jigs to sharpen all sort of tools, from pocket knifes to swords, from carving chisels, to cabinet scrapers. This machine is great to reform a bevel of any shape, change the angle of any bevel, and bring tools to a decent sharpness and to do most of the time consuming steel removal. The stone works quickly and the jigs are fantastic.

With Turning tools and most shop tools that’s all you'll ever need, and probably more.The issue with this system is that it doesn't work very well for carving tools. I mean, it sharpens them, but if you want a great edge you need to finish the tools off on a water stone: the grinding wheel is too rough, even if you use the optional grader to make it finer. The other problem is that the leather honing wheel round edges too easily. The final problem is that, like every wheel grinder, it leaves you with a hollow bevel. This is good for turning chisels, but is bad for carving chisels. Anyhow, this machine is a good thing to have in a wood shop.

Recently I also noticed that Jet came up with a very similar machine. They took the Tormek and copied it, adding a couple of interesting features. I haven't tried one, but you may want to check it out. Frankly I am kind of upset that Jet can so bluntly copy Tormek products to that extent, and get away with it.

Anyway, since I am interested in woodcarving, and since I have a collection of very expensive Pfeil Swiss-Made gauges that I don't want to ruin on a grinding wheel, I decided to invest in a Lap-Sharp 200 sharpening system.

This is the Rolls Royce of sharpeners. It is sold only in a few stores, and it is expensive, but the results are amazing. At my first attempt with this machine, I was able to bring a carving spoon gouge, previously re-shaped on the Tormek to a 25 degree bevel, from a bevel with grind marks, to a polished near-mirror surface and a razor-sharp cutting edge. The difference between "before" and "after" using the LapSharp was amazing. The Lap Sharp created the sharpness required for a very clean cut.

The Lap-Sharp uses hig quality abrasive disks available in grits from 120 micron for fast metal removal, to 1 micron for final polishing and honing. Stropping while carving is not even necessary anymore. I keep a 1 micron abrasive disk mounted on the Lap Sharp, and when I need to strop I just take the gouge for a quick touch up on it. That's all I need. Quick, fast and easy.

Despite the fact that the system has a jig for gauges, I was able to do my carving gouges sharpening by hand, with amazing results. The carving/tourning jig is still good to have because it comes with a handy mount that can be used to hold an accurat angle.

In conclusion, if you are serious about sharpening, and if you are into woodworking, turning and carving, the ideal setup is to have a both a Tormek and a Lap-Sharp, one next to the other.

You use the Tormek for the tool's initial heavy metal removal and bevel forming (if necessary), and the Lap-Sharp to bring the hollow bevels to a flat surface, and to bring any bevel to a mirror finish and perfectly honed quality.

If you can't have both, and you need to pick, buy a Lap Sharp. You will love it.

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