Wednesday, August 25, 2010

Knife Making Belt Grinders

Recently I have had many inquiries about knife making and belt grinders.

Knife making is one of the most interesting parts of blacksmithing and is actually how my interest was peaked. Had I had a knife making belt grinder when I started it would have been so much easier.

In general there are four different steps in blade making.

  1. Forging the blade from the original bar. This is where the rough shape is created. You may have heard the old saying 5 minutes at the forge saves half an hour grinding. For me that certainly is about right.

  2. Primary and secondary grinding of the blade. This is creating the finished shape of the blade through a series of grinding and sanding steps. For me this takes the longest time and is the most exacting.

  3. Heat Treating. This is the hardening and tempering of the blade.

  4. Final sanding and polishing. This is when the blade is actually sanded to a perfect finish. You may choose to buff to a mirror finish as well.
So a lot of questions have come from people just starting out in blade making. They are wondering about the grinding steps.

Belt grinders are the best solution for blade making. They give you a flat surface to work on and remove material quickly with coarse grit. Fine grit can leave a satin finish to shiny if you go super fine.

The problem is that knife making belt grinders usually range in price from $1200.00 to $2500.00. Now that is a lot of money if you are just trying this out as a hobby. If you are committed then I would suggest looking at this price range. The standard in knife making is the 2 inch by 72 in belt grinder with usually a 1 hp or 2 hp motor.

Back when I needed a knife making belt grinder I couldn't afford to pay the $1000.00 plus for a factory built one, so I choose to build my own. So on a shoe string budget I built one. Does it work? Yes fairly well. There are things I should change on it, but in general I am satisfied with the finished piece. I used no plans and scrounged as much as I could.

I recently found good plans for a nice belt sander that requires no welding. It all bolts together!

Just Click on the above image to be taken to more information.

These plans provide simple construction just with cutting and drilling and bolting everything together. Of course you could weld the joints that needed welding, if you had a welder. It would only make it better.

Now you will have to recognize that some of the parts are expensive. Motors and contact wheels do start to add up, but this is the cheapest way to build a good quality grinder.

I also found this tool

This is very similar to a belt grinder that I started with before I built my big one. If you want to try knife making as a hobby and are on a tight budget this sander will work.

Now this is a light tool that bogs down if you are really trying to hog metal off and the small belts ( 2 inch by 27 inch) wear out quickly, but it will work. This one has 1/2 HP motor. The belts are pretty economical and this is a good way to see if you like knife making.

If you do like knife making and knife grinding then you will probably want to upgrade fairly quickly.

Now I did come across this machine and WOW! This is an industrial metal belt grinder. It sells for only $695.00 and has a 4 HP motor. This is twice the power of the best knife grinders at a 1/3 the price. It is solid and versatile. It uses a large 3 inch by 79 inch belt and has both contact wheel and flat platten for smooth grinding. Had I come across this knife grinder years ago I would have bought it.

There is a downside to it. This is 220 volt, 3 phase. Now 220 volt may not be a huge problem as most shops with serious equipment have 220 volts. 3 phase is usually limited to industrial areas. So now you would have the choice of replacing the motor, or buying a phase converter.

Both are about the same price. The phase converter for this belt grinder is recommended as
So we get back to about the $1000.00 mark but with a 4 HP motor to chew through the metal.

From everything that I have looked at, this is the most cost effective knife making belt grinder on the market. So I hope I have given you some options to look at if you are starting out in knife making or if you are looking to up grade to an industrial level.

Oh yes the most recent blacksmithing course I taught, the students were interested in making a knife as their Sunday afternoon project. They did quite well. I will put up a picture of mine when I get it finished. I still have some grinding left to do.

David Robertson
Artist Blacksmith

Tuesday, August 24, 2010

Blacksmithing : Forge Welding Cable Damascus

I' m interested in trying the steel cable damascus knife, any advice?

Cable is actually really nice stuff to weld. There are a couple of tricks that people forget that help a lot.
The alloy in the cable has a good success of welding even at fairly low temperatures. Having said that use a full welding heat until you are comfortable with it.

Crane cable is better than elevator cable. Elevator cable has an inner core twisted one direction and an out sleeve twisted the other direction. This is called counter rotating cable. That is the cable doesn't twist as it spools off the drum.

Regular crane cable has inner and outer strand twisting in the same direction.

What this means and this is the important step, when you first heat the cable up, clamp it in the vise and twist it as tight as you can get without it buckling. This helps close up the air spaces for better weld. The elevator cable won't twist tight as the inside is expanding when the outer sleeve is being twisted tight, causing spaces to open up.

Back into the fire and take up to a nice orange.
Gently wire brush it, and add flux.
Back into the forge to take the welding heat.

The next trick is instead of welding flat on the anvil (although this does work) use a U shaped bottom swage tool or swage block to help support the sides of the cable when you weld.

As you make the actual forge weld rotate the cable with the direction of the strands. That is each hammer stroke is actually tightening the twist.

You will find that once the cable strands are weld the feeling of the metal changes from the floppy cable to a hard bar. Once it is well stuck together as a bar take a series of refining welds on all edges to make sure any loose strands are tacked down.

When you are completely satisfied that it is well welded then stretch out as normal and make your knife etc. as usual. Once completed, ground, hardened, then sanded again then you can etch in acid to reveal the pattern. You can use vinegar warmed up on the stove. Takes along time but will give you a bit of the pattern, and is the safest acid.

I use more aggressive acids such as sulfuric or nitric or some times ferric chloride. Follow all acid precautions with these strong acids.

Neutralize and take a look at your knife.

David Robertson
Artist Blacksmith