Dressing Tools, Part 2

by Albin Drzewianowski

Contintinuing on the same topic as the last three installments of this column, we are going to talk about the equipment used to clean and dress your tools. Last newsletter we talked about using the 4 1A" angle grinder. This issue we move on to bench tools: the bench grinder and the belt sander.

For all of these tools, pretty much the same safety rules apply. ALWAYS wear safety glasses, a full face shield is a good idea. If you are working small pieces, gloves are also a good idea. If you find yourself generating a lot of dust, use a dust mask. Be especially careful of any loose clothing or long hair when working around rotating tools. It only takes a second for a loose shirt sleeve to get caught up in the rotating tool and drag fragile body parts into contact with the abrasive. That would not be a pretty sight.

Bench Grinder: - Don't get a real cheap one. You will find they just don't not have the power needed. I strongly recommend getting at least a 3/4 horsepower model. You want a motor that when you lean into with a tool the motor keeps turning at speed. I have found that with the small, el-cheapo bench grinders, as soon as you push your tool into the wheel, the motor slows and soon comes to a stop. Furthermore, with the 3/4 horse and larger grinders, you can use the 8 inch wheels which run cooler and last longer. With the smaller grinders you are limited to 4 or 6 inch wheels.

Ideally, you need two grinders, or you will find that you keep switching between different types of wheels. I have a wire brush wheel and a rag buffing wheel on one grinder and a ceramic stone and blending wheel on the other. I don't use the buffing wheel a lot, but the other 3 are used constantly.

Buffing Wheel: - I'm not going to say a lot about the buffing wheel. I have one and use it occasionally but not a lot. I do know that it is best to have a separate rag buffing wheel for each type of buffing compound you use. (I keep the wheel and the compound together in a 1 gallon plastic freezer bag, so they don't get mixed up.) If you are into polishing items to a very high shine or luster. This is a area you will need to explore further. Polishing is probably a "BEGINNERS' CORNER" article all to itself.

Wire Brush Wheel: - This is one of the best tools for removing rust, paint, and fire scale. However, mounted on a grinder, it is one of the most dangerous tools in the shop. Generally you are hand holding the item that you are cleaning up and it only takes a fraction of a second for the wire wheel to grab that item and throw it at high speed. Whenever possible clamp the item you are working on in the vise and use the wire brush on the angle grinder as we talked about last issue. This is much safer. Unfortunately, this does not work for small items, and it is the small items, such as little hooks, keyrings, etc that you will need to hand hold into the bench mounted wire wheel, and these can get thrown at surprisingly high speed.

When working at the wire wheel, always push your work into the wheel in the lower quadrant, below the level of the motor shaft. This way if the item is ripped from your grasp (and it will), it will be thrown down and away from you. If you are using the portion of the wheel higher than the motor shaft, it will be thrown right at your face. For this reason, you must wear safety glasses (I have gotten in the habit of using a full face shield in addition to my safety glasses). It is a good idea to wear a leather apron and leather gloves. As you work, you will notice that the wire wheel throws off wires and they are thrown right at you. If you are removing paint, you may want to wear a dust mask. Especially if the paint is real old and may have lead in it.

When you go to buy wire wheels, you will notice they come in a number of different types, crimped and knotted. For our purposes, you want the knotted. They are more aggressive and do a better job of removing fire scale. Also, wire wheels are available in stainless steel. They are more expensive and harder to find, but they last longer and are more aggressive than regular steel wire.

Ceramic/stone Wheels: - These are the wheels commonly called grind stones. Again, they come in a large variety of grits and types. These wheels are hard and have the abrasive material embedded in a stone like matrix. The rough grit stones can remove a lot of steel very quickly, but leave deep scratches in the surface of the work. After hogging off most of the steel that needs to be removed on the rough stone, you then move on to successively smoother stones or to the blending wheel or the belt sander.

When using any of these tools, the tool you are grinding can quickly become quite hot. Hot enough to burn you. Also, hot enough to affect the temper of the tool. Always have a container of water handy to cool the tool as you work on it. As a general rule, the piece you are working on, should never get so hot that you can not comfortable hold the part that has just been ground.

On most grinders, there is a small "shelf mounted right in front of the stone. This allows you to support the tool you are working on and to maintain good control. This "shelf should be adjusted so that there is less than 1/8" of gap between it and the stone. If the gap is too large, the tool or your fingers could get dragged down into there next to the rotating stone. You can imagine what that might do.

With this type of wheel you need to have a "dressing tool". This tool is harder than the stone and allows you to reshape the wheel as it wears down. I find that my wheels tend to develop a concave surface and periodically I need to dress the edge of the wheel back to flat. Sometimes you may need a particular contour on the edge of the wheel. The dressing tool will allow you to create that contour.

Blending Wheels: - These are grind wheels where the abrasive material is embedded in a rubber or resin that is not hard the way stone wheels are. Blending wheels excel at taking out the scratches left by hard stones. However, they are aggressive enough to heat a tool up to the point of affecting the temper. These wheels do a nice job of putting a basic shine on the tool.

Belt Sanders: - This is another tool where it pays to pay a little more money and get a stronger motor. The "Harry-Homeowner" models just don't stand up to the kind of use a blacksmith applies to the machine. The knife makers consider this an indispensable tool. The belt sanders are available in a number of different belt widths, the most common are 1", 2" and 6" wide. The 1" and 2" models are probably the most handy for the general blacksmith. Many of the belt sanders also come with a 6" or 8" disc sander as part of the unit. You will want to have a variety of different belts starting at 80 grit and working up from there. On most machines it is relatively easy to switch belts. The longer the belt, the cooler it cuts. Many of the knife makers use belt sanders with 72" or longer sanding belts.

When using a belt sander, notice that there is a portion where the belt is backed up by a steel plate and a portion of the belt where it is not. When you want to grind something flat, you use the portion that is supported from behind. When working on a rounded or irregular surface, say the end of a rounded punch, use the part that is not backed up. The belt will give slightly and follow the contour of the tool. Also for a hollow grind, you work the tool on the belt as it passes over one of the pulleys.

As an alternative to buying a belt sander, many of the knife making books have plans for building your own belt sander. There are a number of companies that sell the components needed for building your own belt sander. I have seen home made models which have 2 or 3 belts running simultaneously, so that you can go right from one grit to the next without having to stop and switch belts.

-- RebStaup - 25 Jan 2008