Machines

by Gary Straub

This in no way is intended to be a "how to" about machinery, but only a few observations strictly of my own. There are some on this group (rec.woodworking) who distain the use of machines, while others find machinery serves their needs best. Other than those who make green wood furniture I doubt if anyone does work entirely by hand. Personally I prefer to use the tool which will perform the task at hand in the best manner.

Tablesaw:

This saw is probably the most used machine of any shop. It can rip boards with precision that cannot be matched by handsawing. It can produce perfectly square and plumb crosscuts. It can be used as a moulder, and sander. There are many different levels of this tool, but the main purpose is to turn a circular blade at an appropriate speed with enough power to cut lumber. Most brands will accomplish this. Of course there are different quality saws, but one should not feel that unless they purchase the best they are getting junk. As long as the miter slots are parallel, there is no play in the arbor and the table is fairly flat, and the motor is large enough to cut the wood you are using then the saw will be adequate.

To cut properly, the blade needs to be aligned with the miter slots. This is usualy done by adjusting the table (check your manual). To rip properly the rip fence needs to be parallel to the blade. This can be done by measuring to the miter slots. There are different quality fences but even a straight board will work as long as it is aligned.

The most important part of the machine is the blade. You should have at least two good blades, one crosscut, one rip. A good combination blade will perform both tasks fairly well, but not as well as one of each. Carbide will outperform steel, but steel can be made sharper. It is very important to keep the blades clean. Gummed up blades perform poorly, heat up more causing quicker degradation. Gummed up blades also increase the chance of kick-back. It has been found that chemicals in woods attack carbide tips and cause premature dulling and failure.

The tabletop should be kept clean and waxed. Friction is our enemy! Wood dust absorbs moisture and aids rust. We do not like rust. All parts should be kept clean and all moving parts lubricated. Liquid lubricants collect dust so should be discouraged. I mix graphite powder with paste wax (no silicone) and turpentine to make a thin paste. I use this to lubricate gears, threaded rods, bushings and anything else where it can be applied.

Respect the tool. It can cut your finger off before you know it. Most all kickback accidents are attributable to carelessness. Keep a good grip on the wood, and keep it flat on the table. Do not tense up but do not be too casual. I am amazed at how many people who have been using tools for a long time will one day cut part of a finger off because of being in a hurry. Focus!

Bandsaw:

If I could only have one machine, this would be it. With a bandsaw you can rip, make short crosscuts, re-saw, and cut curves. With most bandsaws you can do all the above with different angles as well. With 1/16" blades you can cut very intricate curves, much like a scroll saw. With an attachment you can also sand. This tool will cut wood faster than any other tool and ripping of thick lumber is a breeze. The drawback is that it leaves a coarse surface which will require more attention.

Like the tablesaw, the function of the machine is to turn the blade at the appropriate speed with enough power to cut the material. Unlike the tablesaw it must also support the thin blade to keep it from wandering. Because of this many of the less expensive brands will not perform satisfactorily.

The blades are what the saw is about and quality blades are necessary for good operation. The shiny steel blades which come with most saws are not very good. The blued steel with hardened teeth are the value. There are also carbide tipped and bi-metal blades. There are also blades available for cutting metal, foam, leather, plastics and other non-wood materials. For woodworking I find that standard and hook tooth will perform all functions. In general the standard tooth configuration is best for curved work and the hook tooth is best for ripping and re-sawing. The standard tooth will give a smoother cut than the hook, and the less teeth will give the smoother cut in either. The size of the kerf is determined by the size of the blade. eg; a 1/8" blade has a smaller kerf than a 3/4". The number of teeth per inch (tpi) also effects the smoothness of the cut but more importantly the speed of the cut. More teeth will give a smoother cut but will also create more heat. Re-sawing should have the minimum amount of teeth (3-4tpi) but not necessarily the largest blade. I have found that a 3/8" blade to be the best for re-sawing. However, I use a 3/4" blade when sawing small logs. This is because a log can easily move around and a larger blade is much stiffer and reduces the chance of distorting the blade.

Because of the large number of teeth and the low price of the blades, it is not uncommon for a blade to be less than perfect in set. This will cause the blade to want to cut towards one side or another. This drifting will cause heat build up and distortion if not compensated for when making edge guided cuts. To compensate, draw a line on a square piece of scrap wood parallel to one side. Cut half way through the board, following the line. Do this free hand. When you are at the middle, hold the board exactly where it is, stop the saw. draw a line on the table along the edge of the board that is parallel to the cut line. Remove the board, the line on the table in relation to the front of the table is the angle that the blade will cut best. Using a t-bevel get this angle and use it to align your fence. Every blade will be different and many will have very minimal or no drift.

Guides:

The blade guides are a very essential part of the proper operation of the bandsaw. The quality of these play a major role in the type of cut you will get. Most small bandsaws have a metal guide on each side of the blade and a bearing on the backside. The side guides keep the blade from wandering, and the bearing in back keeps the blade from running off the tires. It is best to have the side guides as close as possible to the blade, unfortunately the metal blocks cannot be positioned as close as should be. Many people make wooden blocks out of Lignum Vitae or purchase after market guides called Cool Blocks which can be made to just touch the blades. This is highly reccommended. The better quality saws have bearings on the side also. This is the superior method. The rear bearing should be set so it just doesn't touch the blade. The upper guides should be set just above the workpiece. Never cut with the upper guide far from the workpiece. This will allow the blade to distort and presents a safety problem.

The two main problems I see when using a bandsaw are; 1. Trying to turn the board without pushing into the blade at the same time. This is the prime reason for blade breakage. 2. Pushing and stopping. When riping or re-sawing it is best to feed in one continuous motion. Everytime you stop the feed the saw will make a extra deep mark on the edge. This will require more effort to clean and can effect the finished dimension. Feeding as fast as possible without slowing the motor or creating extra resistance (in case of a large motor), will give the optimum results. Of course when cutting curves this cannot always be done. Concave or convex cuts are caused by dull blades, feeding too fast, feeding too slow, or any combination of these.

Routers:

This fairly modern invention was developed to make up for the shortcomings of the shaper, pin router, and over arm router. The beauty of this portable machine was that one could take it to the work piece instead of vice-versa. Now many small shops are seeing the limitation of this and feel the need for a shaper, thus creating the router table. Full circle!

This has become one of the most, if not the most, versatile machines in the shop. It can rapidly make edge profiles, grooves, joints, make reproductions from templates, drill, surface, cut, trim wood and many other materials.

Ideally one would have two routers one large and one small. A large 3hp will do everything but is cumbersome for small detail or trim work. A plunging type is preferred for it makes starting and stopping in the middle of a board a snap. It also make multiple depth cutting much faster, and it allows one to retract the bit after each cut which is a tremendous safety factor. The router bit should spin into the work but there are times when, because of grain direction and splintering, you will need to feed the opposite direction. When doing this the machine will tend to run with the cut so you must hold on tight and take shallow cuts. By doing this, though, you will eliminate tearout. It is important to keep the base clean and as slick as possible. I use a plastic polish regularly to accomplish this. Plastic polishes can be found at auto stores and aquarium stores. If there is resistance between the base and the work errors can happen very fast. Carbide bits are preferred as the bits take much punishment. Bits with guide bearings are best for portable work. Helical straight bits will give superior cuts. Bits can be sharpened on a diamond stone, only the flat part is sharpened.

Accurate depth settings can easily be made by using a drill bit of the appropriate thickness, either between the depth post and stop on plunge routers or, using two bits between the base and the work on fixed base routers. Truing the ends of large panels can be very accurately done with a router using a straight piloted bit (preferably helical). Clamp a straight edge onto the work, square and close to the edge. Then using the straight edge as a guide for the pilot, rout it off. Stop just before the end and finish of the opposite direction to prevent tearout.

These are the (IMO) three most important machines in the workshop, and to go into the rest of them would take a book of which many are written. So I will conclude this part with a few notes.

Enjoy!

Gary Straub

gstraub@peoplepc.com
Columbia, MO

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