A frequent question from woodturners is, “I only use the bandsaw for roughing cuts. Why should I be concerned with how well it runs, accuracy and maintenance?”
My answer is, “Why not?” Next to the lathe and tool grinder, it is the most important power tool in our studio/shop. Any saw, regardless of its use, will benefit from a thorough tune-up because a good running saw is a safer saw. Its performance will be improved, vibration reduced, and adjustments easier to make. We may even find the saw will be more easily controlled because the tensioning mechanism is working properly for the first time since we bought the saw.
This presentation is specific to the 14” Delta, but it is applicable to all of the imported copies (Jet, Ridgid, etc.). Except for the lower guide, these saws are generally identical to the Delta. They all share the same faults as the Delta saw because nobody took the time to correct its problems when they copied the machine.
Depending on the amount of work required on your saw, it could take 2 to 3 hours to complete all of the tasks that are described. The quality of new saw has improved because of the competition in the past 5 years, and they will require less work. You have a rare jewel if it doesn’t require any. The open-base saw that I purchased in 1984 was an assembly of misfit parts that required all of the described modifications, while one purchased in 1999 only required the work on the top wheel assembly and tensioning mechanism. These are both good saws, but it took some work to realize their potential.
My experience with the lesser priced 14” clones from Grizzly, Trend-Lines, etc. is that they can be made into a good working saw, but it can be a futile effort. Poor castings and inaccurate and warped machine surfaces are problems that cannot be solved with a tune-up. The one thing that these saws share is a total lack of quality control, and your chances of getting a good one are not good.
Preliminary
Start by removing the top guard, blade, table, top wheel, top guide holders, top wheel cover, and drive belt. Remove the bottom guide assembly only if you decide to work on it after reading the description. These items will be replaced as the tune-up progresses.
Threads and Tapped Holes
Bad threads are a common problem with these machines. Replace any assembly bolts and screws that were difficult to remove and run a tap into the threaded holes in the machine casting. You can make a respectable one-time substitute for a tap to clean threads by filing two notches at 45 to the axis of a machine screw or bolt. Use a drop of kerosene to lubricate the “tap”, and re-sharpen it with a file after each hole.
Top Wheel Assembly
The top wheel assembly must be free to move with a minimum of friction so that the spring can maintain uniform tension in the band. Tight fitting wheel brackets or a top wheel cover that interferes with movement of the bracket are common problems.
Note On Tensioning:
Always release the tension from the blade when the saw isn’t being used, particularly if you are using a ½” blade.
Bandsaw experts have always recommend this because of a concerns about blade fatigue, flat spots on the rubber tires, and bearing damage. Among woodturners, there is a greater concern with fatigue of the aluminum wheel assembly casting, and fatigue of the tension spring. Fatigue damage to the cast aluminum bracket is common to a saw used by a woodturner because they are more likely to be making deep cuts and running the saw with higher tension than other users.
Sliding Bracket and Hinge Assembly.
Check that the top wheel bracket will slide freely the entire length of the retaining slots in the machine casting. Use a mill file to remove the casting flashing, flatten the surfaces, and break the edges of the die-cast aluminum wheel bracket. Then use a scraper or file to remove any burrs and paint from the retaining slots in the machine casting, and break their sharp edges. Work some graphite (soft pencil lead) into the cast iron surfaces of the slots for lubrication.
Top Wheel Cover
The top wheel cover caqn cause two (2) problems with the adjustment and operation of the saw.
Top Wheel Shaft
As it comes from the factory, the wheel shaft is a slip-fit through the die-cast hole in the bracket. They are too often a very sloppy fit, and this will accelerate the fatigue of the aluminum casting. Wrap the shaft with one or two layers of writing paper to tighten its fit in the hole. If it is too tight for a single wrap of loose-leaf notebook paper, it is OK to leave it alone.
Top Wheel Alignment
This is an old subject that is included in every book and article on the bandsaw. But it is important, so we’ll do it again. Install the top cover and wheel. Spin both wheels. Listen to the bearings and replace them if they make “funny” noises. A good bearing will not make any noise. Get the replacements from an industrial bearing supplier, located under “Bearings” in the yellow pages. You can buy three grades better quality for less than the price of replacement bearings from the manufacturer of the saw.
These saws have lightweight aluminum wheels, and their balance is usually OK. The seals in a new bearing will prevent spinning them to see if there is a heavy spot.
Check the wheels to make sure they are round at the rim edge (not on top of the tire). The allowable tolerance will depend on how the saw is used, so I won’t make any recommendations, but a variation of 0.005” is typical for these wheels. Any run-out is usually visible by touching a pencil to the wheel while spinning it by hand. Check with the manufacturer for a replacement if it is not round within a few thousandths out.
The wheel alignment must be checked with a blade installed and tensioned because the load will distort the saw frame. This can be as much as 3/32” at the top of the wheel when a ½” blade is installed on a saw with a riser block.
Check the wheel alignment with a long straight edge held vertically against the rims, near the hubs. Tilt the top wheel until both wheels are parallel vertically.
Check that any offset between the wheels is the same at the rear and front of the wheels. If it is not, the frame is twisted at the assembly joint This is a common problem when riser blocks are installed because there are now two (2) joints and two (2) pairs of alignment pins in the saw column. Enlarge the alignment holes in the riser block at only one joint. I prefer enlarging the holes to removing the pin because this provides a “stop” to hold against while tightening the assembly bolt. A film of epoxy (blue Lock-Tite® works well) on the surfaces will improve the joints. The assembly bolt is difficult to reach, but it must be tight. Borrow two open-end wrenches if you don’t have them. A Cresent-wrench won’t get it tight enough.
When the gap is the same at the top, bottom, and front and back of the offending wheel, their planes are parallel. Now we want to get them in the same plane (coplanar). If the gap is larger than 1/16” when the wheels are parallel, put a good quality 5/8” machine washer behind the offending wheel to move it out from the frame. It is normal for the top wheel to be set back 1/8” from the bottom wheel when the saw is assembled at the factory.
Note:
If you didn’t find it necessary before, you will probably have to cut the top cover to make clearance for the tilt-arm after the wheels have been aligned.
When both wheels are in the same plane, the blades are easier to track, and it is possible to interchange blades of different widths without having to adjust their tracking. You will appreciate doing the wheel-alignment if you ever tried to use a 1/8” blade and found it impossible to track or keep on the saw.
Clean the Tires
Replace them if they are worn, damaged, or brittle with age. A good tire will have a slight crown to its surface; a worn one will be flat. The tires on older saws can be re-crowned with a hand-drill and sanding drum that is held against the tire while the saw is running. Newer saws have a curb at the edges of the wheels that prevent doing this, and the only way to fix a flat tire is to replace it.
The only reason I can see for adding the curbs at the edges of the wheels is to sell more saw blades. Without it the blade came off the wheels and stopped, now it continues to run and the teeth are worn on one side before the saw can be stopped.
If the tires are OK, clean their surfaces with a bronze vegetable brush. Use 100-grit sandpaper if they are really dirty. Don’t use solvents. I use the brush after every time I use the saw, and save the 100-grit for whenever the resin build-up is too much for the brush.
Top Guide Holder
Flatten the inside surfaces of the guide holders with a small file. Run a tap through the aluminum adjusting nuts if they cannot be turned freely by hand. Guide adjustment should not require a pair of pliers. If the threads on the studs are damaged, they can be repaired with a needle file, or replaced with long setscrews. Clean everything with kerosene, dry it with an air hose and reassemble. If you cut a lot of green wood, spray the adjusting screw threads with a little "Liquid Wrench" . This is a very thin oil product that will not become gummy and collect dust after it has dried.
Remove the thrust bearing and soak it overnight in kerosene. Dry it with an air hose, and DO NOT lubricate. The residual kerosene will be sufficient lubrication. Do this often and it will last forever. Replace it if it is damaged or doesn’t spin freely. Get the cheapest bearing available from the bearing supplier.
Bottom Guide Holder (14” Delta Only)
If your saw is a Jet or other copy of the Delta saw, the bottom guide is similar to the top. Repeat the same procedure as for the top guides.
The Dlta guides and thrust bearing are mounted on a sliding frame that places its guide blocks above the thrust bearing and 2” closer to the table than its competitors. This assembly is prone to corrosion when we saw green wood, and becomes difficult to move for adjustment as the saw gets older. Don’t get into this if you are uncomfortable with the work required. Either get help, or just lubricate everything with the "Liquid Wrench" and hope for the best.
If you choose to proceed, loosen the setscrews in the retaining collars and remove the adjusting knobs. Remove the entire guide assembly, including the base plate from the saw. Slide the guide frame off of the steel base plate. Remove the self-adjusting gibs (there are 2 pair), and don’t lose the springs. But, if you do, they can be replaced with a better alternative. The thrust bearing is a press fit on the shaft, so don’t remove it unless it has to be replaced. Just soak the works in kerosene.
Use a flat file to remove the burrs and mill scale and flatten and smooth all sliding surfaces on the steel base-plate, the cast aluminum guide frame, and the gibs. Break the sharp edges of the steel base-plate. Clean and reassemble. Rather than using the springs between the self-adjusting gibs, I prefer to replace them with a small piece of dense felt or sponge rubber. Mouse pad rubber or the foam rubber from a sanding pad works perfectly. Trim the length of the new spacer until the gibs are held against the base plate, but allow the frame to slide smoothly. The problem with the stock springs is that the pressure on the gibs is so strong that the gibs are wedged tightly against the back plate, making the guide frame difficult to move. Give the steel plate and adjusting screws a light coating of Liquid Wrench®, and install the assembly on the saw. Don’t crush the spring washers on the adjustment screws with the retaining collars. The collars should turn freely.
Drive Motor
Run the motor by itself, and listen for funny noises or vibration. Recent Delta saws with black, white, or platinum colored frames are furnished with a motor of a reasonable quality, but the motors on many older machines with gray frames are of questionable origin and quality, run hot, vibrate badly, and deliver less power than their nameplate designation. If you need a new motor, replace it with a 1-1/2 horsepower motor by Baldor or Leeson for about $150. You will regret buying anything less than 1 horsepower - GUARANTEED. Don’t even think about more than 2-hp because that is the upper limit for the saw design, especially with a riser block.
Drive Pulleys
There is a considerable variation in the quality of the drive pulleys furnished with the machines. Some of the new machines have machined steel pulleys, but most of these saws have diecast aluminum pulleys that are neither concentric with the shaft nor round, and they should either be machined or replaced. If you want to try fixing them, refer to Ernie Conover’s book, “The Lathe Book”, on how to trim the aluminum pulleys on a wood lathe. Machined steel or cast iron pulleys are available for about $30.00 each from any power transmission or industrial supplier.
Drive Belt
If you don’t do anything else to the saw, replace the stock belt. These belts are usually poor quality hard rubber with rough splices, and they will develop a “set’. Either will cause a “bump” in the saw every time it comes around a pulley. I recommend the flexible link-belt that is available from most mail order stores for about $6 per foot. This belt is very flexible and will provide a smoother transfer of power. The belt will loosen after a short break-in period. I remove the belt, remove a link, and then replace the belt without moving the motor, and the resulting belt tension is about right.
The Stand
If your saw has an open-frame stand, it will benefit from additional bracing and become the most stable foundation that can be put under the saw. Close up the areas between the legs with ¾” plywood held in place with Liquid Nails adhesive and ¼” stove-bolts. Add a shelf between the horizontal braces, and use it for bags of sand. The saw can use the added weight for stability, particularly if it is sitting on a mobile base.
The newer enclosed -stands have a thin sheet metal top that flexes when the saw is running. A piece of ¾” plywood can be placed between the saw frame and the base. Longer bolts will be required to bolt the saw to the stand. Jet has solved this problem with a 1/8” steel plate reinforcement.
The Table
Polish and clean the table with an orbital sander, a gray Scotch-Brite® pad, and a little WD-40®. Wipe the surface dry. Rub on some Talcum Power for a dry lubricant that will not stain wood.
Preparing the Blade
Check the blade and the weld. Don’t try to straighten a kinked or bent blade. It can’t be done. Use a small stone to smooth the weld down to the same thickness as the blade. I still do this out of habit, even though most manufacturers have solved their problems with thick or crooked joints. Sears used to advertise their saw blades as having a weld that was twice as strong as the blade itself. That was because it was twice as thick.
Remove the set from any distorted teeth near the weld. It is better to miss a couple teeth than have them making grooves in the surface of the cut. Suffolk has solved the thickness problem and their welds are slightly thinner than the surrounding metal, but I do encounter an occasional bent tooth that has to be straightened or removed.
Install the blade and adjust the top wheel tilt until the center of the blade runs slightly forward from the center of the tire. When the wheels are coplanar, this will not be a sensitive adjustment. Experience will determine the best location. Recheck the tracking after running the saw for several minutes, and after making the first cuts with a new blade.
Blade Tensioning
There are several methods for tensioning the saw blade that are more accurate than using the indicator that is included on the machine. If you insist on using the scale, remember that they usually give a reading that is a lower blade tension that the other methods. Therefore, turn in the adjustment until the indicator is up to the next higher blade width marking.
Sound is the most accurate tension gauge that we can use. When the band is plucked like a guitar string, it will vibrate at a frequency that increases with the load on the tension spring. The frequency is the same for the same tension in pounds per square inch (PSI) regardless of the width of the blade. For best operation, the band should be loaded so that its tension is about 12,500 PSI. At this tension, it will vibrate at about the same tone as the bass clef low “F” note. Listen for the tone to change from a dead “plunk” or muddy sound to a clear tone, and this will be close to the “F’ note. This is truly “tuning” the saw. You have to hear it to believe it, and the same note will be the same tension regardless of the width or thickness of the blade.
If you are not musically inclined, the blade can be tensioned by observation of its vibration. This is based on the premise that the proper tension is the lowest loading at which the blade will not vibrate. To find this tension level, back the upper and lower guides away from the saw so that it is running freely between the wheels. Then, with the saw running, Increase the tension and watch the blade vibration. Continue turning in the load on the tension spring until the vibration stops. This is the least tension required. Then turn one (1) full turn more tension to arrive at the operating tension level. This method is described in more detail on the Suffolk Machine web site. It will not work (the band may never stop vibrating) when the top wheel is not round, the tires are flat, or the entire machine is vibrating.
Another tension method that measures the amount of blade deflection from a side load is described in the Highland Hardware catalog and their website. With this method, the spring is compressed until the ½” wide blade can be deflected no more than ¼” when a side force is applied at the mid-point between the wheels.
Tensioning gauges that measure the band stretch with a dial indicator may be purchased from various suppliers. A recent issue of Fine Woodworking describes how to make one that uses feeler gauges to determine the amount of band stretch. Both require calculations to determine the amount of stretch in the band from the tensioning load for the width and thickness. I think their use is a waste of money and time because the sound or vibration methods are easier and faster to use, they require no math, no measurement, and they are free.
The final test is in the sawing. Too much tension and the blade will vibrate in the cut, too little and it will bow or wander. If there are diagonal ripples from blade vibration on the cut surface, release a little of the tension.
Always release the tension after using the saw, particularly a ½” blade. Note where the tension indicator is located, or count the number of full turns of the adjustment screw when you release the tension, and you will be able to return to the same location.
Never use a ¾” wide band on a 14” Delta saw. In addition to their being a wider band, they are also thicker - 0.032” vs. 0.026” for narrower blades. The result is a blade with nearly twice the cross-sectional area of a ½” blade. Most carbide tipped blades have a similar greater thickness. This larger area will require twice the load on the tensioning spring, and it may be impossible for the blade is properly tensioned before the spring is totally compressed. Even where the spring is not compressed, the additional load will cause excessive deflection of the saw frame and accelerate fatigue failure of the die-cast top wheel bracket.
Guide Blocks
Steel, carbide, brass, Cool-Blocks®, plastic, or ball/roller bearings? All have their advantages and disadvantages. While they sound like an excellent idea, the ball/roller bearings create a “pinch point” that collects sawdust, a particular problem with the lower guides when cutting green or resinous wood. Steel and carbide have excellent wear properties and provide a shear to remove sawdust from the blade, but they must have fairly large clearances with the blade to prevent continuous contact. Cool-Blocks and plastic materials have a built-in lubrication that allows them to be adjusted to continuous contact with the blade, but unfortunately, they do not wear well.
In our rush to high technology materials, we have forgotten wood. Cocobolo is an excellent guide material because it is already lubricated, wears better, and is less expensive than Cool-Blocks®. My sensitivity to Cocobolo has increased with the passing years and I have started to use oil impregnated hard Maple for guide blocks. While not as durable as Cocobolo, they are comparable to the Cool-Block material. I saw the Hard Maple blocks to size and length, and soak them for a couple days in a 50/50 mixture of chain bar or mineral oil and kerosene. Some warmth is helpful, and I set the jar on top of a coffee-cup warmer. The top of the hot water heater is a good location. They are ready to use when they sink. I leave them in the oil, and remove them and square the ends when needed. It may be necessary to trim their thickness to get a “light hammer tap” fit.
Several woodturners have told me that the Dymondwood® pen blanks make a good guide block with better wear properties than CoolBlocks.
There have been many descriptions of ways to adjust guide blocks, and I will add mine. For a ½” wide blade, I adjust the frame so the front edge of the guide block is located at the bottom of the gullets of the teeth. I set the inside block so that it just touches and barely deflects the blade, and then set the outside block as close as possible without binding the blade. Use only enough pressure on the setscrew to hold the block in place. We are not tightening it against a steel block. Pull the blade through by hand to make sure there is no binding. For ¼” wide blades and precision sawing with any width, I bury the teeth in the guide blocks, letting them cut their own clearance. After running the saw for a few minutes, I reset the guide blocks.
For sawing green wood, I use a piece of carbide for the inside block. This is the one that wears the most (for me), and the moisture in the wood keeps it lubricated.
Stone the Back of the Blade
Remove the burr and form a small radius across the back of the blade with a small dry stone while the saw is running.
Readjust the guides, Replace the guards, and SAW
