SAFETY RULES AND OPERATING INSTRUCTIONS
FOR THE
GENERAL 15", MODEL 490 BAND SAW
Bandsaw: Hazards & Safety
Hazards specific to this machine include:
Being hit by work pieces ejected from the machine
Dust or swarf/work piece in the eyes
Getting hair/clothing caught in the blade
Being cut by the blade either when it is turning or stationary
Safety
Always follow guidelines:
Observe the general safety points before you begin.
1. Always shutoff the machine before making any adjustments. (i.e. adjusting tracking, altering height of guide)
2. Be aware of the capacity of the machine you are using and the type of blade that is fitted. (i.e. not trying to cut wood that is wider than the maximum permitted width of the throat, trying to cut steel bar with a woodwork blade)
3. Know where the stop switch is in an emergency.
4. Be familiar with the controls and layout of the machine before you start work. If in doubt ask a technician.
5. Know your own limitations ( i.e. If they piece of material you wish to cut is heavier than you can comfortably carry, get help rather than injure yourself)
6. Do not use the protractor and the fence at the same time.
7. The safest way to proceed is to try and allow as much distance between your fingers and the blade as possible. I always try and avoid getting my hands nearer the blade than the edge of the little insert that surrounds the blade (normally circular) about 2 inches. Also I do not let my fingers cross the gap in the table, which is used for removing the blade and is inline with it.
8. To prevent your fingers coming into contact with the blade it would be usual to use a push stick if you feel you fingers are getting to close to the blade. Push sticks are normally supplied and are on the wall near the table saw. You can make your own custom one. To prevent the push stick slipping it is vital that you cut a notch in the end, which will prevent this happening.
9. Inform the technician if the tool seems to be malfunctioning or is damaged
Band saw: Machine Parts
A: Guide/Guard Support
This holds the Guide/guard in place and allows it to move up and down. It can be positioned to allow the minimum area of blade to be exposed for safe cutting.
B: Guard
This item protects you from the exposed area of the blade as it exits the cover of the machine. It is adjusted up and down along with its attendant support by a knob or lever along side.
C: Roller Bearings and Guide Blocks
These attachments are part of lower and upper Guide /Guard assembly. The upper guide/guard assembly contains a roller bearing and two blade guides, which support the blade as it is being used, thus preventing excessive, play and wear. The roller bearing prevents the blade from being push back and when running the blade should not touch the bearing but should clear it by approximately 1/64". The upper set, move up and down on the guide arm and the lower set are fixed to the frame. Both sets need to be adjusted to securely guide the blade and should not be attempted without instruction.
D: Throat
This confusingly is the aluminium section through which the blade passes. It is removable to allow replacement of the blade and renewal when it is worn or a more custom made item can be inserted.
E: Slot
This slot machined all the way through the table is designed to allow the blade to be removed and replaced in case of breakage. It is a handy reference as it is in direct visual line with the cutting blade. Never allow any part of your anatomy to cross this line when the band saw is running.
F: Protractor/Mitre Slot
This is a machined groove on the table, which again runs parallel to the blade. This enables a protractor or mitre gauge to be used in cutting. This attachment enables you to alter the angle of attack when approaching the blade to enable cuts from 90 degrees to be made.
G: Tensioning Knob
This knob tightens the blade. If you open the top door you will see that it attaches to the upper wheel and has a gauge indicator that lets you know when you have enough tension on your blade.
H: Tracking Knob
This knob adjusts the tracking of the blade. When properly set the blade should ride on the crown of the tyre. Once it is set it should not be played with. The technician sets it.
I: Table
This is the operating surface of the machine, which the blade runs through. On this machine it can be tilted.
J: On / Off Starter Switch
This is a simple on/off switch, which is mounted on the cabinet base. The black button is ON and a red button is OFF.
K: Lower and Upper Doors
These cover all the moving parts of the machine.
L: Fence Rail
This saw is not equipped wit its own fence so does not have this feature.
M: Base Cabinet
The saw is mounted on this and the base houses the motor.
SETTING UP A BANDSAW
By
LES SWIFT
Whilst band saws come in various shapes and sizes, some with two wheels and others with three, they all require careful setting up and adjustment before satisfactory work can be undertaken.
It is surprising the number of people who consider a band saw to be a machine for cutting curves only. Of course band saws are unequalled for sawing stock into circles or intricate shapes. However, a correctly set up saw will make straight cuts through thick material with equal ease both safely and efficiently.
All band saws operate on the same general principle. The saw blade, which is a flexible band of steel with teeth cut on one edge, is fitted over the band wheels of the machine. These band wheels are usually fitted with rubber tyres, although some of the smaller machines may have nylon wheels.
Adjustments for tensioning and centering the saw blade are provided on all band saws, even though the method may vary slightly from one manufacturer to another.
In order to prevent the blade from twisting and to ensure that it enters the work accurately and to give support to the back of the blade when cutting, adjustable guides are provided. These guides are both above and below the saw table. Overlooking the guides below the table can cause excessive wear of the blade, as well as difficulty in maintaining correct adjustment of the upper guide, with the result that unsatisfactory performance is obtained from an otherwise excellent machine.
Assuming that a sharp blade has been fitted over the band wheels as per the manufacturer's instructions and with a little tension on the blade, release or back off the blades guides both above and below the saw table. On some machines it may be necessary to tilt the table in order to gain access to the lower guide.
Rotate the upper wheel by hand in a clockwise direction, at the same time increasing the tension on the blade by use of the adjustment at the rear of the machine, shown in Fig. 1. A satisfactory tension is usually arrived at, when by taking the blade between the forefinger and thumb and applying a slight pressure a 2 or 3mm deflection of the blade is obtained. (Some machines have a scale fitted to the tensioning device, in this case follow the manufacturer's instructions and of course, common sense has to be used, it should be obvious that a 5mm blade requires less pressure to obtain the stated deflection than a 20 mm blade.)
Continue rotating the blade and observe its position on the top of the upper wheel. It should lie on the curved surface of the tyre in a horizontal plane, approximately in the centre of the tyre, the position of the blade is adjusted by use of the upper wheel tilting device, turning in will cause the blade to run to the front of the tyre and likewise turning it out will cause the blade to run towards the rear. (Fig.2)
Adjust the upper blade guide so that the side blocks will be behind the teeth and gullets when brought eventually into contact with the blade. (Fig3).
Bring one of the side blocks in until it makes a light contact with the blade, and then lock it in place. (Fig.4a)
Now using an extra piece of paper as a spacer bring the other block into position, and then lock it also. (Fig.4b)
Finally advance the rear blade support until it barely makes contact with the blade; once again lock it in position. (Fig.5)
The same procedure should be followed when adjusting the lower guides.
Lower the table, if it has been tilted to gain access to the guides.
Close the machine up and carry out the following tests.
1. Adjust the top guide assembly until it is approximately 12mm above the work to be cut. Draw a straight line on a piece of wood and make a test cut. Check that the cut is not only straight but also vertically square.
2. Draw a curved line on the wood and observe how readily the saw follows this line.
Should the saw tend to cut to the left, turn the wheel tilt adjuster out about half a turn. Conversely if the saw tends to cut to the right turn the adjuster in. Only a small amount of adjustment is required to bring about a considerable change.
The position of the blade guide assembly will now require a minor adjustment to suit the altered position of the blade.
If the saw cut is not square vertically, the table will have to be adjusted so that it is at right angles to the blade.
Should the saw cut be hollow in the middle, blade tension is insufficient. Increase tension.
When saw cuts tend to wander, check for wear of the blade side guides. Most guides can be removed and filed flat so that maximum support is given to the blade.
1f after carrying out all of the above adjustments difficulty is still encountered with straight cutting, particularly when using a rip fence; the blade itself must become suspect. Due to the method of manufacture or sharpening, some blades tend to lead in one direction. Clamp a waste block of wood to the saw table so that it touches the side of the blade opposite to the direction in which the saw tends to cut. Turn the saw band wheel by hand only; at the same time hold a slip stone against the teeth on the opposite side to the waste block as the blade is rotated. Half a dozen turns should suffice. On no account should a file (for instance) be placed against the blade when the machine is running.
The purpose of this action is to remove the burr created when the blade has been sharpened from one side only.
WHEEL ALIGNMENT
If after carrying out all of the foregoing procedures, trouble is still being encountered with the blade tending to run off the wheel, first up, change the blade and see if the problem exists with one particular blade only.
Not all band saw blades are perfect and two problems some times found, particularly with either new or re-sharpened wider blades are (a) the blade has not been joined squarely resulting in the back of the blade being longer than the front, or vice versa. (b) If the teeth have been heat-treated in order to harden them, the front of the blade may contract on cooling, once again giving an uneven front to back length. Both of these faults are difficult to correct. Fortunately this is not a common problem, but it does occur and when it does, a great deal of time is spent accompanied by an equal amount of head scratching trying to figure out just what is going on.
A more common cause of the problem is aligned band wheels.
CHECKING PROCEDURE
Install the widest blade that you usually use. Adjust tension as explained previously. Open the side panels and tilt the table as far as it will go.
Using a long straight edge position it so that it touches both wheels as close to centre as the hubs will permit. See Fig. 6
If the straight edge touches the top and bottom of both wheels, the wheels are parallel and lie in the same plane. Should the top wheel not be parallel with the lower wheel use the wheel-tilting device as shown in Fig. 2 to correct this situation.
If the wheels are parallel but do not lie in the same plane see Fig. 7. Two choices are usually available. The lower wheel, which is the drive wheel and locked on to the drive shaft, may be adjusted to bring it in line with the upper wheel or the upper wheel packed out with a suitable sized washer or metal shim to line up with the lower wheel. In either case both wheels must be parallel and in line for correct operation.