by THE SAW DOCTOR
In this edition of the saw doctor I will be talking about bandsaw guide blocks. All you need to know about their purpose and how to set up your guide block for trouble - free running of your bandsaw blade.
There are two types of guide blocks. The first type is fibre blocks and the second type is sealed bearings.
The fibre blocks can be made from timber or bakelite. The advantage of using these types of blocks is if it comes into contact with the saw teeth it will not damage the teeth.
The disadvantage of this type of guide block is it requires more attention as they wear quickly and need readjusting and replacing on a regular basis.
The bearing guide blocks have their advantages and disadvantages. The advantage is they are hard wearing and easier to adjust and do not need as much attention as the fibre blocks. The disadvantage is that can easily take the set and round the cutting point off the tooth should the bearing come in contact with the teeth. Another disadvantage is that the bearings need cleaning on a regular basis as the dust builds up around the bearings. Cleaning the bearings regularly ensures that the bearings spin freely to maintain trouble free running of your bandsaw.
So what system do I think is the best? In my opinion I think the bearing system is the best if it is kept in good condition.
Fibre Block System Bearing System Bearing System
There are two components to the guide blocks. The first component is the bearings on either side of the bandsaw blade. The other component is the Thrust Bearing at the back of the bandsaw blade.
How close should the guide bearings be to the bandsaw blade?
The side bearings should be adjusted so they are just under the gullet of the teeth. The second adjustment is the bearings should be as close as possible to the side of the blade without touching.
The purpose of the side guide blocks are to support the bandsaw blade whilst cutting, to keep the blade cutting in a straight line and stop deflecting to the right or left.
If the guide blocks are set too close to the blade this will cause cracks to form under the gullets as the blade is working under stress.
The current practice at the moment with setting up the back edge of the bandsaw blade to the thrust bearing is that the thrust bearing should be as close as possible to the back edge of the blade but without touching the blade.
The method I was as taught was, that there should be a 2mm gap between the thrust bearing and the back of the blade. The back edge of the blade should only come in contact with the back wheel whilst cutting. This is a good rule as this saves the tension being drawn out through the back edge of the bandsaw and causing the bandsaw to become twisted.
Potential Trouble- Shooting
Another problem that can arise if the back edge of the blade is too close to the thrust bearing is the back edge of the blade can become crystallized. This will then lead to cracks appearing along the back edge of the blade. The outer surface of the thrust bearing should not have any grooves in it at all.
If there are grooves in the thrust bearing this will cause the blade to track in the groove, which causes cracks to appear along the back edge as the bandsaw blade is working under stress.
Though this system of guide blocks is a good system, it is important that you carry out regular maintenance on the bearings by keeping them clean, they should spin freely by hand. The thrust bearing should not have any grooves on it at all. If you keep this in mind and maintain the bearings you will have trouble free running of your bandsaw machine.
Until next time ...... Happy Cutting!