|Shopsmith Bandsaw Study from www.PatentPlaceUSA.com|
If you take a look at the illustration at right from the US Patent for the Shopsmith Bandsaw, (Click on it to Biggie Size it) most BS's utilize crowned wheels, like those shown in Fig. 12. The idea is that a flat band of steel, if properly made and tensioned will naturally gravitate towards the highest spot on a spinning wheel. When running on two crowned wheels the tracking is fine-tuned by tilting the upper wheel forward or back to properly position the high spot. Once the blade is properly positioned on the wheels the back-up bearings are brought into position against the back of the blade above an beneath the table to prevent the blade from being pushed off the high spot during the cut.
On the Shopsmith Bandsaw (SSBS) as it is bade today both the lower and the upper wheels are conical, or cone shaped, as shown in Fig 11. In addition to the conical shape the upper wheel is positioned with a slight backwards tilt. This design makes the properly tensioned blade run to the back of the wheel; and if there were no back-up bearings, I'm sure the blade would happily escape off the back of the wheel! To control this the SSBS has not only a set of back-up bearings above and beneath the table, but there is an additional set of bearings on the upright side of the frame whose only job is to control the blade tracking. In fact, this is what Shopsmith rightly calls the "Auto-Track" bearings.
So this is where the "Tune Your Bandsaw" articles cause their greatest frustration for the SSBS owner. First they'll tell you to back-off the back-up bearings and to adjust the tracking until the blade runs centered on the wheels. You can't do this on the SSBS.
Then they'll suggest that you hold a straight edge against the rims of the two wheels to ensure that they are properly aligned. If they are not you'll be encouraged to shim one of the wheels forward until they are brought into "coplanar" alignment. As you can imagine from Fig 11, there's no way this is going to be the case with the SSBS.
No, the SSBS is an engineering marvel that requires no such adjusting. But what if it's not cutting properly? Well, we'll need to check a few things that could hamper any BS's operation:
- Is the blade sharp?
- Is there a burr on the back edge of the blade?
- Are the guide blocks properly adjusted? (Behind the set of the teeth, and just kissing each side of the blade)
- Are the tires in good shape? Was it stored with a blade installed and under tension, which will "flatten" the tires on about 1/3 of their diameter, causing the blade to increase and decrease in tension and wobble.
- If the blade does not run towards the back of the wheels and against the Auto-Track bearings, consult your owners manual or contact Shopsmith Customer Service for instructions on how to adjust the tilt of the upper wheel.