Q & A: Fix a Misaligned Blade-Guide Post
Every time I change the height of the blade-guide post on my bandsaw, I have to readjust the thrust bearings and the guide blocks. Is there any way to fix this?
The problem is that your blade-guide post is not traveling parallel with your blade. As you raise and lower the post, its position relative to the blade can change from front to back and from side to side. This requires readjustment of the thrust bearing and the guide blocks with each setting. The condition can be remedied on a cast-iron saw by shimming the joint where the upper arm connects to the base or riser block. Brass shims are easy to use and come in a variety of thicknesses (see Source, below). The process takes a little trial and error, but once you’ve got the arm shimmed right, your saw is set for life. 1. Use a square to see whether the table is dead-square to the side of your blade. Loosen the table trunnions to correct. 2. Put the square up to the back of the blade to see whether it is square to the table. To correct it, adjust the tracking to center the blade on the wheel. 3. Remove the guard and blade-guide assembly from the blade-guide post. Lower the post all the way and check for square. Note the direction the upper arm must tilt to become square to the table. 4. Release the blade tension and loosen the bolt that connects the upper arm to the base. 5. Shim the joint to correct the outof- square guide post. You’ll have to estimate the size shim needed to align the guide post. 6. Retighten the arm bolt and tension the blade. 7. Check the guide post again. Repeat the procedure using different shim combinations until the post is dead-square front to back and side to side.
Note: Product availability and prices are subject to change. Lee Valley and Veritas, leevalley.com, 800-871-8158; Brass shim stock, sampler pack (one 2-in. x 6-in. strip of 0.001 in., 0.0015 in., 0.002 in., 0.003 in., 0.005 in. and 0.01 in.), #27K07.50.