I am trying to rip Pella aluminum door/window trim with my 14″ Jet bandsaw because I have installed sliding doors in an existing home. Everything is harder than new work. I am using a Kreg fence and a 1/2″ blade with 12 tpi. I have good blade tension, guide blocks close to the blade and the blade guard as low as possible and firmly locked in place. The blade makes a nice clean cut, but pulls the trim uncontrolably away from the fence leaving me with a tapered piece that is not what I want Since the trim is about $10 a piece, I would love to have suggestions on how to get the saw to track straight.before I put myself in the poor house. Help!
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What you are experiencing is called blade drift, very common with bandsaws. You don't set a rip fence in line with the tables, you set it in line with the drift that occurs with the blade. To set your rip fence, make a straight line on your work and cut along it without a fence for 10"-20", then with the piece laying on the table, you set the fence to that. Another technique is to use a point fence. Rather than a straight, long fence, you use a fence that just forms a point in line with the leading edge of the teeth set at your desired size. Bandsaws and their blades are not the same as a table saw with a circular blade, you have to think a bit differently. Most bandsaw books will explain these techniques.
When all else fails, blame the blade
Thanks for the reply. I had lots of problems with this with my previous bandsaw, which is why I replaced it. Seems to me that I read that the problem occurs when the set in the blade teeth are not balanced left to right. There are also lots of opportunities for the blade to be unsquare due to all of the adjustments of the saw. My fence does have the ability to align it off parallel/square. It even comes with instructions on how to set it that are similar to the ones that you provided. However, I realized that the blade in the saw had had an unfortunate encounter with a hidden nail a few days ago. I just picked up an 18 tpi Bosch metal cutting blade at Lowe's (looks like more tpi than that, but who counts), installed it and now it cuts true with no adjustments to the fence. I hope that I can get back on track tomorrow when the frustration has worn off.
BTW - Do you have any suggestions regarding adjustment of the guide blocks? I am wearing mine out very quickly? Should I be thinking of them as highly expendable items and keep a box of them on hand?
Thanks again.
If everything seems under control, you're not going fast enough. - Good for racecars, probably not for woodworking.
There are different types of guide blocks and different ways to set them. The type that are called "cool blocks" look like layers of paper. These can be set tight to the blade and are often the choice when scrolling with narrow blades. With the hard metal type that typically come with the saw, you don't want them actually touching the blade. They are set after the blade has been tensioned and is running so its on the center of the wheels, teeth not touching a crowned tire, next you set the rear bearings so they just barely kiss as the blade turns by hand, then set the blocks so they also just barely kiss, they are set just behind the teeth gullets about 1/32". The teeth should never contact the blocks. When you turn on the saw, the blade should run true and not touch either the bearings or the blocks.
It's the saw operators skill that keeps the work from forcing the blade sideways so it contacts the blocks. Most folks are pretty hard on their bandsaw blades, twisting, forcing and pushing the blade off its true track, trying to get back on their cut line a little too late. If you are sawing correctly, you should see the rear bearings stop spinning if you aren't pushing against the work. I've been running the same metal blocks for 35 yrs. I'm a cabinetmaker and use the saw a lot. I've had several bandsaws in the shop and have used cool blocks and Carter bearings on other machines. Can't say I liked either.
A sharp blade makes all the difference on any saw but especially on a bandsaw. I like Olson blades, check out their website for good info. Using the correct blade makes all the difference but you also need to learn to work with the saw, not bull onward, it takes a little finesse and the correct feed speed. Normally you want 3 teeth imbeded in the material to reduce gullet loading and tooth stripping. 18 TPI would be good for 5/32" material. 32 TPI for 3/32". For straight line cuts, a wider blade is chosen. I'd use a BM (bi-metal) blade 3/4" wide, 32 TPI with wave set for ripping 1/8"+- aluminum. I'd also use a blade lubricant, a cake of parafin works but there are specialized lube sticks.