I recently purchased my first Band saw and am loving its versatility for making curved cuts even in thick wood. However, when it comes to situations where I need a precisely straight line, for example re-sawing lumber and cutting veneers I find that even with a fence it is very difficult, especially with very thick or very hard wood, to not get some drift away from a straight line.
What are some strategies for combating drift on a stationary band saw?
The best thing that I've found is to have a sharp blade with 3 teeth per inch. This is Michael Fortune's recommendation (a Fine Woodworking Contributor). I used to crank up the tension in my bandsaw blade to the point of it almost snapping. I finally listened to shoptalk live (FWW's podcast) and they said a 3 TPI blade will solve 90% of drift problems. It worked like a charm!
So, before buying any expensive tensioners, I'd invest in a cheap 3 TPI blade and see if that works.
In addition to that, I'd check out a video by Michael Fortune about tuning up a bandsaw to make very accurate cuts.
A sharp 3 or 4 TPI blade is the best first thing to try. A slower feed rate can also help, but if your blade rubs against the wood fast enough and long enough to produce significant friction, too slow a feed rate can cause burning.
If you've bought a bunch of high TPI blades after discovering that a higher tooth count often produces a cleaner cut, you may be wondering why a low TPI blades even exist.
Why is it that a slower feed rate and low TPI blade can eliminate blade drift? The simple explanation in many instances of blade drift, burning, and binding with any type of saw is that the blade has nowhere to go.
You may have noticed that a blade with a high tooth count consequentially also has smaller, shallower gullets; and a blade with a low tooth count can have very large, deep gullets.
Gullets are more critical to a blade's function than most people realize. Once you cut the wood, you need to get it out of the way so you can take your next slice. If the blade's teeth slice off material faster than the gullets can carry the material away, that material compresses to the point that it can't compress any more, then it starts pushing back on the blade. At this point, the blade follows the path of least resistance, which often means drifting to one side or the other, where the material is less compacted and cannot provide as much directly opposing force against the blade's forward motion. As you cut thicker material, you need deeper gullets to carry away the waste.
Mattias Wandel has an excellent visual explanation and accompanying video titled, The Physics of Bandsaw Resawing, but the same principles apply to any blade.
If you still have problems with blade drift after trying a sharp 3-4 TPI blade, there is a great video by Alex Snodgrass demonstrating how to properly set up your bandsaw and guides.
Tuning up a bandsaw is definitely equal parts art and science. There are a variety of bandsaws out there and before doing any demanding bandsaw work (i.e. re-sawing) I usually go over the whole saw to make sure that the blade, guides and wheels are properly set up.
However when I am trying to keep a dead straight line, the correct fence is indispensable. Most factory fences are of the kind that resemble a table saw fence. They are anywhere from 4 to 6 inches high and are as long as the bandsaw table. Rarely is this the correct bandsaw fence to use for resawing or blanking out table legs.
Enter the Re-saw Fence
I usually resort to this type of fence for keeping straight lines. The advantage of the re-saw fence is its single point of contact. Most bandsaws have a sweet spot feed angle where the blade will tend to cut best. Rarely is this perpendicular to the table of the saw. Imagine looking top down on the table, sometimes the saw will tend to want to be fed at a slight angle. A fence that cannot accommodate this will put the blade under tension and will cause the blade to bow or drift, even when wood is secured to the fence.
The re-saw fence is much better at allowing you to make adjustments in feed angle and will overall yield superior results when trying to hold a straight line.
It is good to have a couple of these of various heights. If you are re-sawing 6" 8", or even 12" boards, the taller the re-saw fence the better. Focus holding the board flat against the re-saw fence with your free hand and feed the board using a push stick like this guy in the photo ;).
Nothing beats a well tuned bandsaw (seriously), but this particular jig will take your saw to new levels when holding a good line.
Lighten the feed pressure aka don't push so hard on the wood.
Drift is cause because the blade buckles under the load. You can see that by stretching a ribbon between 2 points and applying a pressure to one of the edges, it will turn sideway easily.
A sharp blade and high blade speed will help a lot with that.
Here is what I made for re-sawing. It begins with a piece of plywood that I attached to my stock table. This is a miter gauge that I repurposed from another old bandsaw. Every time I change the blade, I resaw a scrap piece by hand (for a few inches - not all the way) to determine what the "drift angle" is. I then bring up this miter gauge and match it to the wood that I'm still holding and thus match that angle. I can then just hold any pieces up to the fence and use the bandsaw as I might use a table saw. This works better for me in that I can keep the cut pretty flat and require less planing to get the saw marks out. I usually plane these marks out by hand so I like to get the cut as flat as I can to avoid having to plane too much.
The fence itself could stand to be a bit taller but when I made this, I was resawing some pretty short stuff (I don't have a table saw). I can easily replace this one with a taller one if I need to.
Try to adjust the blade to cut in line with the miter slots, then adjust the fence to the miter slot.... probably not going to happen... if not, then adjust the fence for the drift of the blade. Personally, for anything thicker than 3/4 I don't use the fence at all. Just mark a line and cut to it. If I had a big 18" bandsaw I would consider going to the lengths of adjusting everything out very well but for now, cutting to a line is pretty much just as fast.
What you are doing works well, but after an initial adjustment it should not be necessary to adjust the fence angle if the bandsaw is well tuned and the blade is tracking properly. It can be a little difficult to get the tracking just right if your BS wheels uses tires with a crown on them, but it is very doable using a micrometer to locate the blade exactly in the center. Two different ways to get a similar result.
I liked your auxiliary fence which makes it easy to clamp to the stock fence without interference. A great idea!
Thank you so much
