Tuning out Drift on my Bridgewood 21"

[Kenneth Casper]

As some of you know I picked up a used Bridgewood several weeks ago. I have been going through it and tuning it up. But I am still getting some drift when resawing 10 inch boards. The saw came with the original euro guide on the lower and a single bearing Carter Guideall on the upper. I got a new double bearing extra wide Guidall 500 for the lower and ordered an extra set of bearings to convert the upper to an extra wide. I also ordered a new Woodmaster 1" blade.

This past weekend I installed the guides, mounted the blade, and fine tuned the setup. I squared the table to the blade and set the fence perfectly parallel to the blade. This is my first saw with flat wheels, and my expectation was with a carbide blade and no crown on the wheels that the blade would track perfectly straight. However when I made my test cuts, I found the blade had a fair amount of drift. The amount is about 1/4" over the length of the table. Is this normal or is there something else I should check? The main issue is with tall resaws. With short stock, this isn't an issue. I also found that despite the blade being square to the table, a 10" resaw was thicker at the base than the top. This wasn't due to the blade cupping as I simply shimmed my fence and got a much more uniform thickness in the slice, so I think the blade tension was okay. But still I would have expected the blade to cut more uniformly when squared to the table.

If you have any suggestions, I'm open! Thanks.

Ken

[Richard Coers]

Here's my take on resawing. If the fence is set correctly to the way the blade wants to cut, the blade is sharp, and you feed at the correct speed to let the blade do it's job of cutting and carrying away the sawdust, you don't even need guides on the blade. I never set a fence from a static blade. I mark a parallel line on the wood, and cut that line. Then I adjust the fence to the edge of the wood. Clamp the fence down, and make a test cut partially through the wood. The blade must be in a neutral position in that partial cut. If the wood wants to pull away from the fence, or the blade binds in the cut, readjust the fence. Crown in the wheels will not effect the cut. It is there to keep the blade from hunting for a sweet spot to run on the wheel, or to keep the blade running coplanar. If the blade has wandered off to give you a taper cut, first slow your feed, if it still remains, add more tension. Is there any sawdust on the insides of the boards when you finish the cut? If there is, you are feeding too fast. The gullets are full of sawdust and can not carry any more away. This will change the tracking of the blade since there is extra friction in the cut with full gullets. Good luck!

[Jonathan Spool]

Kenneth,
I would suspect that you might not have enough tension on your blade. I would tension the heck out of it and see whether your results, especially the top to bottom variance, diminishes, then if you get the results you want, de-tension to a level that gives you good results and gives the saw a break.

[Mike OMelia]

Drift is a natural component (error) in bandsaw useage. You can try to minimize it, but some will most likely remain. I have even heard discussions regarding tooth set being a contributor. The best way to deal with drift is to first minimize it (get the blade on the crown of the wheel and set for proper tension, and get the guides in the right place), and then take the rest out with an adjustable fence (one that can adjust to the angle of the drift). Some use plywood fences that are clamped to the table. Others use fences designed to for this very task. See the Deals & Discounts forum for info and offers on the Laguna Driftmaster. It's a great add-on, and you will not be dissapointed.

[dave toney]

Richard and others have pretty much covered it.
Bandsaws do not always cut square to the table, set your fence parallel to the natural cut of the blade.
I draw a line parallel to the edge of a piece of scrap and hand feed to find the direction of feed that puts the back of the blade centered in the cut then mark a line on the table and set the fence to that.
Dave

[Kenneth Casper]

Thanks all for the replies. My concern wasn't so much with the blade cutting square to the table as I know tables can be out of square. Rather I thought a bandsaw with flat wheels and a carbide blade would cut true to the line the blade lies on at rest. I adjusted my fence to be parallel to the blade at rest, but when cutting using a normal feed rate, the cut drifts to the left. I easily fixed this by adjusting my fence, but as I thought the cut should not be drifting given the flat wheels and carbide blade, I thought perhaps I was overlooking something on my tuning and setup. I'll add a bit more tension to the blade as suggested by Richard and Jonathan.

Mike, are the guitar builder? If so, we have exchanged postings on guitar building forums in the past.

Ken

[Mike OMelia]

Yup, that's me. I did not catch that part about flat wheels. But still, if the two drive wheels are not perfectly aligned with respect to each other, you are going to get some twist in the blade and that will give rise to drift. IMHO, it's just not worth the aggravation. If you get it perfect (doubtful) then as soon as you swap blades, you are back to square one. Best to use a fence designed to accomodate drift. I know that I sound like a shill for Laguna, but that Driftmaster fence is the cat's meow. :)

Mike