Contributing factors to Bandsaw drift?

[jgourlay]

I have a ~ 12 year old Minimax that up until about a 2 years or so ago had drift well within the limits of the fence adjustments.  The drift now is bad enough that it is well beyond the adjustability of the fence.

While I rarely use the fence, I do have a project coming up where I have a board that is exactly thick enough for the veneers if I can cut as accurately as I could on my last veneer project using the fence.  Additionally, I've noticed that the saw is less controllable than it used to be, by which I mean I find that when resawing I sometimes have steer very steeply to keep the saw on line.

My blade is relatively new and because it's carbide (Lennox trimaster) I doubt blade sharpness is my issue.  Tires are in good condition.  Bearings are in ok condition.  They are 'sluggish' but still spin freely.  What are other contributing factors to drift?  Do bandsaws develop different degrees of drift over time in general?

[mdhills]

blade would always be my first suspect -- any chance that it got damaged when it was first put into service?
Can you check with another blade and see if the drift is similar?

Would the lateral alignment bolts on the lower wheel affect blade tracking?  (I haven't adjusted mine on this saw; had some issue with those on an earlier 14" saw)

Matt

[Phil Thien]

How wide is the blade?  Have you checked to see whether the blade is parallel to the fence?

I've read that if the blade is cut/welded such that the front is a little longer or shorter than the back, drift will result.  So if you imagine laying the blade on the ground with teeth facing up, you would find the angle between the ground and the blade isn't 90-degrees.

I know, I know, seems like a stretch but figured I'd toss it out there.

[JGrout]

trimaster blades like to be tensioned properly so much so it is worth the effort to actually determine how much tension you are applying and then tweaking the tension until the drift is nonexistent.

[jteneyck]

You shouldn't be having drift on a saw of that quality, if you're talking a MM16 or larger.  I would agree that a dull blade or one with unequal set is the first suspect.  The fact that it never tracked straight, however, suggests that something else is a least partially to blame.  Tracking is just as important as a sharp blade, and blade tension close behind, at least on my list.  I would put a new blade on it and see how it runs; doesn't have to be a Trimaster, any new blade will prove the point.  If it cuts straight or at least as straight as it did when the Trimaster was new then you'll know the Trimaster needs to be sharpened.  If nothing changes then you'll know the saw isn't set up right. 

If it's the saw, then I'd start by adjusting the tracking of the blade on the upper wheel with the tension first set according to the scale for that width blade.  And what width blade are we talking about and what specific saw?  I think all MM's have flat wheels so the teeth have to hang off the front of the tire, but there still must be some adjustment capability with the top wheel that affects tracking.  If the blade wants to cut right, away from the frame, then the blade needs to come forward on the upper wheel, back if it wants to cut left.  If adjusting the tracking within the adjustment range you have doesn't fix the problem, then I'd check to see if the wheels are coplaner and, if they aren't, I'd adjust them until they are.  Plenty of folks will say it doesn't matter, and maybe it doesn't on some saws, but I've never seen a BS that won't cut straight because the wheels are coplaner.  Wheel alignment and tracking should get you there with a new blade.  

Good luck.  Keep at it.  There's no reason to tolerate this problem on a MiniMax.

John

[Steve N]

Drift is all about tension, provided of course that the saw is set up properly, guides adjusted correctly. Blade sharp? Is it a quality blade? Does it have horrendous welds? "Lennox trimaster" is simply a blade material that someone bought in bulk, then welded the blades either to spec, or for a blister card. Do you have other information about the blade? Did it come pre welded with a geometry that someone thought was good for your work? Or did you have it made to spec after talking with someone about what type of cutting you wanted the blade for IE: resaw, curves, whatever....

[collins45]

At its age it could be the blade that needs to corrected including the tension.

[jgourlay]

Thanks everyone, you've given me a lot to go on.  I'll let you know what I figure out.

[Delta007]

SteveN said: "Drift is all about tension".... Sorry, I must disagree... IMHO, the set of the blade teeth has more of an effect on drift than tension does.
Think not? Experiment...take a perfectly straight cutting blade and dull one side of the teeth (which effectively reduces the set towards that side) and watch what happens... bet it now cuts crooked... Seen it happen too many times over the years..

[AHill]

So many factors!

• Tracking not adjusted properly (blade riding on top of crown of upper wheel)
  
• Blade not parallel to fence
  
• Table tilted or not square to the blade (more common than you may think)
  
• Upper and lower wheels out of plane
  
• Guides not adjusted properly (one side maybe tight to blade while other is not)
  
• Kink or twist in blade (tension cannot always solve this)
  
• Broken, chipped, or missing teeth
  
• Motor belt not aligned properly with wheel pulley
  

If it's not something obvious, try changing your blade and see if that fixes the problem.  If it doesn't drift, it's your blade.  If it does, then there's an alignment problem.  At that point, it may be worth doing a complete new setup.