Getting my bandsaw to cut straight

Well, not my bandsaw. My father-in-law’s. But I probably use it the most.

He bought it years ago and has used it for all sorts of stuff that probably wasn’t ideal when we didn’t have a chop saw/mitre saw. Then I started using it a bit more and noticed a few problems. The whole saw wobbled because one leg of the stand seems to be too short. The table tipped “backwards” away from the blade, so cuts always went further into the wood on the bottom surface than the top. The lock on the lower door has also fallen apart. I keep that close with a small wooden wedge. Possibly not Health and Safety-friendly, but it does the job. Given that my father-in-law installed a set of grinding wheels right over where he stores petrol for the mower, I think H&S would probably have had a heart attack before they got anywhere near the bandsaw should they have foolishly decided to visit.

Then one of the blade bearings blew itself to smithereenys and I decided that I’d replace them all and fix some of the other issues whilst I was at it.

Since then however I’ve been unable to get the saw to stop a cut “drifting” to the left (or the workpiece moving to the right, whichever you prefer). So last night I sat down and watched a load of videos on that YouTube about setting up bandsaws to see if I could get it sorted. I came up with a few possible causes:

  • Blunt/damaged/worn-out blade
  • Misaligned fence
  • Blade not sitting correctly on the crown of the top wheel
  • Misaliged table
  • Blade tension

I knew the blade was good because it was only replaced recently, so I didn’t worry about that. Same for the blade tension, which I checked when I put the blade on.

Fence alignment to the blade is a bit awkward to check because of the set of the teeth. I believe some vendors produce a tool to help with that, but I don’t have one. Instead, I moved the fence over to one of the mitre slots and adjusted it to line up with the mitre slot. If I get the table square later, then I should be good.

The blade was clearly sitting too far forward on the top wheel, so I adjusted the wheel to get the correct positioning as close as I could tell, turned the wheel a few times by hand to make sure the blade wasn’t moving about wildly and then started up the saw for a few seconds. The blade still looked nicely-seated, so I was happy with that.

All these things made no improvement at all 🙁 A test cut still showed the cut drifting to my left. So, to table alignment. I released the four bolts holding the table to the tilt mechanism and discovered that there’s really not a whole lot of adjustment, but I did my best, rotating the table clockwise from above because the cut was drifting left. For a rightwards drift I’ve have gone anti-clockwise. Whilst holding the table so it couldn’t move back, I nipped up a couple of the bolts to keep it in place and then did all four back up properly.

This time I had more success. A test cut appeared to go in a nice straight line, so until I find out otherwise I’m going to call the problem fixed.

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