Machine Band saw problem

[Grizzly Adams]

So I have one of those generic 6 in. horizontal band saws in my shop. It cut like a damn including some serious solid stock then it started throwing the blade every time I tried a cut, runs perfectly until then. To say I'm frustrated would be an understatement. the blade feels sharp to my fingers but I'm wondering if that's where the problem lies. Thoughts ?

 

[Bandit]

A blade that is cutting at an angle may cause that. Would check the guides also. Don’t know how many hours of use it has had, a bad/loose bearing maybe. Angled cuts, also look at the blade teeth, worn more on one side then the other, yes it does happen. Can pull the blade.
A lot of things for a fairly simple machine. Remove blade, look for wheels loose, bad bearings, loose guides, bearings not turning on guides, mislined guides which is easier to see with blade on. If nothing appears wrong, try new blade, and cross fingers.
Also check wheels for build up on them.

 

[PeterT]

Was it related to a blade change? I've heard where people have bought a so-called replacement size but it was just a bit too large in circumference. You run out of tension adjustment & think its tight but its really just bottoming out the adjustment range. Too loose & it slips off track. With enough use you can get mung on the wheels or bearings or in the assembly so the blade tracking & grip is adversely affected.

 

[Ironman]

I had similar frustrations with a 4x6 saw, and assumed the wheel had become bevelled and worn, so sold it, and bought a new one with an angle cut ability and hydraulic downfeed. It was a wonderful thing, and then it was not. SSDD.
So I was forced to dive deeper and checked the blade guides.
To adjust properly, I loosened the guides so they could move upwards, in relation to the teeth of the blade, until the roller behind the blade wasn't touching the back of the blade at all (i.e. roller stopped turning). Do that with the blade running and tensioned up and aligned. I then moved the guide forward so that the back roller just touched the blade. That way the blade is running from the flange on the top wheel to the flange on the bottom wheel in a direct line and all the guides are doing is twisting the blade so it drops square through the cut.

Loosening the guide fixing bolt on my machine allows the guide to move every-which-away, so I left it partially tightened and adjusted the guide angle with a 10" Crescent and tapped if forward or back with a machinists hammer, re-tightened and checked again for squareness in the cut. JPitkin says use 2"x2" dressed all sides timber for this but I suspect rectangular plastic drain pipe would work even better since only the top and bottom edges matter just don't let it drop to quickly through the cut as you could overload the gullets of the teeth).
Still not satisfying results and the blade would jump if a cloud went over the sun.
So I found Pitkins document, and dove into tracking and alignment. This was my problem. I used a 2x2 angle iron and becan cutting 1/4" slices off it, and adjusted tracking and guides. I found I could cut 1/8" angle iron on the vertical leg (10-14 tooth) very fast with serious down pressure and no blade jumping and the cuts were square.
I recommend going through the process.

 

[Johnwa]

Check that the free wheel is turning easily. The one I had ran in a hardened steel bushing with no obvious oiling points. As long as it was kept oiled it was fine.

 

[DPittman]

Was it related to a blade change? I've heard where people have bought a so-called replacement size but it was just a bit too large in circumference. You run out of tension adjustment & think its tight but its really just bottoming out the adjustment range. Too loose & it slips off track. With enough use you can get mung on the wheels or bearings or in the assembly so the blade tracking & grip is adversely affected.

I have a meat band saw (cheap Asian made thing you see everywhere) the blade that came with it was pure garbage. I couldn't cut a straight line for the life of me. It was suggested to me to replace the blade and I reluctantly did and it was a night and day difference.

 

[SkookumRob]

That's always a challenging issue to troubleshoot as there are a number of potential implications. The things I would check are:

1) Tension adjustment - is there something impeding the full tension being applied? This I think is the most likely issue.
2) Guide set-up (as already mentioned)
3) Is the blade dull on 1 side only (causing it to pull hard that way)?
4) Check wheel bearings (can you "rock" the wheels when the blade is off)?
5) Is the blade possibly "inverted" and the teeth are pointing the wrong direction?

If none of that works, please share a video of the saw in operation and I'll see if I can spot something else!

 

[BaitMaster]

The idler wheels have a bolt / Allen set screw that adjusts the cant on the wheel. The axle bolt and the set screw I’m talking about are used to align the idler with the driven wheel which is fixed.

The idler wheel can be adjusted in and out by loosening/tightening both the axle bolt and the cant adjusting set screw simultaneously. Then the angle can be adjusted if they are adjusted independently.

Hopefully this is making sense.

If it doesn’t I’ll take a picture of my bandsaw for you and point to what I’m talking about.

It took me forever to figure that out and get mine tuned properly.

 

[Grizzly Adams]

Thanks gentlemen, I now have some things to follow up on.

 

[BaitMaster]

The bottom hole on there I’m pointing at has an Allen head set screw. The middle bolt is the axle bolt I talked about.

You can mess with those to change the angle and position of the idler wheel.

I angle it slightly “in” so that it keeps the blade on if you know what I mean.

Pain in the butt.