Bandsaw throwing narrow blades off wheels

[dusty]

Perhaps the PO tightened it with the bearing jammed and instead of pulling the bearing into the bore, the bracket bent. That would be my 'guess'.

Isn't it bent the wrong way to fit that synopsis?

[JPG]

Isn't it bent the wrong way to fit that synopsis?

Nope! The short leg with the slot that is facing up Ed's pix slips over a rib in the 'chassis'. The screw is inserted through the 'slot' from the bottom in Ed's pix. The bracket got bent down in Ed's pix as the screw was tightened.

Up in Ed's pix is towards the 'chassis', Down in Ed's pix is out from the 'chassis'. The bracket got bent out(down in Ed's pix).

[dusty]

Nope! The short leg with the slot that is facing up Ed's pix slips over a rib in the 'chassis'. The screw is inserted through the 'slot' from the bottom in Ed's pix. The bracket got bent down in Ed's pix as the screw was tightened.

Up in Ed's pix is towards the 'chassis', Down in Ed's pix is out from the 'chassis'. The bracket got bent out(down in Ed's pix).

OK, if you say so. Thank you.

[JPG]

OK, if you say so. Thank you.

Tis much easier to visualize things when 'in hand' - No?

[chipmaster]

My bandsaw came with a 1/2 inch blade that worked great. I recently bought both 1/4 and 1/8 inch blades. I first tried the 1/8 inch and it wanted to walk off the wheels (I was turning by hand with the cover off BTW).

Also, my clip holding the lower wheel bearing assembly was bent exactly as the one pictured here. I pulled it off and looked at it and was sure it started life straight, so I straightened it out. With it bent, you could slip the lower wheel bearing assembly in and out of the chassis over about a 1/4 inch slop range. With the clip straight, the lower wheel is tight. Unfortunately, the 1/8 inch blade still wanted to walk. So I tried the 1/4 inch, and it is working fine.

Incidentally, my upper wheel has a lot of runout, or slop for lack of a better term. I pulled it partly off the spindle it rides on, and it has needle bearings. I didn't want to pull it all the way off because I didn't want to deal with bearings going all over the place. The bearings were lubed well but I put a drop of sewing machine oil on them before reassembling everything.

Since the spindle and bearings are steel, I asume whatever wear has occurred to cause the slop has been in the wheel itself, since its some sort of cast lightweight material--aluminum or pot metal; can't really tell.

Question: I considered packing some grease on the needle bearings to take out some of that slop. Any opinions on that idea?

v/r,

Rick

[JPG]

[quote="chipmaster"]My bandsaw came with a 1/2 inch blade that worked great. I recently bought both 1/4 and 1/8 inch blades. I first tried the 1/8 inch and it wanted to walk off the wheels (I was turning by hand with the cover off BTW).

Also, my clip holding the lower wheel bearing assembly was bent exactly as the one pictured here. I pulled it off and looked at it and was sure it started life straight, so I straightened it out. With it bent, you could slip the lower wheel bearing assembly in and out of the chassis over about a 1/4 inch slop range. With the clip straight, the lower wheel is tight. Unfortunately, the 1/8 inch blade still wanted to walk. So I tried the 1/4 inch, and it is working fine.

Incidentally, my upper wheel has a lot of runout, or slop for lack of a better term. I pulled it partly off the spindle it rides on, and it has needle bearings. I didn't want to pull it all the way off because I didn't want to deal with bearings going all over the place. The bearings were lubed well but I put a drop of sewing machine oil on them before reassembling everything.

Since the spindle and bearings are steel, I asume whatever wear has occurred to cause the slop has been in the wheel itself, since its some sort of cast lightweight material--aluminum or pot metal]
Light grease is what they need, not oil. Unless the outer ring is worn, the needles should not jump out.

Now please describe the blade parting from the wheel - which wheel (first) and which side(in/out) and where(12= up, 6=down, 3=blade guides, 9=yoke.

Also have you checked the cant?

Lastly, is the upper wheel 'bent'?

[chipmaster]

Light grease is what they need, not oil. Unless the outer ring is worn, the needles should not jump out.

Now please describe the blade parting from the wheel - which wheel (first) and which side(in/out) and where(12= up, 6=down, 3=blade guides, 9=yoke.

Also have you checked the cant?

Lastly, is the upper wheel 'bent'?

I should have been more specific--The blade doesn't walk all the way off. It migrates to the outside edge of the wheels and stays put (at least during hand turning--I surely didn't try it with power).

I can't say for sure where it "starts." It just seems to evenly walk on over.

As for cant, I believe it is proper when I have the 1/4 inch blade on, riding where it's supposed to, and tensioned. I'd wager it goes out of cant once the 1/8 inch blade walks to the outside of the wheel because of the slop I mentioned.

Bent wheel--I don't think so, but you've got me wondering. I've run it with the cover off (Don't tell OSHA) just for observation purposes. There seems to be movement that I attributed to normal vibration. Maybe there's something more at play. I'll have to try it again in the morning.

Thanks for the input!

v/r,

Rick

[JPG]

I should have been more specific--The blade doesn't walk all the way off. It migrates to the outside edge of the wheels and stays put (at least during hand turning--I surely didn't try it with power).

I can't say for sure where it "starts." It just seems to evenly walk on over.

As for cant, I believe it is proper when I have the 1/4 inch blade on, riding where it's supposed to, and tensioned. I'd wager it goes out of cant once the 1/8 inch blade walks to the outside of the wheel because of the slop I mentioned.

Bent wheel--I don't think so, but you've got me wondering. I've run it with the cover off (Don't tell OSHA) just for observation purposes. There seems to be movement that I attributed to normal vibration. Maybe there's something more at play. I'll have to try it again in the morning.

Thanks for the input!

v/r,

Rick

'On over' to where? Outside edge away from 'bearing' side of wheel?

That would require a LOT of slop'.

Can you cause the 'wandering' by rotating by hand from the 'lower' wheel?

OSHA has no jurisdiction in your home shop!;) CPSC is the big brother in that department!:rolleyes:


P.S. Please describe where you think the 'proper location' for the blade to 'ride' is.

[chipmaster]

'On over' to where? Outside edge away from 'bearing' side of wheel?

Yes -- It wanders away from the bearings.

P.S. Please describe where you think the 'proper location' for the blade to 'ride' is.

I believe the backside of the blade should ride against the bearings.

[JPG]

Yes -- It wanders away from the bearings.




I believe the backside of the blade should ride against the bearings.

Yes, but I was interested in where on the wheel.

Let me see if I understand what is happening.

When the narrow blade is installed on the wheels with NO tension and is located against the upper wheel guide bearing, and against the lower blade backup/guide bearing, then tension adjusted for a 1/8" blade, then when the lower wheel is rotated, the blade drifts across the face of the upper wheel away from the blade guide bearings, but does not drift far enough to slip off.

What is happening on the lower wheel during all that drifting?

Finally does the blade clear the upper blade guide back up bearing when first installed against the upper and lower guide bearings?



I have come to the conclusion that narrow blades drifting away from the upper wheel blade guide bearing is caused by insufficient cant or tire wear. The upper wheel is beveled and the cant needs to be sufficient to prevent the blade from drifting out from the bearing. The narrow blades are the most critical condition due to their smaller surface contact with the tire. It is possible that wear from the larger blades have created a low area on the tire into which the narrower blades drift. If the narrow blade is coming all the way off the upper wheel, the cant is inadequate. All this assumes the blade backup bearings etc. are properly positioned.

That is the way I see it on an early Christmas morn. Better go to bed before that jolly old elf arrives!:D