Bandsaw help needed

[Yorkshire Sam]

Recently changed the tyres on my Record BS 250 bandsaw as one of them had been damaged.
Changing them was no problem but afterwards was unable to track the saw blade...
wondered what I had done wrong as no matter what I try I am unable to track the blade.
Get it all set up by hand but when I turn the power on it throws the blade.
The blade seems to want to wander towards the back of the wheel no matter where set it.
I have tried with two different size new blade to no avail. Tried a 3/8th blade and managed to get it stay on but you could see the blade fluttering very slightly back and forth.
Couldnt find an answer to my problem on my Steve Maskery discs either.

Do the tyres need time to set in?
Is it possible to put one up side down?
If anyone could shed a light on what what the problem might be I would be very grateful as I have tried all I know.
Any other leads gratefully accepted

 

[mbartlett99]

Just a thought - if they're crowned make sure the flat side is against the wheel.

 

[Yorkshire Sam]

Just a thought - if they're crowned make sure the flat side is against the wheel.

Yes I thought of that and checked but both sides of the tyre appear flat.

 

[Lazurus]

Have you readjusted the tracking knob to align the blade in the correct position?

 

[Steve Maskery]

Can you talk me through what you did when you changed the tyres? Please explain how you did that, what you removed etc. I have an idea, but would like some detail before I proffer my thoughts.

 

[Yorkshire Sam]

Can you talk me through what you did when you changed the tyres? Please explain how you did that, what you removed etc. I have an idea, but would like some detail before I proffer my thoughts.

First I removed the top wheel, removing the existing tyre was quite easy as they were quite stretched (must have been around 2 inches larger in circumference).
Cleaned the wheel ( not really dirty). Put the new tyre in hot water for about a minute ( per instruction on packet)
Quickly dried the tyre and then lined up the bottom of the wheel and tyre in the vice and pulled over the new tyre ( a little awkward but nothing really difficult.)
Did the same with the lower wheel (except had to slacken off the drive belt and remove the circip)
refitted the wheels and tightened up the belt again.
Then onto putting on a new blade.....
I have left out the obvious steps of slackening off the guides as part of blade change.

The reason the tyres was changed was because the blade was slipping and stopping and the tyres were quite worn... a few years use from new.

 

[Steve Maskery]

OK, well that's my idea out then!
I was thinking that you may have undone the axle bolts. If you had done that it could well have twisted one wheel relative to the other, which would definitely cause the blade to slough off. But if you did not touch them, that is not the explanation.
The blade wandering back and forth - how much of a wander? If it's only a mm or two it is probably the blade itself rather than your setup. Nothing much to worry about actually.
But if your setup is just as it was before, I don't really see how a new set of tyres would, of themselves, cause the blade to slough off. Sorry.

 

[MikeG.]

........Then onto putting on a new blade.......

This is where I would start. You've got two (or three) variables: new tyres, and new blade. So you don't actually know if the problem is with the tyre/s, or the blade. I suggest taking the new blade off and putting the old one back on, and seeing what happens.

 

[sunnybob]

He did say he;'s tried two blades, same result.

try this if all else fails.
https://www.highlandwoodworking.com/lib ... planar.pdf

BUT!!!!!!...... make sure you mark the lower wheel axle in a way that if this does not work, you can put the wheel back to its starting point.

 

[MikeG.]

He did say he;'s tried two blades, same result.......

Ooops!

 

[CHJ]

How much play have you got in your top bearing axle assembly, in removing the upper wheel has anything been disturbed that has resulted in it being 'floppy'.

With tension on the blade can you rock the upper wheel in the 12 - 6 o'clock (north-south) direction?

It could be that as you adjust the tracking on the upper wheel instead of being a controlled tilt it is snapping over centre because of play in the system. Think of your adjusting thread as a worn lead screw that has to be approached from a positive direction to take up the slack.
Try tightening up the tilt knob locking system until it only just allows you to adjust the knob, removing any excessive slack in the system that may be allowing the wheel spindle to do its own thing instead of staying with the adjusting thread pressure.

 

[Yorkshire Sam]

Thanks to all for your help. I was beginning to wonder if my wheels are somehow no longer co planer, even more now after reading Sunnybobs post. I noticed that there is a difference in the position of the blade on the upper and lower wheels after first putting and spinning them while tensioning , before trying to track them. Having looked up the subject I get the impression that there is much controversy about whether or not they should even be so or even if its possible. I am even more confused now than before I started. I am beginning to wonder if perhaps my tracking system bolt might be a little worn and has play like someone suggested... I shall have to investigate it. Failing that is it possible to have the machine looked at by a professional? (If so who?) Otherwise at the moment I have a dead machine!

 

[sunnybob]

There is a lot of controversy over altering the lower wheel position. Thats why I said to clearly mark everything so that it can be put back in the original place.
as long as you have so marked it, you have absolutely nothing to lose to try to adjust it.

 

[CHJ]

Don't get hung up about the blade running in a different location on the two wheels, the lower drive wheel is fine as long as it's not excessively overhanging either side.
Unless you have Caused the lower wheel support shaft to move by excessive pressure or hammering whilst removing the lower wheel do not attempt to reposition the shaft that is aligned with (usually) four bolts, that way lies into extreme unknown territory unless you have means of setting it square to the rest of the frame assembly.


I'm assuming that the Blade always comes off the Top wheel not the bottom one and ran fine before you dismantled to change tyres.
To prove this you may have to temporarily tape up the two safety switches and run with covers open, obviously keep hands and the rest of your body out of the line of fire whilst observing this.


On the upper wheel shaft and 'play', was there a washer at back or front of the wheel to reduce it's ability to 'slide' along the shaft? freedom to slide along the shaft can have a similar effect to excessive play in the tilt mechanism.