Why did my bandsaw tyre come off

[brianhabby]

There I was merrily cutting away on my Axminster SBW3501B bandsaw when it suddenly and without warning started vibrating. It has never vibrated before so after hitting the stop button and opening the top door I noticed that the tyre had slipped to one side. The blade (a 3/8" from Tuffsaws) was still in the centre of the wheel but the tyre had slipped to one side. The tyre on the lower wheel appears to still be correctly placed.

Why would this happen? Had I got too much tension on? Is the tyre now knackered?

I will phone Axminster in the morning but if anyone has any ideas I would love to hear from you.

regards

Brian

 

[blackrodd]

Sounds like the tyre has stretched and come unglued as some of them are, my top tyre came apart while i was cutting,
Good job the guarding was all set right as it woke me up!.
You can either get a replacement from Axminster, I think they do them, or fit a set of urethane tyres, as I did and have had no problems since, urethane tyres are a tight fit and not glued, you're choice really, unless, of course you're bandsaw maker does not sell any replacement tyres so you will have to get urethane replacement.
I bought from these and can recommend them,--

http://stores.ebay.co.uk/BAND-SAW-TIRE-WAREHOUSE

Just tell them the model/ wheel size etc,
Regards Rodders

 

[brianhabby]

Thanks Rodders,

Your explanation sounds plausible, I wondered if it had got too hot and softened the rubber.

Is it best to replace both tyres at the same time?

regards

Brian

 

[CHJ]

If it ain't broke leave it alone.

Get a spare by all means and save yourself some work, basic law is that if you carry a spare just in case you'll never need it.

My bandsaw was showing a frayed drive belt 3 yrs. ago so got spares, they are still in pristine condition in spares cabinet.

 

[blackrodd]

You don't say how old you're saw is, I would hope it's 3 or 4 years old.
After a time the rubber type tyre seems to go soft and then hard and then degrade.
Yes, buy a set of either type of tyre and replace both, a bit fiddly, but after a couple of goes you will get the "knack"
Track, in you're usual way with the blade in the tyre centre, favoured by most makers, or with the gullet at the tyres centre as mr Snodgrass favours, here's a link,--

https://www.youtube.com/watch?v=wGbZqWac0jU
HTH Regards Rodders

 

[brianhabby]

I bought the saw in August 2006 so it is almost 9 years old, only had hobby use though.

I think I will buy a couple of urethane tyres & keep one as a spare and see how I get on.

Just watched that video quite interesting, thanks.

Thanks for your help guys.

regards

Brian

 

[sunnybob]

You don't say how old you're saw is, I would hope it's 3 or 4 years old.
After a time the rubber type tyre seems to go soft and then hard and then degrade.
Yes, buy a set of either type of tyre and replace both, a bit fiddly, but after a couple of goes you will get the "knack"
Track, in you're usual way with the blade in the tyre centre, favoured by most makers, or with the gullet at the tyres centre as mr Snodgrass favours, here's a link,--

https://www.youtube.com/watch?v=wGbZqWac0jU
HTH Regards Rodders

It always intrigues me when one person goes against the grain. I havent seen any other video that says gullet in the centre. This guy is a showman, but also an undeniable expert at bandsaw.
Who's right? or does it really not matter?

 

[woodpig]

We don't seem to agree about him on here. I've not read anything suggesting Alex's method doesn't work though. I've tried it and will continue to do so as it works on my Record BS300E. The only caveat I can see is that it's probably not suitable for larger blades but then Alex is only using it on blades up to 1/2" as far as I can see.

This explains why it works:

http://thewoodworkersnews.com/2012/11/bandsaw-blade/

If you've spent ages setting up your Bandsaw and you've "tuned" your fence to some odd angle to stop blade drift then probably leave it like that. If however you think your bandsaw could be cutting better and are willing to try something different then give it a try, mines never worked so well and the fence likes being straight! :lol:

This method is obviously aimed at hobby saws with crowned wheels. If you have flat wheels on your machine then check with the manufacturers recommendation. :wink:

 

[Steve Maskery]

What matters is that it cuts true. Many manufacturers suggest that the teeth should overhang the front. No-one has ever explained to me satisfactorily why that should be so. I have always had the teeth on the tyre, and, all other things being equal, the blade runs truest if the teeth are somewhere near the middle. Maybe dead centre, maybe not quite., it depends on the width of the blade and the size of the teeth. Gullets in the centre is a good starting point.

I use the analogy of a barrel, which is curved, to show why the blade should be fairly central in order for the blade to cut true. If you watch that video, you will see that he doesn't get it quite right and does a shimmy with the table to get over it. You couldn't do that with my BS, not without a spanner and ten minutes to spare. He is a good showman, I'll give him that.

Understanding how the tracking alters the direction of the blade is key to getting your blade to cut straight ahead, and eliminating drift is infinitely better than just skewing the table, or even worse the fence, to overcome poor setup.

 

[CHJ]

Just had to go out and take a look at my saw, a SIP 14", to confirm where the blade is running.

Current Blade is a 1/2" and it's running with the teeth forward of the rubber tyre but not contacting the alloy wheel as the rubber/wheel diameter difference is enough to clear the kerf.
It cuts true with fence set as near straight as I can get it in use.

Regardless of blade if I get drift it is an indication that the blade needs replacing or at least sharpening and re-setting.

On narrower blades I just put them on and let them run on the rubber.

The rubber Tyre is Flat not crowned, if it ever was crowned then it has been worn flat over the years.

And yes it does cut true and I expect it to do so regardless of whether I'm cutting rough log blanks or thin slices.

I do buy blades with a large kerf/set as I rarely need a super good finish on the cut, having said that I don't get a surface that can't be cleaned up with a swipe of a plane or even just abrasive.

Even a 1/4" blade runs true without any problems.

And an indication of the wide kerf on the above 1/4" blade and how tight it will cut a radius.

 

[Steve Maskery]

With narrow blades, like the ones we home woodies use, the crowned/flat difference is negligible, because there is so little width in contact with the wheel. The physics is the same, though, because the way the wheel tilts means that the path of the wheel follows the same shape as if it were crowned and it's this tilting that alters the direction of cut at table level, which is what we are interested in.

The barrel analogy stands for both flat and crowned wheels.

Impressive cuts, Chas.

 

[Random Orbital Bob]

Richest and most clear explanation I've ever come across and why I always advocate following the manufacturers instructions as published in the manual for those with crowned wheels. As Scotty would have said "Ye canna beat the laws of physics Captain"
http://woodgears.ca/bandsaw/crowned_pulleys.html

 

[woodpig]

I think the idea of running the blade off the front of the wheel with flat tyres is to prevent damage to both the teeth and the tyres. Flat tyres give more blade support so having the teeth just off the tyre isn't a problem. Mark Duginske says in his book "The band saw handbook" that some band saws used to have one flat wheel and one crowned, normally at the top. He also suggests that only a blade up to 1/4" is fully supported on a crown wheel bandsaw and that it's handy to have two bandsaws in your workshop. A crown wheel saw for use with small blades and a flat wheel one for large blades! I never checked the wheels but that's pretty much what they had where I used to work.

Mark also says in his book that "The crown exerts a controlling force on the band, pulling the blade towards the top of the crown. This tracks the blade close to but not necessarily in the middle of the wheel".

Clearly, trying to draw analogies between dive belts and bandsaws doesn't work as bandsaws have a tilting top wheel to track the blade.

 

[blackrodd]

The need for crowned bandsaw wheels and blades came from using these saws, --

https://www.google.co.uk/search?q=stenn ... Ut13a_g%3D

As they were steel blade, starting at 5 1/2" wide, and discarded at around 3", running on iron wheels, crowning was needed to help keep the wheel centred and running evenly, the saw blade is crowned and "rolled" to the same profile.
The tracking, which was set by the gullet running at 1/16th",over the wheel, Thereby keeping the teeth clear of the wheel and for the sawdust to eject clear of the wheels and not build up between them and saw blade, making them unstable, teeth were between 3 1/4" and 2 3/4" long.
The correct tension, which was a weighted arm, set at the horizontal in each case of a blade change.
There are side guides but no rear thrust bearing to support the blade, thus the crowning.
There are 2 iron boxes, one for the top wheel, and one for the bottom wheel, filled with diesel oil, drip feeding
a bristle brush, set on each wheel, collecting dust an debris build up on the top and bottom wheels.

The bandsaws of which we speak, are designed to run on rubber tyres because of the narrower blade width and therefore for stability, they can be tracked and stable on a rubber tyre, and no damage to the teeth.
It would be difficult to track a 1/2" blade with the gullet 1 mm clear
I've used several what we call 30" bandsaws, ( wadkin, etc) and they were all flat rubber tyred,
crowning is not necessary as the rubber provides enough grip, but because of the various narrow blade sizes,
guides and a rear thrust bearing stabilises the blade in cutting.
On a recent thread, a member said that a persons qualifications ought to be declared to help clarify knowledge
From opinion.
So, I, as a couple of other members served an apprenticeship and have worked all these, and other machines,
for many years, and whilst I do NOT know everything, I did learn quite a bit, and much about SAFETY was drummed
into us in the saw mill.
Regards Rodders