Bandsaw tyre question

[JonJax]

Hi all,

I have a question for the forum; I have just bought a Kity 613 which needed new tyres. I ordered these from France using a link on this forum, however the tyres supplied as for the Kity are 20mm wide yet the wheels are 25mm. Is this correct? If so do I fit the tyres flush with the front edge of the wheels?

Thanks
Jon

 

[Myfordman]

If the wheels are crowned, then fit with the centre of the tyre at the peak of the crown.
If no obvious place to locate then try and get them central with the bandwheel bearings to take the load better.
Set tracking so the blade gullets are at the crown or centre of the tyre.

 

[JonJax]

Thanks for the reply, do you know if the tryes are supposed to be the same width as the wheel? I don’t want to force them on and then find I have bought the wrong ones.

Jon

 

[NazNomad]

If the wheels are crowned, then fit with the centre of the tyre at the peak of the crown.

They're not. The Kity 613 has flat wheels.

Because of that, Kity recommend you fit the blade with the teeth just off the front of the wheel, so I'd install the tyres to the front of the wheel.


Edit - just measured mine, they are the same width as the wheel, 25mm

 

[Ttrees]

I have seen plenty of tires narrower than the wheels
Its not like your going to need the whole width of the wheel on your bandsaw, or most if not all others for
that matter.
The tire width should easily account for the differences in the range of band widths you have with your saw.

[edit] If flat tires originally came on that machine and it runs well with all blades, I would be inclined to source
25mm tires.

Has that Kity bandsaw been changed atall through their time in production?

Tom

 

[Beau]

Think NazNomad has nailed it. And your unlikely to need a blade more than 20mm so cant see a problem but does sound strange that they are not the same width as the wheel.

 

[JonJax]

Thanks for your help, now I am worried that the length is wrong too, I have put in hot water but they need to go from 68mm to 98mm in order to fit? All a bit frustrating as I have completely cleaned and oiled it (looks like new) and after waiting ten days for the postage from France I still don’t have a bandsaw I can use.
I have emailed the French supplier.

 

[Steve Maskery]

TBH, if the teeth are going to run off the front edge, I'd get the tyres as far BACK as possible. That would keep the body of the blade closer to the centre of the wheel.

 

[JonJax]

Steve,

That was my thought now that I have got the tryes on (boiling water). The counter thought is that they need to line up with an edge in order to get them square.

Thanks
Jon

 

[Steve Maskery]

I have never understood notion that the blade can sit right at the front all the time and always track properly. We've had this conversation before on this forum. I do accept that that is how some people have it and it behaves perfectly properly for them. That's fine, I don't have a problem with that. But if the blade is right at the front and it DOESN'T track properly, then what?

The blade is tracked by adjusting its position back or forth, until the blade is cutting square at table position, and if it's not square, you have to shove it over until it is. And if you are using a very narrow blade, I have some that are 1/16", I don't think that there is any way you could get them to stay on the wheel if the teeth were hanging off the front edge.

It doesn't, and never has, made any sense to me. I've asked manufacturers about this and they've not been able to explain the rationale behind it either.

 

[deema]

I think there could be a little confusion with resaws and band saws. The big resaws don’t have tyres and you set the blade to run off the front of the wheel. Bandsaws have some form of tyre and the gullet should be on top of the crowning. Mr Snograss uTube is an excellent reference source.

Tyres don’t actually need to be very wide! The teeth should not be in contact with the tyre, so anything in front of the crown is....well.....just for decoration. A little is needed behind the gullet to allow the blade to settle and take side loads, but again it doesn’t need to support the entire width of the blade. You can probably say that only 50% of the blade behind the gullet May come into contact with the tyre.

The main reason for wider tyres is for setting up and getting the tracking correct. It’s just easier if the blade can wonder around a fair bit whilst you tilt the top wheel to get it running in the right place.

 

[Beau]

I think there could be a little confusion with resaws and band saws. The big resaws don’t have tyres and you set the blade to run off the front of the wheel. Bandsaws have some form of tyre and the gullet should be on top of the crowning. Mr Snograss uTube is an excellent reference source.

Tyres don’t actually need to be very wide! The teeth should not be in contact with the tyre, so anything in front of the crown is....well.....just for decoration. A little is needed behind the gullet to allow the blade to settle and take side loads, but again it doesn’t need to support the entire width of the blade. You can probably say that only 50% of the blade behind the gullet May come into contact with the tyre.

The main reason for wider tyres is for setting up and getting the tracking correct. It’s just easier if the blade can wonder around a fair bit whilst you tilt the top wheel to get it running in the right place.

The Kity does not have a crown on the tyres (at least mine didn't). I take Steves point that setting the tyre further back would be kinder to bearings but theres no doubt the tracking on this machine can work very well with the tips of the teeth just off the front edge of the tyres. Also unusually the Kity has a means to adjust the tracking on the lower wheel as well. My explanation for the tracking system is that it's like a belt sander in that you have two non crowned wheel and tracking works fine but no expert in this aspect but it most definitely works for whatever reason.

It does sound like the tyres the OP has been sent may not be right but never had to change mine so dont know what they should look like off the machine.

As an aside we see lots of questions on here where new tyres need fitting but what causes them to need replacing?

 

[JonJax]

My tyres were so perished that you could rub lumps off with you thumb.
The wheels and tyres are flat and ythe manual clearly states that the teeth run off the edge. If the wheels are flat then I assume that the blade alignment with the fence will be true wherever the blade is on the wheel.

Interesting point about the bottom wheel being adjustable on the Kity as it has 4 adjustable screws holding the axle. These have obviously been fiddled with by a previous owner and I have no idea how to check that it is square.

Jon

 

[Beau]

My tyres were so perished that you could rub lumps off with you thumb.
The wheels and tyres are flat and ythe manual clearly states that the teeth run off the edge. If the wheels are flat then I assume that the blade alignment with the fence will be true wherever the blade is on the wheel.

Interesting point about the bottom wheel being adjustable on the Kity as it has 4 adjustable screws holding the axle. These have obviously been fiddled with by a previous owner and I have no idea how to check that it is square.

Jon

Probably never kept a bandsaw long enough to have my tyres perish so that explains that one for me.

I tinkered with my lower wheel a bit but once right dont remember I had to fiddle with it again. Think its just trial and error turning the wheels by hand with a band on and watch what it does.

 

[Myfordman]

Quite a few machines have the 4 screw mount for the lower wheel. All that I have read about these is adjust at your peril.

My temptation would be to fit a blade just to take up all the slack. DONT POWER IT UP.
Set the tracking adjustment to the middle of its range and check the wheels are co-planar. you might need to remove the table to do this.
If the lower screws have been disturbed from the factory set up, then use them to set the wheels co planar.
Then back off the guides, turn the wheels by hand watching the way the blade moves over a couple of turns, adjusting the tracking so you can see that the blade stays in the same position as you turn.
Power it up and if the blade comes off, make SMALL corrective adjustments to the tracking. After a while you should get it to keep the blade on reliably. Patience is the key.
Then set up the guides so that they conform to the blade free position and NOT try and push it one way of the other. use thin strips of paper to set the gaps.

Good luck

 

[topconker]

Can I ask a daft question, what is co-planar on a band saw?
TC

 

[Myfordman]

Can I ask a daft question, what is co-planar on a band saw?
TC

Each wheel must be in the same plane.

 

[topconker]

How would I check this as I removed the bottom wheel to replace the tyre.
There are 4 bolts that can adjust onto the shaft and then locked in place, one of which I had to replace as it sheared off.
The shaft seems to have a radius at the bearing end which means the whole shaft can be adjusted in all planes.

 

[topconker]

By the way Myford man we live only a few miles away as I'm in Salisbury together with my ML7

 

[Geordie Joe]

Set the tracking adjustment to the middle of its range and check the wheels are co-planar.

No, they must not be co-planar. See the video below, or more importantly LISTEN to it.

https://youtu.be/wGbZqWac0jU?t=358

If you make the wheels co-planar you are setting yourself up for this

Power it up and if the blade comes off, make SMALL corrective adjustments to the tracking. After a while you should get it to keep the blade on reliably.

Patience is the key.

Or you could leave the wheels the way they are and save the need for patience.