Thread: Run out or atleast I think thats it.

Are you re-adjusting the tracking on the saw after you change blades and resetting the guides to suit that particular blade?

Yes DJ,

I have spent atleast 4 hours with each blade
Not much actual woodwork being produced

Not sure what you mean by "run straight on the wheels"...

You didn't say anything about cutting, so I assume you're just running the bandsaw, and seeing some movement in the blade?

Are you saying that the blades move forwards or backwards on the wheels?
On both wheels? In the same direction?

Are the blades all the same width?
Is the blade that seems OK wider or narrower than all the others?

Is it possible to post some pic(s) to show the problem?

Cheers,
Andrew

As for "testing", the only thing I can think of is to use a straight-edge along the back edge of the section of blade which has the weld.

If the ends weren't exactly 90 degrees, the angled join could give the blade a bit of backward-and-forwards movement in that part of the blade.

Cheers,
Andrew

The blades vary in width, the more teeth the narrower the blade.
As odd as it seems it is the mid range blade that works best.
The problem is on the top wheel, no matter which way i adjust the wheel all four blades will either run to the fron or back of the wheel

Next question: are they flat wheels or crowned?

ie. is the tyre slightly higher in the middle of the tread than at the rims? (Assuming it is tyred, of course.)

Are you being very cautious in adjusting the tracking?

I've found that a 1/8th - 1/4 of a turn of the tracking knob can move where the blade runs on the upper wheel on my bandsaw.

I'm not sure it's vital to have the blade always running dead centre on the upper wheel - I think I read somewhere that smaller blades often run towards the front half of the wheel.

Cheers,
Andrew

Originally Posted by arose62

I'm not sure it's vital to have the blade always running dead centre on the upper wheel - I think I read somewhere that smaller blades often run towards the front half of the wheel.

Yes, because the offset of the teeth in effect makes the length of the cutting edge slightly shorter than the length of the "band" of the blade. So the blade will try to move towards the front half of the wheel (to equalise blade tension) and should be allowed to do so. This is why I asked about crowning.

It may also be that with wider blades, the back cutting guides (above'n'below the table) are too far forward, pushing the blade away from wheel-centre. However, in this case I'd expect it to be noticeably running forward on the bottom wheel!? (You are checking the blade position on the bottom wheel too, aren't you Howdya?)

Running to the back of the wheels... now that I'd put down as a simple tracking maladjustment. I suppose a stretched blade could also cause this, but it'd have to be a pretty bad stretch for it to make up for the offset of the teeth (same principle as in my first sentence) and I'm pretty sure that any halfway decent blade would snap well before it stretched that far.

Errrm.... I'm not claiming to be a BS guru, BTW. God forbid! I'm just applying what I've picked up from the forums to what little knowledge I've learned by getting mine to cut veneers. (Which it does beee-autifully BTW. Thanks to these forums. ) I could be well'n'truly off-base, although I don't think so.

I seem to be having the same problem....Except with the bottom wheel. What seems to happen is:
I fit the blade, track, set the guides etc.
Then spin it by hand and the top blade stays in the same spot but the blade on the bottom moves to the back.
Is this just a simple tracking issue or could the wheel need re-alligning ( is that possible?)

cheers

Originally Posted by Skew ChiDAMN!!

Next question: are they flat wheels or crowned?

ie. is the tyre slightly higher in the middle of the tread than at the rims? (Assuming it is tyred, of course.)

They are crowned

Originally Posted by arose62

Are you being very cautious in adjusting the tracking?

I've found that a 1/8th - 1/4 of a turn of the tracking knob can move where the blade runs on the upper wheel on my bandsaw.

Yes, anything more than about 1/3 of turn will make the make blade move in the opposite direction

I'm not sure it's vital to have the blade always running dead centre on the upper wheel - I think I read somewhere that smaller blades often run towards the front half of the wheel.

I read the same thing here on the forums, but the blade actually "walks" off the wheel

Cheers,
Andrew

Originally Posted by Skew ChiDAMN!!

Yes, because the offset of the teeth in effect makes the length of the cutting edge slightly shorter than the length of the "band" of the blade. So the blade will try to move towards the front half of the wheel (to equalise blade tension) and should be allowed to do so. This is why I asked about crowning.

Is the crowning supposed to ensure the blade runs towards the front

It may also be that with wider blades, the back cutting guides (above'n'below the table) are too far forward, pushing the blade away from wheel-centre. However, in this case I'd expect it to be noticeably running forward on the bottom wheel!? (You are checking the blade position on the bottom wheel too, aren't you Howdya?)

Checking both wheels it seems to remain in position on the lower wheel.

I haven't got as far setting the cutting guides with the problem blades, could this be the problem My understanding was that you should set the blade on the wheels first, get the tracking right and then set the guides into place.

Running to the back of the wheels... now that I'd put down as a simple tracking maladjustment. I suppose a stretched blade could also cause this, but it'd have to be a pretty bad stretch for it to make up for the offset of the teeth (same principle as in my first sentence) and I'm pretty sure that any halfway decent blade would snap well before it stretched that far.

Errrm.... I'm not claiming to be a BS guru, BTW. God forbid! I'm just applying what I've picked up from the forums to what little knowledge I've learned by getting mine to cut veneers. (Which it does beee-autifully BTW. Thanks to these forums. ) I could be well'n'truly off-base, although I don't think so.

Just a couple of comments, from a relatively new bandsaw user, which might be relevant, or alternatively controversial.

Firstly, when changing blades, I find it is necessary to redo the setup from scratch, particularly if the blade is a different width. It will track differently, and the guides will be in the wrong place, or will push the blade into the wrong place. The first time I changed to new 3/16 blade, I nearly stuffed it, as it would have run with the teeth so far back, they would have fouled the blocks.

Slack off guides, and withdraw, or at least back off the thrust block/bearing, so blade can run unrestrained. Then adjust tracking to run on crown of wheel. (Some authorities suggest running slightly to the front, so that set of teeth is off tyre; more on this later). I have found that the tension also has an effect. Applying high tension (for resawing) definitely affected the tracking, causing the blade to run to the front (as I remember).
Then position the guides so that they run just behind the set teeth, for maximum twisting support, and snug up till they "just almost" touch the blade. I actually allow light contact. Then bring up thrust to a smidge behind the back of the blade, so that the first pressure from timber brings it into contact.
Also check that the guide/guard assembly does not "twist" as it is raised or lowered. I had to modify the guards to stop this.

Further on tracking and tension, and touching on the effect of set, mentioned in an earlier post. I replaced one 3/8 blade, (the original chinglish one) which I had set up to run and cut without drift, with a new Henry blade, without doing the above. The new blade tracked forward, and cut with huge drift. Set up from scratch, but with the blade slightly forward, as above. Still drifted towards fence, and worse with high tension. So reset from scratch again, this time right on crown of wheel. Drift gone!!.
Can only assume that with the blade unevenly supported on the wheel, blade was stretching under heavy tension, and becoming slightly "conical", which caused drift.
When taken in conjunction with the effect of tension on tracking on my machine, if I am doing tricky resawing, I actually fine tune the blade tension, not only to prevent bow, but also to fine tune the tracking to parallel the fence.

Flaming awaited!!

Originally Posted by Howdya do that

Is the crowning supposed to ensure the blade runs towards the front

No, it helps them stay tracking where they're set up and also prevents the offset of the inside teeth from being "flattened" as they pass over the wheel.

Small blades will run a bit forward of the centreline (but still partially over the centreline) while wider blades should run properly centred.

I haven't got as far setting the cutting guides with the problem blades, could this be the problem My understanding was that you should set the blade on the wheels first, get the tracking right and then set the guides into place.

You should back off the guides first, so they're not interfering with the blade while you set the tracking. (I usually do this when removing the previous blade.) Badly set guides won't make a blade track to the back of the wheel, though.

Originally Posted by Howdya do that

They are crowned

The wheel rubbers must be in good condition and crowned from the centre out.
Generally the blades should run centrally on both wheels if the machine is in good working condition.
More blade tension is better than less.
If the "set" of the teeth on the blade are worn down on one side, the blade will not cut in a straight line.

Cheers
Woodfast Aust

Originally Posted by Alastair

Just a couple of comments, from a relatively new bandsaw user, which might be relevant, or alternatively controversial.

Firstly, when changing blades, I find it is necessary to redo the setup from scratch, particularly if the blade is a different width. It will track differently, and the guides will be in the wrong place, or will push the blade into the wrong place. The first time I changed to new 3/16 blade, I nearly stuffed it, as it would have run with the teeth so far back, they would have fouled the blocks.

Slack off guides, and withdraw, or at least back off the thrust block/bearing, so blade can run unrestrained. Then adjust tracking to run on crown of wheel. (Some authorities suggest running slightly to the front, so that set of teeth is off tyre; more on this later). I have found that the tension also has an effect. Applying high tension (for resawing) definitely affected the tracking, causing the blade to run to the front (as I remember).
Then position the guides so that they run just behind the set teeth, for maximum twisting support, and snug up till they "just almost" touch the blade. I actually allow light contact. Then bring up thrust to a smidge behind the back of the blade, so that the first pressure from timber brings it into contact.
Also check that the guide/guard assembly does not "twist" as it is raised or lowered. I had to modify the guards to stop this.

Further on tracking and tension, and touching on the effect of set, mentioned in an earlier post. I replaced one 3/8 blade, (the original chinglish one) which I had set up to run and cut without drift, with a new Henry blade, without doing the above. The new blade tracked forward, and cut with huge drift. Set up from scratch, but with the blade slightly forward, as above. Still drifted towards fence, and worse with high tension. So reset from scratch again, this time right on crown of wheel. Drift gone!!.
Can only assume that with the blade unevenly supported on the wheel, blade was stretching under heavy tension, and becoming slightly "conical", which caused drift.
When taken in conjunction with the effect of tension on tracking on my machine, if I am doing tricky resawing, I actually fine tune the blade tension, not only to prevent bow, but also to fine tune the tracking to parallel the fence.

Flaming awaited!!

No flames here Alastair Because if your right I'm doing it right.

I might order a new blade from Henry Bros and see what happens