Thread: Advice please

OK. By convention, a 17" bandsaw means it has a 17" throat. This is the distance between the blade and the inside 'spine' of the BS. Just so's you know.


I'm unsure in what sense you're using the phrase "1.5mm deflection." Do you mean deflection as in the blade is bowing in the cut, giving a non-square cut with 1.5mm difference between top and bottom cuts?

Or do you mean that over the length of the board, the cut wanders 1.5mm off true?

If the latter, I'm not particularly surprised. Personally I don't use a long fence for resawing thick stock, I prefer to use a point- or v-fence to keep things vertical while I adjust the cut as I feed to follow a line I've already scribed.

That way I don't become annoyed when I finish a cut before discovering it's not straight. (Although occasionally I instead become annoyed when I realise the idiot operator didn't scribe the lline correctly. )

Thanks Andy, my apologies, The cut from a given length has a difference of about 1.5mm from end to end. say 9mm at the start and around 7.5/8mm by the time I finish the cut. The timber is around 17mm dressed and I am making hopefully a couple of hundred pencil boxes. Splitting the timber allows me to make the box and the thinner piece of the halves the lid.

Hello,
Few things I'll quote you which may help.

"Hi everyone, I have what I think is a 17" bandsaw"

Well it either has 17" wheels, or it doesn't.
It may be measured in mm, and could be 440mm, like the Italian machines.

"Cut a piece of timber freehand down the middle and adjusted the fence of square to allow for blade deflection"

That'll work if it's the same amount of oomph needed for the cut, i.e not testing with little poplar stick, or whatever easy to cut timber,
then cutting something tall and dense.


"Adjusted the tension that when lightly touched the side of the blade it moves only about an 1/8 inch."


That may depend on how skookum your saw is, not many 17" machines may be able to tension a 25mm blade!
The saws weight would be a good indication whether it's able to do so or not.

I wouldn't try tensioning that blade to 2500 PSI without knowing.
been meaning to make a tension indicator for some time, but from the impression I've gotten for this tension, is that figure (if required)
is not a light touch, as it's often called the "white finger test"
This may break something on a machine which isn't honestly rated for such use,
(see machine weight for honesty, and not any manufacturers bogus claims)

"Fit an auxiliary fence on the other side of the blade so tha the timber is kept straight along the cut"

That could mean anything, a picture is worth a thousand words.
Some folk use a shorter fence to stop the timber bowing and creeping away from the fence,
Two long fences could very likely compound this issue further.

It sounds like your test material isn't as much a challenge as the project material is.
Guessing the saw is running well and you have aligned everything, which is far beyond the scope of the gurus recommendations from what I've seen.

Lastly, if that wide blade is the only one you've got, and you're getting drift on both sides of the line, (whilst tensioned as much as the machine is comfortable with)
then it may be worth using the point fence approach instead, for use with an under tensioned blade.

Hope that clears some things up.
All the best

Tom

Originally Posted by Tom trees

That may depend on how skookum your saw is, not many 17" machines may be able to tension a 25mm blade!

That would be my guess as the cause of your problem.

Thanks Tom and always. It makes perfect sense. I do have another blade which is about 1/2 inch wide. I will set that blade up and taking it easy perform another test cut.
Thanks again
regards Tony

Thanks everyone, I put a 10mm blade on the bandsaw and it cut a lot more accurately. Thanks again for your timely advice.