Prizen":3poyu681 said:
Hi all
I'm s beginner at wood work and have recently purchased a n old Luna bandsaw .
I have clamped a fence to its cast iron table . When I cut, the blade just wants to turn towards the machine and I end up with a ,15 degree cut rather than a straight line .
would I be correct in tinking the first thing to check would be the guide blocks ? The blade tends to twist when I'm cutting.
If I should change the blocks , what type should I get? There's hard plastic blocks installed at the moment .. are the blocks sold in standard sizes as my bandsaw is quite a rare type - Luna bs 320
Many thanks
Contary to popular belief, the guide blocks only have an effect if you're cutting curves, or you're forcing straight an otherwise twisted blade. I'm not sayng don't change them - Lignum Vitae sap/resins give it self-lubricating properties, and it's very hard wood too - but a properly set-up blade doesn't run on the guides at all when you're cutting straight.
The issues will be in the basic setup of the machine and the state of the blade. Do some quick tests: first, pull the plug out, so there's no leccy on it. Then hold the blade between finger and thumb (at the sides). Slide your finger to the tips of the teeth and feel them gently. Are they equally sharp on both sides? If a previous owner hit a nail, it's most likely to have been blunted asymmetrically - one side worse than the other. If a lot of repetitive curvy cuts were made, it might have had the same effect. A blade that's not symmetrical will not cut straight, whatever you do.
More importantly, because if this is wrong, changing the blade will not help, is the basic machine alignment. Broadly, the wheels need to rotate in the same plane as each other, the tyres need to be cambered and in good nick, and the blade needs to be tensioned correctly. the wheel alignment needs to be right when the blade is tensioned, too -- on small bandsaws like mine, the machine bends significantly as you tension it up.
There's a process to follow carefully in order, to ensure it's all correct. I wholeheartedly recommend Steve Maskery's DVDs here, as he shows as well as explains, and his method is good for any bandsaw (even ones with three-inch-wide blades!).
If your machine is old, it's probably well made (the ones I've seen have been), BUT it could probably do with a really good clean and a check over. You might find one of the wheel bearings is a bit iffy, which will make precise setup almost impossible. I'd start with Steve's DVDs, so you understand what you need to do, and a full mechanical clean up and check, then setup. Once you have it right, it probably will hardly touch the guide blocks in straight line cutting. I"m sure you'll get really good results from it, too.
E.
