baned saw blues

[blazemite]

I have recently purchased a large freestanding band saw, i am unsure of the brand but it is perhaps 20 years old and very solidly built. i am trying te resaw tops and sides for a ukelele out of some camphor i have stashed away, however my band saw seems to cut unevenly. This baffles me as i have checked that the blade is square with the platform. it starts the cut straight but after 1-2 cm the blade begins to wander off to the left, but not the whole blade, just the top. this means the blade is bending in the middle as it cuts. have any of you experienced this ? or do you know what i need to do to fix it ?

[blazemite]

oh and i realise i have acadentally called by band saw a baned saw in the title, this is a misstype..... it kind of makes my witticism a little less witty.

[Clancy]

Is the blade new.
A dull blade will often wander off line.

It may be actually cutting straight, just at an angle to your percieved "straight".
There should be adjustments available on the fence to correct for this.

Check out the net for bandsaw setup tutes & vids - that's what I did when first starting out & everything seemed to be going wrong

[Dominic]

Blaze, if you have already checked the blade tension and if deflects minimally check the guides above and below the blade, the blade should run straight through them without touching but with only a ciggie paper clearance or less on each side. Also there should be stops behind the blade on the guides, these should be close but not touching the back of the blade. Another thing to check is that the blade is centred on both wheels but more importantly on the top wheel. The tilt mechanism usually on the top can be adjusted to get the blade running in the middle of the wheel. Old wheel tyres with crap on them can make the blade run off centre. Same thing if they have grooves worn in them.
But if you think it is bending in the middle it sounds like you may not have enough tension on the blade. Wider blades used for resawing need to be very tight.
And as craig said, a decent new blade will add losts of value to your wood while a blunt or cheap one will make lots of saw dust. I use these, they are pretty cheap and work great for resawing.
http://www.highlandwoodworking.com/wood ... lades.aspx
Hope this helps.
Cheers
Dom

[blazemite]

thanks for the quick reply guys, one thing i have noticed is that the bad saw has only one bearing above the table and one below, it is not missing any, it just doesn't have them, i am possibly wondering if this could be the cause of my woes. how tight should the blade be ? is there a test or a way to tell if its too tight or too loose?

It probably is the blade, i havn't changd the blade since i bought it so chances are it is as blunt and my chisels ....

[Allen]

There should be a bearing behind the blade. The blade is going to deflect back against it when you start to push wood through. There will also be either bearings, or blocks on either side of the blade to help keep it from moving side to side. This goes for above the table and below the table as well.

To set them up with appropriate relief (they don't touch the blade but almost) you should be able to slip a $5 note between the blade and bearing (or block).

It's hard to err by over tensioning a blade, especially with a big one. Usually the machine frame starts to bend before you can get them over tensioned. That's for newer machines. Those very old cast iron beasts like a Wadkin will pull a blade as tight as you'll ever want.

[auscab]

All of the above , sharp blade ,slower cut, but a very important step is to tune your fence to each blade you put on, every blade cuts different and the fence must be parallel to the way that blade cuts. Get a scrap of wood 800 x100 x 19 , buzz an edge straight then on a table saw trim it down off that buzzed edge so its a straight 95mm wide, then with a gauge scribe a line down the middle.
Take the fence off the band saw and have a black texta ready ,do a saw cut half way down the board on the scribed line and turn off the saw,make sure the board does not move around of the line you have cut with the texta mark along the edge of the board on the saw table.

Put your fence back on and slide it up to the texta line, the fence has to be set to that line.
Rob

[duh Padma]

Try a new high quality wide rip blade as in at least 1/2 inch wide (less than 6 teeth per inch) with deep gullets.

Narrower blades will wander in thick stock.

Then tune up that saw just like the others have advised.

Use this blade only for ripping plates, nothing else and you should get some life out of it.

So to recap...wider better rip blade and tune up the saw.

If your going for a 1/8 inch plate then rip at least 3/8 inch slabs till you know you got the tune up bugs worked out.

Oh ya run test cuts on some 2 x 8 construction planks first.


blessings

[J.F. Custom]

Older bandsaws are less likely to have full bearing supports.

So only having two bearings is not a problem in itself - you should find as Allen said, these two you have, one above and one below are behind the blade - these are your 'thrust' bearings. They should be set as others have mentioned, close enough that when you turn the machine on, they are not running, but as soon as you push timber into the blade, they are engaged and prevent the blade from moving back.

You should ideally however, have some form of side support for the blade. Some older machines only had one set, often above the table, not below as well. From sketchy memory too, some did have nothing at all but I'm not certain of this. But they are likely to be in the form of a block on either side - or they should be. Check you have this and they are set correctly. If there is nothing there at all, above or below, look for evidence something can mount there that is missing. You will have trouble maintaining an accurate cut without any guides.

Finally though, if you have not changed the blade - that is your first point of call. Bandsaw blades can dull very quickly. Chances are, yours is very blunt and that will solve a lot. I'd be changing those bearings too as they are likely to be cactus by now.

As is usual with older machines, seems you need to do some work to bring it back to scratch. On the positive side, once you have, they are usually pretty well built and accurate units.

Good luck.

Jeremy.

[blazemite]

well my bearings seem to be only stopping it from moiving to one side, it has two sets of blocks (one above, one below that can keep it in place but it seems to have no back support ... i tightened the blade and it cut well for ten minutes then the blade slipped of the wheel .... scared the hell out of me when it did it, it made a rather loud noise ..

[J.F. Custom]

Two sets of blocks and a bearing only on one side? Interesting.

Photo of the upper and lower blade guide setups would be helpful Blazemite.

[ZOOTMAN]

well my bearings seem to be only stopping it from moiving to one side, it has two sets of blocks (one above, one below that can keep it in place but it seems to have no back support ... i tightened the blade and it cut well for ten minutes then the blade slipped of the wheel .... scared the hell out of me when it did it, it made a rather loud noise ..

Something doesn't sound right here. Without rear thrust bearing or some type of rear stop this saw will never cut right. You tightened the band and it slipped off then it's way too tight. The blade bowing in the middle is a sure sign that your fence is not compensated for blade drift.

[DarwinStrings]

Hmm something doesn't sound right to me either and if your blade came off while it was running then you either did not set the top wheel correctly before you started it up or you have lost all camber on the tyres. Some photos of the guides and a close up of your wheel profile would be helpful. Also I can't remember your name or I would have used it.

Jim

[blazemite]

i will upload some photo's as soon as i find my camera ......