Thread: Understanding bandsaw drift

Hi jillb,

I could not get that link to work, but I think I have seen what you are describing. The idea is to mark a line parallel to the edge of the board and then cut along the line. The blade may pull to the left or right if the teeth are not set or cutting equally. You would then angle the board as you a feeding in so that the blade still cuts along the line. When you set the fence to the edge of the board, it should no. Be at the 'correct' angle.

In my experience, fresh sharp blades cut straight, and those that drift or pull have either been sharpened with more set on one side, or suffered abuse due to a nail or stone on one side.

If you are serious about ripping material, I suggest fitting the widest blade you can too. It will waiver less in the cut.

Good luck with it.

After reading an article by Michael Fortune, I've always followed his philosophy of tuning out drift using the upper wheel tracking alignment. Align the fence parallel to the mitre slot, then adjust tracking until the blade cuts parallel to the fence. After a bit of practice on different blades it only takes a couple of test cuts and a few minutes to get dead straight cuts.

I've never found any need to adjust the fence to compensate for drift.

Google bandsaw tuning+Michael Fortune for some ideas.

My first bandsaw was a 36" cast iron monster and the fence was a one-piece casting with no adjustment. To tune the saw to cut parallel with the fence, I used the in-built alignment knob – otherwise known as the tracking knob.

I use Fortune's method too.

Originally Posted by Robomanic

If you are serious about ripping material, I suggest fitting the widest blade you can too.

Skip tooth blades help also because they clear out the swarf during the cut a lot easier than regular toothed blades.

However, if you have borrowed a bandsaw. I reckon that you will do fine with whatever blades that you have. Just don't force the cut. The wider the better as stated.




.

Thanks everyone. Being used to a table saw, and never having used a bandsaw, I didn't understand that the bandsaw blade may pull to the left or right if the teeth are not set or cutting equally

I have found the Michael Fortune articles, thanks for that reference, (I notice he recommends a 3TPI 1/2" blade), and now look forward to having a go on some test pieces

Jill - for resawing on a small/medium bandsaw (which is what most of us have) the 3 tpi 1/2" blade is a popular choice.

The bi-metal version from Henry Bros is particularly good, but if you're only making a few cuts (and therefore not concerned about blade life) any good quality carbon steel blade would be cheaper.

I have been working gradually over the last year or so towards the aim of slicing up some LARGE jarrah chunks that were cut only metres from my front door (convenient). The first step forward was a large old chainsaw (stihl 076) and the second a large old bandsaw (36").

I had seen the videos on the net of people running blocks of wood through a bandsaw and achieving perfectly even cuts ... that's what I wanted to do to jarrah roughly 12"x12"x3 foot.

I had read and seen the info about cutting in halfway etc, but there wasn't a problem with material only 4" deep or so. With big chunks post-chainsaw, I was having trouble trying to freehand a straightish line just to reduce them down to more reasonablish lumps, ending up with a sweeping curve that was no help whatsoever in assisting the next cut down the line.

I didn't have a heap of time free over this period so I tended to have a go at it on a weekend ... get so far ... then come back to it a week or more later.

At some stage I realised that although early on I had made some (side) cutting guides out of jarrah for the bandsaw, these had worn away at the front of the block only - creating a rebated effect so that while the rear of the blocks might be virtually gripping the back of the blade there was a half mm of movement possible to either side at the front of the blade.

I therefore went off and took some time - with a bit of experience now and knowing what I wanted to achieve - to make new guides out of some very hard marri I had and to make sure they evenly supported as much of the width of the blade as possible ... and made them a bit longer than before also.

Between that and making a nice high solid fence - the results have been fantastic (for me in my newbie cloud of ignorance). The first time I made a long straight cut through a big whack of jarrah I was a happy happy happy fellow ... (Easily pleased)

So ... verbal diarrhoea aside ... I would suggest paying close attention to the top and bottom blade guides to minimise the degree to which the front of the blade can steer offline.

My blade is 25mm wide .. I'm not sure if it would be more or less important in thinner blades to have them well-guided (or equally important I suppose).

Sorry to go on.
Cheers,
Paul McGee

as regards the setup for ripping the board - are you saying i have to do this every time, or just once?

sorry if it sounds a bit daft but we've got to start somewhere. cheers!

Originally Posted by bluntlarry

as regards the setup for ripping the board - are you saying i have to do this every time, or just once?

sorry if it sounds a bit daft but we've got to start somewhere. cheers!

It's best done every time you change the blade, so you're allowing for any change of set between blades.

Personally, I don't like table-saw style fences for ripping straight lines. At all. I prefer a "point fence" and a scribed line, constantly steering the board to keep the cut on the line.

This is because not only can the blade drift due to unequal set/sharpness of the blade, but sometimes the grain is just difficult enough to cut and at just the right angle to the line of cut that the grain forces a degree of drift, regardless of how carefully you align the fence.

My method caters for both causes.

Another reason for unequal set is the habit of making circular cuts from only one side. Where possible, I cut circles alternating the center inboard and outboard. If you cut only large circles, with the center necessarily outboard, the set will degrade more on one side than the other. By alternating the attack, the set degrades more equally.

Cheers,
Joe

Thanks very much for the info. from a very wet and windy workshop! I understand it more now.

I agree with what has been said above, and with a new blade I tend to use the fence, and afterwards, when the blade has lost its edge (often due to cutting circles in one direction ) it seems necessary to do as Skew suggests. The grain of the timber definitely affects how a bandsaw tracks.
My gut feeling on the uneven cut from wear on the teeth is that it is caused, in part, by pressure on one side of the set -as the blade runs over the wheels. Excessive tension may be the reason, but possibly not undoing the tension when the saw is idle. I have seen discussions about that here previously.
The worst resawing problem I have experienced is bowing within the cut, where the blade actually bellies, so there is a concave/convex surface, not straight 90*! Insufficient tension, and trying to force hardwood through a blunt blade.
When you get consistent results, resawing on a bandsaw is very satisfying!

Cheers

I cut all my veneers on the bandsaw and in my experience, bellying and grain-tracking are caused by high feed rates.

With a square-to-the-table fence, a sharp blade aligned with the fence (using the tracking knob) and by paying attention to the sound of the cut/feed rate, I can cut consistent 1/16" veneers all day long – or until the blade dulls.