Band Saw Blade Drift

[pigoo3]

Hello,

1st post for me.

I saw that there was a fairly recent topic posted relating to band saw blade drifting or wandering...not sure if my problem is the same.

I have a pretty low-end bandsaw from Taiwan...so I know that it is not the finest quality wood-working tool out there.

My problem is the inability to make straight cuts...even fairy short cuts of a few inches or centimeters.

I am using a fence when doing these cuts...and invariabily...the band saw blade will "pull" the wood away from the fence, making it impossible to follow the straight pencil line I have drawn on the wood...or to stay snug against the fence.

It almost seems like the band saw blade is twisting...or that the blade is not parallel to the fence.

I know that the blade is parallel to the fence (checked it)...and blade tension is tight.

I have been woodworking for about 30 years...and I have never had this problem with other band saws.

Any ideas on what is causing this, or how it can be fixed?

Thanks,

- Nick

[ozwinner]

I have the same problem with my cheap band saw, I dont use the fence any more in fact I dont even know where the fence is.

Mine cuts to the right, so I clamped a piece of ply to the table at the same angle that the blade pulls at, crued but it works.

There is also a post by about a sled that you can screw the timber to, so as to get consistent cuts.

Al :)

[DJ’s Timber]

Have you adjusted your guide blocks or bearings above and below the table. Every time you change a blade you need to adjust these to suit the blade.

As for the wood pulling away from the fence, the fence dosen't necessarily have to be parallel to the blade. The fence should be set to follow the direction of cut.

When I setup my fence, I cut the first inch or so by hand which tells me which way the drift is and then set the fence accordingly to that. I check this every time I change the blade, even if replacing a worn one with a new one.

[AlexS]

Try adjusting the position of the blade by adjusting the tilt of the top wheel. It should cut straight when the blade sits in the centre of the wheel, but you may need to vary it.
Drift can also be caused by pushing the wood too hard, often a problem on low end saws where you try to compensate for low power.

[joe greiner]

Bandsaw drift is usually caused by unequal set on each side of the blade. This can vary with increased age of the blade as the sides wear unevenly. As Al & djstimber have inferred, "tuning" the bandsaw should include determining its preferred direction of cut, and placing the fence in that direction.

Joe

[shep1]

I had the same problem with my 14in Elektra Beckum. I actually had reached the point where I no longer used it because of very similar problems,eg blade drift, bowed cuts, impossible to cut a parallel sided slice etc. Everything changed when I read an article in Fine Woodworking, titled "Five tips for better bandsawing". It is no exaggeration to say that this article was a revelation for me and my relationship with my bandsaw. I now cut down to 2mm slices of veneer in blackwood, jarrah, blackheart sassafras, red gum etc etc
The key points in the article are choice of saw blade (critical in my view), blade tension and tracking adjustment. The article is by Michael Fortune and appeared in FW Dec 2004.

[pigoo3]

DJ,

Yes I did adjust my guide blocks & bearings (and always do so depending on the blade).

Sorry, I forgot to mention that in my original post.

- Nick

[pigoo3]

Sounds like some folks have positioned their fence to adjust for the band saw blade drift.

I guess this is an ok fix...but it just seems like if the blade is parallel to a fence to start with, that the blade shouldn't drift or twist once you start to make a straight line cut.

Maybe it is a low-end band saw problem...because I have definitely used higher end band saws that always made straight cuts when using a fence.

On ther other hand...if I get rid of the fence...and try to do straight line cuts "freehand"...I still have difficulty cutting a straight line.

No matter how much I try to follow the pencil line on the wood...the darn blade still drifts or twists enough, that following a straight line is next to impossible.

Again it has got to be the cheap band saw...I guess you get what you pay for.

Any other suggestions are welcome!

Thanks,

- Nick

[Skew ChiDAMN!!]

I found that the tracking of mine changes when under load. I can set it up so the blades perfectly square to table and fence and cuts perfectly accurately through 6mm MDF.

However, as soon as I run a, say, 6" piece of redgum through it it invariably pulls the timber away from the fence.

At first I thought 'twas simply following the grain but after sending a few thick pieces through with the grain running towards the fence and the timber still pulling away, I realised it wasn't that.

Then I blamed the blade... 'twas the cheapy that came bundled with the BS. I replaced it with a known good one and found the problem was reduced significantly... but not totally. So the set of the blade was one cause but not the whole of the story.

I've since determined that the BS frame twists a bit when under load, just enough to change the angle of attack. By fiddling with the guides I could "tweak" the cut so it ran straight for thicker pieces.... but that threw the thin stuff out. 'Twas simply swapping one problem for another.

Now I use the fence for thin materials and a v-block for thick blanks. Much, much better! The v-block is a damned good idea! ;)

[pigoo3]

Yes...I agree with the amount of load theory.

I do notice that the "blade drift" does seem to get worse when I either try to cut thinner lumber too quickly...or if I am cutting a thicker than average piece of wood.

Trouble is...even if I try cutting a straight line, in a thin piece of wood, at a very slow feed rate...I still have a tough time making a straight cut due to the drift or twisting of the BS blade.

Think I will change the blade...and tweak all of the band saw adjustments, and see if that helps.

- Nick

[pjt]

hi piggo and everyone else
i have a 19 inch carba tec 2 hp machine (tiawanese) not bad but not good
i dont speak with yrs of experience but since getting into some serious woodwork i have had some of the problems u speak of and this is what i did to fix/reduce them...

first thing was the blade, cheap carbon steel thing that came with it, 3/4 inch wide fine teeth say 20 per inch, i probably cud get more use out of it since the mods i have made to machine and if i tensioned that blade tighter, anyway, talked to saw blade suppliers and blade is now about 1 tooth per inch, 1 1/4 wide, bi-metal blade, high speed steel teeth carbon back, basically a ripping blade, $80 compared with $20 tho about biggest i can get on there and i tension it as tight as i can get it
u might try tensioning ur blade up a bit at a time and see if it improves
tighter it is the straighter it will cut if all else is correct tho, imagine a piece of string held between ur fingers, tighter u pull it the greater the force required to deflect it
other mods were to chage all the upper and lower guide bearing set up, now has two bearings side by side on each side of blade to fully support width of blade insted of just one per side in the middle (8 in total now instead of 4) larger diameter brgs altho this wasnt necessary and then two of the original side brgs now support the back of the blade
also no clearance between bearings and blade, so no movement at all between guide brgs, blade runs thru the side brgs in a slight chicane, this is achieved by offsetting the hieght left to right of side brgs and use of eccentric adjusters, much better than what was on there b4
big difference in blade stability, with this function i can also adjust the blade square to table without moving table, a finer adjustment
i also put a 4 hp (doubled) motor on it which allowed me to up the blade speed and have plenty of grunt in reserve
i use a fence all the time and set it parralell to blade and i pretty much leave the upper set of guides up all the time regardless of width of board i am cutting
i can cut 350 max (300 max b4 mods) wide boards whatever thickness and parralell no trouble softwood or hardwood
now i have no s shaped cuts (lack of tension) and now if i have any deflection or blade wander it is either me or set has gone off one side of blade or blunt teeth
how many others out there have bought a carba tec machine or a jet or such and had problems and what if anything u did to fix the problems
my machine is a usable thing now and much improved and if anybody wants to chat in more detail about my fixes or doing mods for ur machine id be happy to chat about that as well
hope some of this helps pigoo or at least reinforces what most everyone else is saying
pete

[pigoo3]

Pete,

Yeah, I already tried increasing the tension on the blade...and it didn't seem to improve things too much.

I also adjusted the bearings & guide blocks...but my machines bearing setup is not nearly as "fancy" as your improved setup.

My machines bearings are only behind the blade...and are there (I'm assuming) to keep the blade from being flexed too much in the front to back direction.

For side to side control, it has those guide blocks. Two above the table, and two below the table.

Sounds like you have a pretty fancy bearing setup.

My blade is about 3/4" wide...still seems to cut fairly well...changing the blade could be one last thing to try.

Thanks,

- Nick

[workgoose]

pigoo, you mention guide blocks, which makes me ask the question what is the preferred setup, blocks or bearings? I am in the process of researching which BS to buy, and this and the question in the other thread re twisting on an HF16A are leaving me bewildered - again:confused:, or still.

[Skew ChiDAMN!!]

pigoo, you mention guide blocks, which makes me ask the question what is the preferred setup, blocks or bearings? I am in the process of researching which BS to buy, and this and the question in the other thread re twisting on an HF16A are leaving me bewildered - again:confused:, or still.

I think this is one of those things that everyone has agreed to disagree on.

IMHO, it's best to have a BS that takes both... I use bearings with my wide blades (1/2" plus) and cool blocks when running narrow "scrolly" blades. Which is a fancy way of saying I prefer bearings, I s'pose, as you've no choice BUT blocks with the smaller blades unless you want to "squash" the teeth! :rolleyes:

[workgoose]

Thanks Skew, that makes sense - I'll keep it in mind

[pigoo3]

Well...I "tuned" up my band saw yesterday...and I seemed to have minimized the blade drift. It is not 100% gone...but it is better.

The one thing that needed the most adjustment was the upper wheel tilt/angle. The blade was riding a bit close to the edge of the upper wheel, so I adjusted the angle a bit to get it to ride closer to the middle.

I may also try a blade change to see if that helps as well.

Thanks for all of the help,

- Nick