Thread: Cannot remove drift on blade

I think it is important to remember that the table is adjustable; by this I mean that you can loosen the securing screws that attach it to its trunnions and alter its position.

The mitre slot has to be aligned to the blade with the blade positioned in its most stable and supportive position on the upper wheel; I believe that it should be centred for a narrow blade and positioned closer to the front for blades 25mm and greater.

To align the table, place a straight edge across the edges of the bands, this may be difficult on some saws due to the guard covering returning edge of the blade, but you should be able to project the edge. This straight edge should then be perpendicular with the mitre slot and the insert adjusted so as to be centred as well. Very few if any BS's will be well adjusted from the factory and even my Felder BS610 required many hours to fettle accurately.

Very few if any BS's will be well adjusted from the factory and even my Felder BS610 required many hours to fettle

thanks for this drmark67. For the money that I spent on it, and the name of the brand, I was expecting the Laguna 14-12 bandsaw to be fettled in the factory so that it worked properly once I assembled and tuned it. Not an unreasonable expectation, surely?

I have for a long time believed that the concept of coplanar wheels was more theoretical than practical; however, fettling my other bandsaw (Scheppach 5-4) over Christmas to achieve coplanar upper and lower wheels, I now know that I was mistaken.

Whilst the BS did run reasonably, it is certainly much more accurate with the wheels aligned.

Even my new, high-end Felder required a small re-alignment of the lower wheel to have the band run evenly.

Originally Posted by John Samuel

In fact the Laguna people say (in the assembly instructions) to centre the blade on the top wheel. I did that. It worked.

Logic tells me this is the only way. The wheel is cambered so the only way the blade can be parallel with the fence if the fence is parallel to the TOP wheel axis is for the blade to be centred on the wheel (camber). The only way I can see it being different is if the tyre camber is not asymmetrical across the wheel and that may happen with use of course. The bottom wheel axis is important also but most probably not as important as the top wheel.

One of the most important things that I found on the band saws that I have had anything to do with, was that the blade had to be tensioned properly. (6 wood and several metal). The tension-er marks that are there, are to me a gimmick, I don't take any notice of them. If the blade is 10mm longer, the blade will be under tensioned, if it is short it will be over tensioned, I use a metronome (an electronic tuning/timing instrument) that I use for my banjo and set the tension at C sharp. A lot of the problem will be solved. Check this at the unsupported side of the machine opposite the guides.
Another thing to check using a straight edge, is that the wheels are in line, the table will need to be removed for this. Make sure the blade is tensioned correctly first. Sometimes the bottom wheel may need to be moved in or out. Yes, on expensive machines too.
Hope these tips help.
Kryn

Thanks for this advice, Kryn, gives me confidece to adjust the lower wheel until the blade sits properly.

Your method of tensioning with a tuning fork sounds interesting. Do you strike the blade and then adjust the tension until the beats disappear? Surely the resonant frequency wil be determined by the length of the unsupported blade between the two wheels, and will vary for each bandsaw, and will not correspond to middle C ?

More thinking on this problem. A narrow blade sitting on top of the cambered wheel will not change shape as a wide one would when tensioned, well no where near as much and perhaps a little. A wide blade if enough tension is applied will tend to curl or curve inwards towards the camber of the wheel whereas a on a narrow one the effect would be less. Does it matter? Will that inwards curve be carried to the cutting point and affect the blade angle relative to the fence? The more re-saw capacity the less chance I suppose and it would depend on how much tension was applied.

I could have it all wrong of course and if so please ignore my musings for that is all they are.

Originally Posted by KBs PensNmore

One of the most important things that I found on the band saws that I have had anything to do with, was that the blade had to be tensioned properly. (6 wood and several metal). The tension-er marks that are there, are to me a gimmick, I don't take any notice of them. If the blade is 10mm longer, the blade will be under tensioned, if it is short it will be over tensioned
Kryn

Kryn,

In fact the manufacturers say to use those Tension marks as a rough guide only, for the very reason you mention. I don't have two blades exactly the same length. On my old machine, one blade falls on, another needs to be persuaded to get onto the wheels.

Originally Posted by drmark67

I have for a long time believed that the concept of coplanar wheels was more theoretical than practical; however, fettling my other bandsaw (Scheppach 5-4) over Christmas to achieve coplanar upper and lower wheels, I now know that I was mistaken.

Whilst the BS did run reasonably, it is certainly much more accurate with the wheels aligned.

Even my new, high-end Felder required a small re-alignment of the lower wheel to have the band run evenly.

Your experience with co-planarity is at odds with what Snodgrass has to say. When I set up my saw again I will take your
experience into account.

My saw is a Hafco. The users manual that came with it is almost worse than useless, so this thread has proved to be invaluable.

Originally Posted by artme

Your experience with co-planarity is at odds with what Snodgrass has to say. When I set up my saw again I will take your experience into account.

My saw is a Hafco. The users manual that came with it is almost worse than useless, so this thread has proved to be invaluable.

Arthur, don't forget that a great many of us use Snodgrass' method very successfully, with little or no drift. (Centring the bottom of the blade gullets on the top wheel.) And that's without having to play around with co-planarity of the wheels.
When setting up your bandsaw, take this thread into account, but do try Snodgrass' tuning. It made all the difference to my Hafco BP-305.

Dengue, it's obvious that your problem is not just in your set up. Your new Laguna should not need all of this 'fettling' to make it usable, and the blade rubbing on the plastic table insert indicates a problem. If I were you, I'd contact Laguna directly for advice. Out of interest, you could mention Snodgrass' method to them and ask their opinion. They're far more qualified than any of us.

Also, I must disagree with the 'Middle C' method of tensioning. Common sense tells us that the actual pitch of the blade will vary machine to machine and blade to blade, partly determined as mentioned by the unsupported length of the blade, but also by blade width and thickness.
Personally, I find that tensioning such that when pressed firmly with my thumb, (until it goes whitish), there's about 1/4" of play. As mentioned, the calibrated scale is a guide only and can't be relied upon for precise tensioning.

Good luck with this, Dengue. I went through similar troubles when I bought my bandsaw. Not fun. New toys are for using, not for working on.

Originally Posted by artme

Your experience with co-planarity is at odds with what Snodgrass has to say. When I set up my saw again I will take your
experience into account.

My saw is a Hafco. The users manual that came with it is almost worse than useless, so this thread has proved to be invaluable.

Coplanarity may differ to what Snodgrass asserts but both Lonnie Bird and Duginske agree that it is desireable.

It stands to reason that the lower wheel has as much influence on the blade as the upper wheel, so why should it be ignored as Snodgrass implies!


If you accept that the position of the band on the wheel and its relationship to the camber and hence the support and any twist the camber may impart to the band is important to drift, then the lower wheel and hence the position of the band on it is equally important; therefore the only way to provide even support without imparting twist to the band is through a co-planer arrangement

I'm not dismissing the importance of band tension (THIS IS A GIVEN) nor am I saying that its not possible to have a working BS that is not co-planer, what I am saying it that if we are keen to have the best possible performing BS then achieving co-planer upper and lower wheels should be considered.

BTW, to tension a 25mm blade to 20,000 psi (apologies for mixing ISO and imperial), as measured with a Starrett tension gauge on my Felder requires the pointer to be WAY off the scale and about a centimetre past the 32mm band mark; this shows that the tension scales are a very rough guide indeed. Enough of me preaching

Below is an interesting thread which may shed some light.
https://www.woodworkforums.com/f27/ha...e-stay-119378/

I agree that the lower wheel must have a lot of influence but I am sure the leading (top) wheel would have more than the trailing but it is only a gut feeling and I could be wrong . I am also thinking that the tighter the tension then the more the lower wheel would influence things. I have my new BS parked in the driveway still on the trailer and it will be interesting to see what it is like when I turn it on. I might organise a laser level and measure the wheels to a line outboard of the machine and see exactly what it is like.

Originally Posted by Dengue

Thanks for this advice, Kryn, gives me confidece to adjust the lower wheel until the blade sits properly.

Your method of tensioning with a tuning fork sounds interesting. Do you strike the blade and then adjust the tension until the beats disappear? Surely the resonant frequency wil be determined by the length of the unsupported blade between the two wheels, and will vary for each bandsaw, and will not correspond to middle C ?

I don't use a tuning fork, it's an electronic device that is used for tuning guitars, I pluck the blade and adjust the tension till the note sounds right. If my memory serves me correct, this came from a book at the local library on band saws. Will try to find the details again.
Kryn

Steve, I fully intend to use the Snodgrass approach but what I meant was
that this other view and the experience of the user is worth taking into
consideration if needed.
I don't think i explained myself well enough!

This whole thread has been very enlightening. I'm glad I started it.!!!