Bandsaw resawing cut diagnosis?..pics....

[Tim Martin]

Hi, wondering if any one could shed some light on whats is happening when I am resawing.
The height of the wood is about 6 1/2" and the wood is Australian River Redgum which has a similar density to Rock Maple (Eastern Maple?).

The blade is a 1/2" 3 TPI hook tooth and has been used a bit so maybe a little dull.

As I push, it seems to feed well but tends to skip a bit or sort of cut faster which I think is when it makes the angled cuts(see pic). I am doing my best to keep the feed rate even and at a speed that the saw seems to cut comfortably, it seems to be worse if I go too slow.:confused:
The motor is a 2 HP and does not slow down. Any tips would be greatly appreciated, cheers Tim..

[Pete Brown]

I see some funky lines in there, but they don't line up with your arrows. Before anyone chimes in, are your arrows pointing to the correct places?

Pete

[Tim Martin]

I see some funky lines in there, but they don't line up with your arrows. Before anyone chimes in, are your arrows pointing to the correct places?

Pete

I tried to put them in the general direction, but I guess I'm just referring to the lines that are on an angle to the left at about 75 degrees that occur about every 1" along the plank.

It is cutting fairly straight and there is no bowing of the blade in the cut, I'm just curious as to what might be the cause, as I know from the Duginske book that I should be able to get a nice even cut.

[Pete Brown]

Ok, I see now. I thought you were talking about the big obvious marks that are in there.

Lots of things can affect this. It could be that you vary your feed rate. Or it could be a hard part in the wood. When I hit a knot or some figure when resawing maple, I get some less than stellar results. I always joint/plane afterwards, so I pay little attention to it as long as my thickness is even.

Maybe Mark will weigh in. I've only been resawing for the better part of a year, so there may be a specific, obvious cause I am overlooking.

Pete

[Mark Duginske]

It should be "vibration" not fibration

When you get a diagonal pattern in the saw cut it is because the combination of tooth choice, tension and feed speed create a vibration. I'm sure the engineers can give you a detailed explanation. That is a good tooth choice and it sounds like you have changed the feed speed. Experiment with the tension, at times decreasing the tension will help to decrease the vibration.
Or, increase the tension a little. Experimenrt!!!!!!!

As simple as it may appear resawing technique is a required skill. Like turning it requires being receptive to feedback from the tool. Keep experimenting and be patient.

Good luck,

Mark Duginske

[Tim Martin]

It should be "vibration" not fibration

When you get a diagonal pattern in the saw cut it is because the combination of tooth choice, tension and feed speed create a vibration. I'm sure the engineers can give you a detailed explanation. That is a good tooth choice and it sounds like you have changed the feed speed. Experiment with the tension, at times decreasing the tension will help to decrease the vibration.
Or, increase the tension a little. Experimenrt!!!!!!!
Mark Duginske

Hi Mark, it does make some sense that you suggest harmonic vibrations as the cause.
I had some major issues with vibrations when I got the saw and now have mostly overcome them. Long story short, the entire frame of the bandsaw (Taiwanese) is constructed from pressed 2.5mm thick steel and is a bit of an acoustic guitar:rolleyes: . The main problem however was with the connection of the upright column to the base frame which was a big expanse of sheet steel with no support inside at all. The whole thing was like a big spring.

Anyway, once my dad who is a Mechanical engineer identified the problem, a 5" x 3" 1/2" steel lintel running from the outer edge on the base all the way to the top of the saw frame was welded on and now there is minimal vibration and just passes the nickel coin test.

I will try playing around with the tension now to see what happens, which I think you might also suggest in your book.
Brilliant book too, and I recommend it to every one who is starting out in Bandsawing, even some well experienced woodworkers could benefit from it.:rolleyes:



As simple as it may appear resawing technique is a required skill. Like turning it requires being receptive to feedback from the tool. Keep experimenting and be patient.

Good luck,

Mark Duginske
Yes, that I am beginning to learn.