Concave Bandsaw Cuts

[pjallen]

Hi all,

I am cutting out chair slats on the bandsaw. The oak slats have a 36 inch radius curve and are 3.5 inch thick. I am using a 1/2 inch blade.

I am noticing that when cutting this radius curve my blade is getting pinched because the vertical cut is not linear but convex. Is this indicative that the blade tension is too low? Do band saw blades get dull that fast?

I have cut out 8 sets of back chair legs (1-5/8in thick) and the lower curved slats (which are only 1-3/4in thick). I did have some issues with a few pieces of wood for the chair legs pinching the blade while cutting. I guess after 1 year of drying in the Denver area they still were not acclimatized.

This is my first real workout for my ~1985 vintage used shopsmith bandsaw since I have never really been happy with the results. I have cleaned & tuned it up and put new cool-blocks on it.

regards,

Phil

[michaeltoc]

Hi all,

I am cutting out chair slats on the bandsaw. The oak slats have a 36 inch radius curve and are 3.5 inch thick. I am using a 1/2 inch blade.

I am noticing that when cutting this radius curve my blade is getting pinched because the vertical cut is not linear but convex. Is this indicative that the blade tension is too low? Do band saw blades get dull that fast?

I have cut out 8 sets of back chair legs (1-5/8in thick) and the lower curved slats (which are only 1-3/4in thick). I did have some issues with a few pieces of wood for the chair legs pinching the blade while cutting. I guess after 1 year of drying in the Denver area they still were not acclimatized.

This is my first real workout for my ~1985 vintage used shopsmith bandsaw since I have never really been happy with the results. I have cleaned & tuned it up and put new cool-blocks on it.

regards,

Phil

There have been several post about bandsaw problems and modifications. Some of first things to try are: 1) blade tension, 2) make sure the cool blocks are just barely touching the blade, and 3) don't force the work - let the blade do the cutting.

[charlese]

Your blade may be a little on the not so sharp side, but -- WATCH YOUR SAWING TECHNIQUE.

I've noticed if I get a little concerned about following a line, particularly a curved line, there is a tendency to slightly push the workpiece sideways into the blade. Don't do this! This results in non-vertical cuts. Always sawing on the outside of a cutting line will make slight bobbles a non-issue. Just a Little sanding will fix it up.

With your 1/2" blade, the tension should be set right on the 1/2" mark. You can check the tension setting of your saw by removing the blade and aligning the lower left corner of the "tension indicator scale" with the left edge of the red "tension spring". If alignment is needed, loosen the nut at the top of the indicator scale and move the scale to the proper place - then tighten the nut.

[bobgroh]

The bowing of the blade is certainly an indication of inadequate tension so make sure you have got that set right. You didn't indicate what type of blade (blade material and number of teeth) you are using - this is almost like resawing so you want something with 4 TPI or maybe even a 3/4 TPI skip tooth. Bandsaw blades don't cost all that much so you might want to pickup a new one and see how that goes.

[swampgator]

What I didn't see posted here is to have the upper guides systems just about 1/4" or so above your work to minimize the blade movement. And, don't push the stock very hard. Push only hard enough to feed the blade.