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prkaye

Well Known Member
I have a hard time getting a dead-straight line with my bandsaw. I draw the line on the part, but as I'm pushing it along under the blade it wanders slightly. For the parts I have to cut now (F-605C doubler) I can't use the fence on the saw, because the line I'm cutting is not parallel to a straight edge.
Is there a "trick" to getting an arrow-straight line when cutting with a bandsaw, in situations like this where you can't slide the edge of the part along the fence?
 
The Blade.

I've found to get a straight cut, you must use a *sharp* blade - and don't ever cut anything else with that blade except AL.

My experience has shown that once you use the blade to cut wood, plastic, fiberglass - anything BUT AL, that dulls it, and it will start wandering off that straight cut line.

Sharp blade, and move the work slowly. Maybe (hopefully) that will help!
 
Adjust the blade guides

The blade guides will wear from the metal shavings going thru them. From time to time you will need to adjust the guides. If that doesn't work well enough, take the guides off, and make sure the edges are square. They will wear on an angle after some period of time.

Good luck.

Gary
 
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S-L-O-W is the only way to go to get straight lines without the fence. Patience is a real virtue with the bandsaw!;):)
 
Sounds like speed was my problem. The blade is pretty new and sharp... I'm just not a patient guy!
 
I have given up on trying for straight cuts on the bandsaw.

Now I just cut between 1/16" to 1/8" outside the line to rough out the cut.

Then I'm headed to the belt sander. I use the belt sander to straighten the cut and remove the material back to the line.

Phil
 
Straight cuts require a wide blade, at least 1/2". Follow others advice on lube and speed, but when set up properly, you should have no problem with wandering.
Also, most of us use bandsaws that are really designed for wood, with blades really designed for wood or steel. We can get away with it for Aluminum as a rough cutting instrument. A true upright metal bandsaw costs thousands of dollars, and it is not necessary for the non production use of building an airplane or two.
I have a 14" JET. Good saw, but the aluminum makes a mess of the guides and friction belts on the wheels.
 
All good points so far - the only thing I haven't seen mentioned is "Where are you looking?" It's sort of like trying to drive a car by looking to close to the front end - you'll weave all over the place - you need to look down the road a ways to drive straight. Similar (at least for me) when using the band saw - if I stare right at the blade/material, I have a tough time going straight - if I let my gaze go a bit "broader", I find it easier to make smooth cuts. I also try and cut a little outside the lines, and use my sanding and filing tools to finish up, if the cut is critical.

I just made some gas cap tools out of scrap aluminum yesterday - hadn't used my trusty band saw for awhile, and it was letting out some creeks, squawks, and whines - guess it;s time for a tune-up!

Paul
 
Blade lead

I do a lot of woodwork and what you discovered is called "blade lead", the angular difference between the fence and the angle needed to follow a straight line. Since the cheaper bandsaw blades are stamped out, there is a burr on one side of the blade at each tooth gullet (the lower part of the tooth) and this is the root cause for you not being able to use the fence. To find out how many degrees it needs, draw a short straight line on a piece of wood scrap, parallel to the edge, like a 1 X 4 and start cutting down the line for several inches and stop. Turn off the saw while holding the piece of wood. You'll see that there is a small angle at the edge, not parallel to the table. You can either measure this angle after you draw a line on the table or mount your fence at the same angle.

Regards,
 
Use a metal cutting bandsaw with at least a 1/2" wide blade, Hand feed it and you can cut very straight with a little practice. I've had a $450 Taiwanese saw for over 20 years and kicked the **** out of it in shop production use. I've never overhauled it and it has cut thousands of feet of steel and aluminum over that time.
 
Fence Guide

I also use a Kreg 4-1/2" Resaw Guide (www.woodcraft.com #146051 Price:$17.99) on my fence to guide stock. The resaw guide is curved and allows you to move the stock as you're cutting to compensate for blade lead/drift angle.

Other comments above also apply:
proper blade tension
properly adjusted guides
widest blade for curve you plan to cut, etc.

Regards,
Mike
 
Pierre is quite correct. It does seem wierd to be feeding in a piece at an angle in order to get a straight cut, though. Once you figure it out, you can go pretty quickly, but always plan on smoothing things out later.
 
For straight cuts like the emp stiffeners, I just used a straight edge and a Stanley Utility Knife. I scribed the part several times and just snapped the parts apart. Then off to the disc or belt sander to dress them up.

Roberta
 
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