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Bandsaw problem
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=25304		 Page 1 of 1
Author:  John Hale [ Mon Jan 04, 2010 4:36 pm ]
Post subject:  Bandsaw problem
I have an old 3 wheeled black and decker bandsaw and it's never worked very well I set up the guides and the fence to the appropriate drift angle and all I can say is that it was good enough considering I was given it I recently with the fence ripped a load of chipboard to size with wise and it started to wander off. At first I thought this was a blunt blade so I replaced it and it still wandered off, so I thought it needed me to recheck the drift angle and that was ok too, I then check & trued all the guides still it won't cut straight.

It now at you progress along the cut gradually widens until the machine stops or the fence is pushed away what have I missed?

Thanks
Author:  Mike Collins [ Mon Jan 04, 2010 4:52 pm ]
Post subject:  Re: Bandsaw problem
John;
Is there enough tension on the blade?
Try adding more to see if it helps.
What width blade are you using?

Mike
Author:  John Hale [ Mon Jan 04, 2010 5:43 pm ]
Post subject:  Re: Bandsaw problem
Hi Mike the tension is to maximum without bottoming out the spring, and the blades are 3/8" 6tpi, I can with a lot of corrections by hand nearly follow the line, but today I wanted to rip a load of 1/4" ply to 3/8" wide strips to properly sticker my wood
Author:  Kelby [ Mon Jan 04, 2010 6:28 pm ]
Post subject:  Re: Bandsaw problem
How are you checking and adjusting for drift?
Author:  John Hale [ Tue Jan 05, 2010 11:50 am ]
Post subject:  Re: Bandsaw problem
I check for drift I draw a line parallel to one edge of a piece of wood then try to free hand follow the line I then clamp that wood to the table and adjust the fence so it's parallel to the edge of the wood. Hope that makes sense
Author:  Kelby [ Tue Jan 05, 2010 12:11 pm ]
Post subject:  Re: Bandsaw problem
As you freehand, are you making sure that the back of the blade stays in the middle of the kerf?

The fence should do nothing more than force the board to feed at exactly the same angle it feeds when you freehand a straight cut parallel to the edge (as you do when you correct for drift). So, as far as the blade and board are concerned, they should not be able to tell the difference between the freehand feed and the fence feed. What this means is that if you are getting different results when you freehand a line parallel to the edge than you get when you feed with the fence, then you do not have the fence set correctly.
Author:  JohnAbercrombie [ Tue Jan 05, 2010 1:00 pm ]
Post subject:  Re: Bandsaw problem
John-
The way you check for drift and set the fence is what I do, as well.
However, if the blade is moving away from the fence as you cut, the fence angle is wrong, and you need to 'straighten up' the fence a bit. Sometimes, 'fine tuning' is needed...bandsaws seem to need more of that than most tools.
Also the feed pressure can make a difference- when I am free-handing I am usually cutting more slowly. Then when I am trying to rip with the fence, I push 'em through as fast as they can go. This can move the blade back into the guides and on to a different part of the wheel, and change the blade angle a bit.
All of this 'variability' is exaggerated with smaller & cheaper bandsaws with their more flexible frames.

BTW, for ripping up strips, I'd probably use a blade with fewer than 6 tpi, if I had one around. There's more set on the coarser blades and they don't jam in the kerf as easily, I've found.

Cheers
John
Author:  Howard Klepper [ Tue Jan 05, 2010 2:55 pm ]
Post subject:  Re: Bandsaw problem
Most old three wheelers will never track well. The only exception I know of is the Inca.

Ripping stickers is a table saw job.
Author:  Markus Schmid [ Tue Jan 05, 2010 4:11 pm ]
Post subject:  Re: Bandsaw problem
John Hale wrote:
[...] I then clamp that wood to the table and adjust the fence so it's parallel to the edge of the wood. [...]
I use a bevel square for this operation, without clamping the wood to the table. While clamping you might ruin the adjustment of the angle and afterwards, if the wood is not clamped tight enough even bumping with the fence slightly into the wood, there is another possibility to change the angle by mistake.

JohnAbercrombie wrote:
[...] Also the feed pressure can make a difference- when I am free-handing I am usually cutting more slowly. Then when I am trying to rip with the fence, I push 'em through as fast as they can go [...]
Also makes sense to me.

Howard Klepper wrote:
[...] Ripping stickers is a table saw job.
I rip stickers with my bandsaw ...it's that 3-wheel INCA :mrgreen:
Author:  runamuck [ Tue Jan 05, 2010 11:21 pm ]
Post subject:  Re: Bandsaw problem
It sounds to me that your fence is not parallel to your blade.
Author:  Mike OMelia [ Thu Jan 07, 2010 10:02 am ]
Post subject:  Re: Bandsaw problem
runamuck wrote:
It sounds to me that your fence is not parallel to your blade.


That does not ensure a non-drift cut. One trick I learned was to take a board about 2 foot long, scribe a straight line on it. Then freehand cut along the line. You will note that the blade drift will cause you to tilt the board as you cut. Then, when you are half way through, stop. Note the angle of the board relative to the table. Scribe a pencil line on the table. Clamp a board to the table along that line (most OEM fences cannot tilt). Now do the same cut on another board, this time using the fence. If you have done this correctly, you will cut a non-drift line.

From there, just clamp the board parallel to that line for what ever width you need (I am making a number of assumptions here, but you should get the point).

As to your spring. Your blade is too long. Who makes your bandsaw? And what length blade are you using? Tension will help minimize drift, but the wheels and their alignment play a huge roll. Get a blade about 1/8" shorter (or so). I have an old 3 wheel I use for arc cutting. Lowe's sells two blades that will fit on it, but the smaller is the correct one. But, I am watching that Skil benchtop bandsaw. Goes on sale, and it is mine! Two wheels are much better designs. I don't think many folks are even making 3 wheels anymore.

Mike
Author:  John Hale [ Thu Jan 07, 2010 11:59 am ]
Post subject:  Re: Bandsaw problem
Howard Klepper wrote:
Most old three wheelers will never track well. The only exception I know of is the Inca.

Ripping stickers is a table saw job.


If only I had a table saw

And looking closer there is a little wear in the bearings, and the tighter I tension it the the quicker it wears.
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