Ripping cut not straight but bowed.

mgdesigns · Post by **mgdesigns** » Mon Aug 05, 2013 10:00 pm

I have a 1955 Greenie with 1989 Power head. I had to rip a 3' long quarter sawn white oak from 4 inches wide to 2.25" width. I had the fence set squarely to the blade (tungsten tipped), and when I was finished the center was about 3/16" wider than the emds. I kept the straight side flushed against the fence, and it did not burn, or get wedged. What would cause this to happen?

charlese · Post by **charlese** » Mon Aug 05, 2013 10:15 pm

It is just a guess, but perhaps either the headstock lock or the carriage lock was loose.

JPG · Post by **JPG** » Mon Aug 05, 2013 10:44 pm

charlese wrote:It is just a guess, but perhaps either the headstock lock or the carriage lock was loose.

Or the fence or the quill lock.

In order for this to occur, the blade and fence spacing must change(assuming the blade is not warping). The headstock lock and the quill lock maintain the blades position on the planet. The carriage lock and the fence lock do the same for the fence.

skou · Post by **skou** » Tue Aug 06, 2013 1:52 am

Guys, I can't see how a loose lock would make it bow. I can see it get progressively thicker, or thinner, but not both.

With the fence to the right of the blade, a loose headstock or quill will either move out, or in. Cut would go small to large, or large to small, not small, large and back to small.

With a loose carriage or fence, the same would happen. I just don't see it going one way, then turning around.

Loose setscrew on the arbor, and the blade follows a soft area on the wood?
Yes, I'm guessing here.

steve

JPG · Post by **JPG** » Tue Aug 06, 2013 2:31 am

skou wrote:Guys, I can't see how a loose lock would make it bow. I can see it get progressively thicker, or thinner, but not both.

With the fence to the right of the blade, a loose headstock or quill will either move out, or in. Cut would go small to large, or large to small, not small, large and back to small.

With a loose carriage or fence, the same would happen. I just don't see it going one way, then turning around.

Loose setscrew on the arbor, and the blade follows a soft area on the wood?
Yes, I'm guessing here.

steve

I think 'technique' is involved in addition to loose stuff. If side pressure to the workpiece is reversed half way through the cut, it will indeed revert back towards initial dimension.

dusty · Post by **dusty** » Tue Aug 06, 2013 6:29 am

I would like to see this again - with all locks secure and a feather board in place. If it happens a second time (under those conditions) then I am stumped.

wa2crk · Post by **wa2crk** » Tue Aug 06, 2013 9:03 am

Was the edge against the fence not straight? A bowed board might produce this effect. Also internel stresses in the piece may also be a cause. The cut will mimic the edge that is against the fence and if that edge is bowed it may rock against the fence.
Bill V

dusty · Post by **dusty** » Tue Aug 06, 2013 9:24 am

mgdesigns wrote:I have a 1955 Greenie with 1989 Power head. I had to rip a 3' long quarter sawn white oak from 4 inches wide to 2.25" width. I had the fence set squarely to the blade (tungsten tipped), and when I was finished the center was about 3/16" wider than the emds. I kept the straight side flushed against the fence, and it did not burn, or get wedged. What would cause this to happen?

The error is small enough that you might not have noticed before making the cut. My question would be, was the straight edge truly "straight"? Did you edge joint it before ripping it?

Opps. Bill got there first! However, I would think that internal stresses would produce a bowed piece rather than an inconsistent width.

JPG · Post by **JPG** » Tue Aug 06, 2013 11:16 am

I do not see bow creating width variations unless making a bevel cut.

Ed in Tampa · Post by **Ed in Tampa** » Tue Aug 06, 2013 11:52 am

dusty wrote:I would like to see this again - with all locks secure and a feather board in place. If it happens a second time (under those conditions) then I am stumped.

I'm with you Dusty I would like to see if this can be duplicated.
Short of user error I can't imagine how this could happen.