Why don't you see high production circle mills cut on the back stroke? I know the dogs would have to be end dogs or it would probably turn the cant out. And the sawdust would be shooting up, and the back cut lumber would come off the opposite side. Maybe the blade isn't tensioned for that type of cutting? Is it all of the above?
In addition to the reasons you mentioned, another is that on the gigback, the blade would be "climb" cutting, or drawing the log into the blade instead of against it. The few times that I have accidentaly cut on the gigback were enough to know it could turn into a wrecked saw or worse.
Alan
I suggest you don't try it ;D
I have heard tell of ones that worked that way, but never had proof of the existence of such.
The blades are unguided on the backstroke and knot dodge would be a problem. And there is that pesky board splitter that gets in the way. There is no lead in the saw, and would heat it up.
Cutting on gigback would be like a war zone it would try to pick up and fire stuff at the sawyer.You must have the force down twords the knees.Cutting backwards would try to twist the cant from under the dogs. Frank C.
I believe the splitter would play a big part in it too! :o
I'm pretty sure some of the big band saw mills here in the Pacific Northwest cut as the carriage travels each direction. I've never seen one in operation but I've heard lots of folks describe it and I have a small section...maybe 36"long...of a blade with teeth on each edge.
Saw an old spoked sawmill wheel last week 11' in diameter. Pretty sure the plaque said it was retired from operation in the early 60's.
I have seen overhead end dogging scrag mills that will do it on a back cut but you have to consider they are only running small saws You have alot of dynamic forces involved with a saw of any size ;)
Quote from: jim blodgett on March 10, 2012, 09:38:00 AM
I'm pretty sure some of the big band saw mills here in the Pacific Northwest cut as the carriage travels each direction. I've never seen one in operation but I've heard lots of folks describe it and I have a small section...maybe 36"long...of a blade with teeth on each edge.
I saw a video of one at work on You-tube a while back, but I don't have the link. It was a huge industrial band mill.
There was a big steam driven band mill on the Mississippi River in Missouri when I was going through school. It cut in both directions, but with a band mill the forces are totally different than on a circle mill.
I agree with TR on this!
With a vertical band mill, the pull would always be through the log/cant towards the bed of the mill, but with a circle mill, on the forward cut, the pull would be towards the bed of the mill, but on the reverse cut the blade would actually be trying to lift the log/cant off of the bed!
You have to watch what you're doing with a circular saw no matter if it's a mill ,table saw whatever .
I remember in high school a kid feeding a big DeWalt radial arm saw backwards on a rip cut and tossing a 2 by 6 right through a steel door .
I've seen band mills cut in both directions in hardwoods. We had one within 25 miles of me, and I saw 2 run back to back in Canada. But, band mills aren't circle mills. The teeth move in the same direction, coming and going.
I have seen those scragg mill videos. They are running 48" saws, so it could be done on a larger scale. But, they only saw in one direction. Each of those saws have a board splitter. End dogging or sharp chain yields the same technology.
I have run things through the vertical edger in a back cut. They don't saw as well. There would be a real quality issue if you try it on a deeper cut.
Do swing mills cut on the backcut?
QuoteDo swing mills cut on the backcut?
Yes, but you have swung the blade by 90deg and are effectively cutting with the other side of the blade on the return. So the blade is not climb cutting either way.
Ian
Here is one with two saws cutting from both directions.
http://www.youtube.com/watch?v=VcwFwkfTpmE&feature=relmfu
It does cut both ways but the saw is flipping each pass depending on which way it's going .Rather ingenious method I must admit .
I've seen videos of that mill before. The saws are flipping and becoming either a right hand or a left hand mill. You will notice it still has a board splitter on the outfeed side of the saw. I like the setup.
Nice mill. Anyone know what brand that is? Know anything about it? Wow.
Davco Twin-cut
http://www.twincutsawmill.com/sawmill_faqs.html
Thanks, beenthere.