Gig-back techniques for manual mills

      Sawyers offer various ideas on gig-back techniques, and their impacts on saftely and profitability. June 20, 2000

Q.
Because my mill is all manual, I like to stop the saw carriage just as the teeth of the band break through the end of the cut, remove the sawn board, and push the carriage back with the band still at the same height, and the saw still running.

This allows me to index down for the next cut just by reading from the scale on the machine. It saves jockeying the head up and down to locate the last cut accurately.

Does anyone else use this method? While not actually cutting, the tips of the teeth are still in contact with the last cut surface as the carriage travels back. What are your opinions as far as additional dulling of the band or other problems this technique may cause?



I would try to rig up a scale that has marks on it that correspond to the lumber thicknesses that you saw most frequently. That way you can raise the blade up off the cant, return your carriage and lower your blade to the next mark for the next board, and be right on the money. Wood-Mizer mills have a nice setup to accomplish this very thing.

The only time your band should be running is when it's in the wood, cutting. Otherwise, you're using up blade life and reducing your profits.

It's not a good practice to return the blade while still on the cant. It's real easy to pull the band off the wheels. Not a good feeling when it happens.



The return trip of the blade is called the "gig back". If you gig back with a bandsaw without sliver teeth on the back side, then there is a risk that a sliver on the log will catch the band and pull it off the wheels, with pieces from the broken band flying all over. This is why a band has sliver teeth. (Sliver teeth are teeth on the other edge of the saw blade, widely spaced, that are not sharpened much at all -- you have to see one; it is hard to describe.)

Dragging the band across the already-cut surface without moving the band does indeed wear the teeth slightly -- actually, the wood springs back a slight amount after cutting, so there is less clearance on the gig back than on the initial cut! I have seen some saws that automatically lift the band a small amount during the gig back, and then drop it down when the gig back is completed.

You do need to do something different for safety's (and your) sake.
Gene Wengert, forum moderator



Gene and Brian are dead-on with their advice. I would add only the fuel and engine wear you are wasting while running the blade during the "gig back".


I got a four-foot, aluminum, yardstick-like straight edge from a hardware store and fastened it to the back side of my mill, so it would read the distance (clearance) from my band teeth to the log bed on my mill.

Then I drew lines at one- to ten-board widths, from the bed up. This really will speed you up in cutting slabs and setting and cutting boards.

You could use a drywall t-square if you cannot find a cheaper ruler.



Did you know that if you cut 4/4 lumber 1/32 inch too thick you have cut your yield (on the average) by about 2.5 percent? Actually, you may not get more pieces of lumber, but they will occassionally be longer and wider, increasing the footage now and then.

So, setting the saw as accurately as possible (at least to within 1/64 inch) is critical, even if you are sawing someone else's logs, because we do not want to waste our natural resource.
Gene



After thinking about the first technique described and the problems involved, I got to thinking about how, when my off-bearer is pulling from the far end of the mill, I also stop the blade before it exits the cant, stop the blade turning, and gig back through the saw kerf I just cut.

My question: Do you think there is any appreciable damage done to the teeth from rubbing on the cant and the board that is laying on top of it as I gig back like that?

Is it worth the extra time to go all the way through the cant and raise the blade above the board to gig back?



My first thought is that it probably is O.K., but then if you have 8/4, it might be quite a bit of wear from the high weight of such pieces. So I guess I do not know the correct answer.
Gene


I'm a little confused here. The original poster starts out saying he stops sawing just as the teeth of the band exit the log, but he keeps the band moving.

Then another guy says he stops sawing just before the teeth exit the log and gigs back. I don't see any problem in either case as long as the band is stopped before gig back.

I would say the wear on that part of the band contacting the log exists, but would be negligible.

It seems to me the issue is one of safety first if the band is still moving, and then, to a lesser extent, profit if it is still moving.



I agree, safety is the best reason NOT to gig back with the blade rotating. I was just wondering if the spot on the teeth that rubs when you gig back in the kerf is dulled by the abrasive wood.

If you think about it, the part of the tooth that rubs is THE VERY part that does the cutting. No use in dulling it prematurely.



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