Hello all- new to this forum and want to find out what people think about this. I have some rather large timbers (7X12x18) that are going to be the bottom chord/collar tie of some simple trusses I want to make. The question is what is the best way to cut an arch in a timber? I don't own a vertical bandsaw on rollers! Basically I want to make an arch 14' longish about 4-5'' at the deepest point. What's the best method, Thanks! fire_smiley
If it were me ::) I would lay it out and cut carefully with chain saw (very sharp chain) maybe take 3 passes so you can controle your path then use a curved planer to bring it down to the line. 8) 8)
I cut a lot of curved timbers. But I do have a vertical bandsaw to help. Best way to draw the lines on the wood to be cut, use an old bandsaw blade to make the curve. The curved cuts are called corbels. A chainsaw can do it. Just make certian you can see the lines while cutting. Another trick on the vertical bandsaw is keeping the entire piece supported. And the bigger the blade, the better the cut. The other downside of a vertical bandsaw, the blade has a tendancy to wander in the cut. Must anticipate that for each blade. Another idea, look for someone in your area that cuts corbles and hire them to do it. That is how I learned how to cut them.
Good luck
Kevin Davis
Ruff Cutts
I've made a big trammel rod type compass for the prazi beam saw before, then cleaned it up with a beltsander. Slow but it worked.
You may be able to do it with a chain saw or a prazi saw. You could plan on a series of relief cuts to make it easy for the saw to make the curve cut.....
Jim Rogers
Hey guys- thanks for the input here. I polled some friends on this and got a different answer each time. Loghead, your idea of using the chainsaw and making multiple passes is the idea that I had heard which made the most sense to me. Also using the broken band will be a great way to get the smooth arc, I anticipated a small batten, but a band, clever. Has anyone ever used a ripsaw portable mill. I have one of those,doesn't get much use anymore, but I imagined making a jig the shape of the arc then running the mill on that. It would have a cleaner cut but not sure how the band would react. Think I'm going to go with the chainsaw method, Thanks
Beatlekill, the band will cut the curve with very little clean up. I have a Ripsaw, it is powered with a chain saw. The curved jig will be the time factor. Thin plywood or a thin 1/4" slice off a beam, use the broken band to gain the curve on a board, cut that curve with a skill saw, saw both pieces at the same time, screw some sticks between the two curved pieces, screw down the 1/4" stock, screw that to the 7x12 and cut the curve with the Ripsaw. I also have a Breezewood bandmill, we have used it to cut curves in brace stock via a jig where the stock is pushed through the mill by hand on a similar jig that I just described. The mill is strapped stationary to the mill track and the band is held a given number of inches above the center of the jig, a fence is used on one side of the jig to prevent the stock from moving off the jig. I have also taken the blocking out from under the center of the track and let the weight of the saw push the track down as the cut was made in the beam, this way I can get a 3"-4" curve in longer stock like you are doing. I even raise and lower the band through the cut and follow the natural curve of the timber to better use crooked logs
But with all this why cut a curve in a straight piece. Find a naturally curved tree, it shouldn't be that hard, and saw two sides off the flat sides and level out the top, leaving the natural curve on the bottom, Hew it with an axe maybe to clean it up a bit. Just another thought or two. Tim B.
That keeps the grain in the timber.
I take a 7 1/4 skill saw and sit it about 1/2 deep and make a cut on the line of the arch. Then if you use a chain saw to cut it out you are less likly to tear out wood. You can increase the depth and keep getting deeper. I cut these walnut 3x12x12's with a skill saw by making deeper and deeper cuts. There is also a chainsaw attatchment for a skill saw that will work ok but you have to keep lube on the chain.
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