View Full Version : Arched beam tools
08-22-2009, 4:34 PM
Hi, I need to put an arch on a couple of 5"x10"x 16' long, cedar beams, what is the appropiate tool to use to do this? Please advice.
08-22-2009, 4:36 PM
A foot adze. and ya got one too many measurements unless its a triangular beam.
08-22-2009, 4:52 PM
sorry I meant to say a 4" or 5" x10" x 16' long. would a portable bandsaw work? it will take a long time with a foot Adze no? also it needs to be as smooth as possible
08-22-2009, 5:03 PM
The "best" tool would be a bandsaw. But you will need the kind that comes with a friend. A 16' beam will be a bit much for one person!
08-22-2009, 5:33 PM
I do recall Norm making an arch on a pergola using a template and a router. First you would need to make a template - 1/4 inch hardboard would be good. The template would have to be carefully made, perhaps in two eight foot sections. You can make a good arch shape with a long strip of 1/8 inch pine, tacking it into the shape you want.
Band saw one eight foot section of template leaving a 1/16 of an inch to the line and then sand to the final line on a reciprocating spindle sander. The more time you spend making the template as perfect as possible, the better your profile will be. Flip this template and trace on the other eight foot section and repeat the cutting/sanding..
Then glue or tack your template(s) to the material and rough out on a bandsaw with the help of a friend or two - leaving 1/8 to 1/4 inch to the line. Then use a plunge router with a spiral flute cutter (1/2 diameter inch or more) and an appropriate guide bushing, cutting 1/4 inch in each pass. I know you can buy end mills (on ebay) that are four inches long - you may even be able to find ones that are five inches.
You probably will still have to sand the profile with a ROS. And you will probably want to radius the edges. Good luck
08-22-2009, 6:27 PM
With a portable band saw you could clamp both pieces together, draw a line, and be done in ten minutes. Does anyone in your neighborhood have one?
08-22-2009, 6:56 PM
One of the WW TV shows years ago had a pretty cool method using a 14" BS set on either casters or a dolly. The whole thing was set on a 4x8 sheet of ply that had been leveled. Then the beam was kept fixed and the whole BS moved about to follow the penciled lines they were after. Sort of like using a very big saber saw.
08-22-2009, 9:28 PM
I think a timber framers hand held BS is the way to go with beams of that size. We made a few large pergolas this summer and did the little stuff (4X6X10 and 5X7X12) on a 20" BS with a big table set up to hold the weight. But we took the 8X10X24' beams to a local timber framer to cut the rafter tails. It took very little time and the saw worked great on thick stock. There was a little cleaning up to do, but cedar sands like butter, so not a big deal.
Depending on the arc and your space I think you could pull it off with as little as a 14" saw with a riser and one heck of an infeed and out feed table, but that would not be my first option, nor would that old "Bandsaw on skates" trick from an old TOH episode. The guy we went to had one of these:
Worked great, wouldn't want to buy one for one job.
08-22-2009, 9:53 PM
Absent a portable bandsaw or skill with an adze you could do it the following way. Mark the curve on both faces of the beam. Hog most of the waste off with a Sawsall. While you're doing this, look out for the tip of the blade crossing the line on the bottom side. Then tack curved rails to the faces of the beam, and use a router on a sled to cut the curve. The sled rides on the curved rails. Search this site with "router sled" for more info. This approach will work, and will make a precise curve.
08-23-2009, 10:17 AM
I do some inside arches with a Makita 1002BA 4-3/8 Inch Curved Base Planer. This is truly the right tool for the job. I have also done gradual arches by doing the initial cut with a bandsaw and then following up with a regular flat hand held power planer, and set the blade way out. You hit the high spots first, and I generally use a hand held disc sander at the ends, as they are VERY easy to divot
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