Comments on: I am That Nutjob

By: Darrin

Darrin — Sun, 22 Mar 2009 15:34:47 +0000

To Quote Chevy Chase playing Pres. Ford on SNL

"It was my understanding , there would be no math."

By: Matt

Matt — Thu, 19 Mar 2009 01:12:11 +0000

I made a really long, low bookcase and needed a very large radius curve for the front. I wound up doing what Bob Lang described: made a huge (14′) beam compass with my router attached to the end of it. I used that to create templates and then pattern routed the actual pieces after cutting off the bulk of the waste. My rig was huge! I made a plywood base and stabilized it with my toolbox, a 5 gallon paint can and other heavy things. My neighbors must’ve thought I was crazy. The arcs are PERFECT though. Tried the hardwood bow too, but the curve wasn’t consistent as others mentioned.

You’re in good company Chris!

By: Bikerdad

Bikerdad — Wed, 18 Mar 2009 19:39:05 +0000

Of course its not a perfect arc. If it was, model railroaders wouldn’t have been using the stick method for decades to draw easements. An easement "eases" into a curve, something that prototype railroads usually do, and something that those Lionel trains NEVER did. Remember how they would "slam" into the curve?

By: Christopher Schwarz

Christopher Schwarz — Wed, 18 Mar 2009 12:54:32 +0000

Cosmo,

I’ve done this. It works. You have to have good hand skills to keep the pencil at exactly 90°. Any deviation and your arc is off. Sometimes this doesn’t matter. Sometimes it does.

Chris

By: cosmo

cosmo — Tue, 17 Mar 2009 18:52:57 +0000

Didn’t I see a technique somwhere that uses a string to create an arc? Put two nails at either end of your arc. Tie a string to both nails so that the slack, when pulled taught, will create a third point at the exact apex of the arc you want to draw. Then mark your line with a pencil, pushed through a router collar,or sewing machin bobbin, by riding along the string from nail-end to nail-end. The result should create a perfect arc. No?

By: Christopher Schwarz

Christopher Schwarz — Sun, 15 Mar 2009 02:13:04 +0000

Dale,

I don’t have a plotter, so large curves require several sheets tiled and taped. The trammel was faster I think.

For small curves, I definitely make paper templates. Thanks for mentioning that.

Chris

By: David Stansberry

David Stansberry — Sun, 15 Mar 2009 01:54:18 +0000

How about going to the handy-dandy CAD drafting program (Sketchup), drawing an arc of the desired radius, printing it off on a piece of paper and tracing it on your project?

By: Keith Mealy

Keith Mealy — Sat, 14 Mar 2009 23:31:00 +0000

Chris, Chris, Chris.

It is dead easy to make an arc with two sticks and a couple of nails. No need for extra long trammels nor square roots. I’ll send you an article I wrote.

By: Gary Laroff

Gary Laroff — Fri, 13 Mar 2009 21:44:30 +0000

(I tried to post this earlier this morning but obviously did it wrong. Apologies if this shows up twice)

There is nothing wrong with using a (long) compass arm when drawing an arc. Even ARChimedes would have done so even if he didn’t have easy access to #8 screws. There are other applications than Stickley sideboards that require accurate arcs. Rocking horse rockers are the perfect example. When mass cutting a set of rockers from a long 4′ wide slab of laminated oak, I use a 5′ long oak 1" x 1" as the compass arm, a #6 screw at one end and a pencil in a 1/4" hole at the other. A kerf at the pencil end expands the wood enough to accommodate the first pencil I find. A similar length of 6" wide 1/4" plywood with the pencil replaced by a plunge router serves to cut the rocker ends smoothly in a perfect arc. (photos available in Chris cares)

Gary Laroff

By: Mike Witteveen

Mike Witteveen — Fri, 13 Mar 2009 21:29:26 +0000

Or you could tie a string the length of your radius to a nail, and to a pencil. Strike your arc while holding the pencil perpendicular to the board. Am I the first one to realize this technique? It is now hereby copyrighted and I’ll expect the royalty checks to start flowing in.