cutting a compound curve

bob kellogg

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3
Hi i just joined today and have a question. i am rebuilding a horse drawn wagon and the seat back has a arch. the radius of the arch is about 12 ft and is cut with a 15 degree angle. any guess on an easy way to cut that? the other problem is that there is a concave and convex parts that glue together. thanks bob
 
First off welcome. Now what do you have for tools? The tools you have will help decide the best way to do the job. You could cut the arch with a hand saw then use a draw knife to get the bevel close then switch to a smoothing plane. You could also do this on a bs, which be much quicker.
 
hi bob!
i`d just make a simple router base to hold the cutter at 15º and mount it to a 12` trammel......got any pics?
 
12 feet ?

Gotta ditto the question of tools on-hand. Sabre or jig saw come to mind then ( again ) moving on with draw knife or shave. With 12 ' to work with is bending & laminateing an option ? You might get a stronger / more stable product.
 
I think I have an understanding of what you are trying to accompolish. You might want to look at a book on Windsor Chair Making. There are some pretty severly curved back bows. Some of them are made up of thin laminated strips of wood, which you lay on a jig which you can build using the old back for the model. They you rip off the edge of a board thin strips between 1/16 - 1/8" thick and then they will have the flexibility to follow the curvature in a compound set of curves, once glued and dried, then you will most likely have to hand finish them using a spoke shave or rasp and then sand to final dimension. You can make some truley astonishing curves and convolutions using this system.
 
I have a little experience with compound curves and cutting them. Model T Fords are wood cars with a tin skin. the framework is quite difficult and the joinery is frustrating. I replace the wood in one, not too long ago. I went through a lot of firewood before I figured the sequence of the cuts, after that the cuts were simple and pretty straightforward. This doesn't help you but what I want to experess is that these things were produced by craftsmen without these special contrived jigs and fixtures, or power tools that can do leaps and bounds and turn inside out....

At present time I am re-structuring a wood body Model T Towncar, the rear portion is to bow out whilst the aft is rounded under, Creating a compound corner with thin structured plywood and a ridgid framework. Wasting a bunch of firewood, I took notes and mental reminders of the sequence of which direction to cut first and then made the "good wood" pieces (hard part was duplicating left to right and re-thinking the process. :huh:

Overwhelmed is the first thought but break it down into small pieces and approach one at a time till you master the task. It will take longer to configure and construct the jigs and fixtures than to figure out the plan.
 
thanks for the reply i have a router and table saw and a band saw. i tried mounting the router to a length of 1x4 and using a 15 degree cutter but that didn't work too well thought about cutting the curve on a table saw and then cutting the 15 degree angle with the router. don't have any pic thanks bob
 
hi, it just amazes me that they did these things with no power tools wome of the wood working is quite amazing. and everyone did it different i will get some pics and let you know good luck on yur ford this is the second wagon that i've done. bob
 
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