transfering a wall radius to plywood?
Paul P | Posted in Jigs, Fixtures, Tips & Tricks on
Does anyone know how to transfer a wall radius to plywood? I have 3/4 round Room (think turret) that I would like to build a custom breakfast nook in. I need to figure out how to transfer the wall’s curve to a piece of plywood for bench seating.<!—-><!—-> <!—->
Thank you, <!—-><!—->
Paul <!—-><!—->
Replies
If the room is a true circle, measure the diameter across the room to determine the radius and use that to draw out, and then cut, a segment as long as the bench on something like corrugated cardboard or Masonite. Fit this segment to the wall where the bench is going to go and scribe it to get the exact shape of the wall which will have ripples in it. Once you get the test piece to fit you're good to go.
John White
Your radius, template,scribe solution sounds good.What if the room were elliptical instead of circular?
BruceT
For an ellipse, once you know the long and short diameters you can work out the not too complicated math and draw an elliptical template that you could then scribe to the wall. You could also make a rough template based on the floor as described by a few other posters and then use that to create a final exact template that you could scribe at the height of the bench.John W.
An old linoleum layer's trick to get around pipes, toilets, uneven walls, etc .........
Cut up newspapers into strips or 1-2" squares and lay them against the curve, continually overlapping them. Scotch tape each piece to the former piece as you work your way around. When your done you can transfer this to your piece, or to a piece of cardboard or masonite to use as a template.
You can also kill this bird with a large compass, working your way towards locating the correct radius point and arc.
You could use the boat builders trick and copy the curve to a large piece of plywood laid on the floor or at a convenient height as long as it is level and mark the sheet with a tick stick. The stick isn't anything special. A yard stick could be used. Make a couple of little notches in one side and put a point on the end so that the tip is along the same edge with the notches. Lay the tick stick on the plywood with the point up against the wall. Trace along the notched edge of the tick stick and make ticks at the notches. Repeate for as many points as you need/want. When you are ready to transfer the curve, lay the tick stick on the plywood so that its edge is aligned with a pencil line and the notches are on the ticks. Make a mark on the work at the point of the tick stick. Connect those morks with a thin batten to get the curve.
http://www.shortypen.com/essays/tickstik/
http://farm1.static.flickr.com/154/356946894_a2a8936875.jpg?v=0
Lay a rip of 1/4"plywood on the floor. Measure the distance to the wall at it's deepest point. Say it is 10". Make a "tracer". Nothing but a piece of 3/4" plywood cut into a triangle. Cut an arc out one side so only the two ends touch the wall. I leave about 1/4" on each end so it won't break off. Bore a hole for the pencil more than the depth (10" in example).
Run the tracer along the wall with both tips touching and the pencil scribing the arc on the plywood. Cut the plywood and you have a template.
mike
PaulP
All of the above ways are too slow too prone to errors and won't compensate for variations..
Lightly staple down some pink rosin paper. Using a longish fingernail fold it up around the radius of the room.. mark the sheets in order you pull them up and there you've got your template..
Fast, simple, no measuring, no possiblity of error. plus it can be easily rolled up and stored when not in use.. . The remander of the roll you'll find dozens of uses for a lot of them similar in nature..
Presumably the room has a base molding in which case none of the methods, except mine of course, will work well. The boat builders tick stick method works well on irregular but straight edged shapes, it is still useable but inefficient on large curves. In any case the final fit will have to be scribed at the exact location of the bench.John W.
John.
That is exactly what you wind up with using my method.. You have a template of the room.. exact shape! plus or minus nothing.. no possiblity of error..
I use it on my tower and the bow front of my house..
Frenchy,Your technique is easy to use if you can set the paper on the floor, and you don't have base boards, but I'm presuming that this project, building a bench, requires getting the profile at a height several feet off the floor.John W.
John.
Set the rosin paper on a table or bench the height you require. Mark it with your fingernai, Trim to the mark and double check..
Frenchy,I'm going to have to try it the next time I have a job like that. I haven't used rosin paper in years, does it work especially well for this application?John W.
I keep a roll of "Pink Paper" in my shop at all times. I use it for paterns and for drawing when I need a full scale shop drawing. Cheap, fairly durable stuff that's just stiff enough for paterns, but not too stiff that it won't bend a bit when required.
Mike HennessyPittsburgh, PA
John,
I'm dyslexic and that especially applies to numbers.. 36 could be either 63 or 36 and the longer I study a number the worse it gets. I try to story stick everything. and rosin paper is just a quick way to story stick.
Frenchy,Numerical dimensions are always risky and I try to stay away from them as much as possible, Story sticks, patterns, stops on fences, and such are the best way to go. Talking about this suggests an article idea for FWW.John W.
Hi John and All ,
I think the way we learn to do our layout stays with us and we become used to either a story stick or laying things out on material or the floor of the shop .
Personally I learned to do all my layout on paper with slide rule , I mean calculator except when I am working on very complicated spaces or angles and such . Then I do draw a scale on something . For straight with trick stuff runs the stick works well .
Sometimes I use scribing methods and use a large shop made pair of dividers to transfer the shapes .
dusty , a creature of habit
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