# Working with radius



## MiamiSnook (Dec 4, 2005)

Hello everyone,

I am in the process of buidling a set of Adirondack chairs. In various parts of the plans it calls for a curve based on a specific radius. For example the curved back support calls for a 32.5" (R = 32.5" TYP (NTS) ).

What does this mean and how do I draw that radius. Other than getting a 32.5" piece of string and drawing it out I have no idea how to draw these curves. Is there a better way or is the string the solution?

Thanks,

Peter


----------



## Gilbear (Dec 13, 2005)

Don't know how others have handled large radii, but I've used the string routine (can be a little wobbly though) - also strip of cardboard with hole punched through for pencil and radius point (a little less wobbly - reinforce the radius point hole so it doesn't enlarge on you) - I have access to cadd software with a large format plotter and can draw and plot out very accurate full size templates, which is what I normally do.

By the way, "NTS" usually means "Not To Scale", referring to the plan drawing.

If it would help, you could e-mail me the plan and I could calculate "chord offsets" or middle ordinates for you that would allow you to lay it out without a bean compass.


----------



## Gilbear (Dec 13, 2005)

ooops - BEAM compass


----------



## Hamlin (Dec 25, 2005)

To draw out radius circles or half circles, the best method is to use a straight piece of wood with a nail at one end with an adjustable holder to hold a pencil to draw the circle(s). As mentioned above, using the string method, you don't get a true or a very accurate circle.

Ken


----------



## mikehillclimber (Feb 8, 2005)

Unless you have a very large compass or a set of trammel points, the string approach is simple and accurate enough for an Adirondack chair. If the pencil is placed in a knotted loop and the other end wrapped around a small pin and held tight, the slight change in radius-length will be negligible. But, after drawing the arc I would backtrack to ensure that the length did not change. 
Cut out the template (masonite/hardboard/plywood) and use it wherever called for.


----------



## MiamiSnook (Dec 4, 2005)

Thanks for the advise,

You are indeed correct, using the string created problems with consistency. Even though the Adirondack is very forgiving, I am using this project to learn and establish some very good and basic wooworking skills. So I will probably end up overdoing it a bit. 

I went ahead a picked up a set of trammel points attached to a piece of wood. I assume that is the similar to a beam compass. 

My first step is cut out the template with either hardboard or plywood ( I have to look into masonite, I don't know what that is, but if it is a bit more water resistant it may be the way to go).



Again, thanks for the help. 

Peter


----------

