Radious Techniques

[IrishDave]

I was wondering what way you guys draw radious' when marking out or when you setting up jigs. Also what way would you guys work out the radious on things like walls or footpath's?

 

[Kent]

You mean the string length? Or how to mark it?
Marking out anything from a small set of dividers or trammel points for larger right up to chalk on a string or even sprinkling sand it all depends on what and were plus the accuracy required
String length etc is py remember leads and material thickness if your forming

 

[IrishDave]

Say I was looking to make a bow top railing for a house but the wall it sits on is rounded following parallel with the road that turns into another road. If you can understand what im saying I want to know how would you know what radious you would need to have the materials rolled to?

 

[IrishDave]

Sorry not the radious the shape of the arc if I'm correct

 

[Welderpaul]

Say I was looking to make a bow top railing for a house but the wall it sits on is rounded following parallel with the road that turns into another road. If you can understand what im saying I want to know how would you know what radious you would need to have the materials rolled to?

You would need to template it? Mark out on a strip of ply and use that to roll your bar to?

 

[IrishDave]

You would need to template it? Mark out on a strip of ply and use that to roll your bar to?

Seems to be the only way paul I thought there may have been away to work it out with using ply

 

[Wendelspanswick]

If it's a long arc or one that changes I would stretch a line between the start and finish of the arc and then take measurements at 90 degrees to the line at set intervals, say every 300mm to 500mm, to the centreline of the arc.
Once I have my measurements I can then draw it up full size on the workshop floor.

 

[Welderpaul]

If it's a long arc or one that changes I would stretch a line between the start and finish of the arc and then take measurements at 90 degrees to the line at set intervals, say every 300mm to 500mm, to the centreline of the arc.
Once I have my measurements I can then draw it up full size on the workshop floor.

Yeah, this is the other way, not as accurate as templating, especially if the curve varies, but with careful measuring can work.

 

[Mick B]

There is a curve known as a "semi elliptical radius" where the start of the curve is a small radius and at the top it is a large radius . In the building game we sometimes have to set these out and make a template for the brickies. They get used over window openings and often for single or double garage door openings. This is set out with a string line (or piano wire) and a pencil ..... quite simple really.

Like this ...........

 

[cliff366]

I've seen it done with 2 lengths of battan fixed in a v then run off the start and finish points you can then adjust the battan as you go to change the radius you tubes your friend I'd have thought

 

[IrishDave]

Out of two ways I think the ply template is probably handiest tbh I thought there may have been some sort of formula for this sort of thing

 

[Kent]

Forget formula take a template every time. Formulas ie calculations assume the builder didn't drop one building it

I should template every one if multiples

Sorry I was struggling with what you actually wanted earlier

Hardboard or cardboard is cheaper btw

 

[IrishDave]

I have a problem with the way I word things hahaha and no problem will keep that in mind