# Radius formula



## riptide212 (Mar 30, 2017)

While cutting. A clamp on a water jet,i found it annoying,to figure the radius on both sides of clamp and maintaing the wall thickness through the radius. ie, 1/4 inch wide all the way around radius.

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## RJSakowski (Mar 30, 2017)

What am I missing here?


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## David S (Mar 30, 2017)

Holy smokes.  One too many marts this evening?  The OP is blurry to me.  Time to hit the sack.

David


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## riptide212 (Mar 30, 2017)

Ok i have a,inch thick piece of,steel using,a,water,jet to,cut a clamp the clamp is 1/4 wide at the radius i want,the clamp,to,maintain the 1/4 width. The radius on the outside is of course bigger than the inside. I was nust wondering the easyest way to figure that whe holding the thickness around radius

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## RJSakowski (Mar 30, 2017)

Still not sure of what your question is or what you are trying to accomplish. A sketch would be helpful.  Since you are on a phone, draw one out and post a photo.


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## riptide212 (Mar 30, 2017)

Ok ill try lol

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## Rustrp (Mar 30, 2017)

The position from which you would define your radius for the inside or the outside is what you must work with if the corner is 90°. If you have something more than 90°  (you picked a chord/radius you wanted to work with) then you need to figure out what the radius of the chord is. Who decided on the dimension of the radius.

Edit: I read your comment again and I don't know what program you are using, CAD/CAM,etc. to enter the data, but if the center of your radius to the inside cut is 2" then the outside is 2.250".


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## riptide212 (Mar 30, 2017)

The,problem was the width,of clamp is .250 now when i put in the radius.i wanted,it,to,stay.250 even at the,radius. Hard to draw a picture.

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## Rustrp (Mar 30, 2017)

riptide212 said:


> The,problem was the width,of clamp is .250 now when i put in the radius.i wanted,it,to,stay.250 even at the,radius. Hard to draw a picture.
> 
> Sent from my VS987 using Tapatalk


Okay first question: What is the inside radius?


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## riptide212 (Mar 31, 2017)

Thats what im trying to,figure out you see if the clamp is .250 wide and i measure across the bend or radius it gets smaller width wise and i want it to,remain the same all the way around the bend.. See its a water,jet cutting machine part is 1 inch thick but only .250 wide. And i can make radiues anything i want but getting them both right to hold that .250 is a pain.

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## RJSakowski (Mar 31, 2017)

OK, Ill take a stab at it.  Is this what you're trying to make?


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## Rustrp (Mar 31, 2017)

riptide212 said:


> Thats what im trying to,figure out you see if the clamp is .250 wide and i measure across the bend or radius it gets smaller width wise and i want it to,remain the same all the way around the bend.. See its a water,jet cutting machine part is 1 inch thick but only .250 wide. And i can make radiues anything i want but getting them both right to hold that .250 is a pain.
> 
> Sent from my VS987 using Tapatalk



We are no closer to a solution to your question than when you first commented. I think there's lots of folks here to help you solve the problem but you have to give them something to work with. Based on your comment here, it seems as though your waterjet can't hold the tolerances that have been input, which begs the question; What did you input for it to work with?


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## rzbill (Mar 31, 2017)

The centers of both radii (inside and outside) need to be at the same point.  The difference in radii needs to be 0.25".
If those two items are not held, you will not meet your goal.


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## Tony Wells (Mar 31, 2017)

There is also the issue of kerf loss. So while the radial center must be the same, the actual radius value will not be different by .25. It will be greater by an amount equal to the kerf loss (smaller on the inside, larger on the outside). You have to think of the jet diameter just the same way you would if it were an end mill. Plus the phenomenon of flaring of the jet that makes the kerf wider at the bottom and also the kerf lags at the bottom. Water jets have some oddities about them that present problems with some cuts.


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## Rustrp (Mar 31, 2017)

Tony Wells said:


> There is also the issue of kerf loss. So while the radial center must be the same, the actual radius value will not be different by .25. It will be greater by an amount equal to the kerf loss (smaller on the inside, larger on the outside). You have to think of the jet diameter just the same way you would if it were an end mill. Plus the phenomenon of flaring of the jet that makes the kerf wider at the bottom and also the kerf lags at the bottom. Water jets have some oddities about them that present problems with some cuts.


I agree but most programs have allowances for kerf loss. I think we are still wondering around in space looking for the datum reference point.


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