Good tip from WoodworkingTips.com

[Lord Nibbo]

Just spotted this, For doing or finding a radius quickly. I thought you might like to see it.

 

[Woodmagnet]

Glad i'm not the only one who did'nt know this one. :lol:

 

[wizer]

interesting

I'll never remember it tho

 

[Chris Knight]

Caution!

The picture seems to imply that the marked radius will be automatically accurate and balanced. It is only accurate if the framing square is positioned so that the arms are parallel to the sides of the rectangle being marked. Otherwise the radius only be will be positioned along a line somewhere between a maximum (the "correct" figure and something rather less).

 

[Woody Alan]

Chris that's an interesting point, but if the measuring on the marked edges of the square are accurately placed to the edges of the board, allowing for a perfect 90 degree of course, it's impossible for what you suggest to happen ...? but I never did get the whole eight sided tapering polygon thing so I could well be wrong

Alan

Edit for not thinking before posting

 

[Lord Nibbo]

it's impossible for what you suggest to happen ...? but I never did get the whole eight sided tapering polygon thing so I could well be wrong

Alan

Edit for not thinking before posting

No your not wrong Alan, I've tried it, in fact the bigger the radius the easier it is.

 

[Chris Knight]

Maybe we are talking at cross purposes?

The point I was trying to make is that (taking the picture as an example) the two 4 inch graduations can be placed at an infinitude of positions from the very corner of the workpiece to 4 inches along the respective sides. The apex of the triangle thus formed (by the corner of the framing square) moves position accordingly - along a line at 45 degrees to a side, drawn through the corner of the workpiece. The possible displacement being the difference between a side and the diagonal of a square whose sides are the desired radius (4 inches in the case shown, so with a diagonal of 4x1.41 inches = 5.64 inches - potential difference thus 1.64 inches)

 

[Lord Nibbo]

Maybe we are talking at cross purposes?

The point I was trying to make is that (taking the picture as an example) the two 4 inch graduations can be placed at an infinitude of positions from the very corner of the workpiece to 4 inches along the respective sides. The apex of the triangle thus formed (by the corner of the framing square) moves position accordingly - along a line at 45 degrees to a side, drawn through the corner of the workpiece. The possible displacement being the difference between a side and the diagonal of a square whose sides are the desired radius (4 inches in the case shown, so with a diagonal of 4x1.41 inches = 5.64 inches - potential difference thus 1.64 inches)

Yes your quite correct, but I think most people can judge by eye accurate enough to hold the square so each face is parallel to the workpiece after all it's just a tip on an easy way to find where to place the compass.

 

[Tom K]

I saw the tip and dont quite see waterhead37's problem with the tip 4" in at each side with a 90 deg angle how could anyone go so wrong

 

[Woody Alan]

I see where you are coming from now Chris, yes of course you are correct but using this method you wouldn't be aiming to fit an exact circle in the measured area to exactly skim the very point of intersection between cicumference and straight edge as that would be too high an aim with wood in most circumstance, also you are only creating a reference point and the error would be discovered as soon as trying to draw the circle. Point taken though.
Alan

 

[Niki]

I have two problems with my framing square...first, it's to big and heavy to hold it stable while marking and second, I rounded the apex....

I just set the stop on the ruler and make one line from one side and than another line from the other side and use the intersection as the pivot for the compass.

On the picture, I'm using two just to show but actually, I'm using only one ruler

niki

 

[Tom K]

Given that we are using wood that has been trued and that the framing square has not been abused (much) the equal length of the sides form a perfect Right angle triangle which means provided our wood is true if it was flipped it gives the other side of a perfect square. Of course if the eyes are getting weak a carpenters square against one side could easily show wether it was all at a squint or not. Of course it will clip the edges so add for the kerf. :wink:

 

[jmk89]

If you mark 4" (or whatever) on the two edges and line up the 4" marks on the board with the 4" marks on the square then (if the square is square) you will be close enough. If you can't make the marks match, then the board is not square (or your suare isn't)

 

[brianhabby]

Couldn't you just use a combination square using Niki's idea, that's what I do,

regards

Brian