CIRCLE & SQUARE CENTER FINDER Made from angle steel,aluminum stock.
Attachment 9398Attachment 9399Attachment 9400Attachment 9401Attachment 9402Attachment 9403Attachment 9404
Printable View
CIRCLE & SQUARE CENTER FINDER Made from angle steel,aluminum stock.
Attachment 9398Attachment 9399Attachment 9400Attachment 9401Attachment 9402Attachment 9403Attachment 9404
ENJOY....:O)
Thanks Captainleeward! We've added your Circle Center Finder to our Measuring and Marking category, as well as to your builder page: Captainleeward's Homemade Tools. Your receipt:
<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/circle-center-finder"><img src="http://www.homemadetools.net/uploads/145403/circle-center-finder.jpeg" /></a></div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/circle-center-finder">Circle Center Finder</a> <span> by <a href="/builder/captainleeward">Captainleeward</a></span> </div> <div class="tags">tags: <a href="http://www.homemadetools.net/tag/centering">centering</a></div> </div> </div> </div>
Thanks for another simple to to make, but tough to think of tool. It will go straight to my "often used tool box.
Thank you for your nice remarks.....:O)
Gracias Captain y a copiar el modelito.
for nada :O)
I've a pile of 1" x 8" steel disk's to center drill, making machine leveling pads. Commercial machinist center heads don't range beyond 5'' diameter ~... :headscratch:
So make one!
This will be great. Beats loading them up and chucking in lathe at work.
This is probably a good place to mention the mathematical background of center finders.
There's a provable theorem from geometry that says:
The perpendicular divisor of the chord of a circle passes through the center of the circle.
When you use a center head, the two tangent points where the head touches the circular object define a chord on that circle. The blade is mechanically set to bisect the angle between the arms of the head so it automatically provides the perpendicular bisector of the chord. When two of these chord bisectors are drawn, the point where they cross must be the center.
The technique is extendable to circles or circular segments too large for any sort of hand-held tool. Simply draw two chords (as nearly perpendicular as possible), construct their bisectors and the point where they cross is the center. Surveyors employ this technique, using their transits to establish the perpendicular bisectors.
The diameter of a circle is a chord itself. Thus its perpendicular bisector must pass through the diameter at the center of the circle.
It should also be apparent that this math insight can be used to construct a circle that passes through any three non-colinear points. Construct two chords using the three points. The center of the circle is then the point where their bisectors cross and the radius is the distance from the center to any of the points.
The intended application suggests you don't need tenths (or even thousandths) accuracy in locating the center so perhaps a device based on my math post above might work.Quote:
Originally Posted by Toolmaker51
On a metal bar, mount two identical pins about six inches apart on the centerline of the bar. Draw a line on the bar midway between the two pin locations. This is your "chord generator".
Push it against the circumference of the disk until the pins touch. Lay a machinist square on the top of the bar, align with the center mark and draw the bisector on the disk. Repeat. The center is the point where the two lines cross.
It's just a gedanken-design but it might inspire you in your build.
I like that "chord generator". Akin what tool gunsmiths use to mark centerline of shotgun ribs for beads, woodworkers use a larger version to bisect material. Both are identical to your example; with a hole mid-point twixt the dowels, sized for transfer punch of choice.Quote:
Originally Posted by mklotz
Math and geometry are fine, and I use them regularly. Plates too rusty to scribe with nice old M&W dividers.
But constructing a center finder, I can do wearing gloves and cold weather gear.
It's 21F degrees outside and a couple colder in the building; Wednesday 17F. In the spring I anticipate 375K BTU boiler to arrive and plumb iron radiators I've collected. Several tons of machinery make excellent heat batteries. Next year I'll be working down there any time I dang well please!
Make your "chord bar" with lots of holes and several pin sizes and you've got a dual purpose tool, e.g.,
http://www.homemadetools.net/forum/l...r-finder-27455
In that thread, Paul Jones asked the purpose of the brass bar along the edge of the tool and I remarked that I had forgotten why I put it there.
This thread has reminded my aging brain why I did that. Of course, it marks the perpendicular bisector of the chord when the bar is used as described in my last post to find the center of circles.
In deference to your sensibilities I won't report the temperature here in LA. Let's just say the only white we'll have for Xmas will be the surf at the beach. See for yourself...
https://eatgoodstuff.com/resources/strandcam/
That dodge won't work. Dad and two sisters live there...They've already called to gloat.Quote:
Originally Posted by mklotz
My sensibility is shored up by one thing; only place with an affordable right-sized building. And a nice old [1902] home across town for Ms. Toolmaker. Sounds like two, a package counts as one IMHO.
Now I know why you have a photo of Einstein as your avitar........smart guy.
Hi Captainleeward,
Thank you for sharing. A very nice piece of kit to have in the workshop.
Regards,
Lyle
My pleasure I'm sure....Cap
Very useful, thank you.
