Make a Center Finder

Make a precision center finder from scrap materials.

Recently egbertfitzwilly posted an Instructable on Finding the Center of a Circle. WirelessMonk posted a link to a machined steel center finder. Rimar mentioned making one. I decided to try making one that would be very precise.

Step 1 Materials

I had a steel bracket left over from something. I also had a piece of wood with good straight edges. In addition I used a little wood glue and a couple of short screws.

Comments

[streetrod5]

Phil, this is something I've needed for years, but didn't know it existed! I've been "finding" centers by... well, not the most accurate way. Thank you!

[Phil B]

Thank you for looking and for your comment. I am glad to have solved a problem for you.

[Learndy]

Can we extend this mechanism somehow to find the center axis of a sphere, of a ball?

Application: Find a center axis of a table tennis ball to make it a cheap wheel for a small robot.
--
Airspace V - international hangar flying!
http://www.airspace-v.com/ggadgets for tools & toys

[Datawolf]

Use the center finder to draw a first "equator" line. Turn the ball and use the center finder to draw a "meridian" line.
The two intersections (the "poles") give you the axe for an axle.

[Phil B]

Here is an idea for finding the center of a sphere, like a table tennis ball. For the sake of illustration, your table tennis ball is red in color. Cut a collar of PVC that is just a little smaller in diameter than the table tennis ball. The PVC collar is shown in cutaway and is gray in color. Cut it to length so the top of the ball is roughly even with the top of the ball when the collar is resting on the ball. Use the center finder to mark the center from a couple of directions. You will need to turn the table tennis ball over to mark the extension of the axis. Do that by making a circle on a piece of paper, the diameter of which is the same as the PVC collar. Mark the center of the circle. Align the center you marked on the ball with the dot on the paper. Support the ball from several sides so the center do on the ball remains squarely on the center dot marked on the paper. Place the PVC collar on top of the ball so it is level. Without moving anything, use the center finder to locate the extension of the axis.

[Phil B]

Oops! "Cut it to length so the top of the ball is roughly even with the top of the ball when the collar is resting on the ball." should read, "Cut it to length so the top of the collar is roughly even with the top of the ball when the collar is resting on the ball."

[bettertimes]

If you would enjoy reading "The Boy Mechanic: Volume 1 by Popular Mechanics Co. " here is the down load link
http://library.beau.org/gutenberg/1/2/6/5/12655/12655-pdf.pdf
this is a copy from the Deridder, Louisiana Library. enjoy

[Phil B]

I did download it and have looked at some of it. When I was growing up our public library had a couple of books by Alfred P. Morgan. One was on electricity. One was on all sorts of mechanical devices. I remember a small steam engine with bell cranks to operate sliding valves. The projects were marvelous, but always required tools and materials I did not have available. Thanks.

[DoDo729]

Wow, so simple but works incredible. Solved one of my problems. Thanks for your post. Love this site.

[Phil B]

I am very pleased you found it and can use it. Instructables is a great place to share useful things. Thank you for looking.

[nmh0105]

Simple but yet great use... i could not follow you please help

[Phil B]

Can you say what exactly you did not understand?

[Creativeman]

I just found this, will definitely make one! Will post picture when done. Thanks for the idea/concept.

[Phil B]

Thank you. You may even find a way to improve on it.

[wmarin]

You are still my hero !. Thanks

[Phil B]

Thank you.

[pgcagdol]

thanks great idea and just when i needed it

[Phil B]

Thank you. I try to post useful things.

[zulhanifarifin]

nice job..thanks..

[Phil B]

Thanks. I hope it is useful to you.

[Chadworkz]

You know, it's always the simplest things that are the best, and this just proved that point...excellent job, Phil! ;)

[Phil B]

Thank you.  Unfortunately, it usually takes me a few attempts before I come to a really simple version of an idea.

[roberto sirigu]

una mente creativa ... Lo seplice muove il mondo benfatto!!!

[Phil B]

Grazie mille!

[ignilc]

The angle doesn't need to be 45 degrees. It can be anything. As long as the angles on both pieces of wood are the same it will work well.

[Phil B]

You are quite correct.  Thank you for your comment and thank you for looking at this.

[mcanderson76]

This is very helpful :) thanks

[Phil B]

Thanks.

[manuelle_override]

This is one of those things that makes me think, why didn't I thinkof that?! A straight forward solution to an annoying problem. Nice guide.

[Phil B]

Thank you. I see you joined Instructables less than a week ago. Welcome. How did you happen to find my center finder already? Speaking of simple solutions to annoying problems, you might be interested in a recent Instructable I did. Search for Garmin Vehicle Power Cable. Even if you do not have a Garmin with a 12 VDC power cable, you might be able to use the basic idea on something else.

[DuctTapeRules!]

5* Now I just need to summon the energy to get back to my projects...:)

[Phil B]

Thanks. When it comes to projects, life has a way of forcing you back into them when something breaks and must be fixed immediately. Then you notice how good it felt to do a project and you are on your way.

[sharlston]

love it definetly 5 stars

[Phil B]

Thanks.

[sharlston]

u replyed at 4 in the morning and your welcome

[Phil B]

It was 4 AM in the UK, but seven hours earlier in our part of the USA, which is Idaho, and that is only about 400 miles from the Pacific Ocean.

[sharlston]

oh i forgot about that sorry for the missunderstanding

[ll.13]

I'm impressed with the simplicity and usefulness! +1

[Phil B]

Thank you. In regard to proportion, the number of positive responses from people residing in the UK is disproportionately high. As I thought about this project, it was clear to me the angle on each half would have to be exactly the same. That was solved very simply by making one angle cut to make two pieces with an identical angle and gluing two halves together rather than trying to cut a "V" angle out of the end of a piece and then try to find the bisecting line. Gluing the two halves together also allowed taking advantage of the way the glue line is already on a line bisecting the composite angle exactly. Not many things work out that serendipituously.

[sharlston]

are u in the uk i am the uk rocks