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

[ynze]

Very smart! I bumped into the problem of finding the center of round wood recently. I just noticed this I'ble (first picture), and.... Owwwwwww, of course, that's the way!

Thanks!

Y.

[Phil B]

Thank you for looking. I am glad it is helpful to you. It was fun to develop and I use mine more than I thought I would.

[barefootbohemian]

Wow. Weird that this landed in my comments, but glad it did lol. I could use such a thing :)

[grbennet]

Thank you very much for this simple method.

[Phil B]

I hope it helps you. Thank you for your comment.

[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.

[Col_uk]

Hi Phil
Thanks for the instructable, it came in very useful.
For a sphere, i found it easier to make a center finder the same depth as the ball diameter and put steel on both ends. That allows you to mark both poles at the same time.

best regards

[Phil B]

Very clever. Thanks for your reply.

[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

[Phil B]

As noted II.13 is in the UK. I am in the USA.

[ll.13]

if that comment was at me, yes I'm currently in the UK. :)

[yeagerxp]

EXCELLENT!!!!!, and you can even use wider pieces of wood for bigger round items

[Phil B]

Thank you. One of the great things about Instructables is that readers are free to adapt ideas. You certainly could use a wider piece of wood for a tool that finds the center on a larger round item. You could even taper the assembly toward the end to make a more manageable handle.

[dewmi]

thanks for share, i have been searching this. i will make one too......

[balno]

Very clever !!!

[NachoMahma]

. Excellent.

[Phil B]

Thank you. I hope it is useful to a few folks.

[stamatis]

Bravo Phil! Simply excellent!

[Phil B]

Thank you.

[mickcaulton]

Brilliantly simple design and idea. I have spent alot of time in a workshop, both wood shop and an engineering shop, and this would have found a use on numerous occasions. The only negative thing I can come up with is why on earth had i not thought of making one of these for myself. I have always prided myself on the fact that i am able to find a need for and build simple tools and equipment to make my life easier. Again very good idea, good simple construction and excellent Instructable.

[Phil B]

Thanks. While this was a new project to me, I have enjoyed making Instructables from many projects I did in past years, even past decades. I hope you will show us some of your ideas from past projects as Instructables.

[mickcaulton]

Hello again Mr. Phil B, Thank you again for your response to my comment on your posting, ( The center finder ). In reply to your comments i certainly do hope to get some of my projects made into Instructables. Unfortunately all of the projects which i think are the best and of most interest to others, along with being informative, have long been built and put to use. So for me to make a good Instructable, with good visual content, it entails me either taking one of my ideas and either stripping it down or building a new item from scratch. I personally feel the second option would be better as i can then include more visual information on the build process. If i decide to just take apart an old project the photos for the build would only really show assembly as all the parts would have already been fabricated if you see what i mean. I wish i had found this site along time ago, but be as may. Anyway i hope to put a decent Instructable on before long as i have done my first short testable just to get a feel posting of the process. All i need to do now is build a time machine to slow down time a bit so i can get more done.

[Phil B]

You may be able to post some of your past projects without either making a new copy or dismantling one. I have posted some Instructables I did not dismantle and could not repeat. I used graphics I generated with a CAD program or with Google Sketch Up, sometimes tweaking a few things in MS Paint as part of the process. See my Instructable on "Rescue for a Weed Whacker" as an example. Sometimes you can just move the camera in close for a detail photo of different sections of a project you finished a long time ago. See my Instructable "Make a Carbon Arc Torch for Your 220 Volt Stick Welder."

[rimar2000]

Thanks, Phil!!

[Phil B]

If you make one, let me know how it works for you. Thank you.

[lemonie]

The best centre finder I used was essentially a T, which had two round pegs on the short length. One edge of the long length was central. L

[Phil B]

That would certainly work. The range of circular objects on which a "T" could be used would have to be, at minimum, larger in diameter than the distance between the pegs.

[jeff-o]

Aha! I've had to mark the center of a dowel a number of times and always wondered if there was a simple tool to help. Thanks!

[Phil B]

I certainly did not invent this tool. I only found a simple way to make a good one from ordinary items. If you have no suitable piece of steel, you could go to the hardware store and get a long mending plate.

[jeff-o]

Oh, I realize that. But, a big thanks for posting this. I will definitely make one.

[Shut Up Now]

very smart use of suplies. so simple too.

[Phil B]

Thanks. The materials truly were leftovers and junk.

[mrmath]

Nice work. I especially like the way you put the steel under one piece of wood to create a raised edge to rest the steel against at a later time.

[keng]

here here!!!!

[Phil B]

Thanks. I thought about that for a while. The really good, really simple ideas take a while before they surface.

[keng]

fantastic! this is totally going to save me like $20 to order one!!!

[Phil B]

Thanks. I am glad you can use it. I have gotten through quite a few years without one. There were times when one would have been helpful though. Let us know how it works out for you.

[chaosrob]

Awesome!

[Phil B]

Thanks. It is simple and it works. If made in the same way I demonstrated, it is practically guaranteed to be accurate.

[AndyGadget]

I'll have made one of these before tonight!

[Phil B]

Thanks. I hope you get a lot of use and enjoyment from it. Waiting for the glue to dry took more time than any other part of the project.