Instructables
Picture of A Small Circle Center Finder & Drawing Aid
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I wanted to see what the largest diameter circle I could get from an irregular shaped small piece of wood. There are templates available for finding the center of log sections and locating the center point, but I was working with small stock. I made this center finder/drawing aid at the TechShop, www.techshop.ws.
 
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Step 1:

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I started by placing a .07 inch diameter circle in the center of a 1 inch diameter circle and then constructed concentric circles spaced at 1/8” increments. I used Corel Draw as that is the “resident” program for the Epilog lasers. I made the .07 inch circle "hairline width" and the larger circles .014 inches line width for etching.

Step 2:

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In order to make it easier to see which circle you were looking at when using the circle center finder, I made every-other circle a dashed line.

Step 3:

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To make the circle drawing aid I radiated lines at 30 degrees and located a small circle at the intersection of the lay-out line and each successive circle. These small circles must be “hairline width” to cut, leaving pencil point holes. I then erased the lay-out lines.

Step 4:

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I added a top knot with a hanging hole and specified the perimeter line and hanging hole circle as “hairline width”.

Step 5:

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Using the Epilog laser I engraved and cut the center finders from .093 inch thick acrylic plastic. To use, place the center finder over the stock in question and “eyeball” the largest circle that will fit. Use a push pin to hold the center and scribe a circle with a pencil.
stephenf1 year ago
Like it! Do you have the CorelDraw file available for downloading?
kjegelan1 year ago
Good idea...;) Thank you for sharing...! I will make one myself..

Kjetil
spylock1 year ago
I was making a wooden mallet,and ended up using a nail,and string tied to a pencil to get my basic circle.
Bgerens, fantastic Ible!!!!!!!

I have only one complaint - why didn't I think of that? As soon as I get back into my shop (pulled muscle in my back working in an attic), I'm planning to fabricate a series of those in different sizes.

My intended alterations to the concept - I'm going to use a circle cutting attachment with a pointed cutter on one of my Dremels to scribe the rings and then "paint" the scribed rings with ink (scrimshaw style) to make the rings more visible. Oh, and I'm going to give them a cool name (got to have a cool name). I think I'll dub them the "Rings of Bgerens."
Any easy way I found to Ink laser etch without overlap or mess is to use a Sharpie marker, then when you have "inked" your lines, get a Mr. Clean Magic Eraser and lightly rub over the top of your etchings. The ink in the etch stays and any overlap on top is taken off by the eraser without marring the surface.
rimar20001 year ago
Interesting. ¿Could not get the same result using a compass (the circle drawing tool)?
No. A compass is a navigational instrument.

The "circle drawing tool" is a pair of compasses.

That's what I was taught, many decades ago, in English classes, given by English teachers in an English school in England.

Yes, I know that most people no longer know that.

The reason? English is no longer taught properly and no longer learnt properly.
Actually, "compass" referred to the mathematical instrument about a hundred years (mid 14th Century vs. early 15th Century) before it referred to the navigational one.
bgerens (author)  rimar20001 year ago
Yes, you can draw the circle with a compass, but first you need to know where the CENTER is. That's what this gadget helps with.
aebe1 year ago
I make walking sticks,and chasing my hole guide around has been a waste of time,at best.It is a great idea you had.
bgerens (author)  aebe1 year ago
Glad it worked for you!
Kinda limited on specific small circle sizes, eh? Wouldn't it be easier to use a drafting compass? Walmart has them about $6 bucks, and I don't know anyone who has an Epilog laser. Nice idea for portability though.
This is easier to use because with a compass you would have to spend a lot of time trying to find the center of the object.

You don't have to have a laser to make this. And if you use your handy drafting compass with a needle instead of a pencil you could trace it out on scrap acrylic and drill the holes manually.
Fair enough. I'll give 'er a go. Thanks for the instructable!
great idea . Now i know why i kept all those clear discs one gets when you buy a box of dvd's .
janw1 year ago
Great gadget!
Oldmann551 year ago
Pure Genius! I turn wood to try to maintain my sanity, and this does what several stupidly expensive tools do, simpler and quicker! For anyone who "has no access to an Epilog Laser" try asking at your local College, (Highschool in the US?). My son is going to take this into his tutor today for me, and by tonight I hope to have a couple of sizes hanging in my workshop! The only change that we are going to make, apart from making a couple of different sizes/ scales is to use a coloured (colored for those of you on the wrong side of the big pond)acrylic as I find that clear tools tent to get lost under shavings too easily!
Ground breaking! Made three today in different sizes. No more removing stock from the lathe to draw radius lines. Problem solved!
sermorta1 year ago
Excellent project. Another option to cut and mark the acrylic is mounted on the lathe, with a pattern of circles and holes that will guide grooves. Subsequently, the holes would be made in the drill press. It is so practical and easy to do that I'm planning to do it in two sizes.
doo da do1 year ago
Nice
ozyos1 year ago
ingenious is simple
Karentoo1 year ago
Elegant!
Interesting. I was curious about why you bothered to offset each successive hole by 30 degrees (like a spiral), it seemed like you could just have them in a line at different distances from the centre and get the same result. But then I realised that, with your spiral arrangement, you could use any hole as the "center" hole and that gives you a number of other distances. See the image for examples (not exhaustive) of other distances you could use for centre-finding.
Spiral vs Linear Gauge.jpg
patmac1 year ago
So simple and yet so brilliant!
janlee1 year ago
If I saw one in a store I would buy it. It's a great idea.
Brilliant - I just need to make one without access to a fancy laser doo-dah!
Why isn't this in the "pocket sized" contest? I'd vote for it.
http://www.instructables.com/contest/pocketsized2012/
xaenon1 year ago
Brilliant idea! And so simple, too.
togo19191 year ago

Bob-O!

Only a FINE AMERICORN such as yourself would make and share this one. Thanx!

Mrballeng1 year ago
Genius.
very creative
i am just gonna have to make me one of those
thanks for the idea