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Hi everyone!

In this quick ible I'm gonna show you how to make a useful Center Finder tool using just scrap materials that you can find easily in your home.

Thanks to this simple, yet accurate tool you will be able to quickly mark the center of your square or round workpiece, saving a lot of time.

Step 1: Materials & Tools

MATERIALS:

- 2x scrap pieces of wood

- 10cm x 10cm plexiglas
(the clear side of a CD cover would work as well)

- 3x long wood screws

- 2x flat-head screws

TOOLS:

- drill

- wood glue

- clamps

- precision square

Step 2: Cut and Glue

First of all find or cut two small pieces of scrap wood (mine measure 8cm x 10cm).

Apply wood glue on the joint and clamp the pieces together being sure to let them dry in square (photo#1).

Step 3: Reinforce the Joint

After 15 minutes reinforce the "L piece" adding 3 long screws.

Be sure to pre-drill the holes in order to avoid cracks.

Step 4: Cut the Plexiglass

It's time to work on the plexiglass piece.

First of all cut a piece of the right measure (mine is 8cm x 10cm), and then make a 45° cut.

Plexiglass is an easy material to work with. You could cut it using a jigsaw or a metal saw but I found easier to cut it making a lot of scores with a knife, and finally I bent the piece with my hands breaking it along the line.

Step 5: Secure the Plexiglass to the "L Piece"

In order to secure the plexiglass to the wood I drilled two holes in both pieces, and then I secured it using two flat-head screws.

NOTE: don't tighten them too much or you will break the plexiglass.

Step 6: Use It and Find the Center of Everything!

And here it is! After just 20 minutes (I hate to wait for the glue to dry) we have a simple yet accurate tool that will save you lot of time when you need to mark the center of a workpiece.

It's specially useful for round pieces. Lay your workpiece in the corner against the plexiglass and the wood, mark a line along the 45° plexiglass edge, rotate the piece a little and mark another line. Congratulations! You found the center. (a 3rd line is needed just the first time to check that your DIY tool is accurate)

Thank you for reading my Instructable. ;)
Feel free to comment and ask if you need to know something!

manuelmasc

<p>I wish I had seen this years ago! Had wood and lexan laying around, had it all together in 20 minutes. Nice and simple!</p>
Pheww, now I can mark Centre lines without having to research mathematical techniques that I'd struggle to understand anyway! Thank you for the info
<p>no problem man! nice to know that I saved another life from math :P ahahahha</p>
<p>great idea and real simple. My suggestion would be to use an old plastic mechanical drawing plastic triangle, or just buy a cheap new one. Sometimes getting plexiglas to score and break accurately is problamatic. The triangle is right on.</p>
<p>If you score it 5/6 times along the line it becomes very easy to break along the line, but absolutely yes!! that is a quicker and easier way!</p><p>Thanks for your suggestion! I'll add it in the ible!</p>
The biggest challenge will be drilling the plastic or plexiglas without it cracking.
<p>Drill Plexiglass with wider (flater) drill bit tip, aroung 120 degrees</p>
<p>good idea since the bite will be less drastic and not as likely to produce as much stress.</p>
<p>Perspex is a sod to work with and cracks just by looking at it - drilling is the worst. Drill slow and preferably in a drill press. Don't go for the finished hole size straight off, go up in drill sizes. Otherwise, use a reamer.</p><p>The centre finder doesn't need clear plastic, so just use PVC sheet which is a doddle to work with.</p>
<p>you are right but it's just &quot;plastic&quot;... let's not panic for breaking it ahaha</p><p>make a small pilot hole, drill slow and the holes will be done! </p><p>thanks for the comment anyway!</p>
I have worked with optical acrylics on military aircraft. They do make acrylic drill bits that have a longer. More pointed tip. But using a regular drill bit, drill at a fast speed but very low feed...almost spinning in place...to heat up the plastic ahead of the drill bit tip. Also it is advised to drill a pilot hole then step drill with a unibit to the final size.
<p>right! a small pilot hole is a good suggestion</p>
<p>I would suggest perhaps a small point soldering iron to melt through it. It should go through quite easily. I have put holes in plastic that way before. Works like a charm. No cracking.</p>
<p>yes! and it reinforces the edges of the hole too. the only &quot;problem&quot; is to find a screwdriver of the right dimention</p>
<p>you just need a drill bit of the right size and you have to drill the plastic at a very slow speed. </p><p>another easy method is to heat a screwdriver with a lighter in order to melt the plastic creating the hole.</p>
<p>I'm a newbie working with wood etc., but this seems like a very useful tool &amp; the suggestion about the using a triangle makes it even easier!!!</p><p>Thank You both for a great idea(s)!!!</p>
<p>Thanks for the appreciation</p>
I love this! Made own speed square for same reason... but this covers circles!... im a big fan of.... &quot;Do it once properly (for the sake of the jig) and you'll never have to do it again! :)
<p>ahahah good way of thinking</p>
<p>great because I normally jus guess</p>
<p>ahahahha the guessing technique is the fastest and the easiest but definitely not the most accurate one... it depends on the project that you are working on</p>
<p>This is not the first instructable of a centrefinder, but this one is absolutely the easiest and quickest to make!</p><p>Thanks for the idea. You have my vote!</p>
<p>Thank you very much for the vote!! I really appreciate it</p>
Very useful and simple. Thanks!!!
<p>thanks encicca</p>
<p>Variation on quite an old technique, but nice to see none the less.</p><p>Circular bar sits in the right angle, 45-degree bisects the disk - rotate the block to get several fixes on the centre point - works every time. The important bit is to get the 45-degree rule to site exactly in the 90-degree intersection.</p>
<p>old techniques are the best! ahah</p>
<p>I really like the idea of the plastic triangle</p>
<p>Glad to hear that! I also like it because you see through it being sure to place correctly the workpiece in the jig.</p>
<p>Great idea. Not new but a good reminder on KISS. </p><p>thanks for sharing</p>
<p>thanks for the appreciation!</p>
<p>Easy to make and so useful. Like it!</p>
<p>thanks <a href="https://www.instructables.com/member/nex_otaku" style="">nex_otaku</a>!!</p>
<p>This always was a problem for me. What an simple solution! I will be making one ASAP.</p>
<p>thanks! please remember to post your &quot;I made it&quot; photo.</p>
<p>I like it - great job; a very understandable and useful DIY tool!</p><p>When my students used to want the center of a circle, square, or rectangle on paper or fabric, I'd have them fold the piece (or a pattern piece) in even halves, then fold in half again. One can stick a needle or push pin through the center to mark the real piece of work. If it is not exact to the micron it is still close enough for school art. In working with wood I'd have them trace a pattern piece on paper and use the same technique. I'll be making your center finder, though.</p><p>Thank you for such clear directions and photos.</p>
<p>Thanks for all the compliments <a href="https://www.instructables.com/member/Alaskan%20Bev" style="">Alaskan Bev</a>! please remember to post your &quot;I made it&quot; photo.</p>
<p>I knew there was an easy way to make a tool to find the center of a circular work piece, but I could not recall it. Geometry does work well on paper, but not very well on a 3/4&quot; piece. This tool is simple and easy to use. Thank you.</p>
<p>thank you for the appreciation</p>
Common sense--genius
<p>thanks</p>
<p>Will this exact size jig, work with any size item needed to find center?</p>
<p>Hi Logwolf! The only limit of this jig is the 45&deg; line.</p><p>In my case (since I used just scrap materials and since I don't usually work with big workpieces) it measures about 8,5cm. This means that I'll be able to use the edge of the plexiglass to mark the center of a 12cm diameter circle or a 12cm square. <em>(look the 1st attached photo)</em></p><p>BUT since the 45&deg; line passes through the center of any workpiece that is placed against the 90&deg;angle (aka the wooden pieces faces), I could still use it to mark the center of a square bigger than 12cmx12cm, simply by placing it against the 90&deg;angle, and laying a ruler onto the 45&deg; plexiglass edge. (l<em>ook the 2nd attached photo)</em></p><p>You could use the same method to find the center of circles bigger than 12cm just if the height of the wooden pieces (from the origin of the 90&deg;angle) is the same. In my case since I butt-jointed two pieces of the same measurements, I ended up with one side of 6cm, and the other of 8cm of height.</p><p>Thanks to your comment I'll upload this ible with more infos about the limit of this jig, and with a simple trick that can be followed to modify this jig in order to use it with circles or squares of ANY dimension. Stay tuned! ;)</p>
<p>No, it will only work with things that fit into the jig.</p><p>However, there is no reason why you could not scale the whole thing up and use timber with a measurement of 500 x 500. This would allow you to find the centre of items up to a metre in diameter</p>
<p>Yes! You can scale it to any measurement that fits better your needs, or you could lay a ruler onto the 45&deg; plexiglass edge in order to temporarily extend the capacity of this jig keeping it small enough to don't waste materials and space around your workshop. </p><p>I'll upload this ible with a simple trick that can be followed to use it with circles or squares of ANY dimension. Stay tuned! ;)</p>
<p>I've often thought &quot;Simplicity is the Art of Engineering&quot;. </p><p>This illustrates that idea perfectly. Simple. Efficient. Cheaply made. BRILLIANT!</p>
<p>That's also my way of thinking! thanks for the comment</p>
<p>Thanks for taking the time to post this. Simple and effective</p>
<p>Thanks for the appreciation!</p>
<p>good idea thank!</p>

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Bio: Italian maker, law student, DIY enthusiast. I make lots of projects, I fix lot of stuff and I like to save and reuse materials taken ... More »
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