Center Finder Jig




Introduction: Center Finder Jig

Simple center finder.

Step 1: MDF

Cut two pieces of MDF.

Step 2: Glue

Glue and clamp them at a right angle.

Step 3: Screw

Reinforce the joint with screws and check for square.

Step 4: Angle

Cut a right angled triangle piece of MDF.

Step 5: Glue

Glue and clamp in place.

Step 6: Pivot Screw

Before the glue dries insert one screw to reinforce and to pivot. Check the 45 degree angle and adjust appropriately, then insert a second screw.

Step 7: Seal

Seal the edges of the MDF with glue and give the piece a coat of shellac to prevent moisture from warping the shape.

Step 8: Find the Center



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    13 Discussions

    Oh why didn't I have this before I lathed a bunch of dense foam? So simple and handy. Thanks!

    Good job and nice write up. This is a handy little jig. I just made one last week out of Spanish Cedar. I used Lexan for my diagonal piece. Very convenient for find centers on your work piece to put in a lathe. I thought about scribing measurements on the diagonal but then I thought I was just being OCD about a simple project. Just be careful where you store this jig, too much humidity will make it swell & could throw it out of square. Once again, great job!


    Its simple and easy . Many should find it very useful .

    MDF is good , if you have it . The dust from it can be harmful , so watch out . A more lasting model even in MDF could be made with its edges sealed with crazy glue to make the edges more tough or just make it out of Carbon Graphite .

    But simple is always Good .

    Aloha from Oahu ,

    Mark Baker

    Nice and simple, I like it. Thanks for sharing!

    Didn't I read somewhere, recently, that a large percentage of speed squares are significantly inaccurate? I suppose that's not critical unless you're using this jig for, say, machining to close tolerances, which you wouldn't. But MDF edges aren't going to be, or stay, all that accurate either, so for a quick and temporary tool perhaps it doesn't matter. Just wanted to pass the speed square issue along.

    1 reply

    Heard of that too. But there's a simple way to check if they're off - Google it.

    I needed one of these since about 50 years ago. What took you so long ? :-)

    Another one?

    The old tricks are usually the best, but full marks for trying. I don't know who invented the first one, but Pythagoras might have had a hand in it.

    If you need to leave the screws in, why not countersink and leave them flush? Just being picky, but something to snag on.

    1 reply

    I did eventually countersinked the screws. Just got a little ahead of myself with posting the instructable.

    Clever jig. Now, rather than have the three edges intersect exactly, if there is a slight gap between the intersection of the two square edges and the 45° edge, then lines drawn or scratched on the dowel end can go right through its center. I know this isn't critical, since if at least three lines are drawn, then the center of the area between those lines will be easy to hit, but hey.

    Excellent in its simplicity

    Simple and complete. Nothing else to ask for. Good project.