Occasionally, when I've been working on a project or building a prop, I come across something that seems like it should be simple but doesn't have an easy solution. And getting a straight and centered hole into the end of a dowel has been one of those things for me. But I'm going to show you how to quickly design and 3D print a jig to solve this issue.
Time for some design work!
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Step 1: Quick 3D Design
To begin, you're going to need accurate dimensions of the following items. You can use a ruler or a digital caliper to get an accurate measure of both.
- diameter of the drill bit
- diameter of the dowel
Once you have those dimensions, draw three concentric circles. The innermost should be the diameter of your drill bit plus a millimeter or two, depending on your 3d printer tolerances. The second should be the diameter of your dowel plus a millimeter or two, and the third is arbitrary, based on the thickness you want for the walls. Adding about 15-20 mm to the dowel diameter should be about right.
From there, extrude the center circle. This will be a cutting piece to remove the area for the drill bit to go through. Next, extrude the outer ring to the depth to about 60 mm. This will be the outer wall that will hold your dowel in place. Third, extrude the second circle to about 40 mm. This will serve as a cap and a guide for your drill bit.
Combine the outer wall extrusion with the cap extrusion and then remove the innermost extrusion. If things have gone well, you're ready to export to your 3d printer.
Step 2: Print the 3D Jig & Drill the Hole
Since we're dealing with a simple design with no overhangs, there's no reason to generate supports, and depending on your infill, this 3D printed piece should take about an hour to print.
Once the printing is finished, give it a few minutes to cool down before testing the fit. My initial estimations were incorrect, so I had to make some adjustments to my design and print out a final piece.
When you have a jig that fits well, you can slap it on the end of the dowel and easily drill a straight and centered hole with a hand drill!
As a final step, I wrote the size of drill bit and dowel on the jig so that there's never a question in my mind in the future.
If this Instructable has been helpful to you, or you have a different way of drilling a centered hole into a dowel, please let me know in the comments below. :)