3D Printed Drill Jig (Shelf Peg Holes)

Say goodbye to paper templates, ill-fitting hardware, and "eyeballing it" by using 3D-printed drill jigs, custom designed for your specific job. I realize that reads like I'm trying to sell you something, I'm not, but this is my fourth try at writing an intro for this so it will have to do.

While consumer-grade additive manufacturing has become more accessible and functional then ever it can still be a challenge to find great uses for it that aren't still more easily or cheaply accomplished through traditional means. That said, if you've ever screwed up a piece of a remodeling project by drilling your hardware mounting holes in the wrong place this guide may justify the cost of a printer all on it's own.

For this write-up I'm showing a jig I made specifically for the desk project pictured above (read it's guide HERE) to drill shelf peg holes in a shelf unit but 3D printed drill jigs can be used for basically any type of hardware installation. Shelves, hinges, drawer pulls, knobs, ect. If you need to drill for it, you can make a jig for it so let your imagination run wild. If you do print your own jigs please post pictures in the comments, I'd love to see them!

Designing tools like this is a small part of my job that I never get to talk about so below I am absolutely going to get way to into the weeds and overly technical for a plastic part used to put together a kids desk. You've been warned so feel free to skim. The STL is attached below.

A good drill jig does three major things:

1. It accurately positions holes. That's pretty obvious of course. For design this means it needs a good set of indexes that assure your jig will sit exactly where you want it to.
2. It drills straight holes. Having the position of the hole right only counts if the axis of the hole is also right
3. It's repeatable. Of course there are cases where a single use design is the only feasible option but in most cases you want to get the same result every time you use the jig.

Of course with each design you have to weigh cost and time against how important each of those criteria are to the final result.

For the jig in question here's a run down of the features and how they relate to the criteria.

• The major indexes are the two inside faces, seen in the second image. The larger face is common to the drilling surface of the work piece and the smaller flange butts up to the edge of the board parallel to where you want the holes drilled.
• There is a relief channel running the length of the tool where these indexes meet because the idea is to set the tool off of the faces and if it contacts in the corner it will exacerbate any error in the flatness of the second surface.
• The third index is taken care of with a scribing system. On either side of the drill locations is a slot though the tools face. Each slot is offset the same distance from the nearest end and is spaced in concert with the offset of the drill locations so that a mark made with the left slot and then lined up in the right slot keeps the pattern of holes equally spaced. Sort of like playing leap frog. If your confused there's a little more about using the slots, along with pictures a few steps further down.
• The drill locations are padded up to help guide the drill bit and keep it straight, per our second criterion. The holes are unlined for this specific use but if you wanted a straighter, longer lasting (there's number 3) tool then lining the drill locations with a metal bushing is relatively cheap and easy.
• Above the slots is an open area where clamps can be applied. This is important for making sure we're nice and flush to our main index and for repeatability.
• Finally there's a little room for chip and dust clearance on the far side of each drill location. Not a huge concern here but it doesn't cost anything to add it when you're printing.

I'm lucky enough to have access to a printer with dual extruders and a support material so that takes a lot of extra concern and work out of setting up the print. Don't worry if that's not an option for you, a simple design change will make this particular piece a snap to print on any machine large enough. Just make the entire top surface as thick as the drill location pads and place that surface down on the print bed. You may also choose to teak the corner relief channel but that's a fairly inconsequential part of the design in this case.

The version you see here was printed in ABS and look ~6 hours of print time.

If you don't have direct access to a 3D printer and aren't ready to make the leap yet yourself, don't worry, there plenty of options out there. On demand fab services, like 3D Hubs, use a mix of their own print houses and crowd sourced consumer printers-for-hire, to deliver parts. Most suburban or urban areas are relatively close to a makerspace or similar collective that would allow for use of their machines. Even more general communities like craigslist or a local subreddit could potentially help get you in contact with someone willing to help.

The following steps cover using the specific tool I've been discussing and that has been pictured through out. You can see the full desk project it helped create HERE.

Choose a side to start on, it doesn't matter which and place one edge of the jig flush to the end of the work piece. Clamp the jig in place above the two scribe slots, making sure the edge rail stays flush to the work piece.

Mark the work piece with a pencil through the scribe slot furthest from the side you put flush to the end of the piece.

If you want to drill blind holes instead of through holes then marking the max depth on your drill bit is a good idea. Here I use electrical tape to make sure I don't punch through the back of the work piece.

Drill each location desired and then remove the jig.

Slide the jig down the piece until the scribe marked previously can be seen in the other scribe slot and then repeat the previous steps.

Clamp the jig, mark the new leading scribe, drill the holes, move the jig, until you've placed all the holes you need. Rinse and repeat on any additional work pieces.

(Fun Fact: The "Rinse and Repeat" directions on shampoo is there almost exclusively to try and convince consumers to use, and thus buy, more shampoo. Very few people actually need to wash twice and in some cases it can actually be detrimental to your hairs health.)