Dowel Jig Generator

A 3D printable drilling guide, sized to your board and dowel, with the holes on the center of the edge.

Board & dowel

Board thickness · mm

Units

Dowel and drill diameter · mm

Holes

Spacing · mm

From fence · mm

Hole position across the edge

The guide

Length · mm

Guide thickness · mm

Fence depth · mm

Fence thickness · mm

Clearance · mm

The hole holds

Printed holes come out small. 0.2 mm lets the drill turn without wobble.

drag to turn · scroll to zoom

Length: -
Width: -
Height: -
Guide: -
Fence: -

Hole through the guideflat to flat

From fence-center of the edge

First hole-from the jig end

Print time-rough, see below

PLA, estimated-

Printsflat, no supportsfence up

Price this print in the cost calculator →

computed in this browser only

Local onlyThe jig is built and checked by JavaScript in this tab, and the STL is made on your computer. Your settings are remembered in this browser's local storage, and nothing is uploaded.

A dowel joint only goes together flat if the holes in both boards line up. This page draws a drilling guide for your board and your dowel. It sits on the edge of the board with its fence against one face, and the holes land where you set them: on the center of the edge unless you choose otherwise. Before you can download it, the page checks that the model is a closed solid, so it slices cleanly.

What each setting does

Board thickness. Measure the board with calipers rather than trusting the label. Plywood sold as 3/4 in is often 23/32 in (18.3 mm), and 18 mm sheet can run a little under. The jig centers the holes on half of whatever you enter.

Hole position. How far the hole centers sit from the fence. It follows half the board thickness until you choose My own offset, for instance to keep a dowel clear of a groove. Put the fence on the same face of every board, usually the face that shows. Then the faces finish flush even if one board is a hair thicker than the other, because every hole was measured from that face.

Holes and spacing. The holes are spaced evenly and centered along the guide. 32 mm is the spacing European cabinet hardware is drilled on. The readout shows how far the first hole sits from the end of the guide, so you can hold the end flush with the end of the board and get the same position every time.

Clearance. A printed hole comes out a little smaller than drawn, because the plastic spreads as it's laid down. The default adds 0.2 mm to the drill size so the bit turns freely without rattling. If your drill binds, add 0.1 mm; if it wobbles, take 0.1 mm off. Each hole is drawn as a 64-sided polygon with its flat sides at the size shown, so no part of it is narrower than that number.

Guide thickness. This is the length of hole that keeps the drill straight. Aim for at least one and a half times the drill diameter: 12 mm for an 8 mm drill.

Fence thickness and depth. The fence hooks over the face of the board and gives your clamp something to hold. 20 mm deep and 5 mm thick is stiff enough for hand pressure and a small clamp.

Drill bushing. A drill spinning in plastic slowly wears the hole bigger, and a worn hole lets the bit wander. For a jig that will drill more than a few dozen holes, press in a steel or brass drill bushing. Choose A drill bushing and enter the bushing's outside diameter, and the hole is sized to the bushing instead of the drill. For a press fit, start with 0 to 0.1 mm clearance and print a one-hole test piece first. Make the guide as thick as the bushing is long.

Printing it

The STL comes out ready to print: lying flat on the drilling face, with the fence pointing up. The holes print as true circles that way, and nothing needs supports.

Material. PLA+ or PETG. PLA is stiff and holds its size well; PETG gives a little and is less likely to crack under a clamp.

Infill. 100% infill, or at least 4 walls, so the plastic around every hole is solid all the way through. 0.2 mm layers are fine.

The first layer. The bottom layer can squash slightly into the holes on the bed side. If the drill catches as it enters, ease the edge with a countersink or run the drill through once by hand.

Test it. Drill two scrap pieces, push a dowel in and close the joint. If the faces sit flush, the jig is ready.

The weight and time estimate

The weight starts from the volume of the solid model, worked out from the same triangles you download. A slicer doesn't fill that whole volume, so we count 4 walls of a 0.4 mm nozzle around every side, 5 solid layers of 0.2 mm on the top and bottom, and 40% infill inside, at 1.24 g per cm³ for PLA. That is an estimate, and the readout shows the 100% infill weight next to it.

The print time assumes about 4 mm³ of plastic a second averaged over the whole print, roughly 18 g of PLA an hour. A Bambu or a Prusa MK4 at standard settings will usually beat it, and an older printer may not. Your slicer's own figure is always the better one. The link under the estimate opens the 3D Print Cost Calculator with the weight and time filled in.

Questions this tool gets asked

What size dowel should I use for my board?

A common rule is a dowel between a third and half the board thickness: 6 mm dowels for 12 to 15 mm stock, 8 mm for 18 to 20 mm, and 10 mm for 22 mm and up. In inches, 1/4 in for 1/2 in stock and 5/16 in or 3/8 in for 3/4 in. A bigger dowel leaves thin wood either side of the hole, and the tool warns you when the dowel is more than half the board.

Why is the hole in the jig bigger than my drill?

Because printed holes shrink. The plastic spreads a little as each layer goes down, so a hole drawn at exactly 8 mm usually prints a touch under. The jig adds 0.2 mm by default, which lets the drill turn freely without wobble. Change it in steps of 0.1 mm if your printer runs tighter or looser.

What if my board is not exactly the thickness I entered?

The joint still lines up as long as the fence goes on the same face of both boards, because both sets of holes are measured from that face, and the faces finish flush. The holes just won't be exactly in the middle of the edge. For true centring, measure the board and make a jig for that thickness.

Do I need a drill bushing?

Not for a few dozen holes. A drill turning in plastic slowly wears the hole oversize, which shows up as holes that wander. For a jig you will use for a whole project or longer, choose the bushing option, enter the bushing's outside diameter, and press a steel or brass bushing into the printed hole.

What are the best print settings for a drilling jig?

Print it flat on the drilling face with the fence pointing up, which is how the STL downloads, so no supports are needed. Use 100% infill or at least 4 walls, 0.2 mm layers, and PLA+ or PETG.

Will the STL slice without errors?

The page checks it first. The file you download is read back before the button is enabled: every edge has to be shared by exactly two triangles, every face has to point outward, and the solid has to have a positive volume. When a combination of settings cannot make a sound jig, such as holes that overlap or a drill that would break out of the board, the page says why instead of giving you a file.

Does anything I enter leave my browser?

No. The model is built and checked by JavaScript in this tab, and the STL is made on your computer. Your settings are remembered in this browser's local storage, and nothing is uploaded.