Dowel Rod Spline Jig




Introduction: Dowel Rod Spline Jig

About: If a tree falls in the woods...make things!

Yes, yes, and yes. I did make a spline jig here, here and here (they're all the same feeds my need to feel accomplished). So why make a jig that essentially does the same thing as that one? That would be a good question for the very few simple humans out there that lack any sort of variety (I'm looking at both of you in the back).

No, honestly, this has an important function that the last one does not have. The last one was built to be used on your table saw, this one was not. Or in other words, the last one needs all the clunkiness of a table saw while this jig is portable and is content with sitting in a box quietly, with a lid on top. I write all this with a smile because each's jigs job works in the inverse. The table saw jig is meant to be used for things that are small and can be balanced on top, while the small, portable dowel rod spline jig has it's ultimate use as a jig for larger boxes that will not fit on the table saw.

Of course, if you've looked at the picture, it also has an aesthetic charm to it (as does my table saw variety), but its intended purpose (at least from its time slowly creeping out of its crib) is to do those things that are large and very difficult and dangerous to do on the table saw.

Scroll on, dear spliner, scroll on!

Step 1: Gather Materials / Tools Needed and Used

Material List

Tools Used

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Step 2: First, a Brief Synopsis

In order to make this jig a little more versatile, I decided to go with a hinge system. As making a box is rarely perfect, I didn't want to have a rigid 90 degree angle system to contend with. Instead, I made my jig with the ability to have a little leeway either acutely or obtusely. As mentioned in my video, I also wanted to be able to do different shaped boxes such as pentagons, hexagons, yada yada yada (thanks Seinfeld). And different shapes are achievable, so long as we make sure to drill the angle accordingly.

In this instructable, we're going to stick with a strict 4 sided box that might be slightly off kilter...because, after all, square boxes are the most common shape woodworkers make (at least in my shop). But I wanted more from this jig. I didn't want to get stuck with having a hundred jigs, all with different sizes to please every box wall thickness I made. Instead, I wanted to be able to slide in different 'shims', allowing me to have complete control over the box thicknesses I make.

Now some of you are rolling your eyes at how complicated I've set out to make this jig, giving it too many options that you'll never use. I get it. Sometimes a little is just enough. And for that, I'm going to set out an extra chore in this instructable, to make it just the way you want without actually needing a shim.

Okay? Okay, good, let's get this train rolling.

Step 3: Mitering the Corners of the Jig

We're going to miter the corners of this jig to be slightly less than a normal mitered box would be. If a normal box has 90 degree corners, we'd normally want to cut each side of each perpendicular piece at 45 degrees. Due to possible future imperfections of our boxes, we are going to instead make the angle at about 50 degrees, allowing us to squeeze down a slight bit on an angle that's slightly acute.

To do this we'll go to our table saw, lock our angle at 50 degrees and carefully cut down the the 4" side of both 3 1/2" x 4" x 3/4". Be careful making the cuts as the blade will work against you due to the angle. It is absolutely critical that these cuts be about as perfect as you can make them...these will be making joints on the outside of our boxes after all.

Afterwards, grab a little sand paper and run it down the point of the edge. This isn't absolutely necessary, but it keeps it from getting dinged up later on as well as making it a bit more ouchy proof if you manage to stab yourself with it (yeah, you're all laughing, but Ralphy in the back is nodding his head).

Miter them boards.

Step 4: Preparing (But NOT Installing!) Our Hinges

Let me make this clear: No install of the hinging hinges in this step. We are merely going to mark out exactly where they go so that we can have a better view of where our drilled holes need to be placed. I also went ahead and drilled them out to save myself the headache later on.

I placed my hinges so that the pin (center of the hinge) lined up exactly at the end on both sides. This is a good idea because, well, it's easier than trying to measure both sides the exact same distance, but also because it will give us the biggest window view for the angles we'll be putting in next.

Prepping our blocks for hinges.

Step 5: Multi Functional and Fixed

Okay, this is the part I warned you about back in step 2. Remember those books where you could choose your destiny by going to a different page? Books, you know, bounded pieces of paper... Anyway, if you want your spline jig to always do a certain simple spline thickness, you're going to jump down to 'FIXED JIG". If you like versatility with your jigs, read on (and disregard those slackers that skipped).


We're going to mark over from both sides about 1 and 3/16" and mark up from the mitered (tip side) 2 1/4". The middle we'll mark at 2" (half of the entire block). Before we go any further, check and recheck that these marks are the appropriate sizes to each other. Make sure that they look symetrical. Make sure that buyers remorse won't set in later on and you're left scratching your head thinking, "Boy, how did these get to be so ugly?!" Once you've done that, all three will get an awl poke.

* FIXED JIG (without shims)

For a fixed jig, I've included some numbers in an included image entitled "Fixed Jig". This will give you the exact dimensions for making got it, fixed jig. In other words, if you are planning on making a box out of 1/2" thick walls, you'd want to go up from the mitered point, 2 inches, and so on. Honestly, this is probably more than enough to suit anyone's needs, but don't tell it to the multi functional jig crowd (okay, yeah, I'm in that crowd).

We'll mark over from both sides about 1 and 3/16" and mark up from the mitered (tip side) [number of inches on the chart]. The middle we'll mark at 2" (half of the entire block). Before we go any further, check and recheck that these marks are the appropriate sizes to each other. Make sure that they look symetrical. Make sure that buyers remorse won't set in later on and you're left scratching your head thinking, "Boy, how did these get to be so ugly?!" Once you've done that, all three will get an awl poke.

Step 6: Drilling at 45 Degrees, Methods, Madness

This is a big, important step that needs to be taken seriously. So take the clown nose off, remove the hand buzzer from your finger, take the whoopee cushion off the chair and let's really examine this carefully. And yeah, take off the Groucho glasses (but not if they're your eye protection).

Now it's time to drill our angles. My last instructable, believe it or not, was made for this instructable. Or at least I made that project first as I new it would work out well for this project. But if you don't want to make that one...(a moment of intense silence)...I understand. In fact, most drill press tables do tilt. So why make that one? Drill press tables tilt side to side, making it difficult to get any length needed to do long projects. The one I made is much easier for me to install, gets a better reading and does hold better to the plate. Oh, and I hate trying to realign my bit to the table.

Alright, enough of the defensive maneuvering. Even if you choose NOT to use my last instructable and don't like to move the plate on your drill press, you can still make a dirty version by mitering 2x6's stacked square blocks of wood and attaching it to your drill press table. I've even made a sketchup to show you what I mean, as well as a video of my last instructable. You get to choose!

Now then, we'll put the point of the miter down (the cut angle down) and line up our 5/16" brad drill bit to the hole you made with the awl. It's absolutely crucial that you drill downward at 45 degrees. Turn on your drill press and drill extremely slow, allowing the wood to be cut without creating a lot of deflection with the drill bit.

Afterwards, we'll add our spacers. I didn't use epoxy to put it in (although on a separate one I did), but you may use a little epoxy to hold them in place. There isn't much to this step but to stick the aluminum spacers in and give them a tap.

Drilling our spacer guides and installing the spacers.

Step 7: Shimming, Versatility

* FIXED JIG (without shims)

If you've chosen to go this route, skip this step.

Go on, the rest of us won't laugh...much.


Now it's time to think about shims. I've created a file to show the different thickness sizes you'll need with the settings I've created. For example, if you want your jig to work with a box that's already been constructed with walls that are 1/4", you'd want to go with the 5/16" shim. Got a box with 1/2" walls? Better use a 3/16" shim.

Now all of this, of course, only matters if you stuck with my original dowel spline jig settings. Those settings, again are:

  • (2) 3 1/2" x 4" x 3/4" of hardwood
  • 2 1/4" holes from the mitered corners

In this step I've also left the visual aid to my precise markings. Precision is key here. Geometry is a mother bear allowing you to play baseball with her cubs...and you better play the way she wants you to play. These shims are the same. If your thickness of the jig is not exactly 3/4", you're going to have problems. If your shims are shy an 1/8" here or there, you're gong to have problems.

But don't be discouraged! This idea I cobbled together can be as big as you want it to be. I made another jig that was big enough for 3/4" dowel rods to fit into that that used conduit tubing. It was so large that I didn't even need to miter my box angles. You could use 1/8" aluminum spacers (ID) with 1/8" dowels to match and go smaller. Versatility, this jig offers.

A much bigger example.

Making shims is actually incredibly simple. We're going to need 1/4" t-nuts. We're going to need 1 1/2" x 1/4" bolts. But we can pull this off easily. All we need now are shims that are slightly smaller than the main body of the width of the jig. The jig dimensions are 3 1/2" x 4". We want the shims 2 1/2" x 4". You want to do this because the shims will bump into each other otherwise. See included picture.

We'll measure this out 11/32nd's from both left and right, on both halves of the jig. You might think that you only need to shim one side...but you'd be...well, wrong. True, one side gets all the drilling action, but the other side makes sure everything is lined up and in shipshape condition.

Measuring and drilling our shim adapters.

Refer now to the included image (in this step) that shows the exact measurements you'll need. You'll notice that there's only one piece there. The other half of this jig is exactly the same, excluding the 3 aluminum spacer holes, meaning, you'll have to drill 11/32nd's from each corner. You'll also notice that there are 5/16" holes yet I've told you that you'll be using 1/4" bolts. Since we're adding t-nuts, the barrel of the 1/4" t-nut has an outside diameter of 5/16".

Once you've actually drilled these holes, resist the urge to put the t-nuts in (and ignore me doing it in the video). Now it's time to drill our shims by using both parts of the jig as patterns. Remember that human error we were talking about? Unless you've got everything lined up perfectly, I strongly suggest marking each shim with the jig half it works with, as well as which way up was. Not in the video, but off camera I marked each jig half with either an 'A' or 'B' with corresponding marks on the top of each shim. Again, make sure you look at the shim chart that's included for thickness of your shim.

Using our jig as a pattern.

Okay, now that we've lined up our shims to each jig side, we'll go ahead and use a 5/16" drill bit. Afterwards we'll take the bottom side of the shim and countersink each of the holes so that the bolt we insert through it will lay flat against the bottom of the shim.

Once this is complete, insert the t-nut through the top, give it a little tap and then use a 1/16" drill bit to drill out each of the teeth marks. From here you can either epoxy it in or drill holes next to the t-nuts and insert a screw.

Step 8: Install the Hinges, And...Beyond!

Whew, if you were able to skip that last missed a lot! Then again, there was a lot more to, you're probably even in the middle somewhere.

Now you can add those hinges.

Now let's take this a little further. I'm not going to go into details here for doing polygonal shapes, but it certainly does work for those. I made an 8 sided box that I turned down into a ring on my lathe using this jig. I'll provide that video here as it is an excellent example to how versatile this jig can be:

Eight sided box (that will be a ring later on).

Of course, the jig that you have now made isn't ready to start doing octagons. The reason for that? Your jig is set for 45 degree angles meant to work with 90 degree box angles. An octagon has 140 degree box angles and needs holes to be drilled in it at 70 degrees. The holes for the aluminum spacers also need to be wider away from the center of the jig, which you'll notice in the video.

So the general rule of thumb will be this: For every box angle, you'll need to cut that in half for the correct aluminum spacer guide. Want a 5 sided box? Each angle of the box will be 108 degrees. Your aluminum spacer guide will need to be drilled at 54 degrees.

Step 9: Thank You!

I want to thank you so much for making it to the end of this instructable. If you liked this instructable, I'd love to get a favorite from you as well as a follow. I'm also working on my youtube channel and would love a subscribe there. Please also leave messages if there is a problem with this...or if you found it useful. I LOVE FEEDBACK!

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    3 years ago on Step 8

    I like the drill press jig video and enjoyed the tutorial. It could have been made for a lot less money using something other than maple and the design is a little complicated. Overall it is nice, well built, and will last a long time. Most importantly it is functional.

    In the shop, please refrain from ever putting your hand behind a pneumatic nail gun as seen in the video. All it takes is for 1 long brad to be left in the nailer when changing sizes to change that scenario into something unpleasant. Safety first!


    Reply 3 years ago

    I’ve never seen that before, very interesting.

    Bit expensive though. 🤔


    3 years ago

    Nice work, Hint: Jobber's Length Bits!? Liked the nursery box!


    3 years ago

    Would love to see a jig to make or help with wooden rings etc , as anyone knows its very simple but a long drawn out project


    Reply 3 years ago

    Like a finger ring, or a larger ring?


    3 years ago

    Very nice and a simple but pleasing look , reinvented old classic and total opposite all in one these pocket holes if you like lol are on show , and bloody good at that more please first one I've truly been impressed with slap a patent on it and sell to kreg or rockler bud


    Reply 3 years ago

    Wow...that almost knocked me over! Patents are great...fantastic...and cost more money than I have. Since I've already publicized this, I'm not sure I could do a patent, but there's been a few of my instructables where I thought, "I really think this could be a money maker!" This one, definitely. Picture frames, mitered tabletops and any sort of box that has begun to drift could easily be repaired without having to use a table saw (for regular splines). Oh well! Thank you SO much for this feedback!