Step 5: Sled Building Overview

There's a lot of information covered in this step, so take your time to absorb it all. I suggest referring to the images frequently as your read through this.

cross support design considerations

Each cross support (front and back) is made up of three layers of plywood. When you're working out the dimensions for the cross support components, cut out the five middle layer blocks so that the four carriage bolts have enough room to move side to side about 1/4 inch in either direction; it's better to have too much slop here than not enough. Also, remember that the saw blade will cut most of the way through the middle of the thing, so make sure that the cross supports are tall enough to not get completely cut in half.

cross support assembly

The three layers of the cross supports are held together using screws which come in from both sides. Use lots of screws -- you really want the cross support assemblies to be sturdy. Each screw should fall loosely through oversized holes in the first and second layers of wood, only biting into the third layer deep.

Make sure that you line up the cross support assemblies straight and smooth when you screw them together. Tighten down all of the screws and then back them off a few turns to be sure that all seven blocks of wood are free to rattle around. If this is not the case, you may need to go back and enlarge a few of the oversized screw holes. Align the loose assembly using the surface of your saw as a flat guide. When you do the final tightening down of the screws, go about it in a gradual manner, and (gently) use a hammer along the way to nudge everything flush.

sled plate construction

Each sled plate (right and left) is made up of two layers of plywood. Each layer gets many holes drilled through it before assembly.

linear motion

Rather than riding down the miter slots on rails (as do most sleds) this design uses ball bearings which run against the inside edge of the miter slots. Attach the bearings to the underside of the sled plates using heavy duty screws with necks that snugly fit the inner diameter of the bearings. The bearings need to spin freely from the underside of the sled plates, so put a couple of narrow washers between each bearing and the underside of the sled. If your miter slots are especially shallow, you may need to countersink each bearing assembly into the underside of the sled, or alternately grind down the screw heads a little bit.

The side-to-side placement of the bearings is dictated by the layout of the miter slots on the saw, however the front-to-back placement of the bearings is purely a matter of preference. Placing the bearings directly underneath the cross supports (rather than closer to the center of the sled) results in the most stability, but reduces the amount of effective sled travel because the sled will slip crookedly if the bearings are extended past the edge of the tabletop. A best-of-both-worlds solution to this dilemma is to mount another bearing (or a stack of washers) in the middle of each sled plate and adjust it so that it almost but not quite touches the miter slot wall. This will prevent the sled from jerking sideways if pushed too far, which in turn prevents the blade from getting all bound up in whichever cross support it happens to be passing through at the time.

thread points

As with my machined metal version, this design also has an evenly spaced pattern of threaded holes going through each sled plate. I recommend spacing these hole locations as shown where the distance from any hole to its horizontal or vertical neighbor (but not diagonal) is 1.5 inches. For my example sled (the one that I made to take these pictures) I used press in 10-32 threaded inserts (Servalite 628-E) which I hammered into undersized (6.5mm diameter) holes. Countersinking the threaded inserts without marring up my sled plates was easily accomplished by pounding down on a socket head cap screw which I spun down into each insert before hammering it in place.

Using these threaded inserts was convenient, but they're expensive and hard to find. In retrospect I wish that I had used tee nuts countersunk in between the layers of the sled plates. It would have been a lot more work to drill those countersinks, but I think that it would have been worth it in the end.

Regardless of whether you use tee-nuts (recommended) or threaded inserts, you'll want to get a whole selection of 10-32 threaded socket head cap screws to work with. Get several of each length available, and be sure to get extras in the 1" to 1-1/2" range because they're especially handy. Get a bunch of #10 washers. Get some 1/4" washers as well so that you can step up to clamp over a larger hole. I recommend getting a divider case to hold all of the screws separate from each other and from the washers and other little things that you'll frequently be reaching for as you build up fixtures onto the sled plates.

sled plate assembly

Join the top and bottom plate halves together using screws which come up into the top plate from underneath. Place a few of these screws in between thread points, and also space them evenly around the perimeter of each plate. Countersink the screw heads so that the sled slides smoothly, and to maximize the amount of bite that each screw takes into the top plate.

blade clearance

Plan out your cuts and hole patterns so that the inside edge of each sled plate actually extends into or even slightly past the other side of the saw blade. Once you've screwed the sled plates together and mounted the bearings underneath, trim that extra material off the inside edges of each plate by running them down the miter slots with the saw running. The benefit of doing it this way is that you are guaranteed to get a perfect zero-gap clearance between the inside edges of your sled plates and the saw blade. Getting this plate trimming cut started can be tricky -- lower the blade down so that it's not cutting anything and then hold the sled plate in place (pressed up against the inside edge of the miter slot) as shown in the main image on this page. With the plate firmly held in place like this, slowly raise up the running saw blade to get the cut started.

sled assembly

Once you've built these four main subassemblies, it's time to mount the cross supports onto the sled plates using eight carriage bolts. Hand tighten the nuts and washers down onto each of the eight carriage bolts, and then switch to a wrench or ratchet to dig the square necks of the carriage bolts into the top layer of the sled plates. Now loosen it all up again in order to more carefully align things. Using a small square to line up the cross supports perpendicular to the cut line between the plates, tighten down the nuts on just the left-hand sled plate. Now push the two plates together (pressing the bearings up against the miter slot walls) and firmly hold them that way as you carefully tighten down the nuts on the right-hand plate.

Experiment setting different tensions between the two sled plates -- you want enough so that there's no side-to-side play, but you don't want so much tension that the sled is difficult to push. Don't worry too much about getting the cross supports lined up at exactly 90 degrees to the cut line -- in the next step I'll show you how to mount a secondary (more accurate) crosscutting fence.
<p>Could you send the solution the the very first combination under the completed cube on the first page to <a href="mailto:prettylala10@gmail.com" rel="nofollow">prettylala10@gmail.com</a>? </p>
<p>I need the solution for the very first one </p>
Hello! I recently saw a video in which you demonstrated a puzzle box containing a ball bearing. It was amazing! Do you still sell these puzzle boxes? Thank you. susanatom23@gmail.com
Hello, <br>please find there: <br>http://thebreizmaker.wordpress.com/2013/10/26/jeu-de-patience/ <br>The making of may own jig, 95% inspired by yours <br>Used and done on a Kity table saw, many parts done on may home made cnc mill <br>Trials soon ! <br>Regards <br>Thierry France / Brittany
Awesome instructable. &nbsp;I have finally got around to making my own version of your sled and so far have promising results coming from it. &nbsp;Many thanks!<br> <br> <div class="media_embed"> <iframe frameborder="0" height="315" src="http://www.youtube.com/embed/ddG6qZ90X3U" width="560"></iframe></div>
Where can I find the solution?
what puzzle do you want the solution for?
puzzle 2
number two plaese?<br>
For all
check out burrtools.sourceforge.net for awesome FREE puzzle solving software. I use this program all the time in my work, and highly recommend it for anybody who wants solutions to these puzzles.
Yes, what is the solution for number 2? Could someone show the plans instead of a site because you have to download many things for that software <br>
what is the solution for number 2<br />
I would like to know more about constructing this precision sled.&nbsp; Measurements would be helpful.
&nbsp;Writing you from Colombia in South america, love your work,your hobby,your craftsmanship etc,just great.Thanks, and good luck
I had just enough 1inch cubes left to make this one. I will do the rest in 3/4inch and 1/2inch stock. I also made the three cube ones in 1inch cubes. Great stuff i tip my hat to you and your work. In vol. 2 will you have the plans for the ones you did with the laser cutter if so i would be much obliged.
By the way...........help how do u do it
Hi I'm fairly new to this site and woodwork too. I'm very interested in puzzle boxes and have made one or two, including my own designs of trick and hit boxes. I always start without measuring though and have not taken enough pics for an instructable but I will try next time - promise. How about some simple (is there such a thing?) puzzle/secret/trick box building instructables? Alain
Very helpful. I have tried to make precision puzzles, but they always come out with some gap or another no matter what I did.
I've been making puzzles for a few months now and built a sled to do the dados on burr puzzles. Clearly, I was thinking too small. Thank you. I can't even imagine what you will do in future installments, but I'm curious.
I've really want to get into puzzle making for a while, and this Instructable might be what gets me finally started, thanks Lee Krasnow.
I have made wooden puzzles almost all my life. Here (Belgium) they're called 'breinbrekers' which means 'brainbreakers'. Now I have another addiction: making puzzles. Today I finished 'Convolution'. Thanks lkrasnow for helping me out! I barely can't wait for the next volume...
I ment 'I have solved (or at least tried to in some cases) puzzles almost all my life. etc.
. Wow! Fantastic job.
To me this looks like two separate inst* first, Build a custom sled for your table saw. Second, Make some amazing, incredible wooden puzzles using a custom sled for your table saw. Until I saw the picture I was thinking jigsaw puzzles not 3D wooden puzzles. Great work.
You just do what you want to do! ;) Wonderful puzzles! :)
Sir, you are a genius, I could not possible emulate or even begin to do your sort of work, I will just stand back, gasp, and look forward to the next instalment.
I love your work. I hope to make a puzzle box one day.
one of the best instructables ever! Nice job.
Cool! I can't wait to see the whole series.
Excellent job on the puzzles and instructable! I wish I still had access to a shop!
wow! this is pretty fantastic, man. thanks a lot. i'm definitely going to be adding this to my to-do list! great work. i'd give it a +2 if i could

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