Category Archives: Tools

From Square Sticks to Cubes

I recently wrote about the first of my puzzle making jigs to create square sticks as the first stage in creating the building blocks of many puzzles. With that jig successfully completed, and working pretty well, I had to move to the next stage and create some cubes. I said in the Square stick post that I’d tell you about it soon. Well, soon is now, and it’s time to make a crosscut sled!

The starting point for a crosscut sled

For this jig, I needed a larger platform than the square stick jig, and as such I was going to be using both miter slots on the table saw. I cut myself a slab of MDF and marked it up for adding runners. I don’t have enough of the fancy metal miter bar that I used for the last jig, so I made my own. Starting with a strip of wood rough cut to the correct size for my miter slot, I sneaked up on the correct width by taking thousands of an inch off at a time until I had a snug fit. It didn’t take as long as I thought it might, and I think I now have an even better runner than the metal versions I used on the first jig.

My intention was to drill and counter sink holes in the top of the sled and screw straight into the runners below. Sadly that didn’t quite work out as planned as I didn’t have screws which would fit. What I had was either too short or too long so I had to go to Plan B. I decided to screw through from the runner side into the base. As it turns out, it wasn’t too much of a change and in the end achieved the same end result.

Runners mounted and a slot cut

With the runners mounted, I flipped the jig over and tested the fit in the miter slots with the blade below the table. I had a couple of spots which were binding slightly, so I lightly sanded the offending areas until I had a tight but smooth fit with no wobble in the jig. For anyone wondering, the way I found out where the runners were binding was to run a sharpie along the length of the runner sides, then move the jig in the slots. When you take the jig back out, where the sharpie has been rubbed away is where you need to remove a small amount of material. Simple yet effective!

With the sled moving smoothly, I raised the blade up, and cut myself a slot part way through the sled. That slot will help aligning the crosscut fence as I need it to be perfectly square to the blade. Without having the blade through the sled that would be almost impossible.

Some reinforcement across the back of the sled.

Given the slot I’ve just created, I now have a potential weak point in the sled where it could flex, and degrade the cut. Despite how it may look in the photograph, I wasn’t trying to create a wing to add down-force to the sled.

Each of the three spacers on either side is screwed to the piece below with three screws, and gives enough clearance that with the blade raised to the point that the blade stiffeners are just below the base of the jig, it doesn’t cut into the cross bar. The cross bar keeps either side of the sled stable and prevents any twisting or warping of the sled. Yet again simple but effective. (I’m liking the fact that I can keep things simple. Less chance of things going wrong!)

A beautiful Dragonfly that stopped to see what I was doing

Given that it was getting on for around 5 hours that I’d been working on the saw and building the jigs by this point, I took a break, stretched out my legs and back and relaxed for ten minutes. While I was doing that, I spotted a dragonfly floating around the garden. Standing watching him for a few minutes, he landed on the radio antenna for our car. Given that I still had the camera in my pocket from taking pictures of what I was doing, I grabbed it, as he posed for me! Looking at the pictures later, there really came out well, so I thought I’d share…

Anyway, back to the jig …

Adding the fence and a stop

With the back reinforced, I had to add the fence to the sled. The important thing here is that it is at exactly 90 degrees to the saw blade. If it’s off, then the cut will not be square, which isn’t going to make for a good cube. Using the best square I have, I sat one edge against the blade, and the other against the fence board I’d cut. Keeping both edges in firm contact, I drilled one screw hole, counter sank and then screwed the fence to the sled at one corner. With one corner in place, I double and triple checked the fence was square, on both sides of the blade (using two squares). That may be a little overkill, since the blade shouldn’t be different on either side, but I figured it couldn’t hurt!

Everything checked, I pre-drilled and screwed the other side of the fence to the sled, and checked again for squareness. With everything looking good, it was time to add the stop. Now this was something that I’d been puzzling over for a good few days at this point, and hadn’t really figured out how I was going to perfectly measure the offset so that I ended up with good low tolerance cubes. As is ever the case, the answer came to me when I least expected it, in the shower in the morning before heading to work.

The answer. Make sure that the stop is far enough from the blade to make the biggest cut you’ll need, plus a bit. The reason … Well if you properly size a piece you want to cut (and I’ll get to that) then you can use that piece against the stop, then cut a ‘spacer’ by placing it against the fence, and the piece you want to cut, then cut that piece. You get a perfect spacer, and no complicated measuring required. (Other than the piece you want to end up with). Yes, I know that’s all very confusing, but I’ll annotate the pics below and it will make more sense!

Clamp removed now that the stop is screwed in place

Having screwed the stop in place I could remove the clamp. The stop is placed 6″ from the blade. I’m unlikely to ever cut a stick that needs to be 6″, unless perhaps I’m making 18 piece burrs, so this is lots of space to create whatever sized stick I need.

Creating the spacer for a single cube

If you click on the image on the left, you’ll see I’ve annotated it to make my previous explanation simpler to understand. The single cube in walnut was created by shaving a few thousands at a time from the edge of the block and measuring after each pass until it matched the dimension of the square stick. In some regards, that is probably the most time consuming part of the process, as if you take off too much, then it’s a case of starting again.

With the first cube created by hand, it can be placed against the stop, then a long stick placed against it to create the spacer. In the diagram, you’ll see I created mine from some of the redwood sticks I’d cut when I was testing the square stick jig.

Batching out some cubes

Now it’s a simple task of swapping the order of the pieces so that the spacer is against the stop, and batching out some cubes. I’ve used a clamp to keep the spacer in place, both against the fence, and hard up against the stop to make sure that it doesn’t move between cuts. It’s also important after each cut to clear out any dust that gets between the block and the fence as this will affect the accuracy of the cut. It is possible to adjust the spacer by adding feeler gauges between the stop and the spacer and before each run of cubes, I’ll need to check the sizes to make sure everything is within an acceptable tolerance.

Running through a few cubes, each cube came out almost perfectly. The worst cube had a tolerance of 0.001″ from the size of the square sticks. I can’t really complain when the cuts are that close. It’s going to be pretty good for any initial puzzles I make.

Making double size cubes

Now with a few cubes cut, I measured them, and selecting two that were exactly cubic, I placed them together and verified that the length was exactly double that of a single cube. Repeating the process I had used for the first cube, I cut a ‘two cube spacer’. This spacer will let me make double sized cubes, perfect for making any of Stewart Coffin’s Convolution/Involution/Involute puzzles.

Let the fun commence!

Cutting Square Sticks

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The start to many a good puzzle is a square stick. But not just any square stick. One which is accurately sized along its length and each side square to its neighbor. Not an easy task.

A while back, Scott Peterson sent me a tutorial for building a table saw jig to create square sticks. Over the Labor Day weekend which is a holiday for us in the US, I set about making the jig (mostly) following Scott’s tutorial so that I’m firmly on the road to making my own puzzles. Scott kindly game me permission to make the tutorial available to anyone that wants it, so feel free to download a copy.

The following is my attempt at creating square sticks …

Starting off with a sheet of 3/4″ MDF I cut myself a strip that was wide enough to go between the miter slot and just past the blade of the saw. I left a good sized area on the other side of the miter slot so I had room to attach a handle to help push the jig through the cut, and back after the cut. I marked the position for the miter bar and after pre-drilling the holes, screwed it in place.

Preparing to attach the miter bar.

Miter bar attached to the base of the jig

The miter bar that I bought has plastic screws that protrude from one side to ensure that the bar is a perfect for for the slot. Taking some time I adjusted each of the screws to make sure that there was no wobble in the slot, as this would compromise the cut.

Taking Scott’s advice, I also added a UHMW plastic base to the cut side of the jig to back up the cut and help prevent tearout. Using blue tape I secured the plastic to the base, and marked out the positions for the screws, predrilled, countersunk then screwed the plate down. The Blue tape came in really handy as it’s almost impossible to mark the UHMW plastic with a pencil.

UHMW plastic set in place ready for drilling and screwing

The UHMW screwed down. Note the screws are all below the surface of the plastic

With that done, It was time to make the first cut, and trim the extra material that I had left off the edge of the jig, ensuring that the blade ran along the edge of the jig which is needed for an accurate cut. Making sure that the blade was at 90 degrees to the table top, I made the first cut. And immediately noticed that there was a gap at the front of the jig which wasn’t there at the back. It was pretty small, but enough that I could see light between the blade and the jig, so I knew the jig wasn’t good enough. It seems that I didn’t do a good enough job of adjusting the miter bar, so I readjusted, and remade the cut. Fortunately, I’d left enough space between the edge of the jig and the screws holding the UHMW plastic down to be able to do this. This time things were much better and I got the accurate cut I was looking for.

Ready to screw the fence to the jig

The magnets to hold the steel bar in place

Fence screwed gown and ready to go.

Next up I need to install the fence on the sled which the stick will be clamped against when making the square sticks. As Scott notes in the tutorial, I have a steel bar as a spacer, and use some brass feeler gauges to get an accurate cut. I also embedded some Neodymium magnets in the fence to hold the steel spacer firmly against the fence. The fence is clamped securely against the saw’s rip fence, then predrilled and screwed down.

Those eagle eyed readers out there may notice a couple of extra drilled holes in the fence. Well yet again, I managed to get things a bit wrong, and screwed the fence in a little squint. Now that’s not a lot of use when you’re trying to get accurate cuts, so I re-drilled and re-attached the fence. So there’s a couple of extra holes there now. It won’t affect the jig, but a squint fence would have!

Adding some toggle clamps to the fence and I have something where my fingers are well out of the way, and the sticks will be firmly held against the fence.

Cutting a stick square

Ten minutes later; five identical sticks

With everything set, It was time to put some sticks in there and see if I could make some square sticks and whether they would be accurate or not. At this point I was looking to test the jig, so I used some redwood I had to spare, and ripped it into roughly sized sticks. Now you’ll notice the knots in the wood so even I knew things weren’t going to be perfect. Still it was good enough for a test.

Measuring the sticks using my digital calipers, I am getting sticks with a 0.005″ tolerance between either end of the 12″ sticks. That’s not too shabby. Given the knots in the wood, which will most likely make it twist as the knot is cut, I’m fairly happy with the results. At this stage in my puzzle making career, it should be more than accurate enough for making cube based puzzles, and burrs.

But that’s not the end of the story ….

I came back to the jig in the morning, used some walnut that I had bought a few weeks back for making puzzles, and used that to get some square sticks. The walnut is much nicer wood, no knots, and a beautiful grain to it …. The results. I cut four 9″ long sticks with a tolerence of 0.002″ across all four sticks. Now that’s a result I’m proud of!

Next up, I need to create a crosscut sled so that I can cut these sticks into accurate cubes for use in making puzzles. That post is coming soon, so stay tuned.

New Tools

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Ridgid Table Saw R4512

Some of you who read my blog may already know that I had purchased a new table saw to add to my arsenal of woodworking tools, and that I’d had a few issues in getting it to me. I purchased this saw from Home Depot, they shipped it to me the next day, and it traveled from the east coast US, to San Jose in the West coast, over the weekend. It then sat in San Jose for a full week before it made it to my house. It was somewhere within 30 miles of me, but not at my house. This was frustrating to say the least, however Home Depot, also frustrated by the length of time to deliver refunded the delivery charges (which were not insignificant!). So thanks to Home Depot for that. Just change your carrier please!

Anyway, now that I have the saw I spent most of my Sunday building the saw, and setting it up. So for those who are interested, here’s my thoughts on setting up the saw, and the saw itself.

Opening the Box

Opening the box and removing the top sheet of cardboard, you’re treated to an array of well separated parts. The fence, mitre, magnetic push stick instructions and screws all have their own spot. My only note here is that the spaces in the pre-formed polystyrene are a little large for a few items, which could lead to things sliding around more than necessary.

Opening the Box, revealing the saw itself

Having removed the top layer, the orange body of the saw is exposed along with all the legs and side panels that it will eventually sit on, and the rails for the fence. Again the packaging here isn’t perfect, as that front rail for the fence is rather free to bounce back and forth. Fortunately nothing was damaged. As you can see, the motor on the R4512 is now inside the case, unlike previous models where it was external.

At this point, the instructions tell you to lift the saw out of the box onto two thick planks of wood. Lift …. seriously! I took down a 2×6 board of redwood I had, and ripped it in half to put the saw on as the instructions recommend, then slit the cardboard box open, and with some help, half slid, half lifted the saw onto the boards.

Taking the saw out of the box

The boards that the saw is resting on are supposed to make assembly easier. It certainly helps for attaching the table top extensions. Here’s my first gripe. The extensions are steel, and not particularly thick steel at that. While the main table top is cast iron, clearly Ridgid have decided to save money and not supply cast iron extensions as they did on previous models. This may work to my advantage as I’m waiting on the Benchdog Router table extension to arrive, which will replace one wing, and allow be to attach the wing I remove to the other side. Given that the steel will be lighter, it should require less support.

Using the cardboard from the top of the box, I assembled the base. The instructions at this point however are pretty poor. Initially, I thought all the panels were the same size. WRONG. I realised this when I was putting the last panel in place and found I had a trapezoid, and not a square (or rectangle) as expected. After a quick adjustment, I was back on track. The instructions state that a particular panel is the front, so that’s fine. What they don’t tell you is that the two sides with the Ridgid name indented in them are different, and it matters (slightly) which one is where. Anyway, I didn’t realise this, and in the end it doesn’t matter, but it would have been nice if it was clearer.

The saw with its legs and lift system assembled

Legs assembled, and dust chute in place, the legs get placed onto the bottom of the saw, and screwed in place. Next up is the lift system to allow you to move the saw around. This is going to make things much easier for me, as I don’t have the space to keep the saw in a single location permanently (yet).

Again, the instructions completely fail here. When putting things together for the lift, the diagram shows the orientation of the pieces, but neglects to mention how the bar has to be rotated before putting the wheels on. As a result, I had all four wheels attached, then had to remove them and start again once it became clear that things weren’t going to work. Not a big problem, but the instructions could have been clearer here.

Getting the saw Upright

Now it’s time to get the saw upright. Knowing how heavy it is, I draft in some help in the form of my 16 year old son, and my fiancée. Very gently, and carefully the saw is first lowered onto its side, where my fiancée complains that she’s now covered in oil from the coating on the table top. (Perhaps laughing that this point wasn’t my best idea). Then we lift it up onto it’s feet. At this point, I realise just how high the saw is. It’s taller than I had expected, but actually sits at a really good height so you’re not bent over the saw when you’re working. Something that’s going to be important if I’m making lots of repetitive cuts for puzzle pieces.

Nearly there, and looking like a saw now

The next few hours saw me assembling the rails for the fence, the blade, where I shed a little blood to the project, but not in the way you’d expect, and leveling up the extensions to give myself a flat surface across the entire table. Add to that cleaning the oil from the cast iron, and polishing the surface up, and we have a nearly ready saw. So how did I shed blood? Well when installing the blade (I’m still waiting for my new Freud blades to arrive) you have to release the lock for the splitter at the back of the saw. I did so, and unfortunately, caught the skin of my thumb on that splitter as it’s a really tight mechanism. Cursing (more because I was now bleeding on the saw than anything else) I stuck a plaster over it to prevent any further blood getting on the saw and continued assembly.

This is where I found out about the panels on the base needing to be in the opposite orientation. You might see in the picture above the holes either side of the Ridgid name. These are for two brackets which presumably hold the power cable when not plugged in. Needless to say I didn’t bother adding these.

You’ll also notice that the saw has a built in Blade and spanner storage right on the side of the saw. I doubt I’ll put my spare blades there, but the tools will certainly be kept where I’ll not lose them. The miter also slides into some convenient storage on the side of the case as well, keeping it handy, but out of the way.

Ready to cut

The last thing to do was to install the power switch which hangs from the front rail and turn the saw on. There is a nice touch on the power switch in that it is protected by a larger flap which means turning the saw on requires you to lift the top flap to get to the main power switch (which comes with the usual cutoff key), but turning the saw off you just need to press the larger outer flap. A nice safety feature, and a simple but useful touch.

Included are a kickback prevention attachment, and a blade guard. I haven’t put either of these on the saw since most of my work will be using jigs, so these are just going to be in the way.

So everything together it was time to plug the saw in and turn it on. That’s exactly what I did. The video below is the first time the saw was turned on. The blade isn’t wobbling, it’s just that grey band round the saw isn’t uniform all round the blade, so the optical illusion is that it’s off centre. Honestly, it’s not!

Building a Matrioshka (Part 1)

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This entry is part 1 of 3 in the series Building a MaTRIOshka

I’ve had a bit of a break from working on my own puzzles, as work and life in general have been rather hectic meaning I’ve just not had the time. However over the Easter weekend, I had three whole days that I could do something puzzle related. I’ve still not been able to pick up some wood to get back to working on my burr cube, however I did have a lump of oak left over from the box project my oldest son wanted to make as a birthday present.

After reading Kevin’s review of the Matrioshka here. I noticed that the puzzle is entirely made of triangles. Now I just happened to have a number of leftover ‘scrap’ that would fit the bill perfectly from the box. So I sat down with a pencil and paper to figure out how Vinco created his box, and see if I could replicate it.

Note: This project is purely for my own learning, and experience in working with wood to build puzzles, at the scale I need to be working at to create my own puzzles. This is not for sale. If you like Vinco’s puzzles, please buy them, they really are great puzzles, and the craftsmanship is superb. I own several of Vinco’s puzzles, and highly recommend them.

With all that said, on to the build …

To break down how the puzzle is built, we need some good photos. Kevin happened to upload some excellent pictures, and I’ll not repost them here. Go read his review and have a look if you’re interested. The bottom line is that the outer shell is made of 54 idential pieces. They are equilateral triangles on the edge, with a piece length that is twice the length of the side. So, I set about creating 54 identical pieces.

The first thing was to cut the wedge shaped strips of wood which I would eventually cut to the correct length. I took out my mitre saw, and set about making the cuts. One small issue I had was that the amount of the blade in contact with the wood generated a lot of heat, which warped the strips I was cutting. As a result, I had to tape two together as they cooled to make sure the wood was going to end up straight again when I was ready to cut it to length.

With all the strips cut, I had to cut them down to the correct size for each piece. I measured one piece, cut it and checked that it was exactly right. With that done, all I had to do was clamp down a stop, put a sacrificial fence in place and start cutting. As you’ll see from the photo, I used a scrap piece of wood as a zero tolerance fence to avoid chipout on the pieces I was cutting. It just saves some time later.

After about half an hour, I had a reasonable pile of pieces next to me, and it was time to do a little rough sanding before gluing up the pieces.

With the rough edges sanded down so that things were a bit neater, and all the pieces labelled to make the glue-up easier, it was time to get the clamps out. The shape of the pieces I was gluing up made things a little more challenging, but with a few of the scraps from cutting the pieces out, life was made simpler again.

It’s worth noting at this point, that all these pieces are oversized. This gives me a little bit of material to work with so that I can sand and fine tune all the pieces. For this to look good, it has to have a tight(ish) fit, and the only way to do that is to make sure the pieces are all the same. Despite using the fence, and stops on the saw, not all my pieces came out to be the same size. After all, I’m still learning, and you could say that this is an ambitious project. That said, how do we learn if we don’t push ourselves?

In the next post, I’ll continue with building the Matrioshka and think about putting each of the six pieces together that will form the final puzzle.

Wood is sharp

So you want to build a burr

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I’ve had a request sent to me about making puzzles from Lego, so I thought rather than reply to the person individually, I’d throw something up here, so that everyone can benefit.

I already commented in a previous post that LiveCube was a possibly way to create Burr puzzles, however as I already mentioned, they are not as easily available, and from what I have been told, when you add shipping from the US it’s a rather expensive way to go.

Given this, I was asked what Bricks and plates you’d need to be able to create Burr puzzles from Lego. This post is my attempt to answer that.

I should say, that there are many ways to go about creating a burr piece. There are a lot of Lego designers out there who are far better than I am, however at it’s simplest, the process is fairly easy.

The first problem we have to overcome is that a brick is not a cube, as you can see here.

So to make it square, we need to add a couple of plates. Now the type of plate we add depends on whether the piece is going to form part of the Burr body, or the top of the Burr. For an ‘internal’ piece, we use a standard plate. For the top we use a ’tile with groove’. The images below show the two pieces we will use.

Now that we have the basic pieces, how do we make a cube? Well the dimensions of a lego brick ‘cube’ are 5x5x3. Each stud on a Lego brick represents 2.5 units. Each plate is 1 unit high. So to get a cube, we need one brick and two plates.

So as you can see, the height now matches the width, and we have a cube. Building up Burr pieces is fairly simple from this point. Take the piece you want to build, and using those dimensions, create the part in Lego. Having longer bricks and plates does help to make the whole thing more stable, as long as you remember that each brick requires 2 plates to make it square then you’ll be fine. Of course, if you think about the height of 2 bricks, that’s 10 units. You can make that from 3 bricks and 1 plate or 2 bricks and 4 plates, or 10 plates.

The skill comes in working out how to get the tiles in the right place so that you have smooth surfaces on the top of each Burr piece. Equally, the piece made from 3 bricks and one tile has far less pieces, and by definition less joins, so should be more stable. That’s not always true however , as the thin plates have a greater surface area per thickness, so don’t ‘bend’ as easily!

The example below shows a basic Burr piece made from Lego.

Each ‘layer’ is in a separate colour so that it is easier to see the height of the piece. Creating this piece is left as an exercise for the reader, however the parts used are:

4 – 2×2 brick (part #3003)
2 – 2×4 brick (part #3001)
2 – 2×6 brick (part #2456)
4 – 2×2 plate (part #3022)
6 – 2×4 plate (part #3020)
1 – 2×8 plate (part #3034)
6 – 1×4 tile (part #2431)
2 – 2×2 tile (part #3068b)

So that covers the basic burr parts. What happens when we need a half sized wall? Well it’s fairly simple, we just use a 1×2 brick and plates. The part above is modified to give a more complex piece just to show the difference.

So from that you should have the basics. I highly recommend getting LDraw, there’s a link under Puzzle Creation tools, and also a GUI designer such as MLCad for Windows or Bricksmith for Mac. There a good tutorials on using these on the LDraw website. The tools will help you to build the pieces ahead of time, and work out how best to build each piece. It can make things quicker, depending on how familiar you are with building in Lego. If I’m honest, most of the time, I build it in Lego first, and come back to LDraw later!

Neil's Puzzle Building Blog

The journey from puzzler to puzzle creator.