Introduction: Conduit Track Saw, Only 2 Power Tools (<$50!)
Okay, here's the story. My daughter really wants a desk in her room. But, because we are a family of Making Things, I refuse to buy a sawdust style desk that I know won't make it out of a future move (not that I'm hoping for a future move). Buying most of the desk components shouldn't be a problem with the SUV that I have, but a full sheet of oak plywood...it doesn't have a chance in hades of making it home either inside or on the roof rack.
That leaves spending more money on someone else cutting my plywood down in the store...which seems like a good temporary solution; but I never like feeling choked by the idea that I'm dependent on someone else to solve my problems, or the idea that I'll always be paying more for something due to not having a large enough vehicle (or trailer).
So, I got to thinking, why not build something that'll let me cut that plywood, to size, in the parking lot?
Through a lot of trial and error, I finally came up with something I thought other people could benefit from. Please leave me your ideas in the comments below...I love feedback!
Step 1: Gather Materials / Tools Needed and Used
- (3) Conduit pipes
- (1) 4x8 sheet of 3/8” plywood
- (4) 1x2x8’
- 2x4x8' (unless you have scrap wood)
- 5/8" x 12" Square dowel
- (6) 1” hinges with removable pins (and the screws that come with them)
- (2) 1/8” cotter pins
- (30) #8 x 3/4” sheet metal screws
- (2) #10 x 1 1/2" bolt (machine thread)
- (4) #10 knurled knobs (or nuts)
- Carpet Tape (you might be able to get away with duct tape, rolled up)
Tools Needed and Used
- Circular saw
- Tape measure
- 5/32" drill bit (for drilling steel)
- 7/32" drill bit (for drilling steel)
- 1/8" drill bit (for drilling steel)
- Impact drill (not at all necessary)
- Nail Gun (not necessary)
Advanced Version (Not necessary to make a working track)
- Table saw
- Miter saw
- Metal file
Step 2: A Few IMPORTANT Details...
- Because I know other people don't have a garage full of expensive machines to process materials, I thought it would be a good chance to make this project with as limited power tools as possible. Having said that, there are some upgrades that I'll also list for those that do have the means.
- The two power tools we'll be using are a powered drill and the circular saw that you'll need to make the jig work. While I'm using a battery powered saw, a corded saw will work just as well.
- If, for some reason, you don't enjoy ripping large sheets of plywood down to make this jig, some big box stores have panel saws that they can use to cut down the plywood into the widths that are mentioned in this instructable (THESE ARE MY WIDTHS THOUGH! (ahem, sorry for yelling, but the widths mentioned in this video are based on my saw. We'll have to make a formula for your saw)).
- ALWAYS be careful when you buy wood of any kind (especially pine). Sight down the end of the board and make sure, even if you have to dig through a pile of lumber, you get the straightest lumber possible. In some instances you can pull the curve out of a particular piece of lumber in your project...and then later find that your project has twisted with the wood.
- I did use a nail gun, but this was out of convenience and time restraints. Using a handful of clamps or just screws is just as acceptable.
- I did use an impact driver for putting screws in but you can use a drill for the same thing. I usually use both my drill and impact driver as it saves me from having to switch bits back and forth.
Step 3: Width & Length Formula for Your Sled
My goal is simple. I want you to make this and succeed. Because my circular saw is different than yours, we'll need to plug in numbers to get the exact outcome we're looking for. I would absolutely hate myself if I led anyone into this and they didn't come out with what they were looking to accomplish. So what I'll do is give you some of my numbers so that you can create your own sleds that fit your saw.
The base of the circular saw (or the part that comes in contact with the wood you are cutting) is called "the shoe". The dimension below is for the shoe of my Ridgid 6 1/2" circular saw.
The width of my circular saw is 6"
The dimensions of the other material needed to determine the width of the sled are as follows:
1 7/8" wide
Thin walled 3/4" EMT (not rigid) tubing is about 59/64" wide (we'll call it 15/16"). Since we have 2, that'll give us 1 7/8" wide.
1 1/2" wide
Because a 1x2 isn't really a 1x2 but rather a 3/4" x 1 1/2" (this is due to shrink as the wood dries). Since we'll need 2, that'll leave us at 1 1/2" wide.
Circular saw shoe width: 6"
(2) EMT Conduit: 1 7/8"
(2) 1x2's: 1 1/2"
The width of my sled is 9 3/8".
This means that all 3 pieces of plywood for my sled base will need to be 9 3/8" wide.
The number we're going to calculate here pertains only to the "Main sled". All other sled lengths will be static, or the same.
Above we talked about shoe width. Now we'll talk about shoe length. The length of my shoe for my Ridgid 6 1/2" circular saw is 11". In order for me to cut a full 8' length or a full 4' length of plywood, my main sled needed to be 50". If you're shoe length is greater than 11", increase the length of your main sled. If it's less, go smaller.
My circular saw shoe length is 11", my main sled length needs to be 50".
Sally's circular saw shoe length is 12", her main sled length needs to be 51".
Again, the only thing that's affected here is the main sled. All other sleds lengths will be the same. Now that we have the main sled figured out, let me present the other sleds. But why three sleds and not just two (a question I've already gotten)? Because a full sled needs to be closed off on both ends (since we'll have a large cut down the middle), we'll always need to have two sleds to make the completion.
The smaller piece that's connected to the main sled that makes up the 4 ft cut is 18 1/2" inches. The larger piece that's connected to the main sled that makes up the 8 ft cut is 63 1/2" inches.
Step 4: Cutting Conduit to Length
Whew! That last step was a doozy...this one is a simple. I promise.
We will still need to use the formula we used for your main sled to cut the main sled tubing.
My circular saw shoe length is 11", both of my conduit tubes for my main sled are 44" long.
Sally's circular saw shoe length is 12", both conduit tubes for her main sled are 45" long.
Rico's circular saw shoe length is 11 1/2", both of his conduit tubes for his main sled are 44 and 1/2".
Note: The included picture of the hacksaw with a list to the left side is my track saw dimensions.
Ole Make Things is getting a headache at this point, but I'm trying to make it as simple to understand that even myself reading it, as if someone else had written, would understand, so please bare with me. No assuming I'm dumbing things down, I really just want this to be something that works for you
Now that you've cut both of your tubing to the specs of your saw and main sled, we'll also cut 4 other tubes; but before you start cutting any tubing, we'll lay everything out so that we're working with factory edges. I've included an image showing how I cut my tubing. After you make a cut, place an "X" or some kind of mark on the end that you cut (as noted in the picture). We'll choose to use these ends at the back of the sleds. The tubing that meets up with each other will always be our factory edges.
Step 5: Cutting and Gluing the Walls
Believe it or not, there was a time where I wasn't going to use any walls other than the steel conduit. This would have been a disaster as the sleds would have had to have been clamped down by the steel conduit, which I'm sure would have cause the tubes to move around. I added the walls as a way to keep the conduit straight as well as stable.
Attaching the walls is simple so long as the sled bottoms you've cut so far are nice and parallel. You'll simply cut the 1x2x8' pine to match the sled bottoms you've already cut. That means you'll cut:
- (2) 63 1/2"
- (2) 18 1/2"
- (2) the length of your formula for your main sled bottom (Step 3)
Once those are cut, you'll simply glue them to the edges of each sled bottom. Be extremely careful, though, that the boards are at 90 degree angles to the sled. This, of course, means that we don't want any twists in any of our boards (step 2.4). I used brad nails and a pneumatic nailer, screws will work just as well.
TIP: Most plywood curls when it's thinner (below 1/2" seems to be the worst). Be absolutely sure that the ends of each sled are attached well to the 1x2 walls so that the curl is removed. With my first sled prototype (I had 2 prototypes), I ended up not thinking much of it and my sleds did not connect well which ruined the entire project. Please don't make that mistake (screwing is probably the better option on the ends).
Step 6: Attaching the Tubing
Now we're getting into dangerous waters. I say this because I made another mistake when I first put this together in that I randomly attached screws from both the walls and underneath. I didn't take into account that if you put screws in at different angles, you are putting strange patterns of energy on the tubing that will cause the pipes to twist your sled into oblivion. This was such a disaster that I almost scrapped the entire project. Please, for the sake of your sanity, take my words as experienced precaution.
Place your tubing along the inside corner of the new walls you just created and find a way to clamp it in. A spring clamp works well in a pair and small c clamps are equally effective. Next find where the metal touches the wood at its apex and mark a line as close to the center as you can. You'll do this both with the walls you added and the sled below. You'll need to transfer those lines around the side and onto the opposite side, again, for both the walls and the sled bottom. From here, use a straight edge to connect the other side. This is your center line that you'll attach screws to.
We'll be using #8 screws to attach the pipes to the pine walls, by first drilling pilot holes with an 1/8" drill bit. But before you go crazy throwing screws in, drill a hole and a screw in the front and back end of the sled walls. Finish the walls first before attaching the bottom of the sled to the tubing. As far as how many screws need to be put in, I probably wouldn't do more than 3 per tube on the larger sleds, and 2 per tube on the smaller.
TIP: A tip for keeping the walls lined up is by using a 2x4 and cutting it to the length of your circular saw shoe width. As long as they're straight, stack as many in the middle of your sled between both pipes as you like. It does a great job of lining things up.
Also remember to mark where you put the screws in the walls on the bottom of your sled so that you don't accidentally drill through them when you're screwing through the bottom.
I seriously recommend watching this step in motion just in case I didn't get the words out the right way.
We still need to talk about placement of the tubing, which is why I painstakingly and tackily made some sketches in sketchup, attached to this step.
Step 7: Pin Install Along With Hinge Connection
Now that you've got a good illustration (okay, probably not the best illustration) in front of you, you can see how the tracks go together. The conduit actually plays 3 important parts:
- Lines up the track.
- Gives support to the overall structure.
- Creates a path for a second sled to ride on.
But we still need a couple pins to link the tubes between each track. When I built this first I was thinking that I needed round pegs to line it up in the conduit, which would have complicated the entire project as the size needed to do that would have been extremely odd. But then I started thinking that it really didn't need to be round, so long as it provided a link to connect the two sleds and kept things aligned.
This philosophy shift changed everything! Now I didn't have to worry about rounding objects or finding other materials to slide into each tube to make sure it all fit together. Even a square pin didn't have to be 100% accurate as pushing the pins in would shear the corners slightly. But then I got even luckier when I found that a nice 5/8" square dowel, found at any local crafts store (or simply made on a table saw, for those that have one), would work.
Of course, we would still need to attach it on one side; otherwise they'd move around as we pulled and pushed our sled assemblies together. But let's attach both pins into the conduit on the main sled so that we only need to use 2 pins and not 4.
I squared up the pins as best as I could and drilled a hole through to lock them in place.
But...we're not quite done in this step. Nope. We still need to find a way to attach the sleds together so that they don't move as we're cutting. To do that we'll use 1" hinges. I know, I know, hinges are made to allow two objects to hinge or bend, like a door or a dowel spline jig. In this instance, we're going to bend the rules a little bit and instead use them to line up and lock two sleds together (please, dear reader, if I have broken any international laws with hinge usage, do comment below).
Of course, to attach the hinges it's simple. We'll line up the center of the hinge to where they butt up against each other and make sure that both sleds bottoms are lined up. A quick suggestions: use a clamp to squeeze down at the junction point of the sleds to keep things lined up. Before you put the hinge in, make sure that your square pins are screwed into the pipes and set up (we just did that part in the beginning of this step).
It's important to also note here that you'll be using 6 sets of 1" hinges. Two for each side, two sets of halves for each additional sled. The hinges (with removable pins) I got were less that $2.00 for a pair, costing me less than $5.50 altogether. At this point I'm having a hard time finding the same price point online...so you might try calling your local box store.
Step 8: The Sled for The...Sled
Now that we've gotten the sleds finished, we'll work on a sled that rides on the sled. This sled will be attached to your circular saw with bolts and uses the poles as a trail. The truth is, this might sound like overkill, but I purposely wanted to cut the circular saw sled at a 12 degree angle on either side to stop any sort of kickback, as well as allowing me to cut with the saw vertically. Of course, I'm not advocating the vertical cut but it does a fantastic job of keeping the saw inside the tracks without kickback.
Let's look back at the formula in step 3. We'll need to cut the circular saw sled to the size of the circular saw shoe. My circular saw sled width is 6" and length is 11". This means that I'll need to cut a piece from the left over plywood we started with. If you choose to cut the sled so that the length sides are at a 12 degree angle, be sure that the top of your sled is still the width of your circular saw shoe.
Having said all that, it is not necessary to cut the sled at a 12° on the sides. It's just a nice feature.
Once we cut the sled so that it fits the bottom of our circular saw, we'll attach it by using some double sided tape. Don't have double sided tape? No problem! Use hot glue. Take a piece of duct tape and loop it so that it becomes double sided.
When you've found a way to attach that circular saw sled, slide the circular saw sled plywood inside the tracks and lower your saw so that the tubing and the shoe are touching each other, lining it up perfectly.
Once you've done that, find a place on both the front and the back of the saw where you can drill holes and attach a bolt. I used a series of measurements and transferred them over to the bottom, which makes drilling far easier as I don't have to contend with the saw. Make sure that the holes you drill are the exact same size as the bolts you'll put in so that there isn't any movement. The bolts I used were #10 x 1 1/2", so I used a 7/32" drill bit . After I drilled the holes I used a countersink bit to make sure my bolts were flush with the new circular saw sled.
I added a washer and then used a couple knurled knobs on each bolt as jam nuts to lock it in place. Of course, if you don't plan on removing it often you can just use a couple #10 nuts instead.
Step 9: Adding a Stop Block, Jigs for a Jig, and Making Our First Cut
Adding a stop block to each side of the sled is important in two ways. In a nutshell:
- It prevents us from accidentally cutting too far.
- It gives the plywood sled added strength and stability.
The width of your stop block should be 3 1/4" wide and made from any scrap material around the shop that you have. Length-wise, it needs to fit between the conduit tubing as shown in the picture above. Once you've cut the block to size, adding it is just a glue up away. Of course, you could attach it any number of ways but a little glue and pressure is all you need.
Now we'll create a couple jigs...for our jig. These are simple removable scraps of wood, glued together that will keep our track centered together and straight as we cut large areas (think 8ft plywood).
We'll need 2 scraps of wood that are the width of your inside track (shoe width of your saw) and taller than the walls on the outside of your sled. We'll place both inside the track, add some glue and then use a couple more scraps of wood (for each jig) on the outside of the track. When placed next to the sled, these pieces will need to be just as tall as the inside blocks. We'll add glue to the outside blocks and place another scrap of wood over each jig along with weight to hold it down as it dries. Of course, you could use screws (pilot holes first so they don't split) or brad nails, but it's not necessary.
At this point let's not jump the gun. The first prototype I made was cut the wrong way, and I kicked myself for not thinking ahead of time. Remember, the main sled is the start of the cut, not the finish of it.
Looking back, I even filmed the mistake! You can see that I entered the saw facing the wrong direction...oh if I could send a whisper back in time (but it's okay, it was only a prototype)... Instead, we'll face the saw towards the end caps (either the small or large size), start our saw and slowly cut through both sleds. After we have made a cut all the way through, we'll simply push the sled through the sled, cutting as we go.
Step 10: Upgrades!
I purposely make two versions of an idea before I'm really happy with what I've made. The first, usually out of pine, serves as a test. Sometimes I get lucky and it's just a matter of remaking it with the fine woods I love. Sometimes, it's a complete rethink. With this project, I did a lot of rethinking and mistakes, but what I've shown you so far will do everything that's needed to cut plywood.
There are some bonus ideas that I think you can do (if you've already made this) or improvements you'll want to take advantage of before getting started. Below, I've listed all the upgrades that I think will make this something you'll run to every time you need to cut large sheets, for many years to come.
While pine works, using hardwood allowed me to cut about a 1/2" off of the walls, lowering the jig even more than it was. While this isn't absolutely necessary (my pine sled did fine with 3/4" plywood), it makes it easier to stack and feels streamlined. I also liked the look of it (I'm a jig guy...I love the feel of a good looking jig in my hands).
2. Interlock the sleds
This felt like a huge improvement over just butting the sleds together. Plywood is stable, or more stable than lumber, but it can still bow and lift up, especially where the wood connects between each sled. If you're using a circular saw it is very easy to to cut 45 degree angles in the sleds. Just make sure that the main sled is angled with the point up and that each additional sled is angled with the point down. This will make sure that the sled you move to while cutting will always be below the first sled.
3. Rabbeting the sled bottom
Using this joint, rather than the face to face joint could work better at allowing everything to interlock. The truth? I'm not sure it matters at all. It looks better though. I simply routed the bottom of the walls the thickness of my plywood. Since the walls will be sitting flush with the base of the sled, I had to scale back the width of the plywood sled by about 3/8" on both sides. This will cause your formula to change by about 3/4".
4. Interlocked the walls with angles.
Again, this is probably just cosmetic, but I liked having the walls interlock. I haven't seen any reason why it works better or worse, but it definitely looks better (I'm a sucker for good looking designs). If you do this, you'll need to use a file to sand the screw ends off from the main sled as the screws will protrude slightly. I also recommend using a bit of tape on your drill bits to be careful of the depth you make in drilling.
5. Stop blocks connected on the ends.
This jury is still out on this one. My fear was that the plywood would curl up in the middle if a nice solid chunk of wood wasn't touching the sled base and the sled walls. I don't think that this is a cause for concern. If you decide to do this, remove an inch off of each end of your conduit.
6. Viewing area larger.
Of all the ideas, this one is my favorite, and no, it doesn't cause your sled to become weaker.
Basically, what I did was to take swap out the 10" blade in my table saw with the 6 1/2" blade from my circular saw blade I used to make my first cut. I removed the hinge from the thicker side of the sled. Then I slid the blade into the kerf and pressed the table saw fence up next to the edge of the sled. I moved the sled so that the blade was just touching the edge of the kerf that the saw made. When that was done I simply lowered the blade into the table, tilted it to 45° and slowly cranked the saw blade up until it was just barely above the surface. Next I slowly pushed the sled forward until I had cut to the other end. I finished by shutting it off and lowering the blade.
This is a great idea if you have a table saw...but not something I recommend doing with a circular saw. I like this because it makes it easier for me to line up my pencil marks to the kerf in the jig. Other people have drilled out holes alone the cut to use as small windows, and that works, but I really love having the extra viewing window.
7. Better Jigs
I made my jigs slightly more like handles so that they're easier to remove. Necessary? Absolutely not. But if you want to do it, it's as simple as taking the simpler jigs you made in the last step and marking them to a solid piece of wood and cutting it out.
Step 11: Thank You!
If you've made it this far, I appreciate your taking the time to pour your eyes through this long instructable. If you find that I've made a mistake somewhere in the middle, please do me the favor of leaving me a comment. If I've left something unclear or that doesn't make any sense, you'll be doing me great service if you ask. These instructions were written in hopes that you can make the same thing that I've made. If you made this project, please, do share and let me know!