Double Runner Cross Cut Sled With Blade Guard by Paul Comi

  The process of deciding on a design, dimensions and materials for a sled like this was a long one for me. I asked lots of questions of other Woodnet people and looked at many different designs before coming up with this design. In the end, I was inspired by a sled built by David LaRue and someone else he has on his website. Looking at this sled now, it doesn't bare much resemblance to either of their sleds, but that's the cool thing about woodworking. You can take something you like that someone else has done and tweak it to fit your style and needs. David was helpful to me in the process and I emailed him a couple times and found him to be real helpful. So was Joe Lyddon who has a several good articles on his website regarding other people's sled dimensions, types of sliders etc. Collectively, I boiled down what I liked from everything I read and came up with a sled of my own.

I tend to build lots of things out of plywood and sheet materials since I’m still setting up my woodworking shop, and it’s a hassle to handle and cut down plywood and mdf sheets. A full size sheet can weigh up to almost 100 lbs and be a backbreaking affair to deal with in a small one person shop. After reading a book on building kitchen cabinets in which the author mentions a sled he built that enables him to cross cut full sheets of plywood. After serious consideration, I decided to not make a sled that large because it would have been dangerous in my small shop to handle. The distance between the front of my table saw and the start of the cutting blade is approximately 12”. A cross cut sled large enough to cross cut plywood would have to be about 52” or more long. That would me that when pulling the sled back to position a sheet of plywood, I would have 40” of sled with a sheet of plywood in it unsupported. Even if I were to use a roller stand on the infeed side, it would still be a dangerous proposition.

 Before proceeding, I gave serious consideration to purchasing a sliding table attachment for my Unisaw. A sliding table replaces the cast iron section of the table saw to the left of the blade. Instead of sliding wood across cast iron through a saw blade, a piece of wood rests on the sliding table and the table slides the wood past the saw blade. I like the concept because the chance of the material dragging on the table when being cut is eliminated so accuracy is improved. The problem is that these sliding table set ups either take more room in the shop or they make the saw less mobile. Eventually I may get one, but at this point I'm reluctant to for both the cost and uncertainty about its value to me overall. Instead, I decided it would be best to cross cut sheets using a circular saw and clamp guide to a more manageable size or rip the full sheets on the table saw and then cross cut using a sled.

  Once I had given up the idea of a monster sled capable of cross cutting a full sheet of plywood, I again sought input from others about a more reasonable size for a cross cut sled. The most common sizes I heard were 24” up to 30” cutting capacity. I decided to go big since I have a sliding compound miter saw that can crosscut 12” and also have an Osborne EB3 miter gauge that can cross cut 12” on the table saw. For the width, I decided to make the sled the same as the width of my table saw (minus the table saw extension) which is 40”. With a sled this width, I believe it is mandatory to have dual runners sliding in the table saw miter slots for stability.

  I went to my local lumber yard and at the last minute decided to use ¾” baltic birch for the base of my sled. I was going to use ½” but figured that this large of a sled could flex and I want something that will remain square, true and sturdy for years of use. I picked up two pieces of ¾” maple that are 7” wide and nearly 8 ft long. My plan is to glue two pieces of maple together to make 1 ½” wide stock for the front and back fence. My cost of lumber materials was about $70.

  The one advantage of going to a lumber yard for plywood is that they will help load it into my vehicle, and with a bad back lately that is a big help. When I go to Home Depot, I have to struggle with a big cart, pull my own sheets and then go through a check out and load the wood into my own vehicle. It’s such a pain that I dread going through it so unless there was no other choice, I’d buy from the lumber yard.

  At home, I was thrilled that I now have my lumber cart built. I rolled it out of my shop to the back of my truck, slid the plywood onto the cart and slid the maple boards into the cart as well and rolled it back into my shop. I highly recommend building one of these carts. I have an article on how I built mine on my website also.

  The first thing I did was cross cut each of the 8 ft maple boards down to 43” long x 7” pieces and glued the two boards together so that they will become a 1 ½” thick board using Titebond II white glue and virtually every clamp I own. The glue is dry in 30 minutes but should set for 24 hours before being machined according to the directions on the bottle.

  I then began dimensioning the plywood on my table saw using the rip fence and my splitter. Since the baltic birch is 5 ft x 5 ft, it wouldn’t fit in my vehicle at the lumber yard unless I put it on top. Instead I had them cut the board down to 45” wide x 5 ft long. At home, I cut it down to 43” x 40” just to end up with two straight edges. I then lowered my saw blade and positioned the plywood on the table saw right on the edge where the cast iron saw table stops and the extension table starts. I then marked a pencil line where the plywood is longer than the saw to the left of the cast iron top. I could have then slid the board against the saw fence and trimmed off the excess but since I have a panel cutting sled I used it instead. That left me with a cross cut sled base piece that was cut to my desired width.

  Next, I decided that the length of my sled would be best to not exceed 31” actual cutting capacity. The cutting capacity is the area between the two fences where I will be able to rest a piece of wood. Since the maple fences will be 1 ½” thick, I cross cut the sled bottom to 34” knowing I'd eventually cut it down to its final size around 33". 

  Now it was time to figure out what to use for the miter slot slides. I read a lot about what others had used on their sleds. Many suggested using waxed hardwood strips made out of oak or maple. Others suggested using plastic strips. Still others suggested using high quality metal miter bars. Since it was early in the evening and I still had the desire to press on and get some woodworking done, I decided to try making some slides out of some left over white oak from a shelf project I did recently. I used my piece of junk 6” HF jointer and straightened two adjacent sides. Then I ran the board through my planer until it just barely fit my miter slot, and finally I sliced the board in half on my table saw to make two miter bar slides. After drilling and countersinking using my drill press, I placed a few washers in the miter slots of my table saw, placed the strips in the slots and added a few drops of hot glue along both of the strips. I then placed the sled bottom on top of the slides with the edge of the sled bottom right to the edge of the table saw using the table saw fence as a guide to make sure the sled piece was square to the table saw. After pressing the board down for about 10 seconds, I carefully lifted the assembly up and the miter slides came with the sled bottom. I turned the whole shebang upside down on my bench and screwed in the slides carefully using 5/8” drywall screws. Then I flipped the partially assembled sled over and tried it in the miter slots and now the slides were binding. I tried loosening the screws thinking that the oak was expanding as I tightened the screws but they were still binding a bit, and it was at this moment that I made the decision to not skimp. I decided to order a pair of 36” metal miter bars with adjustable inserts from Prarie Woodworking. I used one of these bars on my panel cutting sled and it works pretty well so I know they’ll work great on this sled. The bars have set screws tapped into the side of the bars. As you tighten the screws, they press a Teflon-like plug out the other side of the bar to take up any slack that may be present between the slot and the bar. They’re not perfect, but for a dual runner system like this they’ll be very durable and won’t distort over time. Each miter bar costs about $18 and with shipping the cost is $43.50. I consider that a worthwhile investment considering this will be my main sled.Until I received the bars this project was on hold. 

It took about 2 weeks to get my bars delivered and when I received them I was ready to get busy. Some people run grooves to set their miter bars into before screwing them in. If these were wood runners, I could see doing that, but for metal ones, I didn't think that was necessary and actually I figured if the grooves weren't perfect I wouldn't be able to align the bars and it might bind so it wasn't worth the risk to me. To be safe, I asked some people’s opinions and they agreed.

The first step in attaching the miter bars was to place them in the miter slots and check them for play. There was a bit of play left to right in the slots and minor adjustments using the supplied allen wrench took out the play. My suggestion using these bars is to tap on the teflon inserts with a hammer to impact them when starting. As you adjust the bars, make 1/4 turns only and check for play. If you have to reverse your adjustment, use a hammer and tap on the insert after reversing the adjusting bolt. 

Before attaching the fences to the sled, you need to attach the miter bars. The process for actually attaching the miter bars to the base of the sled was to place some dimes in both ends of both of the miter slots to raise the miter bars above the table surface.

Next, I placed the plywood base on top of the table saw and positioned the edge of the board with the edge of the cast iron saw table. With the board in position, I slid my table saw fence against the plywood and locked the fence down. With the miter bars aligned with the front edge of my sled base, I slid the plywood board and miter bars backward carefully so that the back of the board was hanging off the table of the saw like this and used a vix bit to predrill and drive screws to attach the miter bars to the end of the sled.

Then, I carefully slid the partially assembled sled forward and did the same thing on the front of the sled predrilling and attaching the bars.

Then I flipped the sheet over, predrilled and drove screws into all the remaining holes. Because of the length of my sled, I found that I had a few inches of miter bar unsecured because there wasn't a countersunk hole toward the end of my sled so I had to countersink some holes in the bars to attach them completely.

I placed a spade bit between the bar and the board to prevent myself from drilling through the sled board and drilled a hole in the bar.

Then I used a countersink bit to give the hole the recess needed. If you don't own a countersink bit, its a really useful thing to have around.

I then trimmed the bars to length using my jigsaw and metal cutting blade and filed the bars to knock off the sharp edges.

Now, the fun starts... Before going any further, I placed the sled board into the miter slots and slid it back and forth checking it for play and made some final adjustments. When I was satisfied, I positioned my sled board directly over my saw blade, turned on the saw and slowly raised the blade the entire way cutting through the board and slid the sled forward and backward but NOT cutting all the way through the sled in either the front or the back of the board.

With the sled board done, I was ready to prepare my front and back fences for attaching to the sled. That meant I had to run them through my jointer to flatten the bottom edges and decide on the height and shape of them. Once attached and aligned, I didn't want to remove them. I seriously considered adding some curves to the fences to give them some style but in the end, I decided I'd like it best to be clean lines and focus on keeping my hands away from the blade. I have a crappy jointer and I don't trust it to produce dead flat surfaces so I ended up hot gluing the fence material to a slightly larger slice of plywood with a factory edge and ran it through my table saw. Once I had a good edge, I removed the baseboard and used my new edge against the saw fence and cut the boards to size.

I started with fences that were nearly 6" high, but after resting them on my sled board and imagining trying to hold down a board with my finger tips, I found I couldn't reach the sled base with my finger tips comfortably so I took off more material until I was happy with the height. The last thing I did was to knock off some material on both corners of the back and front fences with my bandsaw. I didn't try to produce finished cuts. I figured I'd sand them down later, but I wanted to get some of the material off just to make it easier later.

The most critical part of a sled that produces reliably square cuts to the blade is a sled that has a properly positioned back fence. I drove people crazy asking questions to figure out how to set up my sled. It seemed like every idea relied on aligning a framing square with the saw blade itself, but I didn't trust that I was ever placing my square against the teeth precisely. In the end, it dawned on me that the initial saw cut I made through the board was like a zero clearance insert and indicated the precise path of the blade. The first thing I did was drive a screw into the left side of the fence from underneath the sled. The screw was driven in but not tightened all the way. If you drive it all the way, when you go to square the fence, you'll find that the back fence will have a bend in it. DAMHIKT! With one half of the back fence attached, I carefully aligned my framing square along the edge of the cut line and when I was confident that my square was positively in position, I pressed down on the square with my hand to prevent it from moving and placed my back fence into position against the framing square edge.  I then squeezed the fence to the base of the sled to make sure it didn't move and clamped the two boards together so they stayed put while I drilled and drove a screw in the right side. If you look at this picture closely, you'll see that I have a block screwed into the plywood because initially I thought my fence was square and testing for squareness I sawed all the way through my back fence. The problem with doing that is that if you remove the back fence, your sled can now move around in the miter bars so I had to lock up my sled base before trying to add my fence the second time. Hopefully you can avoid that, but if not, you know how to deal with it.

Before going any further, I tested the fence to make sure I was cutting square cuts with my partially assembled sled. There are various ways to test for squareness and I used two methods. First, I took a 12 x 12 piece of plywood and cut on side, rotated it so that the cut side was against my back fence and cut the next side, rotated so that my second cut side was against the fence and cut a third side and so on until I had cut all four sides. With the piece cut in rotation like this, I measured the diagonals and found that they matched. So far, so good.

Next, I took a slice approximately 3" off the same board and measured the width at both ends. They matched. That's good enough for me.... There are other more involved ways to check for square, and if you're interested check out this page. Its where I got these two ways of checking.

Attaching the front fence is not as big a deal, but I used a framing square and squared it to the saw blade cut line like I did on the back fence. It was easy enough.

My plan for this sled included a chip guard made of Lexan and maple strips. The maple strips were left over from ripping the fences down from their rough approximately 7" size down to their final size of 4 1/2" tall. To make the strips, I had a chance to use my new 17" Grizzly bandsaw again. Its such a nice thing to be able to walk up, flip a handle to tension the blade and flip the saw on and go. That is definately a new experience for me. I easily cut the support strips into 1" x 1" strips just using the bandsaw fence and a push stick.

The process for laying out and installing the maple strips involved deciding on the width of the chip guard and then cutting dado's in the fences to sink the strips in. I used a combination square and a marking gauge to layout the lines to cut and then used my dovetail saw and a chisel to chop out the wood.

See, those sawing lesson Picklepork gave me paid off! I was able to cut a straight line after all.

This picture shows the strips after they have been trimmed. I actually left them slightly long and then used my low angle block plane to plane them down flush. I didn't use any glue to attach them to the fences-only countersunk screws in case I need to remove them to cross cut something large that won't fit under the blade guard. I hope I don't have to though because these strips fit really snuggly into their slots.

At this point, I had a functional cross cut sled but after making a couple cuts I decided it would be prudent to add a blade guard on the back so I glued up some scraps of maple left over from gluing up the fences after checking them against the amount of exposed blade I figured I'd need to cover. I didn't give this part a lot of thought. I just cut it down to approximate size using my bandsaw, sketched the approximate depth and outline of the blade that will pass into it, and cut it down roughly to the size and shape I wanted using the bandsaw again.

Using a clamp to hold it in place, I predrilled through the fence into the guard and drove screws to secure it. Ah, I love my new Bessey clamps. Thanks Rockler for that one day cabinet maker set sale.

Here's how the guard looks from the back. See how it is actually above the plywood's level? I didn't want to risk it hanging up on the saw and this way its enough to keep my hands away from the spinning blade.

The catch about making a sled this large is that if you are cross cutting a piece of wood over about 27", it will require you to slide the sled back pretty far. Some people don't like the potential for the sled to tip or rock, but I say its worth gaining the additional capacity so I went for it. Also, when you are cutting anything with a sled this large, it will require you sliding the sled further through the blade than some other sled styles. In order to prevent sliding the sled too far and sawing right through the blade guard in the back, I came up with a bumper system. When I use this sled, I drop two rubber tipped bench dogs into 3/4" holes I drilled into my outfeed table to stop the sled from sliding. It works great for my needs and it gives me the max capacity I was after. If you're not as concerned about cross cut capacity, you could move your back fence forward on the sled and attach a wooden stop block to the underside of your sled so that the sled wouldn't be able to slide into the saw past a certain point.

I know this is only shop equipment, but I wanted something I could take some pride in, so I sanded it with my orbital sander from 80 up to 120 knocking off all the hard edges and smoothing the whole thing down. Then, I wiped it off with a tack cloth and wiped the whole top of the sled with boiled linseed oil (available at hardware stores in the paint section). I like BLO because it brings out the grain of the wood. I haven't done it yet, but the underside of the sled will be wiped down with Johnson's Paste Wax to allow it to slide well.

Lastly, I finished the blade guard by cutting a piece of Lexan I had lying around from another project to fit between the fences from the underside of the maple strips. I was going to attach it on top, but I didn't like the look of it, and am real happy with how I now see wood instead of plastic when I look at my sled. The best part is I can look right down at the blade and don't have sawdust kicking up in my face. To attach the Lexan, I used gorilla glue sparingly and lots of spring clamps.

Every project I can think of coming up including renovating our master bathroom with flat panels, building some closet storage for my boys, and on and on are going to use this sled so I'm really pleased at how it turned out. I think it is worth the time to make one of these and I hope you have fun making one yourself if you decide to.

By the way, a sled this large can take up valuable space in a 2 car workshop like mine. Once I had this sled built, I looked around and found that I wasn't willing to hang it on the walls and give up space for cabinets or other things. I ended up building bracket to hang the sled off the front right side of my table saw extension. The bracket uses dowels glued into a maple board and the dowels pass through holes in the sled that are drilled into the sled base so there is no chance that I'm distorting either the front or rear fence hanging the sled by either fence on the wall or leaning the fence against a wall in my shop.

The holes for the dowels were drilled using a forstner bit in my drill press.

To determine exactly where to drill holes in the sled for the dowel supports, I drove some small finishing nails into the back side of the dowels and clipped the heads off.

With the support temporarily in position but flipped backwards with the nails pointing outward, I held the sled up against it and pressed into the nails to make indentions. I was careful to make sure the sled was off the ground but when hanging wouldn't interfered with the path of wood being cut on the table saw.

With holes drilled through the sled and the dowel support board flipped and secured to the underside of my table saw extension here's what it looks like hanging.

Obviously the blade guard extends above the table surface so if I am ripping a board over three feet, the sled will be in the way, but so far that is sort of rare. If it ends up hindering me to have the sled stored here, I'll have to move it, but having it here has some definite advantages. To load it on the saw, I just lift and place it on the outfeed table and slide it into the miter slots. When I'm done, I slide it off and hang it up.