Precision Saw Sled

if you have a table saw then you probably also have one of these a miter gauge and if you have a miter gauge you're probably at least a little disappointed with it table saws have been around for 150 years and yet manufacturers have yet to come up with anything better for cross cutting than this so if you have a table saw and a miter gauge then you could probably also use a saw sled the difference between a miter gauge and a sled is that the miter gauge pushes a board past the blade whereas a sled carries it past a sled eliminates drag and it's this drag especially on a long board that makes it so hard to be accurate with a miter gauge and not only are sleds more accurate than a miter gauge they are also more versatile and more diverse there are hundreds of designs for sleds each with different capabilities so rather than show you how to make a sled that works for me i'm going to show you all the features that you can pack into a sled so you can design one that works for you there are two different types of sleds single sided and double-sided double-sided sleds straddle the blade supporting the board on both sides of the cut they normally have two fences leading and trailing to tie the right and the left halves together they also have two guide bars one for each miter slot a single sided sled exists on just one side of the blade left or right and only has one fence and one guide bar each type has its own advantages the double-sided sled type offers more support and because it travels on two runners more stability the single-sided type is less bulky and because there's only one fence you can make that fence swing through a wide variety of angles for most of this video we'll be showing just the single sided type this is what i prefer because i feel it's more versatile however you may prefer the double-sided type for its stability many of the features that we will examine will work for either type let's start at the bottom the base of the sled needs to be perfectly flat and it needs to stay that way i've had good luck with mdf medium density fiberboard and also baltic birch plywood this is a premium plywood that has about twice as many plies as regular plywood and all the same thickness keep the thickness to no more than one half inch or 13 millimeters any thicker than that and the sled will reduce the sawing capacity of your table saw over much the base should cover a substantial portion of your saw table to accommodate large work pieces how large will depend on the type of work you do the bases that i'm showing here are about 18 inches wide and 24 inches deep that's 45 by 60 centimeters i strongly suggest that you put a finish on this tool once it's complete not only to keep it clean but to slow the absorption and the release of moisture as the weather changes this is extremely important for the base it keeps it flat be sure to finish both surfaces top and bottom so that both sides breathe moisture at the same rate look at this old sled 30 years ago i covered both the top and the bottom with plastic laminate to slow the exchange of moisture as much as possible and it's still dead flat the base will need a guide or two to ride the miter gauge slots you have two choices you can purchase a ready-made steel miter gauge bar or you can make your own if you do make your own avoid wood wood does not wear well in this application and it expands and contracts with changes in relative humidity a wooden guide bar that slides beautifully in the winter may stick in the summer the best material that i've found for shop made guide bars is uhmw ultra high molecular weight plastic this is a form of polyethylene that is often used for guides bushings bearings and pivots because it wears like iron and you can work it with ordinary woodworking tools because it's plastic it's flexible and because it's flexible you can make the width somewhat adjustable using a wedge you can get it to expand a fraction of an inch or a millimeter changing the way it fits the miter gauge slot to do this you need to mount it using flathead machine screws small bolts really and t-nuts cut a strip as wide as the miter gauge slot and 1 16 or 1.5 millimeters thicker than the miter gauge slot is deep drill and countersink holes for the small flathead machine bolts every few inches or centimeters along the length cut a shallow dado in the underside of the base 1 16 of an inch or 1.5 millimeters deep this is to hold the guide straight position the guide in the dado and mark the mounting holes with a transfer punch drill tiny holes through the base to transfer the mounting hole locations from the bottom surface to the top drill shallow counter bores for the tops of the t-nuts then drill shaft holes through the centers of those counter bores the t-nuts have small fillets concave surfaces between the shaft and the flange this will interfere with the fit of the nuts in the mounting holes to make room for the fillets remove a little stock around the rim of the shaft holes with a countersink attach the guide to the base with t-nuts and flathead machine screws just snugging up the screws don't tighten them completely just yet test the fit of the guide in the slot if it's tight scrape the sides of the guide with a scraper if it's loose tighten the machine screws the flat heads will act as wedges and they will spread the guide ever so slightly if the plastic won't spread far enough cut a tiny slot in the plastic on both sides of the hole using a coping saw or a scroll saw when the guide is secured and properly adjusted trim the edge of the base i usually leave an extra inch or so on the base just for this operation if i lived in a different part of the world i'd leave an extra centimeter [Music] make your fence from a straight grained hardwood such as maple or ash and long enough to provide support and alignment for long parts it also has to be long enough to duplicate long parts with a stop attached to it i've made this fence 38 inches or 100 centimeters long which is long enough to make the legs of tables and stools however before you do anything with the wood bring it into your shop and allow it to shop dry for two weeks this allows the moisture content in the wood to reach an equilibrium with the relative humidity in your shop and at that point the wood is going to be about as stable as it can get or almost consider splitting the wood and gluing the faces back together to keep it straight this is an old trick that helps compensate for any slight warp or any tendency to warp that the board may have it also negates the effect of grain slope if the grain runs at a slight angle through the board when the glue has cured joint two adjacent sides square then mark those sides with x's plane the two unmarked sides parallel at this point the board should be perfectly straight and you can cut it to length now decide on whether or not you want to attach stuff to this fence like stops or clamps and of course you do and one of the best ways to do this is with a t-slot now where you put the t-slot will depend on how you want to attach the stuff i prefer to put it in the face but a t-slot can also be very handy in the top to make this t-slot you can either route it or you can inlay a metal t-track like this if you route the t-slot you're going to need a straight bit and a t-slot cutter first route a 5 16 inch or 8 millimeter wide slot and then finish up with a t-slot cutter to inlay a t-track just route or cut a slot in the fence in which the track fits then just screw it in place and incidentally you may want to put a short t-track on the back of the fence near the outboard and like i did right here and here this gives you a place to store the stop when it's not in use we'll get back to the stop later meanwhile decide if you want to scale on the fence to help position boards before you cut them if so purchase a self-adhesive scale at least as long as the fence itself route or cut a very shallow groove in the face of the fence to hold the scale no deeper than the thickness of the scale itself wait until after you've actually finished the fence before you stick the scale to it we'll come back to this too now decide whether or not you want the fence adjustable or fixed that is do you want to be able to adjust the angle to the blade so that you can do miters and tapers and other angled cuts or do you want it in just one position so you can do cutoffs if the fence is fixed it's a fairly simple matter to mount it to the base and get a precise angle first drill two holes 15 inches or 38 centimeters apart position the fence on the base perfectly square to the trimmed edge using transfer punches mark the holes on the base drill small holes through the base to transfer the hole positions from the top surface to the bottom then drill shallow counter bores in the bottom surface of the base to hold the heads of the fence bolts drill a hole through the counter board nearest the trimmed edge the edge of the past is nearest the blade the same diameter as the fence bolts drill a slightly larger hole through the other counter bore maybe 1 16 of an inch or 1.5 millimeters larger that's usually all you need for fine adjustment this larger hole gives you just a little bit of play so you can adjust the angle of the fence just a degree or two and get it perfectly square insert the bolts up through the base and the fence add washers and stop nuts snug up the nut nearest to the trimmed edge so it serves as a pivot adjust the fence square to the trimmed edge and tighten the other nut to make sure that the fence is perfectly square to the blade joint and rip a short board at least three inches or eight centimeters wide for this test to work both edges of this board have to be perfectly parallel draw an x in the middle of the board on one face and cut the board in two through the x using the sled put the halves of the board back together the edges against the fence and the x facing up turn one half of the board over and bring the boards together if the cut is perfectly square the two halves will come together with no gaps between the cut ends if there is a gap near the fence the fence is more than 90 degrees from the blade if the gap is away from the fence the fence is less than 90 degrees loosen the nut and bolt in the oversized hole and readjust the angle [Music] if you want to make the fence adjustable you've got to route a curved slot in the base so that you can change the angle of the fence to the saw blade in fact i'm going to suggest that you make two curved slots like i show right here that way you can swing the fence clockwise and counterclockwise the second slot only comes in handy once every two thousand years or so when you need to make left and right hand miters but when you need it you'll be glad you went through the extra trouble and it's really not much trouble you just make a compass from your router from a thin piece of plywood and drill two holes one for the large radius groove and the other for the smaller radius then you mount a 5 16 inch or 8 millimeter straight bit in your router and you're good to go drill the pivot holes for the right end of the fence the end at nearest the trimmed edge like the mounting holes i showed before these will need to be counter-bored for the bolt heads make the counterbores first then drill the pivot holes through the counter bores use these pivot holes to route the curved slots for each slot put a pivot bolt through the pivot hole in the base and through the router compass attach stop blocks to the base to keep from swinging the router too far you want the large radius groove to swing through 60 degrees and the smaller one to cover 45 degrees route each groove in multiple passes lowering the router a little at a time until it breaks through after making the grooves switch to a 5 8 inch or 16 millimeter straight bit and route 1 8 inch or 3 millimeter deep counter bores in the grooves move the stop blocks at the end of each groove so you can continue the counterbore about one half inch or 13 millimeters on beyond the end of the groove this makes room for the oblong heads of the t-bolts that i suggest you use for the swing bolts drill a pivot hole in the fence the same distance away from the end of the fence as the pivot hole in the base is away from the trimmed edge mount the fence in the pivot hole with a hex bolt washer and wing nut the end of the fence should be flush with the trimmed edge using a transfer punch mark the location of the swing hole by holding the transfer punch against the end of the curved groove do the same for both curved grooves then drill holes in the fence for the swing bolts mount the fence on the base use a hex bolt for the pivot bolt these have no threads along most of their length so they won't wallow out the pivot hole when you swing the fence back and forth use a t-bolt for the swing bolt or locking bolt that locks the fence at any angle that you want put a stop nut on the pivot bolt and a wing nut on the locking bolt there we go now let's test this in both positions first the back position swing the fence clockwise and counterclockwise through the full arc then the front position do the same thing if the fence sticks anywhere you may have to file the groove a little bit if you're like most woodworkers you'll use your sled mostly for square cut-offs you'll want to stop so that you can bring your adjustable fence back to square quickly and accurately to do this first cut a small block of wood mount a t-nut in one face of the block and insert a small flathead machine screw in the nut add a washer two lock nuts and a knurled knob on the end of the screw then use one lock nut to secure the knob so that you can turn the screw easily mount the block on the base behind the fence when the fence is approximately square to the trimmed edge go through the same exercise that i showed you with the wood scrap to get the fence precisely square then turn the flathead screw until it's up against the fence and lock it in place with the other locking nut to bring the fence back to square simply bring it back against the flathead screw [Music] once you have a fence you need a stop a fence without a stop is like a table saw without a sled this particular stop fits in the t groove or the t track and lets you make repetitive cuts i like to make my stops with a point on the business end this gives the sawdust some place to go instead of building up between the stop and the work piece the sawdust gets pushed to one side or the other so that it can't interfere with the accuracy of the cut the stop is also micro adjustable you see that flathead machine screw running through it that's a 10 32 screw you turn the screw one full turn and that advances or retracts the head one thirty second of an inch one half turn advances it one sixty fourth of an inch one quarter turn one 128th of an inch lets you be ridiculously accurate and if you work in metric you can achieve the same effect with an m3 screw which has 20 threads per centimeter one full turn will advance or retract the screw one half a millimeter one quarter turn one eighth of a millimeter that's equal to about one two hundredth of an inch close enough for government work make this adjustable stop from stock that's a good deal longer than the stop will eventually be it's easier and safer to saw and drill it we'll cut it to size after we machine it drill a hole through the stop just a little smaller than the machine screw make a tap take a long machine screw and cut or file a groove along its length i'm using a small cut-off disc here but you can also use a triangular file drive the tap into the hole the groove in the screw will cut threads in the wood you will have to back the tap out and drive it back in several times as you do this to clear the sawdust that packs in the groove create a point in one edge of the stock with the blade angled at 45 degrees cut one bevel then flip the board and cut another countersink the hole at the pointed edge deep enough that you will be able to recess the flat head of the screw behind the point drill two holes one for a dowel and one for a t-bolt through what will become the middle of the stop finally cut the stop to size the length of the stop should be equal to the height of the fence glue a short dowel into the hole that's closest to the pointed end this will keep the stop from turning keep it properly aligned when it's mounted to the fence thread a machine screw into the threads you just cut and lock a knurled knob on the other end so that you can turn that machine screw easily finally add a tnut a washer and a wing nut and there you have it an adjustable stop you can mount this stop anywhere along your fence simply by tightening the wing nut and then using your fine adjustment or you can store the stop right here on the back of the fence and keep it at ready i strongly suggest that you make a guard for your sled these things don't play well with the guards that normally come with your table saw and besides woodworkers have a tendency of draping their fingers over the fence as they push it forward and this can have some surprising results and it's not all that hard to make it's certainly easier than gluing your fingers back on the first order of business is to counter bore and drill a hole near the front of your base cut and drill a small block of wood the same height as your fence this will become the forward mount for the guard drill two holes in the mount one that goes straight through to attach it to the base and another stopped hole using a dowel center transfer the location of the second hole onto the base then drill another stopped hole at that location in the base mount a dowel in the stopped hole in the mounting block this will keep the block properly positioned when mounted to the base mount the block with the same size hex bolt that you're using as a pivot cut a clear piece of plastic to stretch between the fence and the block then drill some mounting holes in that plastic in case you're wondering you can make a perfectly effective guard out of an ordinary piece of clear plastic it just so happens that day glow orange is my favorite color one of the drawbacks of a single-sided sled is that the portion of the board to the right of the blade is unsupported it's lifted off the saw table by the thickness of the sled it's possible that just before you finish your cut this unsupported portion will break away leaving a small chip or splinter in one corner you can eliminate the problem simply by making an auxiliary surface the same thickness as the sled that rests on the table to the right of the blade during the cut add a little ledge or stop to the back edge of the surface so that it can't slide forward as you're making the cut finish everything including the top and the bottom of the base be sure to put as many coats on the top as you do on the bottom so that it won't warp then wax everything except for this little strip right here where we're going to attach the scale reassemble the sled and cut a board exactly 12 inches or 30 centimeters long using the slat hold the board in place after the cut and mark where the left corner meets the fence then stick the scale in place aligning the proper line on the tape with the mark on the fence this tape is covered with psa stickum pressure sensitive adhesive so you'll get a much better stick if you apply some pressure now i usually use a veneer roller but you can also use a vise this scale won't be precise in all circumstances it may change if you change saw blades it will be right on the money if you use the same blade you use to make the registration cut and any blade that's the same width but if you change to a thicker or a thinner blade you'll have to compensate finally you need a place to store this sled when it's not in use it's a bulky thing and it tends to get beat up if it doesn't have a place to call home so i made this cart that holds both the sled and the auxiliary surface there's even a slot for your semi-retired miter gauge the plans for all of this are at our store you can either see the description or click the link over my head and thank you for watching [Music] mm-hmm [Music] you

Channel: Workshop Companion

Views: 132,066

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Id: ThHQFVD00w4

Length: 25min 39sec (1539 seconds)

Published: Tue Feb 08 2022