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Step 7Setting reference points and making cuts to specific dimensions
Setting up the sled to accurately make cuts to specific dimensions requires you to first establish a lateral reference point. Cut out and clamp down a block on the rightmost side of the fence, making sure it's far enough out so that you can still fit in the longest cut that you're planning to make without bumping into it. Now install a second (adjustable) block to the left of the first one. Put a stack of shim spacers between them and tighten down the adjustable block so that the shims are held tightly in place. Varying the thickness of the stack of shims that you place between these blocks lets you fine tune the length of your cuts.
Setting up a ripping fence is done similarly to this. Build a pair of tall toggle clamp towers and mount them in place as shown. Not only is using toggle clamps a good idea for safety reasons, but it's also friendlier to your fingers and wrists, more convenient for repetitive tasks, and will generally give you much more consistent results than you would otherwise get by holding the wood with your hands. Moving the sled back and forth is also a lot easier (and more consistent) when you're not pressing it down onto the surface of your saw.
With these towers in place, you can use their edges as reference points for laterally adjusting blocks that you clamp down next to them. Pairs of independently adjustable blocks can be aligned with each other by pressing a straight edge up against them as you tighten them down. I recommend putting a small metal dowel pin in with these shim stacks (see the full-size picture for what I mean) so that each of these clamp-down blocks has rotational play. If you don't add dowel pins here, the clamp-down blocks will tend to stay parallel to their respective toggle clamp towers.
Make sure that your toggle clamps are long enough to reach well over the ripping fence. If the rubber tipped screws that come with your toggle clamps aren't long enough to reach the stick that you're ripping, then lay a scrap of wood in between. This is a good idea regardless of the rubber tipped screw length -- it's easier to use different sized scraps here than to get out a wrench and adjust the toggle clamps.
Once you've built your ripping setup, make a test cut and measure the front and back ends for consistency. Adjust the shim stacks and realign the ripping fences if necessary. Once you've got the rips set parallel to the cut line, you can add or remove equal amounts of thickness for both stacks to adjust the rip offset. Rough cut some wood into crude square sticks which are about 0.100" larger than your target stock dimension. Make a big pile of these rough sticks, and then take a pencil and mark all four sides of each stick. It's better to mark the sticks all at one end or the other, but not right down the middle. Marking them in this manner helps you figure out how to properly orient each stick when you load it onto the sled.
With a pile of marked rough sticks at the ready, set the rip fences so that they cut about 0.050" larger than your target dimension, and then trim down the first surface of just one rough stick. Rotate the stick so that the surface you just cut is facing down towards the sled plate, and with the stick clamped in this position, make your second cut. Now adjust the fences so that your third and fourth cuts hit your target dimension. Each subsequent cut on the stick is done with it rotated 90 degrees from its previous orientation.
Just as you were able to set the blade angle using measurements made from your cross cutting fence calibration cuts, so too can you fine tune the blade adjustment by measuring these square sticks, and compensating for any deviations that you may find. Extra effort spent getting this calibrated correctly will pay for itself later on down the line when you're depending upon the accuracy and consistency of the square cross section of these sticks. Run this whole process through one stick at a time, making adjustments when necessary, until you are satisfied with the measurements that you are reading. It is only at this point that you should run the rest of your sticks through this ripping jig as one large batch.
Once you've got some good square sticks to work with, you can use the cross cutting fence to accurately chop them up into cubic or rectangular sections. Before making any cuts on a new length of square stock, be sure to trim a bit off the end to ensure that it's squared off properly. For maximum accuracy, I recommend regularly (i.e. every few cuts) using compressed air to clean out the sawdust from the places where you load in parts. Also, I recommend setting up some toggle clamps to hold the sticks in place while cross cutting. This would be more easily accomplished without the ripping fences attached.
Lastly I want to point out that these photographs show the cross cutting fences spaced rather far apart from each other. This is bad. If I were actually going to use this sled regularly (rather than my precision metal one) I would modify the crosscutting fences so that they were closer to the saw blade. Rather than accomplishing this by modifying my threaded hole pattern, I would just grind those two parallel bars down so that I could move them each one hole closer together. If you're making your crosscutting fences from plywood then you don't need to worry about this -- just set them too close together and then trim them flush to the blade.
Setting up a ripping fence is done similarly to this. Build a pair of tall toggle clamp towers and mount them in place as shown. Not only is using toggle clamps a good idea for safety reasons, but it's also friendlier to your fingers and wrists, more convenient for repetitive tasks, and will generally give you much more consistent results than you would otherwise get by holding the wood with your hands. Moving the sled back and forth is also a lot easier (and more consistent) when you're not pressing it down onto the surface of your saw.
With these towers in place, you can use their edges as reference points for laterally adjusting blocks that you clamp down next to them. Pairs of independently adjustable blocks can be aligned with each other by pressing a straight edge up against them as you tighten them down. I recommend putting a small metal dowel pin in with these shim stacks (see the full-size picture for what I mean) so that each of these clamp-down blocks has rotational play. If you don't add dowel pins here, the clamp-down blocks will tend to stay parallel to their respective toggle clamp towers.
Make sure that your toggle clamps are long enough to reach well over the ripping fence. If the rubber tipped screws that come with your toggle clamps aren't long enough to reach the stick that you're ripping, then lay a scrap of wood in between. This is a good idea regardless of the rubber tipped screw length -- it's easier to use different sized scraps here than to get out a wrench and adjust the toggle clamps.
Once you've built your ripping setup, make a test cut and measure the front and back ends for consistency. Adjust the shim stacks and realign the ripping fences if necessary. Once you've got the rips set parallel to the cut line, you can add or remove equal amounts of thickness for both stacks to adjust the rip offset. Rough cut some wood into crude square sticks which are about 0.100" larger than your target stock dimension. Make a big pile of these rough sticks, and then take a pencil and mark all four sides of each stick. It's better to mark the sticks all at one end or the other, but not right down the middle. Marking them in this manner helps you figure out how to properly orient each stick when you load it onto the sled.
With a pile of marked rough sticks at the ready, set the rip fences so that they cut about 0.050" larger than your target dimension, and then trim down the first surface of just one rough stick. Rotate the stick so that the surface you just cut is facing down towards the sled plate, and with the stick clamped in this position, make your second cut. Now adjust the fences so that your third and fourth cuts hit your target dimension. Each subsequent cut on the stick is done with it rotated 90 degrees from its previous orientation.
Just as you were able to set the blade angle using measurements made from your cross cutting fence calibration cuts, so too can you fine tune the blade adjustment by measuring these square sticks, and compensating for any deviations that you may find. Extra effort spent getting this calibrated correctly will pay for itself later on down the line when you're depending upon the accuracy and consistency of the square cross section of these sticks. Run this whole process through one stick at a time, making adjustments when necessary, until you are satisfied with the measurements that you are reading. It is only at this point that you should run the rest of your sticks through this ripping jig as one large batch.
Once you've got some good square sticks to work with, you can use the cross cutting fence to accurately chop them up into cubic or rectangular sections. Before making any cuts on a new length of square stock, be sure to trim a bit off the end to ensure that it's squared off properly. For maximum accuracy, I recommend regularly (i.e. every few cuts) using compressed air to clean out the sawdust from the places where you load in parts. Also, I recommend setting up some toggle clamps to hold the sticks in place while cross cutting. This would be more easily accomplished without the ripping fences attached.
Lastly I want to point out that these photographs show the cross cutting fences spaced rather far apart from each other. This is bad. If I were actually going to use this sled regularly (rather than my precision metal one) I would modify the crosscutting fences so that they were closer to the saw blade. Rather than accomplishing this by modifying my threaded hole pattern, I would just grind those two parallel bars down so that I could move them each one hole closer together. If you're making your crosscutting fences from plywood then you don't need to worry about this -- just set them too close together and then trim them flush to the blade.
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