Spirals By Steve

This link is to the microscope I purchased.  There are many others that are similar, but you'll want to make sure that the one you choose has a cross-hair overlaid on the image.  This one has the cross-hair on the built in screen, and it also shows as an option when connected to a PC using the recommended program.  When connected to an Iphone 5S over wifi, the cross-hair does not appear.  
I used a toggle clamp that I bought several years ago.  This product looks like the same clamp I use, and is #1 in the toggle clamp category.  These are very useful with workshop jigs.
This jig is my latest invention, it enables you to cut convex polygons as accurately as your printer can print them.  The system has an adjustable sled that slides along the fence, a reticle for coarse alignment, and a digital microscope for fine adjustments to the alignment.  The sled has a pair of adjustable swivel pads that let you adjust the edge of pattern to be cut to be perfectly parallel and inline with the edge of the cut after the part has been clamped down with the toggle clamp.

The clamp is made from a 3/8" thick aluminum plate 6" x 8", and a toggle clamp with plywood spacers.  This type of clamp is capable of exerting hundreds of pounds of clamping force making the heavy aluminum plate necessary so the jig doesn't warp while in use.  I drilled and threaded holes for #10 allen-head screws to attach the toggle clamp. I chose aluminum instead of steel because it is much less likely to damage the teeth of the saw blade if it accidentally comes into contact with it.  I glued down a piece of 120 grit sandpaper under the clamp to reduce the amount of clamp pressure needed to hold a piece of wood without slipping.  The aluminum plate was drilled and threaded 1/4 -20 in four spots shown in the photo above to secure it to the base with countersunk machine screws from the bottom side.  four washers - one on each screw act as spacers between the plate and the base.  One edge of the plate is beveled at 45° to allow the blade to get closer to the sled, and provide more supporting surface under the workpiece for beveled cuts.  The base of the sled is half inch  baltic birch plywood.  The adjusting pads are made from long 1/4 - 20 carriage bolts that formed their own threads through a 3/16" pilot hole in southern yellow pine blocks attached with countersunk wood screws from the bottom side.  The hardwood pads have a counter-bored hole so the head of the carriage bolt will be below the surface that rubs the saw fence.  A washer is between the pad and a pair of 1/4-20 nuts tightened together.  The hardwood pad is a loose fit that is able to wiggle around and swivel much like a pad on the end of a C-clamp.  Make a bend in the ends of the adjustment bolts for handles after threading them through the wood blocks.  I plan on upgrading to a pair of rollers to replace the pads.  I used an aluminum cutting blade on my table saw to make the beveled edge at 45°.  A trick I learned for cutting aluminum is to lower the blade so it doesn't cut all the way through the plate on the first pass.  Complete the cut with the 2nd pass cutting the last little bit of thickness.  This will help keep metal chips out of your face.  Do not even think about making the cut unless you have goggles, long sleeves, and a face shield.  This cut is much safer to do with a band saw.

The reticle is made from a piece of glass from a dollar store picture frame.  The glass slides back and forth in grooves cut into the plywood body which is clamped to the saw table so the reticle line is parallel to the blade and fence.  The glass extends a few inches beyond the end of the base for clearance.  The reticle line is engraved (or rather scratched) into the glass with a diamond rotary burr.  The line is a dashed line made black by marking with a Sharpie, and then removing the excess ink around the line with fine steel wool.  Make the reticle line as thin as possible.  As an alternative, I could have printed a dashed line onto clear transparency film and tape it to a thin piece of plywood to replace the glass, but I didn't have any at the time.  In the picture below I have a 1/8" shank diamond burr inserted into a 1/8" hole drilled in a wood block to use like a marking gauge on the glass.
The holder for the reticle is made of plywood, and has two vertical pieces with grooves to allow the glass to slide like a drawer.  The vertical pieces are friction-fit into snug-fitting dado grooves cut into the base.  The dimensions are based on the size of the glass - I used glass from a 4"x6" picture frame.  The grooves for the glass are positioned so the glass is just above the top surface of the wood being cut.  The rubber band shown in the photo holds the sides snug against the edge of the glass to keep it from moving around from saw vibration. The entire reticle assembly can be shimmed to the correct height.  The base is clamped to the table using a C-clamp, and a homemade T-slot bolt in the miter groove.  Make sure when you shim the base to the correct height you place shims in the locations where it is clamped. I'll be adding more to the jig soon.
The microscope I bought has a metal base and two screws driven into the adjustable support column from the bottom.  The bottom also has four rubber feet which I removed and replaced with a piece of 1/4" plywood to support the base so the protruding screw heads do not touch the table.  I rotated the base 180° using the same screw holes so the base could be clamped down from the miter groove, and the scope can be positioned over the cut path.  The hold-down clamp is another t-slot bolt through a piece of hardwood which I put two of the rubber feet on that I removed from the microscope base to hold against the center of the base.  The t-slot bolt I made from a 1/2" carriage bolt with some of the metal removed from the head so it could fit the t-slot.  Use a small piece of stretch wrap with a rubber band to cover the lens of the microscope to keep dust out.
Steps for setting up:

1.  Position the fence so the edge of the aluminum plate is perhaps 1/4" from the blade, and the fence pads have some room for adjustment.

2. Clamp a piece of scrap wood onto the sled and cut a reference edge along the wood.  Note: all of the wood you use for a project should be the same thickness.  Do not un-clamp the toggle clamp after the cut.

3.  Slide the sled back towards yourself to the the edge of the saw.  Position the reticle and base so the reticle line is aligned with the cut edge.  Clamp the reticle assembly to the table using shims if needed.  The glass should barely clear the wood, but not touch it.

4.  Slide the sled forward so the cut is between the reticle and the blade.  Turn on the microscope, and bring the cross hair to the edge of the cut, then choose the magnification setting you like and focus.  Clamp the microscope into a position where the part can be slid back and forth without contacting the blade.

5.  Make a few test cuts to ensure the cut is where you'd expect it to be.  Align the part with the reticle and use the two adjustment screws to make the pattern line both parallel and inline with the cross-hair as you slide it back and forth under the microscope.  This will take some practice to get up to speed with.  If you have to make a lot of adjustment under the microscope then you might need to check the alignment of the glass reticle, particularly the angle.

Need more information?  I'm putting together a pdf with more details that will be available here when I have it ready.
Want to try it?  Get this single page PDF file with patterns for a regular dodecahedron as shown in the video.  There are no instructions included, it's just patterns to print to adhere to the wood using either spray adhesive or self-adhesive label.  You can edit the price to pay what you like, or get it free.  I would suggest that you get it for free to try, then if you like it and want to pay something for it then just purchase it again and edit the price.  Anything is appreciated.  Thank you.