This saw can be built in a single evening, and if you have to buy EVERYTHING will cost around $80. My total cost was $28 for the sheet of plywood. Everything else I had on hand. I've used it to cut through 1.5" Aluminum Bar Stock, 1/4" 2x3 angle, and 1/8 2" Pipe. It will pretty much cut anything eventually. And it's automatic, just start the cut, and keep an eye on it to stop it when finished.
Tools You Need:
1. Wood Saw (I used a miter saw, and a table saw, but you could do the whole thing with just a hand saw.
2. Drill Press (You could make this without it, but it is WAY WAY easier to be precise with one).
3. Carpenter's Square
3. Basic Hand Tools
Materials you need:
1. A Reciprocating Saw. If you sign up for their coupons, you can get this one: http://www.harborfreight.com/6-amp-reciprocating-saw-with-rotating-handle-65570.html for $20. This one is what I used and is perfect because it's easy to mount once you take off the handle.
2. Some Plywood (3/4" although 1/2" will work).
3. A light dimmer switch (optional).
4. A wood working vice like this: http://store.cbtoolgroup.com/jorgensen-woodworking-vise--4-12-p4302.aspx?utm_medium=cse&utm_source=googlebase I used an 8" vice I had.
5. Some 1/4" 2" bolts with nuts and washers for attaching the vice.
6. 4' or so of 2x4.
8. Some zip ties.
9. Some heavy stuff for weight (I used an old motorcycle starter, and an adjustable pulley).
10. Some High Quality Large Hose Clamps (6" or more).
11. One 8" Or Longer 5/8" Bolt (with only the end threaded) or a 5/8" rod / shaft. (A 5/8" hardwood dowel will work too)..
Step 1: Remove "Extras" From Reciprocating Saw.
Step 2: Make the Base and Top Cover
Cut yorr 2x4's so they are about 4" Longer then your reciprocating saw. Your base plate should be the same length.
Then, lay everything out as show below. Figure out how wide and long your base plate needs to be, and cut it out. (I used some high quality, ply wood (not osb) for this for higher accuracy, however, my first one used 1/2" OSB, and it worked ok too.)
Now, cut your Top Cover. It should be wide enough to cover the 2x4's on either side of the vice, but not the reciprocating saw.
Step 3: Trim 2x4's, Drill Holes, and Attach Vice to Top Cover
Now, take one trimmed 2x4 and the full length 2x4 and drill 5/8" holes approx 1-1/2" from the bottom and back of the boards. I used a twist bit instead of a spade bit because the more precise the holes are, the more precise your saw will be, so measure twice, drill a pilot hole, and then drill carefully...
Step 4: Assemble the Base
Now put the top cover on, and glue and fasten with screws.
Step 5: Create Reciprocating Saw Hinge
Then drill a 5/8" hole all the way through, approx 1" x 1" from the bottom and back of the 3 pieces.
Now, you are going to attach a temporary strip of wood (as in the picture below) to hold the saw. I used my prototype to cut a piece of 1/4" x 1-1/2" x 2/4" Channel which I used for the final version. This is very important, as the stiffer this piece is the more accurate your saw will be.
It is important that the hinge is STIFF. The reciprocating action looses a lot of it's effectiveness if the hinge has a lot of slop in it.
Step 6: Attach Saw, and Install Hinge.
Now put the hinge block in, and push the 5/8" bolt / dowel / rod through the hole in the outside 2x4, the hinge block, and the inside 2x4. It is ok if it's a tight fit, when the reciprocating saw is running, the vibrations will have no problem making it swing.
Step 7: Wire Light Dimmer
Follow the instructions on the light dimmer, and just put the two wires that go to the reciprocating saw motor where the light would go.
Step 8: Making It Square
First Horizontally: Remove the saw from the hinge, but leave the hinge in place. Put the square in the vice as shown below, and loosen the bolts on the vice. Move the vice around until things look perfect and then tighten the bolts again, you may need to remove the vice, and drill slightly larger holes to make it perfect.
Now vertically, re-install the saw and clamp the square in the vice as shown below. The vice has the two slider bars which you want the square to rest firmly against. Now, lift up slightly on the reciprocating saw blade (it is unplugged right?). This will remove the slop and show you the angle of the blade while it's cutting. So, now see if the blade is parallel to the square vertically. If not, loosen the hose clamps, and twist it a little till it is square. This takes some time, and when you tighten the hose clamps the saw will probably rotate just a hair, so you'll need to account for that. Take the extra time, and get this as perfect as possible. Trust me, it's worth the extra 5 minutes to get it perfect.
Step 9: First Cut - Slow Is the Name of the Game... Then Add Weight
Once you have it going, experiment with adding weight. There are lots of ways to do this. On my prototype, I hung some odds and ends from a scrap piece of copper wire I had hooked to the end of the saw (not the blade, the saw), see video below.
<iframe width="560" height="315" src="http://www.youtube.com/embed/0uQkv3NceJM" frameborder="0" allowfullscreen></iframe>
Later, I found a tapped hole on top of the saw, and made a dowel that screws in securely, I then stack small weights on the rod.
Step 10: Protect Your Awesome New Tool by Staining the Wood.
Step 11: Tips for Better Results.
I found NOT using oil with aluminum cuts better. Otherwise the aluminum mixes with the oil and makes this paste that gets in the teeth and prevents it from doing any cutting. For steel, use some oil... Motor oil, Wd-40, whatever.