Re: GME's New 80/20 CNC Build - My Design
Originally Posted by
GME
Here is my joinery jig designed to cut standard joinery off the front edge of my CNC. Although it's my design, I borrowed heavily from the Leigh D4 series commercial jigs. In fact, I did more than borrow from the jig design, I also borrowed the clamps and springs from the D4 jig I've owned for many years. The clamps are the black ones at the top and front corners.
The base for the jig composed of 2 pieces of 80/20 smooth extrusion, 1.5" x 4.5" x 42". If you look closely at the front, you will see 5 holes drilled in the top slot. The holes are for access to button head cap screws used to attach the two extrusions together. When connected, I have 4.5" of height at the front and 6" of depth across the top.
The stock is clamped using a 1.25 x 1.25 x 42" x .125" wall square aluminum tube. 5/16" studs cut from threaded rod are attached to 80/20 fasteners captured in the extrusion slots and held rigid with a 5/16" nut.
You can also see 3 holes in the aluminum tube, 2 with studs and the one in the center open. The studs are readily removable. They allow me to use any width of stock and be able to tightly hold it in place. I have some 5/16" knobs on order, which I'll use to tighten down the tube.
This is a closer shot to the right side. You can see vertical and horizontal pieces of 1" x 1/8" thick aluminum bar stock used as a material stop. The same arrangement is on the left side. Cut the vertical side a little long, so the top extended about 1/8" above the horizontal face of the extrusions. I used a square to align the vertical face, and the 1/8" projection gave me a hard surface to use to align the horizontal stop perpendicular to the vertical.
This is a closeup shot of the right side from a different angle. You can see the stops and how they attach. You can see the compressed screen behind the vertical tubing clamp
This photos show the side of the aluminum tube that contacts the stock. The red material is 220 grit glued on sandpaper. I learned that stock can slip on the Leigh jig and sandpaper cured the problem.
You will also note that the large holes in the tubing. I cut them on my mill. They are large enough to allow the springs to easily go inside the tube, and are large enough to go over the nuts holding the studs captive. That means I can clamp all the way down to the surface of the stops, which allow me to use stock that is thicker than the 1/8" thickness of the stops. I doubt I'll be cutting much on stock in the 1/8"-1/4" range, but I will have the capacity.
There is big difference between the Leigh jig and mine. The Leigh jig uses fingers to position stock vertically and horizontally, and has a large void in the body to allow the cutters to enter the stock without contacting the jig body or parts. That cannot be easily replicated using 80/20. My solution follows:
My solution is a 1" thick piece of acrylic with tapped holes and a 1/4" thick piece of aluminum bar stock screwed to it.
Here is another shot of it in place. I made it large enough to use the clamp to hold it in place with the top bar clamp. I just clamp the stop in place slide the stock up until it makes contact. This stop will work with 3/4" thick and thinner stock. I'll need to make a different stop of thicker stock. I probably won't be making many dovetails in thicker stock, but I will definitely be making tenons in thicker material.
Finally, there is the question of how to attach the jig to my spoilboard so I have a rigid connection that won't interfere with stock mounted horizontally, as when making single pass half-blind dovetails. My solution was 3 pieces of 1.5" x 1.5" aluminum angle. As is the usual case, the two faces of the aluminum angle were not perpendicular. They were close, but no cigar. I use my mill to square the faces, and drill the holes. Using 80/20 fasteners, I was able to slide the angle until it aligned with my t-slots and used 1/4" studs and slide-in t-nuts to hold the jig in place. I ended up with a rock solid connection.
Oh, one other thing. I believe I mentioned it in a previous post, but I ran a cutter across the front edge of the spoilboard to establish a straight edge perpendicular to the Y-axis. So, I just but the jig up against the front edge, tighten it down, and I'm good to go. No other alignment necessary.
I am happy to answer questions. No secrets here.
Gerry, (ger21), if you happen across this post, feel free to share it wherever you want in conjunction with Joint Cam. If you have suggestions where I might post this elsewhere, I'm open to suggestions.
Gary
I like to see your jig in action... shoot some video of it next time your running some material through it. I've been thinking of a design and how to make one for a bit now..
Adam,
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