PIC#1 I chose to use a 2.1 oz. can of Bernzomatic butane because I already had it on hand.

PIC#2 I checked a copper tubing handbook and found the size of copper tube that's inside diameter most closely matched the outside diameter of the butane supply I was using, which happens to be 1-1/2 inch type "L" tubing. I cut an eight inch length of the 1-1/2" type "L" copper tubing. I Purchased a 1-1/2 inch end cap to fit over one end of the tube and another 1-1/4 inch cap to fit inside the tube.

PIC#3 The end of the nozzle on the butane supply is stepped.

PIC#4 A hole for the butane nozzle must be placed in exact center of the 1-1/4 inch end cap. To find center I painted the inside of the cap with a black marker and allowed the ink to dry.

PIC#5 Coiled up scotchbrite pad rotated gently inside the 1-1/4 inch cap to remove the ink.

PIC#6 If done as described you should have a mark dead center. Drill that mark with a 1/16 inch bit followed by a bit just large enough for the butane nozzle to pass through until it contacts the first step on the butane nozzle.

PIC#1 The plans I drew up required an opening cut in the fuel chamber to allow for the parts and linkage that force the butane cylinder forward to discharge it's contents. I wanted to keep the tolerance tight so I cut the opening .96in wide x 1.3in long, .25in from the tube end. I cut the 1-1/2" end cap to match.

PIC#2 Scribed a line from the center of the cutout to the opposite end of the tube and marked a center location 1-1/4 inch from the tube end. Transferred the center mark 120 degrees in both directions and drilled all three locations with a 1/16 inch bit, followed by a 1/8 inch bit and finally a counter sink.

PIC#3 The 1-1/4 inch end cap was too long to fit the butane cylinder correctly so I shortened it to 3/4 inch long. I inserted it open end first into the end of the tube with the three holes until it was 5/8 inch inch from the end. Then marked the location of the three holes in the tube onto the 1-1/4 inch end cap. Drilled those three locations with a 3/32 inch drill and followed with a #6-32 tap.

PIC#4 Drilled two 1/16 inch holes 180 degrees apart, 90 degrees from the center of the slot and 3/4 inch from the closed end of the 1-1/2 inch end cap.

PIC#5 Drilled a hole in the end of the cap with a #29 drill bit and chased it with a #8-32 tap. the location isn't critical just needs to be centered in the slot.

PIC#6 Ran a #8-32 x 1 inch screw into the hole previously threaded and marked all the threads protruding with black paint.

PIC#7 Removed the screw and chucked it in a drill motor, ran the drill full speed while holding a small file against the threads I marked with black paint until they were removed.

PIC#8 Taped the 1-1/2 inch end cap to the fuel chamber tube to transfer the two holes in the end cap to the tube. Then ran through with a 1/16" drill followed by a 1/4" drill.

PIC#9 I cut a piece of 3/4 inch copper tube 5/8 inch long and fish mouthed one end with a drum sander to fit the contour of the fuel chamber tube. This will be the fuel chamber mounting boss.

PIC#10 The four main parts of the fuel chamber.

PIC#11 Soldered the mounting boss to the fuel chamber, assembled the fuel chamber and end cap with a 1/4 inch x 1-3/4 inch hitch pin.

PIC#12 Time to slide the 1-1/4 inch end cap in place and secure with three #6-32 x 1/4 inch screws.

PIC#13 I drilled a 7/32 inch hole 1/4 inch from the end of the tube and attached the ceramic insulated ignitor electrode with a #10-24 x 3/8 inch machine screw, flat washer lock washer and nut. I then drilled a 3/16 inch hole 180 degrees from the first hole 1/4 inch from the end of the tube and fastened a ground electrode fashioned from a paper clip with a #8-32 x 1/4 inch long machine screw and lock nut through this hole.

PIC#14 For asthetic purposes I capped the end of the fuel chamber mounting boss with a nylon cap.

PIC#1 I built the grip frame using 1/8 inch birch plywood, it is made up of eleven layers laminated together. I used a laser to cut all the parts but they can also be cut with a scroll saw and drilled with a hand drill if necessary.

PIC#2 Glued it all up with Titebond wood glue. Held the pieces in alignment with 1/8 inch cotter pins and spring clamps until the glue set.

PIC#3 The right side frame is glued up from three layers, the left side eight layers. This facilitates easy disassembly and reassembly. The 1/4 inch oak dowel was cut slightly long to be trimmed after final assembly. Also the dowel is only glued to the left side. Both sides were held together while the glue set to hold the dowel in alignment.

PIC#4 This picture shows the placement of the cotter pins used to hold the left and right sides together as I rounded the right side edges( bottom) on the router table. Used a 1/4 inch round over bit.

PIC#5 This shows the completed grip frame assembled for the first time. I used #8 x 3/4 inch screws.

PIC#6 I drilled a 1/8 inch diameter hole in the center of the grip frame and glued a 1/8 inch diameter x 3/4 inch tension pin to engage the mounting boss soldered to the fuel chamber.


PIC#7 I cut a 1/2 inch long piece of 1-1/2 inch x 1-1/8 inch x 1/8 inch aluminum angle to secure the rear of the fuel chamber to the grip frame. Drilled two 1/8 inch holes through the 1-1/8 inch leg 1/2 inch apart and attached to the grip frame with two #6 x 1/2 inch wood screws. Then measured to locate the hole for the pin which protrudes through the rear of the fuel chamber and grip frame and drilled a 3/32 inch hole at that location.

PIC#1 These are the parts needed to depress the ignitor and slide the fuel cylinder forward to discharge it's contents. They were laser cut using 5mm extruded acrylic. It is possible to cut them with a scroll saw and drill the holes with a hand drill. The ignitor push rod was made longer than needed so the ignitor and fuel discharge could be timed. Two of the parts, noted in the picture have been omitted in the final assembly because they were not needed and added to overall complexity.

PIC#2 Before assembling I removed all sharp edges with 220 grit sandpaper.

PIC#3 I used 1/8 inch diameter tension pins 5/8 inch long to allow all the parts to pivot. I inserted the shanks of drill bits to hold the parts aligned as the glue set (super glue), applied the glue only to the ends of the pins so the parts pivot as intended.

PIC#4 This is the left side grip frame with the action parts and ignitor in place. I inserted a fuel cylinder in the fuel chamber, assembled the fuel chamber, left side grip frame and right side cover to test the timing, trimming the ignitor push rod untill satisfactory timing was established.

PIC#5 The completed action assembly. As you can see quite a bit of the ignitor push rod had to be removed to time the ignitor and fuel cylinder.

PIC#1 To ignite the fuel, I borrowed the pulse ignition from my gas grill. It uses a single AA battery and supplies a steady flow of sparks at about six to eight per second and will jump about 3/4 inch. The grip frame was designed around the ignitor to keep the the total package as compact as possible.

PIC#2 This is the cap that contains the battery and push button contact in the ignitor body. To keep the grip frame as slim as possible I removed the flange around the base of the cap with a Dremel and drum sander.

PIC#3 To secure the ignitor to the grip frame I simply screwed the cap to the ignitor body sandwiching the bottom of the grip frame. It only needs to be finger tight to hold it securely.

PIC#4 I attached the ignitor electrode to the fuel chamber with a #10-24 machine screw, flat washer and lock washer. The ground wire will be attached to the fuel chamber under this nut.

PIC#5 Final step before test firing, I shortened the wire harness that was part or the pulse ignition and attached one wire to the ceramic insulated electrode and grounded the other to the fuel chamber. Time to gather a video camera and a fire extinguisher and go outside.

The website below has some files in which you can download for some better views of what seems to be the trigger mech or internal mech inside....