TIPS AND TECHNIQUES:
Installing End Caps on Big-Hole Beads
by Larry Barefield
End Caps: Tools, materials, and procedure (for 3/8 holes
A circle cutter www.contenti.com Item #190-009)
A center finder (woodworking store or, possibly, Home Depot, Hardware
A center punch (Home Depot, Hardware store)
A dapping set [punches and block www.contenti.com Item # 190-225);
youll use the 3/4 and 7/8 punches and corresponding dapping block holes.]
Files ( a flat fine cut and a 1/4 round chainsaw)
Some kind of center hole generating method
A small metal plate (with a hole made with the drill bit listed below)
One 13/64 drill bit (hardware store, Home Depot)
A tubing cutter (hardware store, Home Depot)
A Dremel tool, buffs, and buffing compound
A torch of some type
Water for quenching the copper tubing when annealing it
Safety equipment (safety glasses and gloves)
An ample supply of cuss words
Anneal the metal materials
Cut the circles
Mark the center of the circle using the scribe and the center finder, and prick the center with the punch
Dome the circle with the dapping punch and block (if you use a step drill,place the punch mark down; if you are using a lever punch, place markup)
Make a hole (Set the dividers to ~3/16 and scribe a circle around thepunch mark. Using the nut, lock the dome on the flare fitting. Use a stepdrill to make a hole about 5/16 dia. and check for concentricity; if ok, drill
out to 3/8. If not, use some of those cuss words and the chainsaw file to enlarge the hole in the correct direction; using the scribed circle as a guide. The lever punch is self explanatory)
Scrub the faces of the end caps on the file to remove burrs, etc.
Select a well annealed bead with no projections, bumps, etc. on the ends where the caps will fit.
Hold an end cap on each end of the bead and push the tubing through the assembly until it projects a little less than 1/2 the diameter of the bead hole (about 5/32) past the end cap.
Scribe a mark next to the end cap and measure the distance to the end of the tubing.
Scribe a mark next to the other end cap, measure out the amount of projection and make a mark on the tubing at that point. You have now established the overall length of the tube/rivet (well start calling it a rivet now) and you have located the position of the bead/end cap assembly on the rivet
Secure your 13/64 drill bit upside down in the vice and put the plate on it. Place the bead/end cap/rivet assembly over the drill bit and slightly loosen the vice and slide the drill bit up or down until the end is just below the
upper end of the bead.
Select a dapping punch that that is slightly larger than the inside diameter of the rivet, place it on the rivet and tap it to slightly spread the end.
Flip the assembly over and do the same to the other end (you may wish to use a thin rubber band to hold the end caps and bead in the center of the rivet while you are doing this).
Select a larger punch and repeat the previous two steps.
Continue flipping the bead and using larger punches until you notice that the blows to the punch are causing the rivet flanges to flatten out where they contact the metal plate. Then, flip the rivet on the drill bit and using light blows with the hammer tap until the flanges of the rivet are horizontal (at 90 degrees to the axis of the rivet).
When the flanges are flat, use light hammer blows to turn the flange down so that it evenly contacts the end cap all the way around.
Take the drill bit out of the vice and use it as a mandrel to hold the bead for polishing. Using a gloved hand, hold the bead on the drill bit with your thumb (to keep it from spinning) and polish it with a liberally rouged felt buff in the Dremel. You can use the flare fitting referenced above, a small pilot drill (~1/16), and a step drill to make holes without a punch. This method has an advantage: you can correct an off center hole by stopping short of full hole diameter and correcting with a Dremel and a grinding burr.
Heres how it works:
And thats all there is to it.
Happy end capping,