How to Make Copper Cap Boppers1
By James C. Keffer
1. Copper plumbing caps, sizes 1/2" to 2"* (available at most major hardware stores).
Tools and Materials:
The objective is to get the copper cap as round and smooth as possible. The more round the
cap is the better control you'll have in striking flakes. You want to be able to strike the rock
with a single point of the bopper end as shown below.
Next clean the inside of the cap with sandpaper or a small sandblaster (I use either a small
cabinet sandblaster or an inexpensive siphon sandblaster).
Level the cap and secure (I use a vice and bubble level).
Then melt some lead and pour into the cap. Leveling the cap helps to balance the weight
distribution of the lead creating a more consistent bopper.
sufficient area on the handle and inside the cap for the epoxy to adhere and also places the
weight forward making the bopper more efficient at delivering the energy to the platform on
Let the cap/lead cool. There is a high degree of probability that the lead will not adhere to
the copper, particularly if using hard head. I find the easiest way to secure the lead to the cap
is with epoxy applied when attaching the cap.
lead. This doesn't work as well with hard lead containing either zinc or antimony (the two most
common alloys used to harden lead).
using a blunt punch (or carriage bolt), hammer the lead to where is swells within the cap
thereby creating a tight fit. Again, this also doesn't work as well with hard lead. Since epoxy secures the lead to the cap and the hardened lead doesn't deform, I prefer to use harder lead and epoxy.
any residue or glazing cause by the hot lead. This will help insure the epoxy has the best
opportunity to create a strong bond.
personal preference but most are usually 3-5 inches in length and made of hard wood. Oak, walnut, maple, alder, fir or any other wood that does not contain oils (such as teak which does not take glue well) will work for a handle.
A wood lathe allows for fast and easy turning of custom-fit handles. A variety of shapes,
Turning a handle on a wood lathe:
Checking the fit:
Mix a good two-part epoxy according to the directions. Use only enough epoxy for the
Liberally coat the inside of the cap (if using the epoxy to secure the lead, coat the entire
Clamping the cap:
One the finish is dry you have a bopper!
Drying Boppers (a drying block helps!):
All that is require to maintain the boppers is to occasionally re-seal the handles with your finish of choice.
When a copper cap wears through - and if you use it a lot - it will, you can remove the cap from
From what I've observed the primary reasons for caps becoming loose:
2. Too smooth surface on cap/handle. Solution - roughen the inside of the cap with sandpaper
3. Wood shrinkage - wood shrinks or expands with humidity. Solution - seal the handle with
4. Too much lead in the cap resulting in insufficient glue surface area. Solution - fill the cap just to the top of the domed area.
5. Too tight of a fit between cap and handle, not enough glue area - solution - make sure the gap
1Bopper Cost (as of 9/27/15)
Making boppers can be cost effiective - IF you already have most of the materials on hand. Otherwise it can be much less expensive to purchase a bopper or set of boppers tham make them yourself. The following is a material cost breakdown of making a set of 5 boppers, sizes ½” , ¾”, 1”, 1¼” 1½”. These are material cost for the least cost amount of material you can reasonably purchase at your local hardware store – most cost come from Home Depot. Although the amounts and types of materials are the least cost, you will end up with more than you need, especially polyurethane and epoxy. Unfortunately purchasing smaller amounts may not be possible or at least practical. Also scrap lead, if pure lead, is too soft. It needs to contain an alloying metal like tin (wheel weights) or zinc or antimony. Each of these alloying metals can add an additional cost.1. Polyurethane – ½ Pint (water clean-up) $5.98
2. Copper Caps
a. ½” = $0.63
b. ¾” = $1.36
c. 1” = $2.91
d. 1¼” = $4.25
e. 1½” = $6.12
Total = $15.27
3. Chip Brush 1” Economy = $0.97
4. Scrap lead 3 lbs @ $1/lb = $3.00
5. Sand Paper 9 in. x 11 in.
a. 80, 150, 220 Assorted Grits Advanced Sanding Sheets (6-Pack) $6.97
6. Steel wool
a. 12 pad Steel Wool, Coarse, Medium, Fine $3.98
a. Loctite 8 fl.-oz. Professional Job Size Epoxy $15.67
8. Acetone (cleanup) 1-pt = $4.97
9. Paper towels (cleanup) Basic 1-Ply White Paper Towels $1.00
Total cost of materials1 = $57.81
This does not include the cost of sandblasting sand that I use to clean and roughen the inside of the caps to insure good glue-up. Silica sand is $8.47/100 lbs
Labor CostIt takes about 2-3 hours of actual labor time to make a set of five boppers. This includes time for doming the caps (assuming one has doming blocks/punches)2, melting lead, pouring the lead, sandblasting the caps, turning and sanding the handles, gluing and clamping the caps to the handles, applying the three coats of polyurethane and sanding with steel wool in between coats. This does not include the time it takes for the lead to cool or the polyurethane to dry. It also does not take into account the amount of time or the cost it takes to get the materials. At the Federal minimum wage of $7.25/hour the cost of labor would be about $18.12 (2.5 hours of labor).
Total cost for a set of 5 boppers - $75.93
©2010 J Keffer