Speargun Fabrication By Matt Willmott
01. Cut strips to ¼ by 2 inches. After cutting the strips need to be left to age for at least a month. This will allow all of the internal stresses to work themselves out and make for a much more stable finished product.
02. Glue and clamp the strips together to make your rough stock blank. Use West System epoxy as shown and place steel straight edges on both sides of the laminations. Make the stock ¼ inch bigger than the finished size to allow for planing. It is much easier to remove stock later than it is to add it.
03. Remove rough stock from clamps after 24 hours.
04. Attach a straight edge to the rough stock and cut the opposite side on a table saw. You will now have a perfectly straight edge to work from. ( a jointer is obviously easier but not everyone has a jointer)
05. Run all sides of the rough stock through a planer to achieve your finished stock size.
06. Make a template out of something cheap (I use poplar) for marking out and setting up machinery. Better to make a mistake on this than on your finished gun.
07. Make the mortise for the trigger with a drill press and forstner bits. Finish with chisels.
08. Run the shaft groove with a core box cutter in a router table. Make multiple shallow cuts and check each one for straightness. This is the most important factor in determining accuracy of the gun.
09. Use the router table again to shape the stock to accept the handle. It is important to make this a very snug fit. Any voids between the handle and the stock will translate to weakness and noise (like a drum).
10. Finish the handle area with chisels and sandpaper.
11. Check the fit and position of handle.
12. I now add an additional piece of teak to the underbelly of the gun. This is needed here because this is a very short gun (32?) and needs the extra buoyancy.
13. The dovetail slot is used purely to hold down the acrylic cover over the remote trigger rod. (Unnecessary on a rear handle gun).
14. Cut the slot to accept the power bands on the drill press with a forstner bit.
15. Smooth the slot with file, rasp or sandpaper.
16. Round the edges of the slot with a 3/8? radius bit.
17. Use the same procedure for the tag line hole in the rear of the gun.
18. Bore a hole for the muzzle reinforcing bolt.
19. Cut a groove for the tag line to run in. Use either the table saw or a router with slot cutter.
20. Smooth any rough edges from the groove.
21. Epoxy extra teak to the rear for a butt plate. (If using pre-fab rubber but you will need to shape the rear to accept it now)
22. Shape the butt using drum sander.
23. Cut the slot in the muzzle.
24. Take the gun to the water (pretend that blue chair is the ocean? I forgot to take a camera to the beach!). Use lead sinkers to determine how much mass needs to be added to the gun. At the very least the gun wants to sink slowly with the shaft in and float when the shaft is released. When the amount of mass has been determined move the lead forward or backward on the gun until you find the right balance. Mark the positions of the lead on the gun.
25. Drill holes where the lead needs to be and melt the sinkers into these holes. Leave a little space at the top of the hole and fill with wax or a timber plug.
26. Apply any finish desired. (I use the same epoxy or an automotive clear coat)
27. Assemble hardware and go hunting.