- I cut the ramp about 1/8″ oversize, in this case 7/8″ tall at the end (2 1/4″ x 7/8″ x 1/4″ x 20º). That gives plenty of wiggle room when the ramp is machined. I surface the bottom only, I’ll get the other two edges later. Make two, one will be used to clamp the other for welding. I cut two ramps out of one piece of 2 1/4″ long 1″ bar stock.
- Square the sides of the sole (5″ x 1 1/2″ x 1/4″) as they will be reference surfaces, leaving at least 1/16″ of overhang per side; we’ll be doing a bit of pounding on it (I just skim the edges).
- Rough shape the ends as it is easier before the ramp is attached. I use a bandsaw and files, a disk sander works great to get it square and smooth. The ends will be finished after the shell is attached.
- Weld on the ramp. Or [silver] braze it. Just be careful about the amount of heat you pump into it. The sole is going to banana some or a lot. I TIG tack (no filler) in three places (on each side); it is quick, clean and strong enough. I’ve also silver brazed but that is slow, messy and way strong. Position the butt of the ramp 5/16″ from the end. Note: It is a good idea not to tack the ends of the ramp as we’ll be machining there and a quick tack will harden even this mild steel (the rest of the sole draws the heat so fast that the puddle is quenched). This makes alignment a bit more problematic but we won’t have to anneal or use coated carbide endmills.
Here I’ve put clamps at each end of the ramps (to keep them from sliding) and have a square set to center the ramp. I’ll tack one spot, remove the clamps and, starting in the middle (which will help minimize warpage), tack the rest of the ramp, alternating sides. If I would let it cool between tack pairs, it would probably reduce warping.
- Post weld/braze, the toe will likely be kicked up (due to metal expansion/contraction). If you over did the weld, the sole will also be curled (the sides rolling up towards the ramp). You may or may not want to remove it. I do, just ’cause, by pounding on it with a dead blow hammer. Curb your enthusiasm, don’t make it worse. Most of the bow is over the front half of the welded area.
- Face the sole. This is why we don’t care all that much about welding warp, all the critical areas will be machined square.
- Lap the sole to remove machining marks and make sure it is flat (critical to getting the mouth right). I’m usually out a thou or so due to vise induced warpage. Remember that rubbing the sole back and forth on sandpaper is a good way to make it less flat so check often and be selective where you sand and apply pressure.
- This is the last time this surface will be machined but we’ll be doing [much] more lapping later.