Drill Thick Steel Without a Drill Press
Using a clamp to apply steady mechanical feed pressure so a hand drill can cut cleanly through steel too thick for body weight alone.
Lay Out a Pipe Saddle Cut With a String Compass
No pipe notcher? Mark the joint centerline, measure down one full pipe diameter, and swing that length with a string and marker to trace the saddle curve — grind to the line and the joint fits tight.
tube notching by hand, cope tubing for welding, fishmouth template alternative, cut pipe to fit around another pipe
The Problem
Joining round pipe to round pipe means the end of one pipe has to be scalloped — a saddle, or fishmouth — to wrap the other. A notching tool does it in seconds, but without one, most people cut the end square and try to weld across a gap that opens to an inch at the sides. That's a weak joint and a lot of filler.
The Technique
This fabricator lays the curve out with nothing but a measurement and a string:
- Mark the centerline of the joint on the pipe being coped — where the center of the crossing pipe will land.
- From that center mark, measure down the pipe a distance equal to the full diameter of the crossing pipe, and mark it.
- Cut a piece of string to that length. Anchor one end at the center mark, tie the other to a marker, and swing an arc — the string works as a compass, tracing the saddle curve around the pipe.
- Cut along the traced line with a grinder and clean up the edges.
The coped end now nests over the crossing pipe with a tight, consistent gap all the way around — a joint you can weld properly instead of bridging open space.
Pro tip: The string-compass radius isn't derived from fancy geometry — the full-diameter length lands close enough for field fit-up on common pipe sizes. Test-fit after grinding and kiss the high spots; you're aiming for a consistent gap, not a machined cope.
Safety note: Cutting curves in pipe with a grinder means the wheel edge is doing off-axis work — use a proper cutting disc, keep both hands on the tool, and wear a face shield over your safety glasses. A pinched or side-loaded cutoff wheel can shatter.
DIYsolvr helps you find the best DIY videos. Browse all 526 techniques