Steady-Rests

Why Straightness Matters in Drill Collars Drill collars are thick-walled tubes used in oil and gas drilling strings. They need a through-bore for drilling fluid circulation. The bores are typically 50-100mm in diameter through 6-10 meters of length. The straightness requirement is about 0.5mm per meter maximum. I have seen what happens when a drill collar exceeds this spec — the eccentric mass causes vibration in the drilling string that accelerates tool joint wear and can lead to down-hole tool failure. ...

Drilling a long shaft — say 1.5 meters of solid steel with a 10mm hole through the center — looks simple on paper. But it’s one of those jobs where the setup matters more than the cutting parameters. If you’re working on cylinder bores instead of solid shafts, I covered BTA drilling for hydraulic cylinders here. This one is about shafts. The shaft wants to whip. The drill wants to wander. Coolant has a long way to travel. Here’s how I deal with each. ...