Real problems, real solutions, no fluff. I have spent years working across multiple shops running gun drilling, BTA drilling, and ejector drilling machines — setting up jobs, troubleshooting coolant pressure and chip evacuation issues, drilling deep holes in everything from hydraulic cylinders to aerospace titanium. This site is where I share what I have learned.
Why Layout Matters More for Deep Holes A deep hole drilled in the wrong position is scrap. The deeper the hole, the more material I waste when I miss the location. A 500mm hole missed by 2mm at the entry end might be off by 5mm at the exit end, and the entire workpiece is lost. The geometry of deep holes amplifies layout errors. A 0.5mm error at the entry point becomes a much larger error at the exit, especially for long holes. The critical dimension is often the hole position at the exit face, where the hole needs to connect with a cavity or another hole. ...
I use bore gauges for most deep hole measurements. I have measured thousands of holes across dozens of shops, and the right tool always depends on the tolerance and the hole depth. Measuring the diameter of a deep hole is not the same as checking a conventional bore. Access is limited. The bore is long and narrow. Standard calipers and bore mikes will not reach past the first 100mm. Over the years, I have settled on five main methods that cover the full range of what I encounter on the shop floor. ...
Machine spec sheets list dozens of numbers. Not all of them are equally important. Here’s how I read a spec sheet and what I focus on. Critical Specs These specs determine whether the machine can do the job: Drilling diameter range. The minimum and maximum diameter the machine can drill. The effective range is narrower than the spec range because tooling availability limits the actual range. Drilling depth. The maximum depth the machine can drill in one pass. This is determined by the feed axis travel and the drill tube length. ...
I dial in parameters in a specific order. Skip ahead and you’ll chase problems that were avoidable. Here is my workflow for setting up a new deep hole drilling job. This guide assumes you already understand the basics. For a deeper look at the underlying theory, see my parameter guide. For material-specific speed and feed tables, check the speeds and feeds reference. My Step-by-Step Workflow I start from the work material and work forward. Each step depends on the one before it. ...
Gun drills are precision cutting tools. They have a carbide tip, a long slender shank, and a critical cutting geometry. Improper storage damages the drill and reduces its life. Here’s what I’ve learned about storing gun drills. Storage Racks Gun drills should be stored horizontally in dedicated racks. The rack supports the drill along its full length to prevent sagging. The rack should have individual slots for each drill with a V-groove or U-groove that supports the drill shank. The drill should not contact other drills in the rack. ...
I’ve lost count of how many hydraulic cylinders I’ve worked on. They’re everywhere in this trade — earthmoving equipment, forklifts, press brakes, oil field gear. The core problem is always the same: you need a straight, smooth bore to a depth that a conventional drill can’t touch. I’ve done them with gun drilling and with BTA. Here’s what works and what doesn’t. BTA Is Usually the Right Call For most hydraulic cylinder work, the bore diameter falls between 50mm and 200mm, with a length-to-diameter ratio somewhere between 20:1 and 50:1. A typical job might be an 80mm bore through 2 meters of steel. ...
Deep hole drilling machines rely on hydraulic systems for feed axes, steady rests, clamping, and sometimes spindle drive. When the hydraulic system has a problem, the machine stops or produces bad parts. I have diagnosed hydraulic issues ranging from simple low-oil problems to failed pumps on machines with 200-liter reservoirs. Problem Description Hydraulic system problems show up through a set of recognizable symptoms. Low pressure, slow operation, overheating, noise, and erratic movement each point to different root causes. The challenge is matching the symptom to the cause without replacing parts randomly. ...
How In-Process Gauging Works In-process gauging measures the bore diameter immediately after the drill retracts, while the part is still in the machine. The gauge enters the bore at the end of each drilling cycle and takes readings at programmed depths. The two main types I work with are air gauging and contact probing. Air gauging uses a small plug with orifices that measure the gap between the plug and the bore wall. Contact probing uses a mechanical finger that touches the bore surface and sends a signal through the machine’s probe receiver. ...
When I started in deep hole drilling, I didn’t understand why the experienced operators spent so much time looking at the chips coming out of the hole. They’d pick up a chip, look at it, and then adjust a parameter. It seemed like magic. My mentor explained: “The chips tell you everything. Short and broken means you’re cutting. Long and stringy means you’re rubbing. Fine powder means you’re forcing it.” ...
Leveling and aligning a deep hole drilling machine after installation is one of the most important steps in setting up the machine for production. A machine that isn’t properly leveled and aligned will produce holes that are off-center and non-straight. Here’s the procedure I use. Tools Needed Precision level (0.02mm per meter sensitivity) Test bar (precision-ground, fits the spindle) Dial indicators (0.001mm resolution) Feeler gauges Wrenches for leveling pads Step 1: Rough Leveling Place the precision level on the machine bed ways near the headstock end. Adjust the leveling pads until the bed is within 0.1mm per meter of level in both the longitudinal and transverse directions. ...