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.
Workholding is the bottleneck that nobody budgets for. When I walk into a shop that is struggling with deep hole drilling throughput, nine times out of ten the fixturing is the problem, not the machine. Modular fixturing systems have changed how I approach setup planning, and the numbers speak for themselves. The Case for Modular Fixturing Dedicated fixtures for deep hole drilling parts commonly cost $2,000 to $8,000 each and take four to eight weeks to manufacture. For a shop running fifty different part numbers, that investment becomes prohibitive quickly. Modular fixturing, built from standard base plates, locating towers, clamp brackets, and support elements, can cover 80% of those parts with a single system investment of $15,000 to $30,000. ...
Coolant pump motors on deep hole drilling machines need properly sized starters and drives to operate reliably. A pump that starts and stops frequently under high pressure draws significant current during startup, and the starter must handle this without tripping or welding its contacts. I have seen coolant pump motors fail prematurely because the electrical system was undersized or improperly configured. Motor and Starter Sizing Guidelines The motor full-load current is listed on the motor nameplate, and this is the starting point for sizing the starter and protective devices. I follow standard electrical engineering practice with some specific adjustments for coolant pump applications. ...
MQL uses a small amount of oil or lubricant sprayed as a fine mist instead of flooding the cutting zone with coolant. It is common in conventional machining operations like milling and turning but rare in deep hole drilling. The main challenge is chip evacuation, which in deep hole drilling depends on high-pressure coolant to push chips out of the bore. Recent research on MQL in deep hole drilling (2025 Manufacturing Letters, and a 2023 comprehensive review) confirms that MQL is technically feasible for certain deep hole applications and can actually outperform flood coolant on tool life in some cases. But the data also confirms what I have found in practice — the L/D ratio and material type are the deciding factors. ...
Every deep hole driller remembers their first breakage. It’s like a rite of passage — one of those moments that divides your career into “before” and “after.” Before the break, you think you know what you’re doing. After the break, you know how much you don’t know. Mine happened in the fall of 2008, on a Tuesday morning that started like any other. I was twenty-four years old and had been running deep hole drills for about a year. I thought I had it figured out. I’d done a hundred jobs by then, maybe more. I’d changed drills, adjusted feeds, swapped guide bushings, and read chips like a pro. The senior guys had stopped hovering over my shoulder, which I took as a sign that I’d arrived. ...
When a bore comes out oversized, pressing in a thin-walled bushing can save the part. The process involves boring the damaged hole to a larger diameter, pressing in a bushing, then boring or drilling the bushing to the original size. I have used this technique on hydraulic cylinder barrels, pneumatic valve bodies, and machine tool housings. It is a reliable repair method when done correctly, but the details matter a great deal. ...
It was a Friday afternoon in November, and I was ready to go home. The week had been long — a series of small problems that added up to a lot of frustration. A coolant pump failure on Tuesday that took half a day to repair. A bad batch of raw material on Wednesday that had to be returned and replaced. A customer change order on Thursday that forced us to rework thirty completed parts. By Friday at four o’clock, I was running on fumes and looking forward to a weekend of doing absolutely nothing productive. ...
Coolant filtration is critical for deep hole drilling. Chips that recirculate through the coolant will damage the drill edge and score the bore surface, causing poor surface finish and short tool life. The two common filter types for deep hole drilling coolant systems are paper band filters and cartridge filters. I have used both extensively and each has strengths depending on the application. Filter Comparison: Paper Band vs Cartridge Paper band filters use a continuous roll of filter paper that advances as the filter media loads up with chips. The paper catches particles down to 20 to 50 microns. The dirty paper is discarded and clean paper feeds in automatically. Cartridge filters use replaceable filter elements with ratings down to 5 to 20 microns. ...
Injection molding machine platens are large steel blocks that hold the mold halves. The moving platen slides on the tie bars through precision-drilled holes. The platens also need drilled cooling channels for temperature control. In my experience, the tie bar hole accuracy determines whether the injection molding machine produces consistent parts over millions of cycles. Platen Sizes and Material Specifications A platen for a large injection molding machine can be 1-3 meters wide and 30-60cm thick. The tie bar holes are 80-200mm diameter through the full platen thickness. The position tolerance between the four tie bar holes is typically within 0.1mm. ...
Large BTA drilling machines weigh 15 to 30 tons and generate significant cutting forces during operation. The foundation must support this weight and absorb the vibration from high-thrust drilling. I have been involved in installing several BTA machines, and I have seen the consequences of poor foundation preparation. A foundation that is not done right causes alignment problems that affect every single hole drilled on that machine. Foundation Design Specifications The foundation should be a reinforced concrete slab that is structurally separate from the building floor. I recommend a minimum slab thickness based on the machine weight and the soil conditions at the installation site. ...
Thin wall tube collapse during deep hole drilling is a problem I have encountered on hydraulic cylinders, gun barrels, and structural tubing. The cutting force pushes the tube wall inward, the drill binds in the reduced diameter, and both the tube and the tool are damaged. Prevention requires managing the forces on the wall and providing adequate support. Problem Description A thin wall tube collapses when the radial component of the cutting force exceeds the buckling strength of the wall section. The tube wall deflects inward under the drill tip, and the bore diameter effectively shrinks. The drill then jams because the bore is smaller than the drill head. ...