Retrofit

A manual lathe can be converted for gun drilling with the right equipment. The conversion costs a fraction of a dedicated machine but comes with real limitations. I’ve done this conversion on a 14-inch Colchester lathe and gotten usable results. The main requirements are a through-coolant toolholder, a high-pressure coolant system, and a guide bushing support. The toolholder mounts on the lathe carriage and holds the gun drill. The coolant system delivers fluid through the tool at the required pressure. The guide bushing supports the drill at the workpiece entry. ...

I get calls from shops that bought a gun drill and want to run it on their existing CNC lathe or manual mill. Half the time, the machine can handle it. The other half, they are fighting the machine’s limitations from day one. Here is how I evaluate whether a machine is suitable — and what to look for if it is not. Spindle Speed Range Gun drilling needs relatively low RPM compared to conventional drilling. For a 10mm gun drill running at 250 SFM, spindle speed is about 2400 RPM. Most lathes and mills can reach that easily. ...

I use gun drilling attachments for occasional deep hole jobs on machining centers. A dedicated gun drilling machine is better for production work, but an attachment makes economic sense when you only drill deep holes a few times per month. The attachment turns a standard VMC or HMC into a capable deep hole drilling setup for a fraction of the cost. Attachment Types: Spindle-Mounted vs Self-Powered Two attachment types are available and each covers a different application range. ...

I’ve worked on machines that were 40 years old and still drilling good holes, and I’ve worked on 5-year-old machines that were falling apart. Age isn’t the only factor in deciding whether to retrofit or replace. Here’s what I’ve learned about the decision. Why Retrofit A retrofit replaces the control system, drives, and sometimes the spindles of an existing machine while keeping the base structure — the bed, columns, and way systems. The idea is that the structural components are still sound, and the outdated parts are what’s limiting performance. ...