Walking into most metalworking and woodworking home workshops, you’ll see various machine tools populating the shop floor: a lathe, router, grinder, bandsaw, hand-held power tools, variable speed drill press, several hammers, an assortment of clamps, and a few abrasives for sanding.
However, sitting on a workbench next to the bench grinder might be the shop’s most versatile piece of equipment: a mill drill. It’s a multi-function machine that doesn’t often appear in large manufacturing shops, but hobbyists and self-employed machinists are pretty familiar with it.
What is a Mill Drill Machine?
Those in the home metalworking and woodworking trades and many hobbyists are likely familiar with the mill drill, sometimes referred to as a drill mill. These machines represent compact versions of a drill press and Bridgeport-type vertical mill combo.
The drill press part of the mill drill uses a drill chuck to hold the cutting tools (typically drill bits) that give the machine its drilling capacity. An R8 spindle taper on many machine tools allows the operator to use collets and cutting tools such as end mills to machine slots and flats on a workpiece.
Although the multi-function mill drill machine looks like it has all the attributes of a Bridgeport-type vertical mill and drill press, they are only similar. The heavy-duty vertical mill is a freestanding model that weighs considerably more than a mill drill and can go well beyond the benchtop machine’s light milling and drilling capabilities.
However, the mill drill can be an invaluable addition to the home workshop because it is much more affordable than a full-size machine tool and takes up less of the limited space in a small DIY shop or garage.
If you like having one machine that performs two distinctly different operations—drilling and milling—you should know what to look for before shopping for your mill drill machine. Although several vital features make an excellent mill drill, here are five of the essential elements you should consider:
1. CNC Capability
Some might be surprised that anyone would recommend a mill drill with CNC milling capability. Although this would have been entirely out of the question in the past, today’s models and software are user-friendly and affordable, making them available to hobbyists and one-person shop who wants to machine complex parts or even take on a few production jobs.
That’s not to say that you must have a CNC mill drill. Only you know what type of work you intend to do, and you may not need or want to go through the learning curve that CNC requires when your work won’t take full advantage of it.
If that’s the case, the rest of these features apply to manual mill drills, so make sure the machine tool you’re considering has them.
2. Power Feed
A power feed on the X-axis of your mill drill is an invaluable feature. You can set a constant feed rate, giving you a better finish and freeing you up to walk away and do some other productive tasks. If you have lots of milling work, you don’t want to be manually cranking the table for hours on end.
Some power feeds even have a rapid traverse feature that moves the table back to the starting point at a high feed rate with the push of a button. The lack of rapid traverse may not be a deal-breaker, but having one will make you more productive–and a lot less tired at the end of the workday.
3. Digital Readout (DRO)
A digital readout (DRO), sometimes called a digital position readout, indicates the position of the cutting tool relative to your workpiece. The positions are detected by encoders mounted on the X, Y, and Z axes. The encoders in DRO systems have a scale that remains stationary and one that moves with the workpiece. The encoder measures the variations in the position of the two scales and sends the readings to a display.
A DRO allows an operator to machine parts faster and with greater accuracy. There are fewer calculations and less time spent checking and measuring. With a DRO, you eliminate the possibility of misreading the mill’s handwheel dials and losing the count of the wheel rotations. Also, you don’t have to worry about switching from metric to imperial since the DRO makes the conversion quickly.
4. Adequate Work Table
Even though you’re goal is to take up as little space as possible, your mill drill’s work table should be large enough to handle the work size you are anticipating. Remember that if you hope to machine small parts, you must attach a vise, which will take up table space. For a general guideline, your work table should be around 8″ x 28″ to accommodate moderate-sized workpieces and should have travel limits of 19 “on the X-axis, 7″ on the Y-axis, and 5” on the Z-axis.
Also, look for a machine with a 360-degree head swivel and an ironclad warranty.
Look at the machine’s horsepower and ensure you are getting around 2 HP, enough to power a carbide end mill through a stainless steel workpiece, for instance. Also, check out the spindle speed, which should get up to 3,000 RPMs. Your mill drill should have variable speed controls, allowing for speed adjustment for the various materials you’ll be machining.
Keep in mind that some small benchtop milling machines will have more power, giving you opportunities to do a greater variety of work. Larger machines are typically more accurate because they are more stable than smaller models. They also have heavy-duty collets that can accept up to 3/4″ diameter shanks for producing substantial parts.
What Type of Mill Drill Machine Meets All the Essential Criteria?
Although other brands and models might have some of the essential features that define an excellent mill drill machine, one machine rises to the top of the pack: the Jr. Table Top CNC Mill from CNC Masters.
This benchtop mill has plenty of power and doesn’t require much of your valuable floor space. As a CNC machine, you’ll be able to take on production work and some of those complex jobs you’ve shied away from in the past.
With a working area of 28-3/4″ x 8-1/4″, this machine can handle small to mid-sized workpieces, so you won’t be as restricted as you would be with a mini-mill. And its versatility means you can program the complicated work and use it as a manual machine for those quick and dirty operations.
Like all our machines, the Jr. Table Top is built in California and backed by the CNC Masters One-Year Warranty. We also offer unlimited “Life-Long” Tech Support, step-by-step troubleshooting, and a walk-through process by email or phone, Monday-Friday during regular business hours, Pacific time, for as long as your company owns the machine. Unlike costly servo systems, our machines are easy to repair, replace, and maintain!