中文（繁體字）
English (international)Definition of Mill Drill Gear Head Drive
Speed changes are made by moving a lever with the spindle stopped, so the operator is not opening a belt cover and shifting a belt by hand several times a shift. Gear heads are heavier, noisier and more expensive than belt drives, and they pass more vibration to the spindle at high speed. Most shops accept that in exchange for torque and convenience.
Why it Matters for Band Saw and Mill Drill Machines
The cost appears at the top of the speed range. Gears have backlash and they have tooth mesh frequencies, and both reach the workpiece as surface finish. A belt absorbs some of that. Where fine finishing at 2000 rpm and above is the main work, a belt head, or a belt head driven by an inverter, will usually leave a better face. Many mill drill machines sold today pair a gear head with an inverter, which covers both ends of the range reasonably well.
Gear heads need oil, and they need respect for the shift procedure. Change the head oil at the interval given in the manual, typically after the first 100 hours and annually thereafter, and check the level before each shift on a machine in daily use. Never move a speed lever with the spindle turning. Forcing a shift chips the gear teeth, and a chipped tooth announces itself as a regular tick that grows worse and ends in a strip-down.
Related Terms
Spindle SpeedBelt Drive
Quill Feed
Gear Backlash
Variable Frequency Drive
Spindle Torque
FAQ
When does a mill drill gear head drive outperform a belt drive?
At low spindle speeds under load. Drilling a 40 mm hole, tapping, or running a 63 mm face mill in steel all call for high torque at 100 to 300 rpm, and a belt at that end of its range tends to slip before the motor reaches full output. A mill drill gear head drive puts the motor's torque through gear reduction with nothing to slip, so the machine works to its rated drilling capacity. Above roughly 1500 rpm the advantage reverses, since gear mesh vibration reaches the workpiece and shows in the surface finish. Shops doing both kinds of work usually keep the gear head and slow their finishing passes.
How should speed changes be made on a mill drill gear head drive?
Stop the spindle first, every time. Moving a lever while the gears are turning chips the tooth faces, and a chipped tooth in a mill drill gear head drive shows up as a regular tick that grows worse until the head has to come apart. If a lever will not engage, rotate the spindle by hand a few degrees to line up the dogs rather than forcing the lever. Some machines have a jog button for exactly this. It is worth returning the levers to the lowest range at the end of the day, which takes spring pressure off the shift forks and makes the next morning's selection easier.
What maintenance does a mill drill gear head drive require?
Oil, and attention to how the head is shifted. Check the sight glass before each shift on a machine in daily use, and change the head oil after the first 100 hours and annually thereafter, or on whatever schedule the manual gives. Use the grade specified rather than a general hydraulic oil, since a gear head relies on the film strength of the oil under tooth pressure. Listen for changes: a mill drill gear head drive that has developed a tick, a rumble or a new pitch at one speed setting is reporting a problem while it is still cheap to correct. Keep swarf off the top of the head, where it works into the lever seals.
