Magnetic drills for twist drills, tapping and countersinking

In short: twist drills need a drill chuck or a Weldon shank, countersinking calls for low speed, and tapping requires reverse.

Weldon or Morse taper

Annular cutters have a Weldon shank. Commando, Lynx K and Panther CS K have a 19.05 mm (3/4") spindle bore for them, and Raven, Eagle and Gator have the same tool mounting.

Falcon and Scorpion are built differently. The spindle has a Morse taper — 2 on the Falcon and 3 on the Scorpion — and annular cutters are fitted with a 3/4" Weldon adapter. Rotabroach describes the Falcon as one of its most versatile machines.

Twist drills: drill chuck or Weldon shank

Twist drills can be fitted in a drill chuck on an adapter, and the chuck size is then the largest drill the machine will take. Rotabroach also has twist drills with a Weldon shank from 6 to 13 mm, which fit straight into the machine without a chuck. The chuck capacity is stated as follows:

• Commando — Ø13 mm drill chuck as standard. Rotabroach highlights that the machine is well suited to twist drills and countersinking
• Element 30 and Element 40 — Ø13 mm drill chuck with key included
• Lynx K — supplied with a 13 mm drill chuck. The twist drill capacity is 13 × 110 mm, far deeper than the 50 mm it manages with annular cutters
• Panther CS K — quick-release coupling for an arbor, adapted for a 13 mm drill chuck
• Falcon — Ø13 mm
• Scorpion — Ø16 mm
• Raven, Eagle and Gator — Ø16 mm drill chuck as optional equipment

Machines that only take annular cutters

Adder K is listed as suitable for annular cutters only, and Cobra cannot be used with an ordinary drill chuck. Both are built for one task: Adder K for confined spaces, with an overall height of 210 mm, and Cobra for large holes up to Ø65 × 50 mm.

Countersinking is not ruled out, though. In the accessories overview, Adder K is listed with the CK30 countersink, and Cobra with CK30, CK40 and CK55.

Tapping requires reverse

A tap has to come back out the same way it went in, so the spindle must be able to reverse. Of the machines in the catalogue, Falcon and Scorpion are the ones listed with reverse and tapping capacity.

Tapping should also be done slowly, and both have low gears with variable speed control. It is the combination that makes them suitable, not the reverse alone.

• Falcon — taps up to M20. Low gear 100–280 rpm, high gear 135–500 rpm, 1250 W
• Scorpion — taps up to M30. Four gears, the lowest 45–110 rpm, 1900 W

Countersinking and large diameters call for low speed

A countersink cuts with a large diameter at its outer edge and should run slower than a small drill. Element 40 has a two-speed gearbox with 300 and 600 rpm, and Rotabroach describes the combination as suitable both for countersinking and for larger annular cutters. Commando has six speed settings from 270 to 610 rpm.

Machines with a single fixed speed, such as Adder K at 650 rpm and Lynx K at 620 rpm, do not have that leeway. In the catalogue, Lynx K is described as best suited to softer grades of steel.

When you contact us

Tell us what the machine needs to do in addition to core drilling:

• Largest twist drill, with diameter and depth
• Thread size, if tapping is needed
• Countersinks or other tools you already have, and what shank they have
• Material and material thickness
• Electricity, compressed air or hydraulics at the work site