Electric tapping arm — GUANGDU M20

Electric tapping head on a balanced articulated arm, for cutting internal threads M3–M20 in pre-drilled holes. The arm guides the head; the tapping motion and reversal are motorised.

Tap chucks

• Quick-change system: GT12. DIN and ISO chucks from M2 to M18, stored in labelled 3D-printed organizers. Return each chuck to its labelled slot.

• M2 chucks exist, but the machine is rated from M3. No M20 chuck is available.

• DIN and ISO taps of the same thread size have different shanks — pick the chuck matching the tap's standard, shank diameter and square. Example: M6 DIN 371 = Ø6.0 mm / □4.9 mm; M6 ISO 529 = Ø6.3 mm / □5.0 mm.

• Most chucks have a preset torque clutch. Do not adjust it. The outer ring with two holes is the torque adjuster, not a release.

• Some large chucks (including M18) and all die chucks have no clutch.

• The touchscreen's electronic torque limit does not work — don't rely on it.

Choosing tap and hole

• Use the tap drill size from the tap's data or the Gühring tables below (e.g. M6 × 1 cutting tap → Ø5.0 mm).

• Deburr the hole before tapping. Use tapping fluid.

• Allowed materials: metal and plastic. No wood or composites.

Controls

The touchscreen shows Chinese labels:

Handle buttons in manual mode: upper = reverse (unthread), lower = tap. In automatic mode the reverse button stops the cycle. The red rocker switch is the power switch; there is no separate emergency stop.

Automatic mode, deep-hole cycles, left-hand threads, dies and changing the head orientation require separate instruction.

The values shown in these photos are examples, not defaults.

Safety

• Clamp the workpiece and fix the vise/fixture to the bench. Weight is not workholding.

• Eye protection. No gloves; secure hair, clothing and jewellery.

• Don't side-load the tap with the arm, and never bottom the tap.

• Stop before measuring or clearing chips. Power off before changing chucks or cleaning.

How to use (manual mode, right-hand cutting tap)

1. Drill and deburr the hole. Select tap and tapping fluid.

2. Clamp the workpiece in the vise and secure the vise to the bench. Check the arm can reach without obstruction.

3. With power off, put the tap in the matching chuck and click the chuck into the GT12 coupling. Check it's locked.

4. Power on. Set manual mode, pitch, tapping/return speed and depth. Don't trust values left by the previous user.

5. Position the tap square over the hole with the arm relaxed.

6. Press tap (lower button) and guide the head without pushing sideways.

7. Press reverse (upper button) at depth and keep the head aligned while the tap backs out.

8. When stopped, inspect the thread. Power off, remove the chuck, brush/vacuum the chips, and return the chuck to its slot.

Troubleshooting

Maintenance

• Keep chips and fluid away from the touchscreen, vents, connectors and arm joints. Don't blow chips with compressed air.

• Check column fasteners, pivots, gas struts, head alignment, coupling and cables.

• Lubrication, strut adjustment, machine parameters and electrical work are maintainer tasks.

• Maintenance and repairs log

Specifications

Speed from a cutting-speed recommendation: rpm = 1000 × Vc (m/min) ÷ (π × tap Ø mm), capped at 500 rpm. The tap advances one pitch per revolution.

Documents and links

• Tapping arm manual, English (PDF) — generic manual for the M12–M42 family (lists M20 radius as 1000 mm). Controls pp. 8–11, parameters and faults pp. 12–13, care and chucks pp. 14–15.

• Gühring: tap drill sizes, cutting taps · tap drill sizes, forming taps · tapping formulas · tap standards

• Shank dimensions: Bilz DIN · Bilz ISO

• Carmex tap selection guide

• Metal — Open questions