Air Screwdriver Over-Tightening? Pick the Clutch, Torque and Grip

Air screwdriver stripping threads, cracking parts or leaving every screw a little different? Start with the clutch, then match the torque range to your screw, the grip to the joint and the air line to the tool.

PartsForMachines has 22 air screwdrivers in its Air Screwdrivers range: shut-off, cushion-clutch, stall and impact models from Chicago Pneumatic, Sealey and PCL, in pistol and straight bodies.

Shut-Off, Cushion or Stall: Which Clutch Stops Over-Tightening?

A shut-off clutch is built for exactly this. Shut-off models such as the CP2621 straight shut-off screwdriver (0.8 to 6.5 Nm) stop the drive at the preset torque, so each screw finishes the same without relying on the operator’s feel.

A cushion clutch, as on the CP2612 (1 to 6 Nm), also has an adjustable torque setting but does not shut the air off, and suits a broad mix of fastening work.

Stall and direct-drive models such as the CP2810 have no torque setting, so the final torque depends on the air pressure and the operator. They run screws down quickly, and on the positive-clutch CP2780 the operator controls when the clutch engages, for more torque.

Which Torque Range Do I Need for My Screws?

You need a tool whose range covers the torque your screw and joint call for, so check the drawing or the fastener maker’s data first. For small screws, the CP2814 pistol shut-off screwdriver covers 0.4 to 4.3 Nm.

For mid-sized work, the CP2611 covers 1 to 7.5 Nm and the CP781 6.2 to 11.3 Nm.

Higher up, Sealey rates its SA58 at 115 lb.in (about 13 Nm), and the PCL APT407 and APT408 give 17 Nm. For more torque from a compact tool, see the impact FAQ below.

Pistol or Straight, Trigger or Push-Start: Which Suits the Job?

Choose by the joint: a pistol grip suits driving horizontally into an upright panel, while a straight body, such as the APT408, keeps the drive in line with your wrist for detail assembly on a bench. The CP2611 pistol shut-off screwdriver has a progressive trigger and three air inlets for easier access.

Most pistol models start with a trigger, but straight tools vary. The CP2621 and CP2622 are push-start models, while the CP782 has a progressive lever start.

What Air Pressure, Hose and Fittings Does an Air Screwdriver Need?

It needs its working pressure at the tool while it runs, a hose of the right bore and a plug that matches its inlet thread. The CP models are rated at 6.3 bar while running, the Sealey ones at 90 psi. Low pressure at the inlet costs power and, on a stall tool, lowers the final torque, so check it at the tool.

For a 5 m hose, the CP2611 needs a bore of at least 10 mm and the CP2810 8 mm.

Inlet threads differ: 1/4in NPT on the CP2621, but 1/4in BSP on the SA58 pistol air screwdriver, which uses 4 cfm at 90 psi. NPT and BSP threads are not interchangeable, so match the plug to the inlet.

What Should I Check Before I Buy?

• the clutch: shut-off, cushion, stall or impact, to suit how exact the torque must be
• the torque figure for your screw, inside the tool’s range
• the grip and start: pistol or straight; trigger, lever or push-start
• the working pressure, the minimum hose bore and the inlet thread, NPT or BSP
• 1/4in hex bits to suit the holder, and reverse if you take screws out

Not sure which suits your job? Contact the PartsForMachines team by WhatsApp, telephone or email with your screw size, torque figure and air supply, or browse the Air Screwdrivers range.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Can an air screwdriver take screws out as well?

Almost all of ours can. The CP models here are reversible, the SA58 has reverse control and the APT407 a forward/reverse switch. If you rework or strip down assemblies, check for reverse before you order.

Will my 1/4in hex bits fit?

Yes. Every model here has a 1/4in hex drive. Most hold the bit in a quick-change holder, the CP2141 uses a ball detent, and the SA58 and SA623 have a quick-release chuck.

What is an air impact screwdriver for?

More torque from a compact tool. The CP2141 impact screwdriver covers 10 to 24 Nm and the CP2136 8 to 21 Nm, both with a rocking-dog impact clutch. They vibrate more: 5.3 and 7.4 m/s², against under 2.5 m/s² on most other models.

How is the torque adjusted: key or ring?

It depends on the model. The CP2814 is set with a key, while the CP2611 has a rotating ring that needs no tools. Some ring models, such as the CP2612, add colour rings so you can see the setting at a glance.

How do I know the torque is right?

Check it on the real joint, not just the setting on the tool. Torque checks are recommended, because a tool that is wrongly set, misused or short of air pressure will not give the torque you expect.

Why does my screwdriver stop before the screw is home?

Check the air first: low pressure at the inlet costs power and can stall the motor before the screw seats. If the pressure is right, the torque setting may be too low for the joint, or the tool too small for it.

Which air screwdriver is easiest on the hands and ears?

A light, quiet, low-vibration one, so compare weight, noise and vibration on the product pages. Weights run from 0.68 kg on the CP2136 to 1.36 kg on the CP781. Sound pressure runs from 73 dB(A) on the CP2824 to 99.5 dB(A) on the CP781.

Can I change where the air hose connects?

On some models, yes. The CP2611 and CP2612 pistol screwdrivers have three air inlets, so you can connect the hose in the position that suits the job and your grip.