Impact Force Comparison of Short and Long Barrel .401 Shank Air Hammers

Air Hammer Impact Force Theoretical Calculation

The theoretical impact force calculation is based on the formula Energy = Force x Distance, plus a calibration factor (explained below), and a few assumptions such as bore-piston clearance and the distance the piston travels before it slams into the bit.

Calibration Factor

Using the available BPM, stroke length, bore diameter, air pressure, and energy from several CP air hammers, we calculated theoretical energy values for each hammer. Then, using the theoretical and published energy values, we obtained several calibration factors (published energy/estimated energy).

The average calibration factor is the one we used in the subsequent calculations, regardless of the brand.

Driving Force = Air Pressure x Piston Area
Piston Area = π x Piston Radius²
Piston Diameter = Bore Diameter - Estimated Clearance (0.003”)

Energy = Driving Force x Stroke Length

Brand	Model	Bore Diameter (in)	Stroke Length (in)	Pressure (PSI)	Published Energy (pounds)	Estimated Energy (Joules)	Calibration Factor
	CP7150	0.75	3.5	90	9.5	15.60	0.61
	CP7165(K)	0.75	3.5	90	11	11.72	0.71
	CP7111	0.75	2.63	90	7.2	7.53	0.61
	CP714	0.55	3.15	90	4.7	11.39	0.62

Average calibration factor = 0.64 (Friction, leakage, and valve losses within the air hammer will eat about 64% of the theoretical value).

Impact force

As above, we determined the energy the piston carried upon impact with the bit. The BPM, bore diameter, stroke length, and air pressure are known values. The bore-piston clearance was assumed once more as 0.003”.

Determining the impact force is just a matter of rearranging the energy formula to Force = Energy / Distance, where distance is no longer the stroke length but the tiny distance over which the piston stops when slamming the bit. For the purpose of this article, we assumed that the distance is 0.0197”.

Impact Force Values Comparison

.401 SHORT BARREL SHANK | 90 PSI AIR PRESSURE
Brand	Model	Bore Diameter (in)	Stroke Length (in)	BPM	Estimated Energy (Joules)	Calibrated Energy (Joules)	Force (lbs)
	CP7110K	0.75	2.64	3,200	11.76	7.53	3,384
	123MAX	0.75	2.63	3,530	11.72	7.50	3,373
	LT955AH	0.75	2.31	3,000	10.30	6.59	2,964
	5100-A-T	0.696	2.63	3,000	10.09	6.46	2,904
	CMXPTSG1010NB	0.696	2.6	2,800	9.97	6.38	2,870

Short barrel average force = 3,099 lbs.

.401 LONG BARREL SHANK | 90 PSI AIR PRESSURE
Brand	Model	Bore Diameter (in)	Stroke Length (in)	BPM	Estimated Energy (Joules)	Calibrated Energy (Joules)	Force (lbs)
	TK-AH40-100	0.75	3.75	2,200	16.71	10.69	4,808
	LT955AH	0.75	3.75	2,300	16.71	10.69	4,808
	123MAX	0.75	3.5	2,530	15.60	9.98	4,489
	CP7110K	0.75	3.5	2,300	15.60	9.98	4,489
	CMXPTSG1010NB	0.696	3.63	2,100	13.93	8.92	4,009
	5100-A-T	0.696	3.00	2,500	11.51	7.37	3,312

Long barrel average force = 4,319 lbs.

While purely theoretical (and unbiased), the values obtained are within the order of magnitude of those reported by reputable YouTube reviewers using gauge equipment, such as the Torque Test Channel.

Based on the calculated average forces, .401 long-barrel air hammers deliver 39.4% more power than short-barrel versions. The result becomes even more interesting given the narrow price gap between short- and long-barrel air hammers (a task we leave to our readers).

Two brands stand out in the table of long-barrel models for their impact force. One of them is probably unfamiliar to you: Tekamo HD.

Tekamo HD Mini Chooch Features Breakdown

The Tekamo HD air hammer, AKA “The Mini Chooch,” comes in a versatile set for multiple applications right out of the box. Here’s the features breakdown:

Technical Specifications

• Impact force: 4,808 lbs.
• Blows per minute: 2,200 BPM.
• Shank opening: 0.401".
• Stroke length: 3-3/4".
• Air inlet: 1/4"-NPT.
• Recommended air pressure: 90 PSI (6.2 BAR).
• Average air consumption: 4 CFM (28 SCFM)*.
• Sound level: 100 dBA.
• Length: 11.5" (292 mm).
• Weight: 6.0 lbs (2.72 kg).

* CFM (Cubic Feet per Minute) measures the actual volume of air flowing at current operating conditions, while SCFM (Standard Cubic Feet per Minute) measures airflow adjusted to fixed, standardized conditions of temperature, pressure, and humidity.

Accessories Included

• TK-AH20-100 Pneumatic Hammer.
• Tie Rod Releasing Chisel.
• Plate Chisel.
• Ball Joint Chisel.
• Square Chisel.
• Three 1/4" air fittings.
• Air fitting types:

• M-Style - Canada / USA (1/4" NPT).
• European Type (1/4" PT).
• Nitto Type - Asia / Australia (1/4" PT).

Conclusion

If you’re up for investing in an air hammer, a long-barrel model is your best bet. If you wanna take that investment to the next level, the Tekamo HD TK-AH40-100 Pneumatic Hammer Set offers a well-balanced package to tackle most tasks: 4,808 lbs of impact force, a variety of adapters, and 3 air fitting types to avoid downtime, no matter which region of the world you’re in.

The nickname “Mini Chooch” might seem contradictory for this air hammer, given the fact that it is categorized as a long-barrel model. The reason is its larger sibling: The Tekamo HD BIG CHOOCH Pneumatic Air Hammer. Check out what heavy equipment mechanics think about it and what they’ve done with it on the Tekamo HD YouTube channel.