anvilfire! Power hammer Page   Page 1   Page 2   Page 3   Page 4   Page 5   Page 8  

The NEW Air hammers

Which is right for you? anvilfire comparison shops.
Hammer Ram Anvil Ratio AE HP Stroke Work
s/m Pwr
Inst Cost T$/lb $/k
C'burg Util 100 1,800 18:1 62% 10 13" 10" 200? k $56,000 $18.6 $
Kuhn 88 572
5 8" 5" 228 k $16,000 $9.5
User Mod
75 275
5 11" 8" N/A
k $5,900 $7.4 $
Bull 75 675 9:1 35% 5 11" 8" 160 k $5,550 $7.2 $
Old Blue 75 500+ 6.7:1 25% 5 10.5" 7.5" 200 k $5,350 $4.5 $
Trip Air 40 320?? 5 10.5"? 7.5" 120 k $5,700 $5.2 $
AE = Anvil Efficiency based on ram/anvil ratio from Chambersburg Engineering literature.
Working Stroke For this comparison is based on a working height of 3" (1" work + 2" tooling). Power-K factor = Ram * Working Stroke * s/m * AE is a rough power equivalency in non-standard units.
k-factor is given in thousands of units. $/k is the installed cost divided by the k-factor
Bang for the Buck

NOTE: We made some errors in this initial evaluation and are correcting the data and results. Changes include a heavier anvil for the Old Blue (500#) and a different method of applying stroke. The KA-75's stroke will also be properly represented.
We are sorry these changes are taking so long.


Now we get creative, do some fancy number crunching, and determine the performance K factor for each hammer and then the bang for the buck. The k-factor above is a non-standard energy unit that works for our comparison purposes.

When you look at the greater stroke of the Chambersburg and realize that its 4.5" diameter cylinder can really use up the air produced by a 10HP compressor, THEN you can understand why a heavy duty industrial machine really IS different. The Kuhn running half the horse power produces almost exactly half the impact (which is the way things are supposed to work). Its appreciably lower dollars per K indicate that it is a better deal than the Chambersburg and as cost effective a design as the less expensive hammers.

Due to lack of data we had to fudge on the KA numbers. The 9:1 anvil ratio is based on the current recommendation to add a heavy base plate under the hammer. I'm recommending adding at least a 400 pound block under the hammer to achieve that 9:1 ratio. Without that additional mass things look pretty bleak. We used 170s/m for a velocity factor (the machine is non repeating), 9" for stroke (a guess). With a 13% anvil efficiency the k-factor = 15 and the $/k = $367 (After adjusting the installed cost by the $1/lb for the mass removed). Add that base block! Its a cheap performance enhancer.

The Old Blue ....... Its greater mass is in the frame which gives it that nice throat depth. The sand fill in the frame (noise control), does add mass to the hammer but not the kind that improves anvil efficiency. Its short stroke also hurts the numbers. Short stroke means low velocity and less power.

NOTE: The new price for the Bull we are using is for the new upgraded model with an all-steel cylinder replacing the old aluminium cylinder.

The Kuhn is no slouch either! With the lowest installed price per pound and the second lowest $/k this is NOT an expensive machine. The Kuhns are built to last and provide the same bang for the buck as the less expensive hammers. This cost/performance rating is largely due to the addition of the optional steel base block. This 3100 pound hunk of steel is what gives the hammer that 23:1 anvil ratio and a 75% efficiency. These base blocks are sold as a substitute for pouring a raised concrete foundation. Personally I think the steel block is better. NOTE: Only half the base block was applied to the anvil mass due to its long length.

Bang for the buck is not the only criteria for rating a hammer. More to come later. . .

Copyright © 1998 by Jock Dempsey, DEMPSEY'S FORGE
Page 5