Air Hammers

Part of this material I used in the 20 hour granite course I taught at Pratt. Most of the info is from Tom Urban’s workshop at Camp Brotherhod, some from a workshop by Don Ramey that Hank Nelson organized at my place years ago. If you find anything useful, please add it to the article – Kirk

Pneumatic hammers

Sources: 

• Trow & Holden
• Bicknell Supply
• Cuturi

Types:

• D (Dallet) long stroke 3/4 “, 1 inch.  Used for removing lots of stone.  More impact, vibration.
• B short stroke 1/2, 3/4, 1 inch.  Less vibration, used for detail.
• Bantam-fine detail, lettering
• Many carvers use 3/4D, control impact by amount of air.

Air consumption:

• 4 CFM-1/2 & 3/4;
• 6 CFM-1”

• For 1″ hammer a whip connection (see photo)is recommended so as not to beat up the coupler. It is likely that once you put a whip on one then you’ll find yourself putting them on all.
• Control air flow to hammer with an adjustable valve (stop cock). Chose a valve handle that is small enough so as to not get caught on everything yet big enough to easily turn it without fumbling.

Chisel diameter:

• B & D take 1/2” shank,
• Bantam smaller.  Many European chisels fit Bantam.

Bushing chisels:

• 4 pt square or 5pt round:  stone removal 
• 9 pt: stone removal, final shaping 
• cup, criss-cross, axe:  finish. 
• Rippers, long 4 pt: Deeper carving.  NOT used like toothed chisel. 
• Criss-cross for cleaning up frets

Carving chisels:

• roughing have heavy profile, finishing a bit thinner. 
• Limestone thinner and wide
• Granite requires carbide blade set into steel.
  • Avoid wedge insert (marble blade), tends to pop out. 
  • DO NOT pry on chisel, let it do work.

Safety:  Vibration, noise, dust & chips.

• Usual eye, hearing and breathing protection.
• Wear padded gloves, grip gently.
• DO NOT grip tightly, lean into stone.
• Take frequent breaks  from work.

Air hammer care:

• If sticking soak in kerosene overnight. 
• Or, add WD-40, run, then put in white spindle oil (10 SAE). 
• Oil hammers before and after use. 
• Run at low speed for minute before putting under load.
• Running hammer full speed without chisel can damage it.

ed Note: Videos at Trow&Holden provide Pneumatic Tool Basics and Getting Started.