View Full Version : Air impact Hammer Questions

Shed Machinist
10-21-2003, 08:08 AM
ok, i just bought the air impact hammer at harbor freight for 6 dollars. I don't know if i wasted 6 dollars or not, buti really don't care since it is done and over.

I have a few questions about air hammers,

o they completely stop, or can they vibrate a little when the trigger is not pulled?

about how far is the travel of the chisel?

do you have to unscrew the coil to get the chisel out?

These may sound like common sense questions to you people but i need to know. The set came with absolutely no intruction.

I thank you for your replies.

10-21-2003, 10:16 AM
I hope this helps.
A)Air hammers should not "vibrate a little" when the trigger is not pulled. Most likely the "O" ring in the trigger valve assembly is damaged or hardened or has some dirt/manufacturing metal shavings in it. In either case air is getting by the trigger valve assembly for some reason and shouldn't. Harbor Freight is good about exchanging items when defective and new.

B)The travel is about 3/4" for .401 shank chisels. Longer barrel length means more power at slower rate of hammering (blows per minute, bpm), not more chisel travel.

C)There are basically 4 types of retainers for air chisels.
1)Spring that requires removal to remove chisel. This is the safer type of spring holder and is conical in shape. A pain in the buttox to change chisels though.
2)Quick change spring type which has a "tang" on the outer end of the spring that can be used to force the spring off center and allow removal of the chisel. Not safe if you should pull the trigger without having the chisel against an object since the chisel can come out easily. The conical spring type can do this too with age and wear but the spring coils would have to come over top of the threads on the chisel barrel.
Incidently, pulling the trigger on an air chiesl without a chisel in place or without the chisel against an object is not good for the tool.
3)Chuck type of retainer. An aluminum collar with a cutout on one side that threads over the barrel and retains the chisel. I have this type, like it best and feel it is safest. This collar must be unscrewed to remove the chisel but that is easily done because there is no spring pressure against the threads. An "O ring inside the collar prevents it from vibrating off.
4) Quick change retainer. Works like a coupler on an air hose with a collar you pull back to release the chisel. Fastest/easiest chisel changing method, most expensive retainer. Can be unsafe because it can "look" like the chisel is in place but in reality isn't locked in. Always pull on the chisel before use to insure it is properly retained when esuing this type retainer. This is not bad advice for all types really.

There are large variety of chisels for these tools from panel cutters for sheet metal to needle scalers for rust removal. There are tail pipe cutters, tail pipe expanders/shrinkers, hammers, tie rod removers, chisels and punches, bushing drivers and rivet sets. The biggest problem is having a tool too small for the various tools in use. Small tools are OK for riveting, sheet metal and tail pipe cutting, but larger tools with longer barrels are required for heavier work. Standard pressures for these tools is 90 PSI, but tools are available for heavy duty work that operate at 300 PSI.

Air chisels are quite reliable if you get a quality tool. They have few moving parts. The main thing one can do to prevent problems is to oil the tool before and after use. Rust in the barrel is your enemy. A water separator should be used with all air tools to reduce moisture. Be sure you have a compressor that produces sufficient CFM to operate your tool. Air chisels are quite hungry, but not as hungry for air as die grinders.

Now you know way more that you ever wanted to about Air Chisels.

Shed Machinist
10-21-2003, 05:29 PM
Thank you for your reply, i think i may have a defect tool, it barely moves the chisel(just vibrates) and leaks air somewhere. i will take it back and see if they would exchange it for a different one.

10-21-2003, 07:37 PM
It is defective, and they will take it back. Bring the recipt.

10-21-2003, 07:53 PM
Shed,have you ever used one before?You do have to make contact with the work and apply a little pressure for them to work correctly.

I usually hold down and pulse the trigger,more control that way as well.

10-21-2003, 08:34 PM
I'd like to convert an air hammer to one that would give just one blow per trigger pull. Any suggestions before I sacrifice one in a learning curve would be appreciated.

10-23-2003, 02:51 AM

It is called a "nailgun"

10-23-2003, 07:31 AM

how much air are you trying to run it at? are you oiling hammer?

email or msn with me about this.

10-23-2003, 11:41 AM
When I moved in to my present house in '85 I did a lot of work finishing the basement. There is nothing worse than overhead nailing to whip your arms. I took one of the rivet sets for my long stroke air hammer and turned it to fit the head of a 3 1/4 common nail. Worked slicker than snot on a glass doorknob.

10-24-2003, 08:32 PM
Evan, I like the way you think. I've been toying with the idea of cutting the chisel end off of a couple of broken chisel bits and modifying them so I could install different types of tooling for specialty work on forklifts and pallet jacks. Something along the line of the KD or Lisle, I don't remember which, pickle forks that can be used in an air hammer or with a regular hammer. In fact, I don't know why I haven't bought one of those yet.
Similar idea, yet different tooling for different purpose.

10-24-2003, 09:07 PM
Yep.pickle forks they make with a burp gun shank.I also have a neat tool that I made with a socket extension,I welded a handle to one and when I got a stock bolt I put a short socket on and use the impact while turning,it will losen a bolt that a normal impact wrench would wring off.

I also made a few wood gouges they work good too.

Shed Machinist
10-25-2003, 02:02 PM
is it bad to use an air hammer for flux removal after welding, or will it e\weaken the weld.

Keep in mind that if this is a stupid question i am only 13.

10-25-2003, 08:28 PM
No its not a stupid question,and yes you can use one to chip welds,with safety glasses of course.

Go easy on it though it will tend to markup stuff.

10-25-2003, 08:51 PM
Shed Machinist, I believe it is an accepted practice, since I have seen commercially available descalers that have about a dozen little hardened rods sticking out the business end that do the chipping and I seem to recall reading that it does a little stress relieving of the weld also. Can anyone verify that for certain?

10-25-2003, 10:55 PM
They are called needle scalers and they work great for weld clean up. You can get an attachment for your air hammer, or a dedicated tool. Both are reasonably priced at H.F.

Edit: I often hold the needles together with a zip-tie.

[This message has been edited by Joel (edited 10-25-2003).]

10-25-2003, 10:58 PM
Don't bother geting HF's needle scaler. It doesn't have the power. I got one to play with for a planishing hammer. http://bbs.homeshopmachinist.net//frown.gif

It's going to need a few mods. As Tim Alen says; "More Power!". Bored, stroked and ported.

Shed: Forgot to mention. It might be hard to convert to a "one-shot". The air hammers have a different valve system--not only the trigger but also the piston valve. The cylinder has air ports at both ends and these are controlled by the valves at the back of the cylinder and by air pressure differential. You can't just plug one of the ports.

[This message has been edited by CCWKen (edited 10-25-2003).]

10-26-2003, 06:49 PM
Wierdscience, I've seen something like you describe in a Snap Off tool catalog. Only much, much more expensive than if you make your own. Good idea, I just never got around to getting or making one.