Air tool question

[240ZMan]

I was at HarborFreight yesterday morning and picked up an air compressor and impact wrench and a few misc. tools to go with it. Its main use is for those occasional bolts attached to something that moves, such as flywheel bolts, cam bolt, etc where a ratchet isn't going to get it done. The compressor is rated at 5.0 scfm at 90 psi and has an 8 gallon tank. I realize this means I can't use it for continuous use, but as I said above, that's not what I bought it for.

The wrench is supposedly rated at 260 lb-ft of torque at 90 psi. Yet I'm not getting anywhere near that. As a test, I loosened a wheel lug, set the wrench on its highest setting, and tightened the bolt as far as the gun could go. Then I took my torque wrench and gradually turned the setting up until I could move the lug. It appears that the wrench can't go much over 75 lb-ft.

So my question, before I go back to HarborFreight, is if you think I need a bigger gun, or if the problem is really with the compressor being too small.

Please don't say both

[LanceM]

Both, OK OK sort of both...

The impact is 260 at 90psi, what cfm? What size hose are you using? and what kind of fittings inbetween?

I'm guessing but to get 260 at 90 you probably need 10-11 cfm, if you are using 1/4" hose you will never get there, 3/8" is better, 1/2" would be best. If you are using quick disconnects you are loosing cfm at everyone in the line. To get the most from what you've got go to 1/2" hose direct from the impact to the compressor with no other fittings, if you must have a QD so that you can use other tools go with at least 3/8" QD, and make an adapter whip hose that goes to the more standard 1/4" for things like blow guns and the like.

Another thing to check is the turn on point for the compressor, if it is adjustable set the turn on for 80 psi, that way you aren't way down in the dirt when it kicks on trying to catch up.

Impact wrenches are about the most hungry air tool and need lots of cfm at pressure to meet their rated specs.

All is not lost in any case, I've found that often times the hammering of an impact is more important in getting stuck things loose than shear horse power...

[240ZMan]

Lance, The gun calls for 5 cfm at 90 psi so I figured I wasn't going to be too far off with this compressor.

The hose is 3/8". I have 2 QDs in the path so I'll take one out.

The hose is 50' long but now I'm wondering if that's hurting things too much. Do you think going to a 25' would make much of a difference? Or I guess I could go to a 10' (if that's even available) and wheel the compressor closer. How much impact does the length of hose make?

Lastly, the gun's input takes fittings with a 3/8" ID. If I understood you correctly, you were suggesting I put a 3/8" QD on it and the hose? Just want to confirm as I didn't notice any at HF yesterday (although I wasn't looking for them either).

Thanks,

Daniel

[LanceM]

I did some looking and 5 cfm should be good for a 1/2" impact, I thought it was more. Yes you will be loosing some in the length of hose, friction and all that. In my looking I found that most impacts were rated w/1/4" inlet, though my experiance has been that they hit alot harder with bigger hose.

I would guess now that the HF impact is a bit over rated, or rated in "impact torque" or some other type of fine print marketing lingo...

I would maybe look for a short (25') 1/2" hose and connect it to the impact with a QD at the other end for the compressor, the fittings are all the same size, and see if that helps. Hose is pretty cheap. HF won't have 3/8" QD, you will probably have to check an industral supply or maybe NAPA.

Though often used (probably most incorrectly) for assembly an impact is best used for disassembly, getting stuck stuff unstuck...

[2ManyZs]

This might be one of those :stupid: kinda things, but does the tool have an adjustable torque setting on it? Should be near the air inlet in the handle if it does.

A shorter hose should help some, especially with the smaller compressor.

[240ZMan]

Originally posted by 2ManyZs

This might be one of those :stupid: kinda things, but does the tool have an adjustable torque setting on it?

Not a bad suggestion at all. When I first tried it the setting was at 1 (of 4) and I don't think it would have removed the cap off a Coke bottle. But I resorted to the manual and switched to the 4 setting from then on.

I put a 3/8" QD on and shortened the hose to 20'. At this point it's got around 75 lb-ft of torque. I think the real solution is a better wrench, and I'll go by HB later to see what else they have. After all, there's a reason this model was on sale for $20:stupid:

[240ZMan]

Thought I'd close this out for anyone considering buying air equipment for the first time like I just did. Today I returned the 250 lb-ft impact wrench ($40 model on sale for $20) and purchased their "earthquake" 650 lb-ft model. I chatted with the store manager for a while who had nothing but good things to say about the earthquake unit. He even gave me another $10 off the $79 sale price.

So the difference is amazing. The unit seems to use much less air than the old unit, and had no issues taking the lug nuts off my Expedition (needed to rotate the tires anyway) on only the #2 setting of 6 positions. While I doubt the #6 is 3 times higher than #2, it performed exactly as I hoped it would.

So lesson learned is that for impact wrench torque, divide the max spec by about 3.5 to see what you're likely to get in the real world.

[AChev]

i do not mean to insult you by this, not in the least. But I have purchased things at Harbor Freight before, and don't get me wrong they have great prices and some of their products are good products, although I have also bought products that turn out to be much less then they appear. It's happened to me and I know it has happened to friends. Don't get me wrong, I cannot avoid goin to Harbor Freight, they have a good thing goin there. Just something to ponder about

[sblake01]

You just have to be careful what you buy there. Some of their stuff is okay, some is junk. My small mig welder came from Harbor Freight. It has worked fine for several years. Their impact sockets are junk, especially the thin wall ones. They're are lifetime guaranteed but after returning the 17 mm at least 10 times, I figured what's the use. If you want quality tools you have to pay for that quality.