Air hose and fittings to maximize 3/4" ratchet power

[lipancreek]

I want to take off John Deere MX6 blades. I've tried a 3/4" Harbor Freight impact that is supposedly 1,000 ft lbs torque and takes 7.5 cfm. It won't even budge the bolts, even after soaking all weekend in WD40. Bolts are only torqued at factory to 400 ft lbs I believe. So I'm thinking maybe my compressor and fittings are to blame. I'm using a 20 gallon compressor rated at 5.5 cfm at 90 psi. Would going up to 3/8" quick connects or 1/2" hose or both make a big difference? Or do I just need more compressor?


Thanks for any thoughts or help!

 

[HarryN]

Wd40 won't do you much good. Use a wrench with a log cheater bar for leverage to break them free.

 

[hosspuller]

If you're using 1/4 quick couplings and 3/8 hose, you're starving the impact of air flow. With your compressor... no couplings and 1/2 inch or better hose. Short as possible. Straight fittings right from the tank, no regulator, one 1/2" ball valve. Even a 1/2 hose barb reduces flow to that of 3/8 fitting. 3/4 inch valve & fittings would help the impact reach its rating.

 

[lipancreek]

Well in case it helps others with mx6 or similar, I finally got the bolts off with about 7' of cheater pipes pieced together...

 

[Billrog]

I think you may need more like 120 psi to get the most out of your impact.

 

[Fawken]

Biggest impediment to even cheap impact wrenches is hose and fitting diameter- ALONG WITH the use of those crappy self-coiling, PVC hoses. Your compressor is adequate, but you need 1/2" hose and fittings and keep the hose as short as you can.

 

[CalG]

One "shortcut" is to place a "small" tank just before the tool that is fed from the main compressor.
You know, one of those portable tanks, about 5 gal. Then, with a 6-8 foot large diameter whip that connects to the tool, you can get a powerful burst that makes the best advantage of any impact tool.

Most "car mechanics" run their air pressures on the high side ;-)

 

[williaty]

Yes, you're almost certainly starving the ratchet for air. Your impact gun is 5/5cfm average, which is NOT what it's using while you're holding the trigger down. The 5.5cfm average means a MINIMUM of 11cfm running and probably a lot more like 15-20cfm.

First, move up to 1/2" hose and 3/8" fittings. I would STRONGLY suggest that you spend the extra money and convert to Prevost High-Flow (Euro) fittings. They produce about twice the flow/half the pressure drop of the standard I/M fittings commonly used here in the US.

Second, your filter and regulator need to be able to flow everything the gun can use without restriction. If you look up the pressure-flow chart for your filter and regulator, you can easily be dropping ~20psi in a consumer regulator at 10cfm. You might need to pick a better flowing setup there as well.

Finally, if you can hold your trigger down for more than about 10 seconds without causing the pump to kick back on, you're definitely not getting enough air to the gun. That 20gal tank is really on the small side for a strong impact gun. My IR 2135QTiMAX gun claims around the same strength as your HF gun and yet it clearly states you have to supply 24cfm (continuous) at 90PSI to get the rated figure out of it.