lets talk impact wrenchs

[Bird]

Thanks Bird, I agree that it probably is a CP734

So I guess the question is, will a 3/4 inch gun (run on a 3/8 line) have more power than a 1/2 inch gun run on a 3/8 line?

Greg

That's a tough question, Greg, and to tell the truth, I don't really know, but I would expect the 3/4" gun to have just a very slight advantage.

 

[gsdavis1]

I am also a little confused because the Harborfreight site says

Air inlet: 3/8"-18 NPT

If the actual tool inlet is 3/8, I am thinking that 3/8 hose should be fine.

Greg

 

[gemini5362]

Bird I am totally clueless about how a pneumatic impact gun works. If I were to guess though I would think it had some kind of piston that was moved by air volume and pressure. Would a 3/4 inch gun have bigger pistons that could develop more force with the same amount of air pressure and volume ?

 

[Bird]

I am also a little confused because the Harborfreight site says

Air inlet: 3/8"-18 NPT

If the actual tool inlet is 3/8, I am thinking that 3/8 hose should be fine.

Greg

I agree . . . that it would seem that way, but I'll let someone else try to provide the technical explanations of pressure/volume loss due to friction, distance, etc. While it seems like it would work, I've seen it fail to do so. I've repaired some 3/4" impacts that ran, and even hammered, just fine on 1/4" and 3/8" hoses, but nowhere near the power they had when you hooked them up to a half inch hose.

 

[Bird]

Bird I am totally clueless about how a pneumatic impact gun works. If I were to guess though I would think it had some kind of piston that was moved by air volume and pressure. Would a 3/4 inch gun have bigger pistons that could develop more force with the same amount of air pressure and volume ?

I'll see if this link will work to an exploded view of the parts of an IR231. All the impacts, ratchets, orbital sanders, and drills have similar air motors; i.e., a cylinder, a rotor, vanes or blades, etc. There are differences in the size of the parts, the number of vanes or blades, the material from which the vanes or blades are made, the angle at which the vanes are installed, and differences in the air passages and bearings, but no pistons. Air hammers (or chisels) and in line sanders do have reciprocating pistons.

Now I'll try a link to a CP734. While they all have somewhat similar air motors, there are two basic impact mechanism designs, and then, of course, a lot of variations on those two designs. So the IR231 and the CP734 are comparable power, quite possibly each company's most popular model for many years, and they're the most copied designs. The IR231 design uses grease to lubricate the impact mechanism while the CP734 uses motor oil in the impact mechanism.

Hope this helps.

 

[SPYDERLK]

I am also a little confused because the Harborfreight site says

Air inlet: 3/8"-18 NPT

If the actual tool inlet is 3/8, I am thinking that 3/8 hose should be fine.
Greg

There is a discontinuity in sizing between plumbing pipe sizes and tubing sizes. 3/8 pipe to 1/2" tubing is a very good match. The larger 1/2NPT would be needlessly bulky and no freer flowing than the 3/8NPT when they are used to go to 1/2" ID tubing.
larry

 

[SPYDERLK]

Thanks Bird, I agree that it probably is a CP734

So I guess the question is, will a 3/4 inch gun (run on a 3/8 line) have more power than a 1/2 inch gun run on a 3/8 line?

Greg

Unless you are doing bolts bigger than 5/8" a strong 1/2" Impact will be quite ample and much more pleasant to use. In order to get acceptable performance with the big gun [above what the 1/2 offers] while using 3/8" hose, you would have to keep the hose short and use free flowing connectors. Normal 3/8 hose uses 1/4" connectors. Oetiker makes the only 1/4 connector I know of that flows free enuf to give really good performance on a 3/4" gun. A 50 foot 3/8" hose with an Oetiker powers an IR 261 with noticeably more wallop than an IR2135TiMax will give on the same setup. Further shortening the hose to 25' causes real benefit on the big gun. With 1/2 hose and 3/8 connectors it would work perfect, but its bulky.
Paying the premium cost of a top performing 1/2" gun will set you up well for virtually all tractor sized work. Itll be hard to find a cheap 3/4" that will compete without taking pains to provide plenty of air.
larry

 

[CATMAN]

Thanks Bird, I agree that it probably is a CP734

So I guess the question is, will a 3/4 inch gun (run on a 3/8 line) have more power than a 1/2 inch gun run on a 3/8 line?

Greg

I can answer this one. Our C-15 CAT engine main bearing cap bolt is 7/8"-14. The spec is to torque it to 190 lb ft, then turn it an additional 120 degrees (2 flats). This is called a torque/turn method. My 3/4" Blue-point impact with a 3/8" hose can completely "turn" this bolt to its final spec. I have yet to see the 1/2" impact that can do this. Most 1/2" impacts might only get 60 degrees(1 flat) additional of the final turn method. This Blue-point is longer than some other 3/4" impacts, so the internal mechanism might have more weight or surface area that allows it to perform reasonably well with a smaller air line attached.(The Model might be AT770???) I do remember it was $550 when I purchased it.

 

[Bird]

I repaired quite a number of Blue Point air tools of all kinds, but only one 3/4" Blue Point impact and that was an AT750. It was basically the same style as the CP734 half inch impact, with a few variations, but mostly just everything bigger and heavier.

 

[CATMAN]

Bird; Now that you mentioned it, that Blue Point does look a lot like an overgrown CP734. Thanks