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

 

[RobJ]

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.

So you used an impact to do the final turn? That's not a no-no? We were instructed to never use an impact on torqued bolts.

The torque/turn method is what we used on "stretch bolts". You must replace them after every torque.

 

[CATMAN]

RobJ: I hear what you are saying. These main bearing cap bolts usually end up in the 600-750 lb ft range. There are certain engines that require new main cap bolts each time(per CAT engineers) but currently most do not. This is changing as engines are getting lighter in weight and smaller bolts are being used to handle these same stresses(or as HP/torque increases on that same-sized engine).

Now, as for the great debate on using an impact for the last turn method; on one hand, you have teachers and some engineers=no impacts! On the other hand, you have "generations of mechanics" and some engineers that say it is acceptable and have well over 45 years experience in "real life" without problems(older mechanic's that taught myself). Next, you factor in "flat-rate" times (called TRG=time requirement guidelines) that those same "no impact" engineers come up sitting behind a desk and you too will use real life experiences as your guide.​

Actual, things have change a little on the impact issue(in some areas), an example is the new C-12 head gasket procedure. It is a torque/turn method w/ new bolts, then RELEASE/LOOSEN all bolts, then torque/turn again for final torque. CAT engineers have all said the use of impacts or totally ACCEPTABLE(in this procedure). If you think about it, head gaskets are one of the real critical areas that was always "Torque wrench only" in the past.

I mention one other area that differs greatly between teachers/engineers and real-life. This involves hand polishing of crankshaft journals when there is just a slight bearing material adhered to the journal itself. CAT trained instructors say that the complete engine must be torn down and a CAT reman crankshaft MUST be installed BECAUSE NO ONE can provide the surface finish that CAT can!!! If every mechanic was to follow this, you wouldn't have any customers(they'd go broke). In real life, many times you can WET hand polish this material off (less than an hour or two) and install new bearings, and that engine will live for many years without any bearing failures. Sure there are times where the adhesion won't polish out and you are forced to install a reman crankshaft, but you should always try a salvage it for the customer before you just blindly condemning it.​

Also, remember who makes a profit by the sales of parts(CAT & Dealer) but who might lose the customer if you constantly over-repair(mostly Dealer).

 

[RobJ]

Yeah a lot of new procedures, these days I just go by the manual since I just do it in my spare time now adays. I have polished a journal or 2 or 3. My BIL keeps running his JD 350 out of oil. Bearing material is much softer than the crank. Lets see time before last it put a hole in the block, he patched it but didn't tighten the rod bolts correctly (who needs a torque wrench and spec anyway!!). Then we installed a used engine. Its down again below a pond dam broke again. I give up, heck I can rent a good dozer that works for less trouble if I need it!!

Back on impacts...not air but I find these REAL useful many times. I kept forgetting to take a pic of mine, but it looks just the same.

Rob

 

[IXLR8]

I'm currently looking at IR2135QTiMAX for $250.

Where are you finding that gun for that price? That is the gun I am looking at, but have not seen it for that low of a price anywhere. I bought a Stanley Professional model, rated at 500ft/lbs. Direct connection with 3/8" tubing, no quick disconnects, it would not loosen the wheel lug nuts I put on a month ago, tighten with the 8" lug wrench that came with the car. I should have known better, it was only $80. It was returned the same day.

 

[Bird]

Where are you finding that gun for that price? That is the gun I am looking at, but have not seen it for that low of a price anywhere. I bought a Stanley Professional model, rated at 500ft/lbs. Direct connection with 3/8" tubing, no quick disconnects, it would not loosen the wheel lug nuts I put on a month ago, tighten with the 8" lug wrench that came with the car. I should have known better, it was only $80. It was returned the same day.

How much air tool oil did you put into the air intake before using that Stanley impact?

 

[IXLR8]

I put in what the instructions said to, then pulled the trigger as gently as possible to give the oil a chance to work it's way around and not just get immediately blown out.

 

[CATMAN]

Where are you finding that gun for that price? That is the gun I am looking at, but have not seen it for that low of a price anywhere. I bought a Stanley Professional model, rated at 500ft/lbs. Direct connection with 3/8" tubing, no quick disconnects, it would not loosen the wheel lug nuts I put on a month ago, tighten with the 8" lug wrench that came with the car. I should have known better, it was only $80. It was returned the same day.

Hi There IXLR8; The website that I purchased from is called; thetoolwarehouse.net . Please note: This is such a new product to their site that it won't show up normally, you must go to the upper right and corner (at the search function) and entry the exact model number:2135QTIMAX , then hit enter. This is probably the forth or fifth time I have purchased from this site and have never had a problem. I actually e-mailed them about this model before it was available, and they e-mailed me back when they finally got it available.Search Results for: 2135QTIMAX

 

[CATMAN]

RobJ; Those impact drivers for phillips head screws are a life saver, when the screws are really stubborn or rusted into place. Note: Your BIL must be getting a pretty good labor rate from you. My dealer charges $110 per hour for in-shop service, but the foreman tries to flat-rate what he can on similiar jobs. Basically, if you just keep busy at a reasonable pace, then everything usually works out pretty well.

 

[IXLR8]

Hi There IXLR8; The website that I purchased from is called; thetoolwarehouse.net .

Thank you. Have you had a chance to put this gun 'to the test' yet? If so... how well does it work?

 

[CATMAN]

IXLR8; No, not yet. I have only loosen 1/2" NC bolts and nuts,so far. It did those instantly. Lately, I haven't done any big jobs or "rod and main bearing roll-ins". Lots of these later(newer) engines are just spend troubleshooting and changing small parts or sensors. It is when the older engines come into the shop(if I get put on that job) that the "test" will happen. One of the other mechanics has the Non-quiet(standard) model. He listened to mine today, and wished he had the quiet model also. At less then one week's use, I am currently happy with it so far.