impact wrench

Torque values are never accurate with an air wrench since the conditions of use vary so much: things like delivery pressure , hose and fitting sizes can vary the delivery by a large amount. Best bet is to set a known air pressure and turn the gun to low and do something up, then check roughly how tight that is. When you are used to an air wrench you can roughly judge the tightness by sound and feel, but I would recommend using it for dismantling and light tightening, then check with a torque wrench till you are really used to it, assuming you are doing up anything important like wheels etc. If you really want to use it for wheels for final tightening then get torque limiting sockets to suit your application (about thirty quid each) I generally use a 1/2 inch impact wrench for medium-large dismantling and some large doing up. and a 3/8 version for small stuff.

mrcheerful

The No's mean nothing to me, but to answer the first part of your question. My Chicago Pneumatic impact wrench has a large intertwined CP logo cast into the body. All the others I've seen have also had this cast logo. Since you're asking the question, it sounds like whatever wrench you're asking about, is not a genuine CP impact wrench. I know for certain that there are/were copies made. Almost exactly identical, to the point where parts, including the motor, impact mechanism etc, were interchangeable. The only visual difference is that they don't have the CP logo on the side.

In fact come to think of it, the thick protective plastic body cover on my CP came off a broken copy. It fits perfectly.

As for the second part of your question. I'd go along with what mrcheerfull says, except to save buying torque limiting sockets, I simply use it as a nut runner on wheel bolts/nuts or assy work, and do the final tightening with a torque wrench. Unless you use them almost on a daily basis, it's really not worth buying torque limiting sockets. Mike.

mrcheerfull

Thanks both for your replies.

It seems that my original question was a bit misleading. The wrench I have

*does* have the CP intertwined logo on both sides so it is almost certainly the genuine thing. When I asked for identification I was trying to discover what torque range it covers since there appear to be at least two CP 1/2" drive models, presumably with different ranges similar to torque wrenches. My impact wrench has 10 settings but no indication of what range they cover .

I'm quite interested in the idea of torque limiting sockets despite their price and limited use. The reason is that my torque wrench is only 21" long (range 44 - 230 ft/lbs) and I need to tighten front hub nuts at 181 ft/lbs. That's not an extreme target but I've had a hip replacement and I don't want to risk dislocating or otherwise damaging it by using excessive force on the torque wrench. Bracing oneself for a steady heave on the torque wrench puts quite a strain on everything and I'd prefer the cost of a good tool rather than the inconvenience of another ten days in hospital.

Any ideas of a source for the torque limiting sockets?

Many thanks,

Cic.

For that sort of torque figure you need a decent length torque wrench, although the impact wrench "may" be able to undo/doup to that figure, something like a hub nut needs to more accurately tight than it will be using an impact wrench.

The torque limiting sockets are usually used for wheel nut applications only so vary from about 40 to 90 ish. They are sold by tool suppliers and vans including snapon and mac.

mrcheerful

=============== Thanks again for your reply.

I agree about the need for an accurate setting for the hub nuts so it looks as if I can use the impact wrench for undoing but the torque wrench will be needed for tightening. It seems that torque wrenches are a more or less standard length determined by their torquing range. I vaguely remember that my first torque wrench (Norbar - bought about 1974) had some kind of capability to add an extension bar. I'm not sure whether this was to increase the range or to reduce the effort needed to achieve a given torque. Either way it seems that these extensions are no longer available and I don't want to risk using a home-made extension without knowing what the effect will be. I'll probably have to experiment a bit unless I can find a definitive answer about this.

Norbar make a torque multiplier but the cost is about £450-00 so it's not really a viable option for my purposes. Another Chinese company (found today via Yellow pages) make a range of torque limiters but the maximum torque is only about 120N so again not much use to me.

For the time being I'll do some 'googling' to find out more about extensions - provided that my ISP (Blueyonder) has got things working again. They appear to have had a complete blackout since 6:00 p.m. yesterday until

4:00 p.m today.

Cic.

A 300Nm torque wrench can be baught for £100-150. Obviously at that price they're not top quality, but will be adequate for doing up hub nuts.

There is nothing wrong with simply using a tube on a torque wrench to reduce the effort. It might harm the finish a little, but it won't affect the final result. Mike.

The message from "Mike G" contains these words:

Provided you don't slip the tube beyond the pivot point near the ratchet head. There's a rivet through the handle about which the business end pivots - and straddling that with the leverage tube may well screw up the readings 'cos one end will be pushing the other way. Other than that

- no trouble.

I was aware of that, but thaught it too obvious to mention. On reflection, I probably should have. :-) Mike.

To answer my own post. If it's of any interest, Draper lists a reasonably priced 3/4" torque wrench. 51.6 - 291 lb-ft, 70-395 Nm.

put torque wrench in the text search box.Strange that their website only shows the price of the repair kit.In their 2004/5 catologue the wrench is listed at £85. + VAT.Mike.

================ I've just bought a 'Halfords' own brand 60 - 300N for £59-99 so I'm hoping that this will do the job satisfactorily. Are you sure about extending the wrench with a piece of tube? Can you quote chapter and verse because I've been getting very mixed comments from people I've spoken to about this? My thinking is that it is OK but I've also been warned that extending the length can reduce the actual torque. As I said in an earlier post Norbar used to sell some kind of extension but I've long since lost the instructions for my 30 year old Norbar wrench.

Cic.

Absolutely.

Can you quote chapter and verse because I've

That really is nonsense. The handle of a torque wrench is simply a lever. It performs in the same way as any other lever. The longer it is, the less force is required to move it, but over a longer distance of course. How can the working end 'know' whether an extension tube is used or not. :-)

As I said in an earlier post Norbar

No problem. Set it as recommended, then stick an extension tube over the handle. Avoiding the pivot point at the end as previously mentioned. Mike.

================= Thanks again for confirmation. I removed the hub nuts this morning without any difficulty so things are going OK. The crunch will come when re-fitting time comes - something to look forward to!

Cic.