Which impact wrench size to get?

I’m thinking the 1/4″ M12 fuel wrench is the least useful to start out with. I’m thinking the 3/8″ inch M12 fuel impact wrench is the best bet to start out with, but part of me wonders if I should get the M18 3/8: Fuel compact impact wrench. It’s for minor car repairs and out door power equipment. I’m just stuck on making a decision so looking for some help from some TIA’ers

The 12 volt wouldn’t cut it for most auto repairs. It would be fine for small equipment though. I would go with the m18. It will have plenty of power for most auto work.

I never got into the Milwaukee m12 wrenches.  I just don’t know how useful they are.  But I shouldn’t talk, I’m convincing myself to buy the m12 palm nailer.  

Anvil style is kinda limited to strictly nuts and bolts. Id look into an 18v hex style with a limiter like a dewalt dcf895

I already have the M12 and M18 fuel impact drivers the adapters to use sockets make the tool to large for some tasks.

For automotive stuff I’d go 1/2″ M18. Most 1/2″ impact sockets go down as small as 3/8″/10mm and you won’t be using an impact on anything smaller than that anyway.

I have the 1/2″ compact. It’s great for assembly work and driving lags, but it just doesn’t have the ass for most automotive stuff. If you’re using an impact on an automotive repair you’re typically using it on lugs or undercarriage work where fasteners are likely corroded and stubborn.

I’d get a 1/2″ high torque if it were me. I’d also consider a 3/8″ cordless ratchet.

Oh, and the compact impact wrench is merely an impact driver with an anvil instead of a hex chuck.

Also, go with a hog ring anvil instead of a pin for automotive stuff. Pin is fine for when you use 1 or 2 sizes all day, but the ring is much less frustrating when changing sockets regularly.

Conductor, you sir are a plethora of knowledge. 

Harold Wray wrote:

Conductor, you sir are a plethora of knowledge.

Thanks for the kind words Harold. Many, many, hours of talking shop to thank for it. You learn a lot about tools hanging out on tool forums everyday.

I’ll share some pics this evening when I get in.

Already have the M12 3/8 ratchet got a sweet deal when Home Depot was selling some Milwaukee kits cheap as the deal of the day. The auto is not as of a major concern I don’t really do anything too crazy myself. I would pick of the High Torque when I really need it. Ugh decisions decisions.

I think the m18 will have more than enough power unless something is really rusted on. It gets 200 ft lbs vs about 125 with the impact driver plus you lose some with the adaptor. As conductor said go with the hog ring for sure, the pins are fine if you only use one or two sockets throughout the day but if you need to change it you need a small punch and a third hand.

I’d say m12 for the size and compactness, m18 for more power but the trade off is size.

In a perfect world these would all be milwaukee and the impact driver would have multiple torque settings.  imo

you can adapt a 1/2″ square drive to the 1/4″ hex as well as the other way around. just depends which you use more often.

The pre-fuel compact 1/2″ inch is rated @ 183 ft. lbs.The pre-fuel compact 3/8″ is rated @ 167.

Do I REALLY believe there is any actual difference in the 2? Nope, it’s just hoodoo numbers for the same damn tool.

Same with the compact Fuel versions. 200 for the 3/8″ vs. 210 for the half. Again, I’d bet the farm there is in reality no difference between the 2.

The pre-fuel high torque offers 450 ft. lbs. While the Fuel puts out 700 with a whopping 1100 nut busting rating.

One of the primary benefits to an impact is the ability to bust loose stubborn bolts. The more busting torque the better. You may realistically never need 1100 pounds if you aren’t into any serious automotive work, but you will need more than 200. I can best the compacts with a 1/2″ ratchet, but I can’t do 450 ft. lbs.

The moral of this story is that the compacts offer you no advantage whatsoever over a ratchet except for speed.

The high torque models give you abilities that the good Lord didn’t. Since you aren’t doing heavy automotive I’d say your best bet is to go with a bare, pre-fuel, high torque.

Remember the hitch ball I took off in my Proto impact review? I tried my 1/2″ compact on it first and it didn’t even spook it.

If an impact can’t bust bolts I can’t with a Proto 5450 than it’s of no use to me outside of assembly, but maybe that’s just me.

Thanks for all of the opinions I’ll probably wait till I have some extra cash and pick up one of Fuel High Torque impacts down the road.

1/2″ and use adaptors to go down works for me.

Easier to have more power and use it gently than not have enough grunt on a job. 🙂

3/8 m18.. Thats what im getting for the auto field

Conductor562 wrote:

The pre-fuel compact 1/2″ inch is rated @ 183 ft. lbs.The pre-fuel compact 3/8″ is rated @ 167.

Do I REALLY believe there is any actual difference in the 2? Nope, it’s just hoodoo numbers for the same damn tool.

Same with the compact Fuel versions. 200 for the 3/8″ vs. 210 for the half. Again, I’d bet the farm there is in reality no difference between the 2.

The pre-fuel high torque offers 450 ft. lbs. While the Fuel puts out 700 with a whopping 1100 nut busting rating.

One of the primary benefits to an impact is the ability to bust loose stubborn bolts. The more busting torque the better. You may realistically never need 1100 pounds if you aren’t into any serious automotive work, but you will need more than 200. I can best the compacts with a 1/2″ ratchet, but I can’t do 450 ft. lbs.

The moral of this story is that the compacts offer you no advantage whatsoever over a ratchet except for speed.

The high torque models give you abilities that the good Lord didn’t. Since you aren’t doing heavy automotive I’d say your best bet is to go with a bare, pre-fuel, high torque.

Remember the hitch ball I took off in my Proto impact review? I tried my 1/2″ compact on it first and it didn’t even spook it.

If an impact can’t bust bolts I can’t with a Proto 5450 than it’s of no use to me outside of assembly, but maybe that’s just me.

The only difference is the anvil, the slight extra torque you get from the 1/2″ is just from basic physics. You have a slightly longer leaver arm on it therefore more leverage and a little more torque.

yamatitan wrote:

The only difference is the anvil, the slight extra torque you get from the 1/2″ is just from basic physics. You have a slightly longer leaver arm on it therefore more leverage and a little more torque.

I suppose that makes sense.

Hog ring 3/8 fuel

Conductor562 wrote:

I suppose that makes sense.

I’m a civil engineer and it doesn’t make immediate sense to me. If the same torque is applied to each anvil, surely the only way they could be different is any torsion(?) losses in the anvil itself…

dwain wrote:

I’m a civil engineer and it doesn’t make immediate sense to me. If the same torque is applied to each anvil, surely the only way they could be different is any torsion(?) losses in the anvil itself…

Im not a engineer but have taken many college mechanical engineering classes.   Honestly though this is just  simple basic physics problem.  Just draw a basic free body diagram for the difference size anvils and it becomes apparent.

but the anvils only deliver the torque, they don’t generate it. if they receive the same torque from the motor, the 1/2″ anvil will have less force with a longer lever arm. the 3/8″ will have greater force on a shorter lever arm, but the net torque (force x distance) should be the same, because they anvils don’t generate the torque …

does this make sense to anyone else? I could be completely wrong…

I know all kinds of stuff about Engineering and I couldn’t tell you who’s right or wrong.

Of course my Engineering knowledge pertains to driving a choo choo train 😆

I would think an identical motor would spin the larger, heavier, anvil, slower thus generating less force, but again, I just blow the whistle and wave at little kids most of the time.

Conductor562 wrote:

I know all kinds of stuff about Engineering and I couldn’t tell you who’s right or wrong.

Of course my Engineering knowledge pertains to driving a choo choo train 😆

I would think an identical motor would spin the larger, heavier, anvil, slower thus generating less force, but again, I just blow the whistle and wave at little kids most of the time.

hehe. i only mentioned being an engineer to illustrate that a basic knowledge of physics didn’t make the previous point clear. designing pipelines etc doesn’t help me with this at all 😉

if the anvil was the actual load, your point would be very valid . however the force required to make the anvil rotate is insignificant compared to the force required to drive the socket/screw etc.

interestingly, if you had two anvils that weighed the same and had the same centre of gravity (the actual difference would be insignificant) but had different size, they would rotate with the same RPM at no load. That is, the outside velocity of the bigger anvil would be higher, but the RPM would be identical. As Dewalt have stated it, both 3/8″ and 1/2″ 20v compact wrench models have the same RPM (2300).

this is all a long way of saying that, IMHO, the motor would determine the torque, and the size of the anvil should have no impact (no pun intended). 

Now that makes sense