Hammer drill vs. impact driver - Pros / Cons

[mickyd]

Impact drills are for turning things that are difficult to turn.
Hammer drills are for drilling holes into masonary and stone.
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The problem most people have with power drills is they can't hold the drill in alignment with the screw and the bit cams out of the screw head and strips the head. The can be overcome with practice, if you screw enough screws you will eventually learn to keep the screw and drill in alignment. I have also found that square head screws are more forgiving in the alignment area. ........

A.C.R. (anti cam-out rib) bitsare fantastic for reducing cam-out / stripping the drive. A must have as far as I'm concerned. Very common in military / aerospace industry and high use production environments.

[JPG]

A.C.R. (anti cam-out rib) bitsare fantastic for reducing cam-out / stripping the drive. A must have as far as I'm concerned. Very common in military / aerospace industry and high use production environments.

Unfortunately the common 'phillips' head was designed to 'cam out' if excessive torque is applied.

I always liked the reed prince head, but that just exposes the advanced degree of old fogey I suffer from! Haven't seen one in decades!

The torx are very much an improvement and unlike the phillips, you MUST use the correct size driver.

Remember clutch head screws?

[dusty]

Unfortunately the common 'phillips' head was designed to 'cam out' if excessive torque is applied.

I always liked the reed prince head, but that just exposes the advanced degree of old fogey I suffer from! Haven't seen one in decades!

The torx are very much an improvement and unlike the phillips, you MUST use the correct size driver.

Remember clutch head screws?

I don't know how we got from impact drivers to clutch head screws but YES, I do remember them. Having been an Airstream owner, I got well introduced to the clutch head. I am not sure it was a good experience (as far as the screws are concerned) but I loved my Airstream almost as much as my Shopsmith.

I let the Airstream go for a bigger and "better" fifth wheel which I never got to liking.

Yes, I remember clutch head screws. I prefer torx because they don't automatically cam out.

[mickyd]

Unfortunately the common 'phillips' head was designed to 'cam out' if excessive torque is applied. ......

Not all design features benefit all users all the time. If the screw head is going to snap off due to excessive torque, you've got your hands full with trying to get that fastener out anyway.

[mickyd]

I don't know how we got from impact drivers to clutch head screws but YES, I do remember them. .......

It's that miracle that God gave all of us called a thought process. Gotta love it.

[foxtrapper]

Unfortunately the common 'phillips' head was designed to 'cam out' if excessive torque is applied.

Not quite. It was designed for production line assembly as a replacement to the straight slot screw. It offered two major improvements:

1. It would automatically cam out when the screw was fully seated. The straight slot screw would not and the heads were frequently damaged or torn off as a result.

2. It automatically self centered the bit in the screw. A straight slot does not, and many body panels were being damaged by the screwdrivers slipping out of the screws while screwing them down.

[Ed in Tampa]

Since we got off on cam out of phillips head screws let me add my 2 cents.

Everyone might be right about phillips head screws being designed to cam out when seated or when excessive torgue is applied but I have found 99.9% of the cam outs I have seen is because the screw and driver be it a impact, hammer drill, regular drill or some other type of screw driver is not in perfect alignment with each other.

I have seen guys shred the top of phillip head screws when they have their whole weight pushing down on the screw but they are holding the driver at an off angle to the screw. And they keep doing it over and over thinking they are straight alignment. I can't count the times I have seen guys cuss the wood or the screws saying the wood is too hard and needs drilled or the screws are cheap. I can take the drill off them and using reasonable pressure and as perfect alignment as I can get and drive the screw home with the head recessed in the wood. Oh yes lest I forget the drive bit is critical too. If the bit has driven a lot of screws or if the user has stripped a lot of screws with it, the bit itself is probably shoot. Toss it, don't put it back in the box and pick up another one you put in the box the last time. New bits, good driver to screw alignment and sufficient pressure pushing against the screw is what is needed.

Square drive screws are a lot more forgiving and I really wish phillips heads would be fazed out once and for all.

Back to the question on impact or hammer drill I hope all the information offered here has helped the author of this thread make his decision.

[mickyd]

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Back to the question on impact or hammer drill I hope all the information offered here has helped the author of this thread make his decision.

Author found thread extremely helpful in making the determination. Went with an 18V impact driver........HF.......$20 for driver + $10 for battery + $5 charger. My needs were more toward driving lags, long screws, loosening frozen fasteners so that made the most sense. I rarely drill into aggregate / stone so impact wrench made sense.
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[Ed in Tampa]

Sounds like you made the right choice.

How about in a few months doing a Tool review of the HF impact driver? There has been many pros and cons about HF tools and I for one would be very interested in hearing your impressions and experiences with it.
Thanks

[JPG]

Sounds like you made the right choice.

How about in a few months doing a Tool review of the HF impact driver? There has been many pros and cons about HF tools and I for one would be very interested in hearing your impressions and experiences with it.
Thanks

Me Too! Just don't let A1 hear of it!