roberth33tiger

+1 for the hammer and impact driver. just removed original DS BB cup from '76 Le Tour.
Hit it on the face 5 or 6 times with hammer. Came out easily with open end HS wrench.

phoebeisis

A hand impact-you can get a Snap On-used on Ebay-for $30- is a great tool.The Sears one is fine-works just fine-but the Snap On "feels better" in your hand.Granted it sure as heck doesn't feel $200 good which is what Snap On probably wants for their little hand impact kit.

I doubt the OP has a hand impact, hence my cheapo advice .Of course the right tool is always better, but most folks have to work with what they have. A length of pipe over his wrench is a "longer wrench"- not my first choice in dealing with a bolt in place for 12-15 years.
Patience to let the penetrating oil get in the cracks, and to repeat the oil, tap the head,, oil tap the head, and-getting another set of hands to help-go a long way on stuck fasteners.
The OP was having doubts about applying more force-the little voice in his head was telling him " careful not too hard." I used to ignore that voice and twist away.$30 for a hand impact is a good purchase.

DannoXYZ 

If you're gonna use a hammer, I'd recommend putting the allen-socket into the bolt and tapping on that. Or using an impact-driver. Both methods will spread out the load.

However, using a nail or punch will concentrate the force on a single off-centre spot on the bolt-head. This will create a divot. Where did the metal that used to be in this hole go???

I don't see how the use of a hammer is in any way "better" than using the proper tool (long ratchet wrench). In my 10-years at a shop, I've never ever had to use a hammer on the crank of the tens of thousands of bikes I've worked on. Is the OP going to use a hammer to re-install the crank? Is the hammer going to generate the proper amount of torque? Whatever tool he's going to use to re-install that crankarm bolt properly might as well be used to remove it.

phoebeisis

The hammer/metal to metal sharp rap is to send a sharp vibration thru the bolt to crack up the corrosion that is holding it in place and to allow the penetrating oil to penetrate thru the cracks-this is why patience is such a virtue.

I mentioned using a punch or nail because I was thinking in terms of a standard bolt head, not an Allen head.For an Allen just use your allen socket.Some bolt heads are hard to get to-hence the punch or nail.

I'm not from the "get a longer wrench and eat your Wheaties" school of stuck fastener removal.

There is/was a famous motorcycle tuner-Yoshimura-he threatened to fire any mechanic if they snapped off a bolt head and it didn't have a hammer ding on it. He had them hit the head directly with the hammer if possible.

PS Maybe I have reacted a bit too harshly to criticism, if so, my apology.We all tend to think that what worked for us is the best and only way. Sure a longer wrench is easier to modulate even if you don't use it to apply more torque. The OP seemed a bit reluctant to put more ooommmmph into it, so I suggested non ooommmph ways. Hitting the end of a wrench is a bit tricky-blow can sideslip and hit frame etc.But, if you don't have a hand impact, it is a useful technique.