The Ford Barn

Joe K · 02-26-2014, 01:19 PM

Plus one to all of the above.

One of the marvels of my engineering experience is "pein straightening" which is the use of a rather dull impact tool placed against a shaft and "hammered" with a device like a chipping hammer - but making no discernable marks or hammerblows on the surface of the shaft.

Contrary to expectation, the tool is placed not on the "high" side as in effort to push the shaft into straightness, but rather on the "inside curve" of the bent shaft.

I saw a boiler feed pump shaft that was fully 1/4 inch out of straightness brought back into 0.000 by the use of such a tool.

Another advantage of pein straightening are it stress relieves the shaft as you go along - existing stress, such as caused by the impact or whatever that bent the shaft - are "erased" by the sonic shock wave that such straightening creates.

It also does not change the diametral dimension of the shaft.

As you do it, you can literally see the shaft "walking" towards you.

When the shaft is straight - one can be assured that no residual stress will remain that will cause the shaft to act "funky" under increase in temperature or normal stress of operation.

It's magic.

I marvel.

Joe K

02-26-2014, 01:19 PM	#5
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 5,013	Re: Warping sheet metal - sandblasting Plus one to all of the above. One of the marvels of my engineering experience is "pein straightening" which is the use of a rather dull impact tool placed against a shaft and "hammered" with a device like a chipping hammer - but making no discernable marks or hammerblows on the surface of the shaft. Contrary to expectation, the tool is placed not on the "high" side as in effort to push the shaft into straightness, but rather on the "inside curve" of the bent shaft. I saw a boiler feed pump shaft that was fully 1/4 inch out of straightness brought back into 0.000 by the use of such a tool. Another advantage of pein straightening are it stress relieves the shaft as you go along - existing stress, such as caused by the impact or whatever that bent the shaft - are "erased" by the sonic shock wave that such straightening creates. It also does not change the diametral dimension of the shaft. As you do it, you can literally see the shaft "walking" towards you. When the shaft is straight - one can be assured that no residual stress will remain that will cause the shaft to act "funky" under increase in temperature or normal stress of operation. It's magic. I marvel. Joe K __________________ Shudda kept the horse.