Extractor overview (pic heavy)

[garfunkle24]

Re: Timeless Thread

I read every post in this thread, and there is one thing I do not fully understand:

I understand "axial load" to more or less indicate application of downward pressure to the fastener (or "pushing the fastener in"). If this understanding is correct, why would a tap socket be necessary to achieve this? I could just as easily push down using an eight-point socket, for example.

Ultimate necro FTW

Yes an 8 point socket would work fine too, although tap sockets come in a finer range of sizes and have a retention o-ring, which combined give a better fit on the extractor.

The main point, however, was using a socket rather than a wrench, so it is easier to apply axial force while trying to turn the fastener out.

 

[garfunkle24]

Old thread but hope some newer folks may find useful

 

[JradM]

I thought this was a great overview! I concur 100% with the original post.

I think Proto's square is the best - surprisingly durable in my experience, yet they seem to bite very well too. The worst thing that can happen with an extractor is when they snap - Protos resist breaking the best of any I've used.

I also have Rennsteig extractors. They don't break either. The reason I rate them a little lower is just because they seem softer than the Protos. Proto stays sharp no matter what I do, whereas Rennsteig will dull/deform on the flutes slightly.

However, Rennsteig has advantages too that make them worthwhile. In addition to working both ways as mentioned, they have a hex on the end that means you can easily slip a socket on them. Not only does this mean you can use a ratchet without a special socket, but it makes it simple to use with a manual impact driver too. Impact + twist + a good extractor = bolt submission.

 

[NORTON'S SHOP]

I have many extractors and it seems like what may work well one time may not work as well the next time. I do have to say that the Wilton tap extractors (finger type) have never worked well for me.

 

[garfunkle24]

I thought this was a great overview! I concur 100% with the original post.

I think Proto's square is the best - surprisingly durable in my experience, yet they seem to bite very well too. The worst thing that can happen with an extractor is when they snap - Protos resist breaking the best of any I've used.

I also have Rennsteig extractors. They don't break either. The reason I rate them a little lower is just because they seem softer than the Protos. Proto stays sharp no matter what I do, whereas Rennsteig will dull/deform on the flutes slightly.

However, Rennsteig has advantages too that make them worthwhile. In addition to working both ways as mentioned, they have a hex on the end that means you can easily slip a socket on them. Not only does this mean you can use a ratchet without a special socket, but it makes it simple to use with a manual impact driver too. Impact + twist + a good extractor = bolt submission.

Thank you.

That's a great point on the Rennsteigs. I've never tried nor even thought of using an extractor with an impact driver. With tap sockets you could do it with other types too. I'm compelled to give it a try now!

One thing I've always thought about the Rennsteigs is that the taper is maybe too steep. Seems like because of that they only have a very small biting point on the very edge of the drilled hole.

 

[ChefRex]

I have many extractors and it seems like what may work well one time may not work as well the next time. I do have to say that the Wilton tap extractors (finger type) have never worked well for me.

The finger type will never work unless the tap is loose which isn't usually the situation.

 

[seber]

On heating pulleys to remove them from shafts:

When I was just out of school I worked in a repair-oriented machine shop. We did a lot of repairs for sawmills. One day I was heating a cast iron pulley to remove it from a shaft, heating the whole pulley. The boss, an older gentleman, walked by and noticed what I was doing. He stopped and asked why I was heating the whole pulley? I explained that it was to expand the pulley away from the shaft so it would slip off. He said "that won't work" and explained why:

When you heat the pulley to expand it, in theory the whole pulley expands and the whole "donut" gets bigger, including the hole. In practice, the mass of the pulley is greater as it gets bigger (except the hub area, which will be explained later), so it takes more heat to bring it up to temperature. In practice, the heating is uneven, with the area at the outer edge absorbing the most heat and the bore the least. If there is a hub built into the pulley, it increases the mass near the shaft, again requiring more heat to expand. What seems like a simple process now is very complex because of the variation in mass of the pulley. But that isn't the most important part of the answer!

When you heat the pulley, some of the heat transfers to the shaft, and the shaft also expands. If you are dealing with a steel shaft and aluminum pulley, the more rapid expansion rate of the aluminum helps you greatly, but heating the whole pulley increases the time the shaft is exposed to the heat and allows it to transfer heat and expand.

The boss explained that what you want to do is heat a narrow area radially outward from the shaft across the pulley. The best place to do this is over the keyway, if there is one, or over the set screw hole if there isn't a keyway. What you are doing is expanding a wedge of the pulley which will force the rest of the pulley to "peel away" from the shaft as that narrow area expands. It takes less time to heat up the narrow area so less heat reaches the shaft.

If the pulley won't come off after a fairly quick radial heat, let it cool off completely and try again, using penetrants in the meantime. Chances are you opened up the shaft/pulley joint enough for the penetrant to do it's work. Make sure the shaft is dead cold before you repeat the heating process.

Glad to see this thread revived. I had never heard this particular argument but I like the jist of it. One thing I would add is after getting it cherry red, cool it with water. The rapid shrinkage can break it loose without adding anything else.

 

[Provincial]

Glad to see this thread revived. I had never heard this particular argument but I like the jist of it. One thing I would add is after getting it cherry red, cool it with water. The rapid shrinkage can break it loose without adding anything else.

If it cracks from shock cooling, it comes off easier, too! Not a good idea if cast iron, but works on steel, brass, and bronze, which are more ductile. Aluminum expands so much that it will break the bond just from the expansion.