Removing Socket Cap Screws With Lok-Tite

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In summary, if you have access to only one side of the screw, it doesn't matter if you heat it or not.
  • #1
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OK, not the usual kind of question posed here, but not entirely off-topic either.

Last weekend I was trying to remove a couple of socket cap screws (recessed hexagonal drive) that were installed with lok-tite (thanks to the lawyers). After multiple applications of heat from a propane torch, liberal amounts of penetrating oil, and using a hex socket drive on a torque wrench, I managed to remove 1 and strip 2 others, so I'm looking forward to an adventure of drilling, screw extractors, etc.

During the struggle, at first I was trying to turn the screws immediately after heating. Later, after heating again, I waited until everything had cooled to try again. Now I'm wondering, ignoring the effects of the loktite, is heating more likely to make a screw looser or tighter, or neither? Clearly, the screw must expand. What happens to the hole? Does it get bigger as the drilled part expands, or does the material expand into the hole, making it smaller?
 
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  • #2
gnome said:
OK, not the usual kind of question posed here, but not entirely off-topic either.

Last weekend I was trying to remove a couple of socket cap screws (recessed hexagonal drive) that were installed with lok-tite (thanks to the lawyers). After multiple applications of heat from a propane torch, liberal amounts of penetrating oil, and using a hex socket drive on a torque wrench, I managed to remove 1 and strip 2 others, so I'm looking forward to an adventure of drilling, screw extractors, etc.

During the struggle, at first I was trying to turn the screws immediately after heating. Later, after heating again, I waited until everything had cooled to try again. Now I'm wondering, ignoring the effects of the loktite, is heating more likely to make a screw looser or tighter, or neither? Clearly, the screw must expand. What happens to the hole? Does it get bigger as the drilled part expands, or does the material expand into the hole, making it smaller?

If you heat quickly, heat the hole part and the screw will loosen. Be ready - you'll have a fairly short time before the screw comes up to temperature. I'm surprised lok-tite, even the permanent stuff, worked that well. Were these stainless screws? Or, small diameters?
 
  • #3
No, they don't seem to be stainless. They're 5/16, 18tpi, 3/4 in. flathead screws, marked with letters 'Y' 'D' on the head. And the loctite was supposed to be the non-permanent type, but who knows what they used in the factory.

So, ignoring the screws for the moment, you're saying that the hole gets bigger as the material expands? That's a bit surprising. Clearly, if I draw a circle on a solid piece of material, the circle will grow as the material is heated. That makes sense because the material inside the circle must expand. But it's not so obvious when the circle is actually a hole. Why doesn't the surrounding material expand inward towards the axis of the hole?
 
  • #4
gnome said:
But it's not so obvious when the circle is actually a hole. Why doesn't the surrounding material expand inward towards the axis of the hole?
Take a 6 foot length of chain, lie it on the ground in a circle, joining the ends.
Now try to add one link to the loop. Will the loop increase or decrease in radius? Obviously, it will increase.

Next, instead of adding one link, replace each individual link with links that are 10% larger. Once you've replaced them all, will the loop have a larger or smaller radius?

The links, obviously, are your atoms of metal around the hole.


Finally, add another chain around the first (which will be slightly larger in radius than the first and use a couple more links). Add as many as you want in concentric circles. Now do your swapping-in of larger links again.

See what happens? Every chain, in order to take up more room, will have to expand outward, not inward.
 
  • #5
OK, thanks, that's a helpful analogy. Applying simple geometry to it convinces me that even though the individual links expand in all directions, the distances between their centers increases sufficiently so that the inside diameter of the circle expands by the same ratio.

Then apparently, except for any effects relating to the speed of transmission of heat through the parts, assuming all parts are heated approximately equally and that the coefficients of expansion are approximately equal, the screws will be equally tight whether hot or cold, correct?

Unfortunately, TVP45's suggestion doesn't help me. These screws are fastening a blade onto a rotor (it's a wood chipper), passing through the blade into threaded holes on the rotor, and I have access only to one side. I can't get to the back of the rotor without taking the whole machine apart, and heat applied to the blade is likely to be transmitted to the screws faster than to the rotor.
 
  • #6
You may have done better with an impact tool.
 

1. How do I remove socket cap screws with Lok-Tite?

To remove socket cap screws with Lok-Tite, you will need a heat gun or blow dryer, a socket wrench or hex key, and a pair of pliers. First, heat the area around the screw with the heat gun for about 30 seconds to loosen the Lok-Tite. Then, use the socket wrench or hex key to turn the screw counterclockwise. If the screw is still difficult to remove, use the pliers to grip the screw and turn it.

2. What is Lok-Tite and why is it used on socket cap screws?

Lok-Tite is a brand of threadlocker, a type of adhesive used to secure screws in place. It is commonly used on socket cap screws because they are often used in high-stress applications and Lok-Tite helps prevent them from loosening or vibrating loose.

3. Can I reuse socket cap screws after removing them with Lok-Tite?

It is not recommended to reuse socket cap screws after removing them with Lok-Tite. The Lok-Tite may have weakened the screw, making it less reliable and prone to breaking. It is best to use a new screw with fresh Lok-Tite for optimal performance.

4. Is there a specific type of Lok-Tite that should be used on socket cap screws?

Yes, it is recommended to use a medium-strength Lok-Tite, such as blue or purple, on socket cap screws. This type of Lok-Tite provides enough hold to prevent loosening, but still allows for removal with hand tools.

5. Can I still remove socket cap screws if I don't have a heat gun or blow dryer?

Yes, you can still remove socket cap screws with Lok-Tite without a heat gun or blow dryer, but it may be more difficult. Try using a soldering iron or boiling water to heat the area around the screw before attempting to remove it. It may also help to use a more powerful tool, such as an impact driver, to remove the screw.

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