Hi,

I can definitely understand the dilemma about putting heat up there.

You may have to treat this screw like a stuck spark plug with lots of patience.
What I mean with this, is to torque the screw a little bit tighter and then back a little bit tighter and actually strain the body of the screw to stretch it but not to actual move it for quite some time.
PATIENCE is the biggest factor here.
It can take several five minute sessions over times while trying to get a plug out of an aluminum head.

So far I have never stripped out threads before but I have put in a few Heli-Coils used in manufacturing specifications.
Engineers claim they can provide more strength especially in thin or weaker materials used in a product.
The idea of thread insert’s being used in plastics follows those lines.

The soaking of penetrating oils and of course heat is a technique of expansion and contraction alone with the capillary action that all of the techniques present to loosen the bonding that has happened.

In your case that you are concerned with is keeping the heat constrained to that precise area.

I would suggest using a tin can of about a 303 size. That would be a Pork & Beans size can.
The end that is not open would need to a slot cut part way across and of course a slot down one side enough to encompass the joint.

You would apply a propane torch flame to the set screw end and it surrounding body. You want to get it hot for only a few hundred degrees quickly.
Maybe the pin will grow longer and shift under the set screw.
If any plastic bushings melt so be it, they are done anyways.

In thinking this out a little farther, as you have, you might consider a wet rag laid up on top of your modified tin can.
Wrap the stick going upwards just in case you get over zealous with any heating device.
A heat gun can work but will involve lots of air flow and time and who knows where the excess air may go too.
The rag will soak up any extra heat if you use a heat gun as well.
I like the thinness of a torch better.

Thanks for the Oxford 👀 up.
We are both correct because as you say, they make up a connection.
Clevis terminology is far more popular than shackles.
As shackles relates more to constraints rings and chain. Not a pleasant thought for those in them. 🤨

In my days of machining and within the scope of overhead cranes, the “process of hooking” up to eyelets, nylon straps or lifting fixtures I didn’t consider “shackles” as a useful term either.
But if I spotted a Clevis that had a tonnage rating “forged” into the side of them it was considered different, so there you go? The Purchasing or budgeting Department needed a justification for the expenses.

A Clevis can be replaced by a more common referenced thing called a “fork” as in mechanical linkages.
The shifter would qualify here better for terms of assembling.
In my opinion. 😎 and we know how that flies.


Phil