Gib Key trials and tribulations + welding !!!

Discussion in 'Help Wanted' started by pp-admin, Feb 26, 2016.

  1. pp-admin

    pp-admin Member

    On my tombstone I will have the following text...

    "goodbye cruel world........goodbye gib key hell!!".

    well, its not really quite that bad, but gib keys are not my favourite part of our hobby. I currently have a difficult lister gib key that I have been trying to remove for many many months. There is very little left of the gib key that I can weld to and the head has long since gone leaving a half inch stub sticking out as the only part I can actually get to.

    I have made a tool to weld gib keys to and then pull them out. It has worked very well on the 6 occasions I have used it but on this particular key, the weld on the remains of the key fractures every time in the same place. I have a very sexy new Mig welder that produces astounding results and a 16 amp supply to feed it. I am fastidious about weld prep and the area to be welded is polished and de greased.

    I wonder if the problem is that the cast iron flywheel in a cold damp workshop is acting as a massive heat sink and reducing the effective bonding of my mig welding on the gib key metal.

    My question to all you experienced welders is would it make a difference to the integrity of the MIG weld if I heated the cast flywheel first before I welded it using a decent gas blow torch. I know that wedling cast iron requires pre heating of the casting first. I have never needed to do this welding mild steel sheet or machined items....would I gain anything ???

    Any technical wisdom would be most welcome.

    I will eventually post some details about by heath robinson gib key extractor and chain flywheel puller as they really do seem to work (to my surprise !!).

  2. JohnM

    JohnM Member

    Pre-heating is a good idea even on mild steel if it's thick enough (10mm+). Although the key isn't that large, the thermal effect of all that metal around it makes it behave as if it was. Also, a bit of heat may help loosen the key. Just be careful how much heat you put into the cast iron flywheel boss.

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