I was inspired by GrimlockAutobot's Head mod for FOC Grimlock and decided to try to see if you can do it without cutting up a Galvatron. Well I found out that the balljoint for Grimlock is very close to that of a Titanmaster/Headmaster. If you want to make a headmaster Grimlock you should go GrimlockAutobot's awesome route.

First I unscrewed the Headmaster and took off its head and faceplate. Also unscrewing Grimlock's head.



I then placed it on the original balljoint.



Replacing the faceplate and rescrewing it.



You can always unscrew the head and put the headmaster head back, or you can do this...


(Don't screw it too tight or the ball joint will be super stiff)

 

But... doesn't that defeat the point of headmasters?

 

Yeah but you don't have to kill Galvatron's for it and you can always unscrew it to return it to its regular self.

 

I take it FOC Grimlock's head ball joint is actually the right size or did you have to whittle it down any?

I put Apeface on CW Cyclonus and I had to whittle the ball joint on that one. Most figures' heads aren't uniformly attached so it's not common that you find a figure where it 'just works'.

 

Neat!

 

It's slightly loose, but it will not fall off at all.

 

A hint of Super Glue inside the Headmaster cavity should take case of the wobbliness.  

 

I'd recommend doing it around the Ball, not the socket. Just so it won't leak onto anything and glue moving parts together, but yes, that'll work.