Sat dish & seized bolts.....

[w9wi]

More a mechanical question than an electrical one...

We have an Advent dish atop an (old!) satellite truck. There's a sensor in there that's failing intermittently, causing the controller to fault & forcing the operator to climb on top with a crank handle & manually crank up/down the dish.

We have a replacement sensor. To get at it, we have to unbolt the dish from the elevation axle.

Which has, unfortunately, proven impossible. There's at least one bolt that's seized. We can't get it to budge -- and having been under a fair amount of pressure to get it fixed, tried enough force to damage the corners. (it's an Allen-head bolt, probably #12 stainless)

We've tried WD-40. We've tried heating the assembly -- and cooling it. We've tried banging on it with a hammer. (in the hopes of breaking up whatever kind of corrosion might be in there binding it up) It's a flathead bolt, so a chisel is out of the question. (not that we'd be able to put it back together if we *did* use a chisel )

I'm an absolutely useless mechanic, but some of our other guys aren't, and they haven't had any luck either.

Anyone have any other ideas?

Thanks!

[NECRAT]

Two things come to mind...

Try to pry the dish to see if you can get it to move ON the bolt, using some kind of leverage.

If that doesn't work, then have a auto mechanic look at it. He might be able cut it out using a torch and cut a new hole on the base using a torch too..

[Deep Thought]

I've seen mechanics weld another piece of steel on top of a seized bolt in order to gain some leverage, and then use penetrating oil (WD-40 does not penetrate well over larger areas despite its reputation) specifically designed for these kinds of problems. Not sure how that would work on a recessed bold head though. See if you can find Gunk L106 Liquid Wrench Penetrating Oil, which is much more aggressive.

[boiseengineer]

The final step is to break it off, drill it out, & re-tap it.

[RGORJANCE]

Two other types of penetrating oil:

KROIL

MARVEL MYSTERY OIL

Fossil

[w9wi]

Suggestions received & appreciated! Will take a spin past an auto-parts store tomorrow & see what I can find.

I don't think breaking it off is going to be an option. It's a recessed bolt, we can't shear it.

[RGORJANCE]

When I mentioned KROIL penetrating oil in a previous post, I forgot to mention that it is also available as "AERO KROIL". This product should be easily available through the aviation support stores. You should be able to obtain KROIL from a tool and machinery supply company..

I am told by a very high time CFI/A&P mechanic that it is a superior product.

Fossil

[boiseengineer]

Tower climbers I've dealt with dislike stainless due to their tendency to seize, permanently. Once they're stuck they don't waste a lot of time on it. Just haul out the "breaker bar" for their wrench or resort to power cutting tools.