View Full Version : How do I get this mount off the Aero Ektar 178mm?

24-Aug-2011, 18:21
I can't seem to figure out how to get the old mount off this Aero Ektar here. All the screws are removed and it is moving a little but won't come off or screw off. Any clues??

Here is a picture of the rear group and stubborn mount:


24-Aug-2011, 19:19
Hello Bryan
There are two possable things happening. First the screws may have made dents in the threads that will cause the mount to lock up. The threads in the mount will not slide on the opposing threads. Second and really hard to fix is did the aluminum mount gaul. Gauling is where the softer metal abraids against the harder metal and makes a fine powder that is gritty and locks up. The only way to fix it is to mill the ring in half.
If you have any questions email me. k4sb@frontier.com

24-Aug-2011, 19:34
Ah, thanks for the info! The mount moves slightly but doesn't feel gritty, so I think the threads are messed up. I had to drill out two screws so that makes sense, if someone tightened them down so much.

What are my options if this is the case? Will it unscrew with enough force? I have access to some heavy-duty tools, but obviously I want to be careful...

24-Aug-2011, 19:55
Ah...You drilled out screws. Did you get all the screws metal out? Did you hit brass?
If not there might be a pointed bit left? Or some grit? Chuck the mount in a lathe chuck and see what gives.........A bit of force?

24-Aug-2011, 20:33
I can see brass at the end of all three holes, and the mount wiggles a little and I see the brass moving. I'll try tomorrow at the shop I work out to force it...gently hopefully.

24-Aug-2011, 20:38
In the holes where the screws used to be try injecting some anti sieze compound and working the parts back and forth. This has worked for me before especially with dissimilar metals. Beware cuz it's a bit messy -- keep it away from lens elements.

24-Aug-2011, 20:53
Will do, I've got plenty of that stuff at the shop too for frozen parts.

Dan Fromm
25-Aug-2011, 06:51
I once bought a 12"/4.0 TTH telephoto in an F139 cone and couldn't unscrew the lens from the cone. It had been locked in position with radial setscrews that had damaged the threads on the lens' barrel.

So I sent it to Steve Grimes with a request to cut the cone off the lens. Steve was much better with a hacksaw than I am. He didn't cut, he handed it to Adam and told him to squirt lapping compound into the screw holes and work it. Adam later told me that getting the lens free took half a day.

Lapping compound, not anti-seize, is what you want. And patience.

25-Aug-2011, 14:08
For posterity:

My friend helped me out with this, he used a left-hand drill bit a little bigger than I had on hand to drill out the holes a bit bigger and then it came free. Thanks for the help guys!