Epoxy undercuts

[doug mc]

Any luck using epoxy to fill tapered undercut.

[Merlin66]

These “safety undercuts” are the devil’s work!!!!!
I’ve tried various fill methods including epoxy.....with no permanent success.
They should be banned........

[Kunama]

Heat shrink works

[doug mc]

Just bought some Orings to place in the undercut on the eyepieces that were a problem. Will try them out when the rain clears. Just purchased a TS bino with self centering eyepiece holders. They don't like undercuts. Was able to unscrew the threaded barrel on a few of my eyepiece pairs and reverse them with the undercut at the bottom.

[Merlin66]

I found something more solid than Orings or shrink tubing was required to prevent being chewed up by the focuser screws or jamming with the brass strip....
I always seem to end up with adaptors which don't sit nicely in all my focusers.
Answer: keep searching for "smooth sided" options. Manufacturers should offer the choice "No pain smooth sided" or "the other"

[Wavytone]

There's an opportunity in this, for a clever mechanical engineer.

What's really needed is someone who can design an eyepiece holder that holds eyepieces with undercuts without pushing them off-centre or tilting them, and without the barrel jamming when removed, and with a range of different screwthreads to retrofit to the usual ranges of diagonals and focusers.

The worst are the ones with tapered undercuts.

They'd make a fortune IMHO.

[Merlin66]

I agree 100%.
And getting all the “others” to agree on a suitable “standard” sizing for the land on the bodies and the position of the screws......
Go back to smooth sided, end of problems.....

[doug mc]

I do believe that GSO plossls have eyepiece barrels that you can turn around so that the undercut is at the bottom. Seeing that i mainly use the binoviewer for lunar and planetary, plossls are good enough. With a power increasing oca the focal ratio is long enough to keep the field of view flat.