Grub Screw Trouble - SW 80ED

[Grifflin]

Hi All

In the process of fitting an autofocuser to my SW 80ED.  Trouble I have is that the grub screw holding the coarse focus knob refuses to budge and I feel that there is a risk that I might be starting to shred the allen key head. 

Before I go any further, has anyone else had a similar experience?  Any advice?

Neil

[RT65CB-SWL]

Yes! 

I am going to have to drill out the offending grub screw on my ETX105 focus knob with a left-handed drill bit.
I got my drill bit from the well known auction site within a few days of ordering.

[Grifflin]

4 minutes ago, Philip R said:

Yes! 

I am going to have to drill out the offending grub screw on my ETX105 focus knob with a left-handed drill bit.
I got my drill bit from the well known auction site within a few days of ordering.

Thanks Phillip....Yeah, I had a growing sense of dread that this was where I was going to have to go.  Probably a dumb question but what is a left handed drill bit and why would i need it for this?

Neil

[Laurieast]

If any of the thread is visible try the tiniest drop of WD40 on the end of a tooth pick and apply it to the thread, avoiding getting it in the grub screw head, leave to soak for an hour.
Are you using the best fit allen key you have, they do vary.

Mine was tight, and the key was starting to bend, but it did let go with a bit of a click, but it was not so tight I thought it would shred the grub screw head.
 

There were no traces of glue in mine, although FLO do mention that might be the case on their page for the kit.

Good luck!

[skybadger]

Heating and tightening might help before going for the loosening. 

[RT65CB-SWL]

1 hour ago, Grifflin said:

Thanks Phillip....Yeah, I had a growing sense of dread that this was where I was going to have to go.  Probably a dumb question but what is a left handed drill bit and why would i need it for this?

Neil

Hi Neil... a left handed drill bit is turning anti-clockwise. They look the same as your 'typical' right hand drill bits, apart from direction of the flutes when you look at them side-by-side.

Theoretically the drill bit 'bites' the metal of the grub screw anti-clockwise to undo it and if it has enough 'bite', it should follow the screw thread and come out.   

Edited September 18, 2021 by Philip R

[Grifflin]

20 minutes ago, Philip R said:

Hi Neil... a left handed drill bit is turning anti-clockwise. They look the same as your 'typical' right hand drill bits, apart from direction of the flutes when you look at them side-by-side.

Theoretically the drill bit 'bites' the metal of the grub screw anti-clockwise to undo it and if it has enough 'bite', it should follow the screw thread and come out.   

Ahh...ok...yep, makes sense.

[Grifflin]

1 hour ago, Laurieast said:

If any of the thread is visible try the tiniest drop of WD40 on the end of a tooth pick and apply it to the thread, avoiding getting it in the grub screw head, leave to soak for an hour.
Are you using the best fit allen key you have, they do vary.

Mine was tight, and the key was starting to bend, but it did let go with a bit of a click, but it was not so tight I thought it would shred the grub screw head.
 

There were no traces of glue in mine, although FLO do mention that might be the case on their page for the kit.

Good luck!

Thanks Laurence....I have tried the WD40 option although to no avail so far.

[Grifflin]

34 minutes ago, skybadger said:

Heating and tightening might help before going for the loosening. 

Thank you.....I'll give that a go.

[Grifflin]

Hi All

Just a quick update.  Ended up going down the "screw extractor" route.  Plenty of options out there and some useful youtube videos.  Found the process straightforward and not as scary as I thought.  Offending grub screw removed and autofocuser fitted.  Not used it yet but that is for another day.

@Philip R   @Laurieast  @skybadger  Thank you for your comments and advice.

Neil