Changing the focuser of a Lunt 40mm

[MChiara]

Good evening, I bought a lunt40. I'd like to replace the original focuser, but I can't unscrew it from its seat even with considerable force. How can i fix this?
thanks

[davidem27]

No reply for you MChiara
Welcome to SolarChat Forum.

[Oak]

There is glue on the threads but they will come apart with some force. The black piece at the end of the tube is an adapter for whatever dimension the tube is to the helical focuser which is about M35. Some people use strap wrenches or heat guns for similar problems, but I did not need to with mine.

[marktownley]

WElcome to the forum, sorry, I don't have a Lunt 40.

[Rusted]

Dismantling fragile parts of an optical instrument requires great care. Damage will reduce the value catastrophically!

Try wearing grippy, rubber, work gloves. Not all rubber gloves offer a good grip. So test them out before purchase.
Have somebody hold the main tube, again while wearing rubber gloves, while you try to turn the focuser.

If that fails then look for a car oil filter remover with a rubber strap and plastic body. Look up strap wrench online.
Or even buy two of them. They are inexpensive and useful for plumbing. Or even for removing oil filters.
The straps will obviously have to be fitted in opposition to each other to unscrew the focuser.
Don't try to turn the focuser by the knobs. You will bend or break the pinion shaft.

Silicone cooking mats can be very grippy if those are available locally. Try supermarkets.

I have even used climber's Prusik loops on occasions while working alone.
Don't try to hold the main tube in a vice! You will ruin the finish or crush something.

[MChiara]

Ok, thank you very much for the advice, I will try to do as you advised me.
If I manage to unscrew it I'll update you.

[hopskipson]

Did you ever manage to get the focuser unscrewed? What focuser are you planning on upgrading to? I have a 40 coming on Monday and am considering upgrading it also.