C8 + Vixen porta Crunching/grinding Alt

[Lognic04]

Hi all,
I got a new setup: a C8 + vixen porta a few days ago. Just today after sitting unused with the scope attached it started crunching in alt when moving it up and down. Is there any fix for this? Help!
:shrug::help:

[Wavytone]

Alt worm is loose against the worm wheel and has mashed some of the teeth off (the crunching).

Look closely at the way the worm is mounted - it’s in an eccentric sleeve. Using needle nose pliers or similar you can rotate this, pushing the worm tighter against the worm wheel.

If the crunching was bad it may be permanently damaged.

[dannat]

i would have thought c8 is pushing the limit of a porta

[Lognic04]

Any chance you could clarify how to do this? pics maybe? :thanx:

[LewisM]

Got to agree there - a C8 on a Porta??? No way Jose!

Vixen load rating is 5kg. C8 is very close to 6kg. 3/4 max load is what I'd recommend.

Porta really is a refractor mount.

[Wavytone]

Lewis I have a friend who will try anything, if it fits. He puts a C8 on a Porta as a grab-n-go rig, it works... he had exactly the same problem with the alt worm which was not meshing tightly with the gear wheel. He also has an EQ6 when he's more serious about what he's doing.

Likewise I tried putting my Skywatcher 180mm mak on a $500 All-View mount... while that might seem gross to some, what I discovered is that the weak point is really the rubbish tripod supplied with the mount - with a much better tripod this mount was entirely suitable for visual use with scopes upto a 130mm APO or the 180mm Mak or a C8. As an altaz mount it worked beautifully, the GOTO and alignment worked perfectly. But Skywatcher really don't want you to know this, they'd much rather you buy an EQ6 at 4X the price. As a result of a crap tripod the All-View mount found no friends, was very un-loved and killed off quickly.

Logan, sorry in my case its a friends mount and I don't have a close photo. Look closely where the alt shaft sticks out. It is enclosed in a cylindrical sleeve, with the shaft slightly offset from centre of the sleeve. Two tiny holes should be visible in the sleeve either side of the shaft - get a grip on these and you can rotate the sleeve. The right way will make the worm tighter against the worm wheel, the wrong way makes it looser.

My friend used a pair of needle-nose pliers with the ends ground down to fine points. A pair of tweezers from a chemist would do as well, or a pair of 1mm jewellers screwdrivers, or a couple of pieces of piano wire.

[Lognic04]

Thanks! That fixed it! :thumbsup::thanx:

[Lognic04]

Aaaand it's doing it again:sadeyes:

[Wavytone]

time for a new mount.