Gibraltar - Altitude Bearings
Posted 24 June 2009 - 07:40 PM
I've recently acquired a nice TV Gibraltar on the ash tripod. Overall I'm enjoying using the mount but I find the altitude bearings a little "stickier" than I'd like.
Is it OK to apply some lunbricant to the brass alt bearings or is there a better way to smooth the motion ?.
Posted 28 June 2009 - 07:31 AM
I own 2 of the TV Gibraltar Mounts and tripods. What I did was to remove the brass tension screws to allow greater access to the exposed gap area of the side arm / bearing surface. I then applied 2 drops of Slick 50 oil additive to the bearing surfaces and I rotated the arm 360 degrees to work the lube in all the way around the bearing. I then reinstalled the brass thumbscrews but first added a thin Nylon washer onto the brass thumbscrew.
If you get your OTAâ€™s balance set correctly and the elevation tension set about equal on both sides it will work very well for you. Keep in mind that the closer you can have the center axis of the OTA matched to the center axis of the 2 Alt bearings the more uniform the OTA's balance will remain as you go from 0 degree elevation to near 180 degrees elevation.
One last tip, itâ€™s very important to get the large 4-fluted screw knob underneath the tripods cast head very tight. This helps with vibration and stabilization. I have other tips as well.
I hope this helps...
Clear Skies, Donnie Garrett
Posted 28 June 2009 - 05:24 PM
Those are very useful tips - I'm interested in any others that you have for getting the best out of the Gibraltar mount.
I'm using mine to mount a Vixen ED102SS F/6.5 refractor which is a lightweight (7 lb) OTA so well within the Gibraltar's capabilities I would have thought.
I have already learned that balancing the OTA is key - I'm planning on getting TV Equaliser to make my 1.25" eyepieces weight a closer match with my 2" eyepieces.
Is the panning handle a worthwhile addition ? - there is one for sale over here (the UK) and I'm considering it.
Any other tips would be very welcome !.
Posted 28 June 2009 - 10:25 PM
The panning handle is not needed! Just move the OTA by grasping the scope at the diagonal. Even Al Nagler will tell you this. Also if you have the handel installed it will cost you a few degrees of your maxium elevation because it hits the mounts horizontal cross bar at near zenith.
You should make sure the 6 screws are snug that secure the wooden legs to the mount head. I replaced mine with Brass Thumb screws. Do a search in Cloudy Nights on the Gibraltar mount. I posted pictures of my mod using the brass thumb screws. This makes it possible to hand tighten them in the field, then slightly loosen them when you break down the tripod.
Posted 29 June 2009 - 01:54 AM
I have seen a gibraltar mount or two in operation in my club over many years and I'm just not impressed with them. You will get a more stable ride and less bouncing and vibration even with something fairly humble like a Vixen Super Polaris mount which is great for this scope. The SP mounts have of late sold for as little as $175 without drives, at that price they are a steal. I guess they run around $400 to $500 with motor drives, haven't seen a large number of them for sale lately because they're worth more than what the market says they are and are keeping them instead of selling them.
The Super Polaris can also be set into alt-az configuration just like your Gibraltar.
Super Polaris in alt-az configuration
HOWEVER, be careful in buying, because the Great Polaris series won't do this. You need the SUPER Polaris.
And you can turn it into an EQ mount as well which means you'll have both possibilities and be much happier and you'll have clutch locks and can change eyepieces without worrying about the whole rig going nuts.