Finally got a chance to get the counterweight correct, rather than machine the massive cast iron weight, I decided to pay a visit to Sportsman's Warehouse.
2 x 5Kg and 1 x 2.5Kg plates with a new locknut and the balance was perfect.
I am not that familiar with EQ mounts. I know that you are looking at some brass gears for slow motion movement. I assume that your setup is a 'push to' EQ at the moment and that there is enough 'stiction' to have the scope rest in place when on target?
Last edited by Shark Bait; 15-12-2012 at 05:47 PM.
Its turned out nicely Stu, yes it is a push to and at the moment the counterweights are set perfectly so it will stay on target, I can also adjust the preload on the bearings to give more grip on windy nights by the nut at the end of the RA shaft and the chromed lock collar just next to it. For declination 'stiction' there is adjustment on the setting circles.
I am going to install a worm drive for RA thanks to 'astroboy' and his warehouse of bits and pieces.
It will be a 185mm brass worm gear which will also allow manual coarse adjustments. It will be my first project in 2013.
Absolutely beautiful restoration job you've done there, one to be proud of for sure!
Your project reminds me of a great 4" Zeiss refractor I purchased cheap about 20 years ago from an elderly gentleman who was selling out. It was all painted standard white with black fittings, but they turned out to be brass underneath. Naturally I promptly took it apart and painted the OTA black and polished all the brass parts, it looked fantastic just like your mount I used it every clear night for several years until in a moment of acute aperture fever I sold it to fund a 10" Newtonian...
Thanks Rolf, I would love to have that Zeiss, I bet you regret that decision to sell. Just had a look at your astropics, sensational !!!!
Finally the skies cleared enough to wheel out the big Istar last night.
At 150mm F10 (fl 1500mm) with the 2" dielectric diagonal with the Baader Semi Apo filter attached and Vixens 13mm 17mm and LV 5,6 &20mm trained on Jupiter and the Moon the views were nothing short of spectacular. With the 20, 17 and 13 chromatic aberration was non existent, with the 5 and 6mm the thinnest margin of CA was visible.
It was only with the LVW 3.5mm at 428X that the halo was a bother but the seeing wasn't good enough for that ep anyway.
I am very pleased with the Baader S/A filter, the light loss was minimal and certainly not a factor when viewing Jupiter and Luna. The big refractor does take some time to acclimatise especially today as the temp was 30C during the day and 14C at 10pm.
Due to the push-to being so light and smooth I am finding that as I rack the focuser in or out with the heavy LVW eyepieces balance changes enough for the OTA to start moving.
I think I will have to build a sliding counterweight linked to the focuser so that as the focuser moves out the balance weight moves in and so on.
A small brass slider weight connected via a pulley should do the trick.???
LOVE it Matt! Bring that up next year instead of the R200SS
Only thing I would do differently is have had the Moonlight as gold anodised/brass anodised - would have matched the whole enchilada a little better IMHO.
LOVE it Matt! Bring that up next year instead of the R200SS
Only thing I would do differently is have had the Moonlight as gold anodised/brass anodised - would have matched the whole enchilada a little better IMHO.
I agree Lewis, but as I bought the scope and focuser 2nd hand I have to be happy with it the way it is.
I do have yet another little addition in the pipeline that will 'brass it up' a little bit. That will come in the new year.
If there is a starparty gathering or two around the time I come up I might just load the lot into the 4wd.
RA gear set arrived today (thanks Zane )
Just giving it a clean up to fit in with the mount.
I will have to machine a bush to fit over the RA Setting Circle Plate.
Still have to source a Dec axis gear which will need to be smaller.
Pic 1 Worm gear set on arrival 1030hrs
Pic 2 One side cleaned up at 1120hrs
Pic 3 Test fitting at 1615hrs (bit more polishing to go, rim will be polished, centre painted black)
With many thanks to Lars (lhansen) for his generous donation toward the completion of the Istar-Gaunt rig, I now have the perfect solution to balancing the OTA for different sized eyepieces.
These two 800gr brass weights with endbrackets will soon have their new home under the Istar. This extra weight of about 2.5Kg will also mean I can slide the OTA further forward thus raising the eyepiece height further.
(Lars, I have some 12yr old Scotch here with your name on it, or some Penfolds Bin 389 if you prefer a nice red.)
I was looking at the tube weights trying to decide whether to paint them satin black to match the scope or use a bit of elbow grease to see what lurks under the paint ........
This time it was a case of draw filing to remove the saw marks, then arris the corners, followed by 320grit, 800grit and autosol paste to uncover the gem within .....................
1600hrs: One down one to go! (then I will have to clean the kitchen sink before Jen gets home)
Here are before and after pics (Thanks again Lars, these are just perfect for the Istar)
I think I will need to find a brass finderscope for the opposite side of the scope to keep things balanced ...... brett (bert) I hear you have one hidden somewhere
Matt your frac is looking more like Dr Tim Wetherell's 8" scope...and for visual I still like black everything, no night time glare coming from the focuser. Beautiful bit of work
Matt
With many thanks to MattT, his donation of the 160mm tube rings is much appreciated and now the tube weight set is almost complete. I bought a metre of 12mm solid stainless rod today in Canberra which will be polished to mirror shine and cut down to about 480mm.
All that is left is to mount the worm and add some flexible extention handles................. when will I ever escape this vicious circle ??????????
I used it every clear night for several years until in a moment of acute aperture fever I sold it to fund a 10" Newtonian... 
