Setting Circles and other mods to my Lightbridge

[Astralstroll]

Fantastic Base! TIme I headed off to the garage to make something similar methinks!

Dave.

[Dellis]

I've been asked where I sourced my knobs from and though it might be useful to post the details here too:

The knobs are from my local engineering supplies, I'm sure you'll have something similar nearby or here are a few eBay examples. The bases are from Astro Engineering and are available on eBay

My method was to take 3 x M10 stainless bolts and hacksaw the heads off then screw them into the lobe knobs (female type) and secure them with Araldite at the other end I screwed on a dome nut and secured them with non permanent Loctite thread compound (the blue type, this is so I can remove them at a later date if I need to. The nuts on the board are M10 T nuts and the wing nuts are there just to take up the tolerance in the threads.

The reason I hacked the heads off the bolts is that I couldn't get and lobe knobs with the M10 bolt attached at the length I needed.

Dave

[Carbon]

I thought of using locknuts to lock the legs after leveling but decided not to at this point as the tolerances are pretty tight as the studs are also threaded through the wooden portion of the 1" thick base resulting in some resistance, in addition to the threaded inserts used.

[Dellis]

Having got a bit fed up of humping the scope in and out I decided to add some wheelbarrow handles......

I tried bolts with wing nuts but they were too much of a faff in daylight let alone in the dark with freezing fingers so had a rethink and opted for brackets on the side of the base that the handles could slide under and just lift - easy peasy and works a treat. I extended the handles beyond the wheels so I could store the handle vertically without having to chock them.

Dave

[astronymonkey]

Hi Dave,

Do you have any more details and photos of your counter balance set up ?

I have a Lightbridge and was thinking of how best to go about this but you seem to have a really neat solution so any further info would be great,

Thanks,

Astronymonkey

[Dellis]

Hi Dave,

Do you have any more details and photos of your counter balance set up ?

I have a Lightbridge and was thinking of how best to go about this but you seem to have a really neat solution so any further info would be great,

Thanks,

Astronymonkey

Have a look at post number 5, the link on that post takes you to the right page of the e-magnet website and I've used the E622 type.

Dave

[astronymonkey]

Hi Dave, thanks for the PM,

Ive had a look at the website and notice the ones you use have a threaded bolt attached. Do you use this bolt to attach the magnet to the tube... with the weights then sticking by magnetism to it, or do you use the bolt to fix the magnet to the weight and then use magnetism to attach to the tube .

By the way how heavy are the magnets themselves ?

Cheers,

Astronymonkey

[Dellis]

Hi Dave, thanks for the PM,

Ive had a look at the website and notice the ones you use have a threaded bolt attached. Do you use this bolt to attach the magnet to the tube... with the weights then sticking by magnetism to it, or do you use the bolt to fix the magnet to the weight and then use magnetism to attach to the tube .

By the way how heavy are the magnets themselves ?

Cheers,

Astronymonkey

The magnets weigh approximately 200 - 300 g each. I thread the weights onto the magnets and use the magnets to attach to the scope, I have four weights 3 x 1 kg and 1 x 0.5 kg and attach 2 x 1kg to the front and use the 1 kg and 0.5 kg to adjust the balance (these are the weights pictured on the thread I pointed to above), I need a fair bit of weight as I have a Telrad plus a 10 x 50 finder before I even think about a nice heavy ep Don't forget you need around 3 x the weight of additional accessories in balance weights.

The dimensions of the weights are 65mm dia x 40mm for the 1 kg and 65mm dia x 20mm for the 0.5 kg, these are within 30 grammes based on a specific gravity of 7.85 g/cm3 for mild steel and allowing for the threaded hole, they can be fine tuned if an exact weight is required by drilling to reduce the mass. The accuracy doesn't matter as they'll be attached to the magnets, but I just wanted to have exact weights so they could be used for other purposes if needs be.

Hope that's of some help.

Dave

[Champagnerocker]

One of the first mods i made to my dob was to hand draw (not terribly professionally like these examples) some setting cricles so I knew where [not] on earth i was pointing it.

It baffles me why manufacturers don't add these things to the scopes themselves. If they can print, perfectly level to the ground, their logos all over a dobsonian base why can't they print an angular circle on the baseboard and a 0-90° on the uprights? It would add nothing whatsoever to the production costs but make the scope much more attractive to buyers.

[Carbon]

There's at least one vendor here in the States that make these mods as an added option on the bases of some of the popular dobs they sell, including the Lightbridge.

[steveb1977]

Setting circles are a great advantage. I was able to track down Venus once on the day it was at inferior conjuction using them. Impressive sight, you could almost see right around the planet.