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Spaced Out

Concrete Pier, Brake Discs, Bolts..... Questions

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Hi All

I’m just in the process of planning a concrete pier for the garden, a budget affair, a metal air con pipe with some drilled Vauxhall Corsa disc brakes on the top to take my HEQ5. I’m a newbie at all this so just wondering what people would advise regarding the numbers of nuts and threads to connect between the pier top disk and the mounting disk ?

Obviously I’ll need some space underneath the mounting disc for the main mount bolt, but I’m guessing the more threads/bolts connecting the discs, and the closer together these discs are, the sturdier it will be ? Or doesn’t it make that much difference ? Also how many bolts would be ideal for adjustment and levelling, I see lots of people online just use 3, but is there any benefit in having more to make things sturdier ?

Thanks in advance for your advice.

Edited by Spaced Out

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The only reason to have some space under the mounting plate would be to attach the mount.
Levelling is not an issue, because level is not needed with an EQ mount, so keep it as close together as possible and with more, thicker threads to make it as rigid as possible. Be sure to get the concrete footing below the frostline and use a sort of pyramid or cone shape.

Probably more work than you think...

Edited by Waldemar
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This thread:

May contain some useful information for you.

There are no doubt others containing useful advice. This one is mentioned only because I could find it easily!

David.

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1 hour ago, Waldemar said:

The only reason to have some space under the mounting plate would be to attach the mount.
Levelling is not an issue, because level is not needed with an EQ mount, so keep it as close together as possible and with more, thicker threads to make it as rigid as possible. Be sure to get the concrete footing below the frostline and use a sort of pyramid or cone shape.

Probably more work than you think...

Thanks. Yep I've spent the last week surfing the net looking at what others have created. The basic idea is fine, it's no problem to dig a deep hole, borrow a cement mixer, re-enforcing it with rods etc. It's just the little details I'm not so sure about like the bolt thing, people seem to take different approaches with that.

I was thinking more than 3 bolts might be more stable and that’s good advice on the thick bolts, I was aiming for M12, maybe I need to consider thicker ?

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57 minutes ago, Carbon Brush said:

This thread:

May contain some useful information for you.

There are no doubt others containing useful advice. This one is mentioned only because I could find it easily!

David.

Thank you, some useful info in there. The only other thing I am still uncertain about at this stage is tube diameter, so that thread is quite relevant !

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I love the brake disc idea , how much is a plate like that made for an astro mount in comparison to a couple of old discs ?

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3, 4 or 5 thick bolts, all is ok, as long as it is as rigid as possible. Like I said, leveling is really not important for an equatorial mount.

The 'rat-cage' construction, being two plates connected by bolts is prone to resonancy on specific frequencies. No way to tell which frequencies on forehand.
Fact is the more rigid the construction, the higher the resonance frequency, the less it will bother you.

Keep the bolts or threaded ends or studs as short as possible. that will make a difference

Think about this:  you do everything to get a nice, heavy, rigid construction to attach your mount and scope to. And then for the last bit everything has to be carried by a few threaded ends... Why all the hassle to make it rigid in the first place if you are going to undermine the whole construction with a few bolts anyway. Welding a piece of thick pipe in between the plates with an opening to get to the centerbolt of the mount would be way better than bolts.

Treating the brake disc with an anto corrosion spray like NanoProtec or powder coating them may be a good thing.

Edited by Waldemar
added some info

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3 hours ago, PaulR1 said:

I love the brake disc idea , how much is a plate like that made for an astro mount in comparison to a couple of old discs ?

I'm not looking at old disks, just found these brand new ones for nine squid on ebay ! ?

https://www.ebay.co.uk/itm/2x-BRAKE-DISC-SOLID-240-FRONT-VAUXHALL-OPEL-CORSA-MK-3-C-BOX-1-2-16V-00-06/382111798354?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D52543%26meid%3De4187bb7781a49bc8523b31a684ae0ec%26pid%3D100005%26rk%3D1%26rkt%3D4%26sd%3D142407141309%26itm%3D382111798354&_trksid=p2047675.c100005.m1851

 

 

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2 hours ago, Waldemar said:

Treating the brake disc with an anto corrosion spray like NanoProtec or powder coating them may be a good thing.

Thanks. Did think about powder coating but on a tight tight budget and trying to keep the costs as low as possible for now.

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Hi I used 4 threaded rods think M16 and scaffold poles in between the two disks. Very stiff. all then painted with hammerite white no issues with rust.

1119341127_IMG_4641-Copy.jpg.62898823765166244a1304a4609b75cb.jpg 

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15 minutes ago, SW130p said:

Hi I used 4 threaded rods think M16 and scaffold poles in between the two disks. Very stiff. all then painted with hammerite white no issues with rust.

1119341127_IMG_4641-Copy.jpg.62898823765166244a1304a4609b75cb.jpg 

Wow, that's a tidy job ! I was considering getting some hammerite.....

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How about this as an alternative. I used the tripod head as the mounting plate and bolted onto some concrete blocks. The blocks were all bolted together and then mortared onto patio.

You could stand the last block upright if you don't have an extender tube.

IMG_1175.jpg

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Might have to upgrade to a brake disc - cracking idea. Using a 3d printed adapter on top of a todmorden pier (which is working perfectly) but it cant hurt to use steel instead of plastic lol

IMG_2522.jpg.4374de081059b94fee21a4991311dbaa.jpgIMG_2523.jpg.ff0837e9f3fa73d68228966adf49d043.jpg

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