Piers and brake discs

[SamAndrew]

5 hours ago, Adam J said:

It would depend on your focal length. 

Depends on your imaging resolution, how susceptible your rig is to wind, and how windy it is. I was imaging just below 1"/pix and had no problems.

[laser_jock99]

On 03/06/2020 at 02:35, Adam J said:

The issue I always have with these is that you dont need to level a pier top to polar align and so you introduce a vibration source in making the leveling device using threaded rods.

Quite right. I'd avoid the 'leveling bolts' approach. So many times we see good solid piers sunk into x tonnes of concrete- only to have the entire scope balanced on some M12 studding!!!!!

Another issue to be aware of with wider brake discs is the possibilty of the scope clashing with mount. This could become apparent when pointing the scope close to vertical.

A better solution is to get a local machine shop to make a custom, drop in puck for your steel tube.

A drawing I made for the puck.

[prusling]

A "SUZUKI OPEL VAUXHALL 50357 Front 246.5mm Solid Brake Disc Coated By Pagid" works well for the HEQ5.  I paid around £16.50 for mine from eBay in 2016.

[jiberjaber]

6 hours ago, laser_jock99 said:

Quite right. I'd avoid the 'leveling bolts' approach. So many times we see good solid piers sunk into x tonnes of concrete- only to have the entire scope balanced on some M12 studding!!!!!

Another issue to be aware of with wider brake discs is the possibilty of the scope clashing with mount. This could become apparent when pointing the scope close to vertical.

A better solution is to get a local machine shop to make a custom, drop in puck for your steel tube.

A drawing I made for the puck.

 

 

How much did they charge to knock that up ?

 

[laser_jock99]

1 hour ago, jiberjaber said:

 

 

How much did they charge to knock that up ?

 

Free to me- one of our subsidary companies is an engineering shop. I cashed in a few favours!

[edarter]

On 06/06/2020 at 17:02, laser_jock99 said:

Free to me- one of our subsidary companies is an engineering shop. I cashed in a few favours!

Can I ask, how is the Puck secured to the pier? 

[maxchess]

I'm planning to build a pier using 2 x Skoda disks as described. However I notice that the four holes in the pads have a diameter of 13.8mm. What size rods did you use? I assume M14 would be too fat or does it work. The next standard size seems to be a lot thinner. Thanks for any help.

My plan is to fill a 125mm Round Ducting pipe 1m high with concrete and then to use a  joining section cemented in the ground to hold it.  I would like to be able to lift and move the pipe to one of three locations in my garden.   I calculate that when filled with concrete the pipe will weigh 28 kilos, so  movable, any wider and the weight increases rapidly.  I would only be putting widefield kit on this, so it only needs to be better than a tripod. Any observations on this plan are most welcome. The advantage over a tripod is that I can leave the pier and mount polar aligned and its easily covered. A tripod is too easily moved.

 

[saac]

Dont't know if anybody has already mentioned this (sorry haven't read all way through) but hey don't go buying brake discs any decent garage will be happy to give you a scrap set from free if you explain what you want them for.  That's how I got a set when I did it.  

Jim