Pier Design

[MarkS]

I need to think about what design to use for a pier.  In terms of resistance to deflection, vibrations, oscillations etc.  and any other usability factors - e.g. Carole's "shelf" being hit by the telescope or heat rising from a concrete pier upsetting planetary imaging.

Any recommendations/articles or any factors I should consider?

Mark

[mickw]

Use a rotating shelf and have it D shaped rather than round.

You could insulate a concrete pier

[The Thing]

I have seen piers where carpet is stuck around the concrete to insulate it and make it more user friendly in a confined space.

[Ian]

I think the biggest issue will be avoid the light pollution from the dodgems at the end. That and the risk to your waistline and teeth due to ready 24 hour access to candyfloss.

Remember to build it a fair distance from the house to reduce the risk of collateral damage when the skinheads inevitably burn it down.

[MarkS]

I have seen piers where carpet is stuck around the concrete to insulate it and make it more user friendly in a confined space.

Good idea.  In any case I think the problem with rising heat came from a pier that sat in direct sunlight all day.

I think the biggest issue will be avoid the light pollution from the dodgems at the end.

Good point

[Carole]

Just to say Mark, since I changed over to mounting my guide scope piggy back instead of side by side, I have not had any further problems with the scopes hitting the pier shelf.

I do find the pier shelf and the shelf below quite handy at times.
Maybe a smaller shelf might be a good compromise.

I also had problems with the CG5GT not being able to see through the polar scope because the pier plate was in the way of my chin - again not been a problem since I got the NEQ6 which has the polarscope further out than the CG5 GT.  Thought I'd mention this since you have both mounts.

Carole

[MarkS]

Interesting couple of video clips about pier vibrations and oscillations:
http://www.youtube.com/watch?v=AOeLnecOMeg   Part 1
http://www.youtube.com/watch?v=LI3PkC0aT2E   Part 2

Pier deflection calculations:
http://www.cloudynights.com/item.php?item_id=1275

[RobertM]

That third link is very interesting.  I'll try and measure the deflection (in arcsec) of my pier on the next clearish night.  I reckon it'll show that I need to get some webbing welded to it

For reference my pier is 8" diameter bollard welded to a 0.5 inch thick steel plate of 12" x 12".  That is bolted to concrete of 18" x 18" x 48" (approx).

Robert

[RobertM]

Well, I pushed the pier with with my hand (probably 10-15 lbs pressure) and the guider moved two pixels which equates to 3 arc sec   It's more than enough to ruin images but would take quite a bit of wind to apply that much pressure.  5lbs probably equates to 1-1.5 arcsec which again is far too much.  Unfortunately I cant tell whether it's the pier or concrete block causing that but is enough that I'm going to get the pier strengthened jic.

Robert