Completely botched pier rebuild

[jetstream]

9 minutes ago, vlaiv said:

Less than 1/10th of arc second.

Btw - that is completely inconsequential for planetary type imaging - it is only important for long exposure imaging if this angle is high enough.

Thanks vlaiv, so no gussets are needed with the 8". I'm going to build one or two and may as well make them with DSO imaging in mind eventhough for now lunar/planetary is on the agenda.I'll put one down at the lake concrete pad I poured years ago and one on the hill.

 

[900SL]

Calculation for angular rotation (tangent at end) is PL2/(2EI)

(in radians)

 

That's P * L * L / (2 * E * I)

[Bukko]

Hello Vlaiv,

I was sorry to read the tale of your pier problem. I was trying to understand what went wrong and remember back when I did mine. You say you could break off pieces of concrete in your hand.. The only thought I had was lots or air trapped in the mix.

When I poured the pier bases, I used an industrial vibrating poker to get rid of trapped air in the mix. I was surprised at how much in compacted. I can only assume your builders did not do this and so you have problems. A well poured concrete pier should work for you..

Good luck.

Gordon.

[vlaiv]

1 minute ago, Bukko said:

Hello Vlaiv,

I was sorry to read the tale of your pier problem. I was trying to understand what went wrong and remember back when I did mine. You say you could break off pieces of concrete in your hand.. The only thought I had was lots or air trapped in the mix.

When I poured the pier bases, I used an industrial vibrating poker to get rid of trapped air in the mix. I was surprised at how much in compacted. I can only assume your builders did not do this and so you have problems. A well poured concrete pier should work for you..

Good luck.

Gordon.

It was probably that and the way they separated mold from concrete.

In any case, I decided to go with steel pier, but all of that is going to wait for spring next year.

[Bukko]

2 minutes ago, vlaiv said:

It was probably that and the way they separated mold from concrete.

In any case, I decided to go with steel pier, but all of that is going to wait for spring next year.

Frustrating when things go wrong... A winter season missed...

Gordon.