Which pier to get?

[peroni]

Thanks for the pictures. That looks like something I could repeat. Hopefully. B-)

[Zakalwe]

made a few pier's , its 10mm wall pipe , HEAVY , its rock solid only need to remake az peg ( don't like the cut cap head)

A few fillets on the bottom plate and I reckon that that would be perfect.

[teleskopjo]

I cannot figure out why bolts closer to the pier are better than further out...? Wouldn't there be a greater chance for it to 'rock'?

Yes, some weird terminology used in that video.

The most important feature on a surface mounted pier is to correctly fillet the base plate to the sides of the tube. Use 6 or 8 smaller pieces rather than 4 tall ones.

Braces 200 mm tall will be more than adequate. If you need tall braces then the tube diameter choosen is too small ! 

Drill the holes through the base plate close to, and with in the radius of the braces - this makes a big difference in the final pier rigidity.

The base plate doesn't need to be large in area , just wide enough to fit the braces.

( Next time on the motorway, look at the overhanging information signs. The tube is a large diameter and the base plate is just a bit larger than the tube with lots of small braces.)

One thing I do agree with in the video is the use of studding to separate the top plate. Some 30mm or 40mm diameter solid spacers kept as short as possible would be more suitable, as levelling adjustment is definitely not needed for an EQ mount.

Dave.

[Scott]

I cannot figure out why bolts closer to the pier are better than further out...? Wouldn't there be a greater chance for it to 'rock'?

I don't think he means closer to the pier, just that it should be not further out than the fillets and as close to them as possible. if your fillets reach 200mm from the pier, the bolting it 300mm would give you 100mm of base plate that might allow flex. this is my understanding of the post. whether it's right, I don't know

[1parsec]

@ teleskopjo

Scott's description is right.  Put the bolt holes adjacent to the fillets and at slightly closer radius to the pier tube than the outer reach of the fillet.

The image shows the bolt position would be better re-positioned next to the fillet.

[Zakalwe]

I cannot figure out why bolts closer to the pier are better than further out...? Wouldn't there be a greater chance for it to 'rock'?

Its holding a mount and telescope, not supporting the Forth bridge. Bolt it down using the recommended torque for the bolt or fastener size and it'll be reet.

Honestly, I've seen steel frame buildings erected (and put a few up too) and I've never seen as much discussion about bolt placement! Any steel column that I've seen have had the bolt holes in the middle of the web. Why? The base plate is properly specced and it's easier to get tools in to access the fastener.

[1parsec]

I'd agree for a building the bolt placement doesn't matter much. The rigidity comes from the building's structure.

For a pier putting the bolt next to the fillet is mechanically better and doesn't take any more work to do so, so why not ?

[Zakalwe]

I'd agree for a building the bolt placement doesn't matter much. The rigidity comes from the building's structure.

Ever wonder what the lift on a pitched roof in a hundred-year wind would be? :-)

Lets face it...if the base plate is 8mm or above on a pier then you could hang a house off it. A load like a mount and telescope will NOT casue it to flex no matter where the bolt holes are.

[damnut]

Hi Kirkster,

If it can be made Graham can make it, he is not great at answering e-mail    and can be found on east midlands stargazers in the traders section. Drop him a pm from there.

[1parsec]

Ever wonder what the lift on a pitched roof in a hundred-year wind would be? :-)

Lets face it...if the base plate is 8mm or above on a pier then you could hang a house off it. A load like a mount and telescope will NOT casue it to flex no matter where the bolt holes are.

Do you mean an 8mm base with fillets or just a flat plate ?

[Owmuchonomy]

I think if I were going this route again I would make my own. I purchased the AA pier because I'm lazy and whilst it does the job it's not without its own foibles. You'd think they would consider cable routing etc but no. You'd also think they would provide an Az pin with the adaptor and a nice bolt to connect your mount but no. Yes, easy to make yourself but also easy to manufacture when you make the adaptor. Now the adaptor, that is a nice piece of work so top marks for that.

[Zakalwe]

Do you mean an 8mm base with fillets or just a flat plate ?

With fillets.

Welding a flat plate onto a tube will bowl the plate upwards (unless it is very thick- 15mm+). The fillets will help to control the distortion, especially with judicious welding.

I think if I were going this route again I would make my own. I purchased the AA pier because I'm lazy and whilst it does the job it's not without its own foibles. You'd think they would consider cable routing etc but no. You'd also think they would provide an Az pin with the adaptor and a nice bolt to connect your mount but no. Yes, easy to make yourself but also easy to manufacture when you make the adaptor. Now the adaptor, that is a nice piece of work so top marks for that.

If I sill had access to a workshop then that is what I would have done to.  I am glad that I don't though...it was lots of hard work and poorly paid.

Petty much any fabrication shop will have lots of offcut plate and tubing. I could knock up a pier, with "levelling" plates in a lunch-break for a fraction of what commercial piers sell for.

if I was to do it, I would use a minimum of 10mm baseplate, SHS tubing ( 150mm per side would be ample. 5mm wall) and 8mm top plates. Fillets top and bottom. 16mm stud between top plates.

A  slightly fancier design would be to cut an access hole at the top to give access and do away with the "levelling" plates, though that would mean making absolutely sure that your pier height was correct.