Pier - H beam/iron?

[tooth_dr]

Looking to erect another pier, currently trying to source some metal pipe.

As an alternative could I use a section of H iron?

 

Cheers!

 

 

[saac]

3 hours ago, tooth_dr said:

Looking to erect another pier, currently trying to source some metal pipe.

As an alternative could I use a section of H iron?

 

Cheers!

 

 

An H beam would work fine but may give you more work in attaching the pier plate, but certainly doable. 

Jim 

[M40]

Mines made of 100mm box section, about 1M tall with a flange on each end, solid as a rock. Try and find a friendly welder, they will soon knock one of them up for you.

[tooth_dr]

15 minutes ago, M40 said:

Mines made of 100mm box section, about 1M tall with a flange on each end, solid as a rock. Try and find a friendly welder, they will soon knock one of them up for you.

Would you be able to post some photos?  I’ve this one here that my friend made but I want a simpler (cheaper) option this time and I plan to weld it up myself.

 

 

[tooth_dr]

26 minutes ago, saac said:

An H beam would work fine but may give you more work in attaching the pier plate, but certainly doable. 

Jim 

Cheers Jim. Good to know options 👍🏻

[bwj]

H beam should be very doable.  Welding on the base plate and top plate will be no harder than welding to a pipe. If you're concerned about twisting moment at all you could just weld a couple of gussets in halfway up. You could even use those as mounting points for accessories. 

Clear skies!

[saac]

Here's mine.  I had it fabricated and installed by a local agricultural blacksmith.  Basically square section tube, I think 6 mm thick with the base and webs welded on. 

Jim 

Edited October 23, 2023 by saac

[inFINNity Deck]

There is less risk of vibrations if the pier widens towards the base. Here is my tubular pier:

The tube is 250mm in diameter, 3.4m tall, weighs about 350kg and stands on a 0.80m diameter base-plate. It is held at this base by 16 M12 anchors, not bolted down, but clamped in between nuts below and above the base-plate to minimise stress on the chemical anchors.

Nicolàs

[tooth_dr]

Thanks guys. If I’m imaging remotely or not moving around does it matter much about vibration suppression?  I suppose the wind could cause vibration?

[JeremyS]

On 23/10/2023 at 18:37, inFINNity Deck said:

There is less risk of vibrations if the pier widens towards the base. Here is my tubular pier:

The tube is 250mm in diameter, 3.4m tall, weighs about 350kg and stands on a 0.80m diameter base-plate. It is held at this base by 16 M12 anchors, not bolted down, but clamped in between nuts below and above the base-plate to minimise stress on the chemical anchors.

Nicolàs

That’s a very pointy hat being loaded onto those two guys 🤔

Edited November 8, 2023 by JeremyS

[inFINNity Deck]

Just now, tooth_dr said:

Thanks guys. If I’m imaging remotely or not moving around does it matter much about vibration suppression?  I suppose the wind could cause vibration?

I think it does. All movement may lead to vibration if you are (un)lucky enough to have something producing the pier's own frequency. Possible causes are walking (not in your case), traffic, tremors, meridian flip, image centring, etc.

Nicolàs

[UKDiver]

26 minutes ago, JeremyS said:

That’s a very pointy hat being loaded onto trose row guys 🤔

Slytherin? 🙂

[saac]

Vibration is not the issue that it is often made out to be , all structures will vibrate. What is important is the decay time, neither a box section nor and H beam of typical height suitably secured to the base would have a sufficiently lengthy decay time particularly if the observatory is used remotely for imaging.  Like the need for a cubic m  foundation these design characteristics take on legs  

As for wind, it is more likely to have an effect acting on the telescope itself rather than the pier; so as long as your observatory walls are offering some shelter from the wind I would not be overly concerned.  Have you had any vibration concerns on your existing pier, I would imagine the dome keeps it very well protected from wind?

Jim 

Edited October 23, 2023 by saac

[saac]

46 minutes ago, inFINNity Deck said:

There is less risk of vibrations if the pier widens towards the base. Here is my tubular pier:

The tube is 250mm in diameter, 3.4m tall, weighs about 350kg and stands on a 0.80m diameter base-plate. It is held at this base by 16 M12 anchors, not bolted down, but clamped in between nuts below and above the base-plate to minimise stress on the chemical anchors.

Nicolàs

Did you have a visit from the weapon inspectors after you took delivery of that - it has the makings of a super gun   That is a cracking pier👍

Jim 

[tooth_dr]

2 hours ago, saac said:

Vibration is not the issue that it is often made out to be , all structures will vibrate. What is important is the decay time, neither a box section nor and H beam of typical height suitably secured to the base would have a sufficiently lengthy decay time particularly if the observatory is used remotely for imaging.  Like the need for a cubic m  foundation these design characteristics take on legs  

As for wind, it is more likely to have an effect acting on the telescope itself rather than the pier; so as long as your observatory walls are offering some shelter from the wind I would not be overly concerned.  Have you had any vibration concerns on your existing pier, I would imagine the dome keeps it very well protected from wind?

Jim 

Cheers Jim. Another friend just text to say he thinks he has some 100mm or 150mm flanged iron pipe left over from a job so could be in luck.  I’ll know tomorrow when he checks sizes. 
Currently have no vibration issues that I’m aware of in the dome. No wind on the scope is one of the big advantages of the dome 

Edited October 23, 2023 by tooth_dr

[saac]

2 hours ago, tooth_dr said:

Cheers Jim. Another friend just text to say he thinks he has some 100mm or 150mm flanged iron pipe left over from a job so could be in luck.  I’ll know tomorrow when he checks sizes. 
Currently have no vibration issues that I’m aware of in the dome. No wind on the scope is one of the big advantages of the dome 

That sounds like it would work. I just went out and measured mine, it's 150 mm x 150 mm and it is as I thought earlier 6mm wall thickness. The top flange where the mount adapter is attached is a little thicker at 8mm - most likely because that is what plate off cut was available.  I image remotely too, as well as the odd bit of visual work at the pier and I've never noticed any vibration concerns; my obsy walls are pretty high,  so good wind protection all round keeps the scope out of bother. It's been there close to 10 years now I think; the only thing I have changed was to recently reposition it and lower it to accomodate a new Esprit 120 for clearance with the roof closed.  It was actually quite a good move as I had always thought it was originally a little too tall, certainly for visual - either that or I'm too short . It was easier to lower the pier to sort that one out  

Jim 

Edited October 23, 2023 by saac

[900SL]

16 hours ago, tooth_dr said:

Looking to erect another pier, currently trying to source some metal pipe.

As an alternative could I use a section of H iron?

 

Cheers!

 

 

I'm a structural engineer. What height pier and mount type/load?

[tooth_dr]

1 hour ago, 900SL said:

I'm a structural engineer. What height pier and mount type/load?

Hi. I’m looking at 1m in height.  EQ6, total load 35kg (mount CWs scope).

[M40]

On 23/10/2023 at 18:15, tooth_dr said:

Would you be able to post some photos?  I’ve this one here that my friend made but I want a simpler (cheaper) option this time and I plan to weld it up myself.

Here you go....

I have tidied the cables up a bit since then 😁

[900SL]

12 hours ago, tooth_dr said:

Hi. I’m looking at 1m in height.  EQ6, total load 35kg (mount CWs scope).

OK. A H section (wide flange) is better than an I section but still has significantly lower stiffness in bending about the weaker axis. Having said that, you'd likely not have any issues with a 6" (152mm) universal column section if only 1 m high with your rig. 

 A circular section is ideal, this has the same stiffness in any direction. Square hollow section also has similar properties about both principle axes and closed hollow sections have good torsional stiffness too.

[tooth_dr]

15 minutes ago, 900SL said:

OK. A H section (wide flange) is better than an I section but still has significantly lower stiffness in bending about the weaker axis. Having said that, you'd likely not have any issues with a 6" (152mm) universal column section if only 1 m high with your rig. 

 A circular section is ideal, this has the same stiffness in any direction. Square hollow section also has similar properties about both principle axes and closed hollow sections have good torsional stiffness too.

Thank you.

[tooth_dr]

My friend delivered some free piping.
Starting building up my pier last night. This is for my solar scope so only going to be a lightweight setup <10-12kg total.

I have another larger pipe but it needs cut and a piece welded onto the base so need to dust off the welder.

 

Edited October 28, 2023 by tooth_dr

[david_taurus83]

Good old DN80!

[tooth_dr]

4 minutes ago, david_taurus83 said:

Good old DN80!

Have some DN100 but it’s a 2m length so going to chop it half and weld a plate onto it. 

[david_taurus83]

24 minutes ago, tooth_dr said:

Have some DN100 but it’s a 2m length so going to chop it half and weld a plate onto it. 

I used DN100 as it was the perfect length for what I wanted and free! Perks of working in construction 😉