42 replies to this topic

[macdonjh]

SimonIRE,

 

The dimensions of your base plate will mostly be determined by the diameter of your pier and the anchor bolts you choose.  You need to have enough room to use a wrench to tighten the nuts down during installation.  

 

Gussets are likely not necessary for a pier only 100cm tall.  

 

If your fabricator has some scrap stainless he would sell you cheap, go for it.  Structurally there is no benefit.  I wouldn't worry about weight, either way.  You are making a permanent installation, so who cares how heavy your pier is?  As for making it heavy on purpose, the benefits will be negligible.  Rather, aim to make a secure connection to a good footer/ foundation, and making the pier itself stiff and rigid.

 

As for the pier you posted in #24, I don't like the separate top plates.  That's often called a "rat cage" and is used for leveling the top plate independently of making the pier plumb.  You can also use it for routing cables through the pier to a mount without through-the-mount cable provisions.  However, there is expense in buying and assembling all those parts and it isn't necessary.  If your pier is fabricated will, making it plumb will also result in a level top plate.  If you want cables routed through your pier (I highly suggest that) and your mount doesn't have through-the-mount cabling, you can have a couple of holes made in your pier to allow for cable exits near the top.  It won't affect the stiffness of your pier.

 

As for rust prevention, stainless steel is of course inherently rust proof.  Galvanizing will work fine for a steel pier.  It may, though, be easier to find a painter or powder coater.  Then you'll have your choice of colors, too.  The direct to metal (DTM) primers are getting good, so you could also paint it yourself.  A good paint should last several years even outside.

[macdonjh]

The stiffness is all from the diameter.  Doubling the weight by going to schedule 40 from schedule 20 might add 1% to the stiffness.

 

I understand that.  My point is an 8" pipe is probably going to be plenty stiff enough for this application and, at least here, sch 40 pipe is much easier to find than sch 20.  If I called around to some fab shops I might even get lucky and find a "drop" long enough for a 40" tall pier.  If I was set on sch 20 I'd likely have to buy a whole joint (20 feet).  Weight won't matter in this application since the pier will be permanently installed.

 

I agree with you about that rat cage...

[SimonIRE]

This probably more like it, design-wise?

 

http://www.10micron....lar-for-gm3000/

[macdonjh]

This probably more like it, design-wise?

 

http://www.10micron....lar-for-gm3000/

That's what I would build, except I'd probably leave the gussets off.

[Waldemar]

This is the pier for my ASA DDM85

A friend of mine made it according to my drawings. The size is 130 cm tall; 27,2 cm diam; 10 mm wall thickness; weight app. 115 kg.
I made the coupler from bamboo plywood. 2 layers of which one inside the pier. It sits on a concrete pad, 1 meter deep, attached to a retaining wall made from L form elements, 1 x 1 x 1 meter. total about 30 meters horizontal length, which were put in 40 years ago to raise the garden. The garden is about 1 meter higher than the surrounding land. The soil is heavy river clay.

 

[macdonjh]

Waldemar,

 

That bamboo is certainly pretty.  Have you noticed whether it expands/ contracts/ warps over time?  Have you had to refine your polar alignment since you installed your mount?

 

I like the conduit right next to your pier.  It's a good improvement over having cords laying across the walking area.

[Waldemar]

Thank you Macdonjh, I think so too 

 

This setup is not operational yet, but I did the same before and did not notice any changes in pa or shape of the coupler.

I use a very hard and durable varnish to finish it called Glitsa ( https://glitsa.com/ ) no mold or fungus or warping or whatever, just a beautiful satin glow. I finished the pier with 3 layers of black Hammerite, no primer either.
I used these materials for a couple of things outside and they never failed me.

The mounting plate is bolted through the bamboo with rampa nuts on the other side. There is no chance of cracks or tears.

Even a harder kind of Bamboo is available, it is very high pressure compacted and is harder than the hardest wood and heavier...it sinks in water... You have to use tools for ironwork to shape it...

The other thing about bamboo is that it is a very sustainable material, though in this little application that does not mean much.
 

Edited by Waldemar, 29 September 2020 - 10:06 AM.

[macdonjh]

Thank you Macdonjh, I think so too 

 

This setup is not operational yet, but I did the same before and did not notice any changes in pa or shape of the coupler.

I use a very hard and durable varnish to finish it called Glitsa ( https://glitsa.com/ ) no mold or fungus or warping or whatever, just a beautiful satin glow. I finished the pier with 3 layers of black Hammerite, no primer either.
I used these materials for a couple of things outside and they never failed me.

The mounting plate is bolted through the bamboo with rampa nuts on the other side. There is no chance of cracks or tears.

Even a harder kind of Bamboo is available, it is very high pressure compacted and is harder than the hardest wood and heavier...it sinks in water... You have to use tools for ironwork to shape it...

The other thing about bamboo is that it is a very sustainable material, though in this little application that does not mean much.
 

I am sure the sustainability of bamboo for use in telescope pier plates will be a reason for explosive growth of our hobby.

 

Thanks for the information.  The use of wood in this application makes me cringe even though I fully realize there may be no detrimental effects in actual practice/ use.  It's good to hear from people who have actually done it.  It does make me curious though, why the spacer at all?  Why not simply bolt your mount directly to your pier?

[Waldemar]

I am sure the sustainability of bamboo for use in telescope pier plates will be a reason for explosive growth of our hobby.

 

Thanks for the information.  The use of wood in this application makes me cringe even though I fully realize there may be no detrimental effects in actual practice/ use.  It's good to hear from people who have actually done it.  It does make me curious though, why the spacer at all?  Why not simply bolt your mount directly to your pier?

First of all for vibration demping reasons (there is also a lead layer in between the two 40mm layers of bamboo plywood), but also to make adjustments really easy, so however the pier is situated I can always point North, because it is 360° adjustable. The pier is open ended, so the choice was easy to make. And let's be honest... it is beautiful :-) As you can see the two layers of bamboo with the lead slab in between are bolted together through and through. It may well be overkill, but I had great fun making it and that counts as well...

 

[t-ara-fan]

 (there is also a lead layer in between the two 40mm layers of bamboo plywood

Why?

 

 

[Waldemar]

Why?

An extra demping factor.

Lead is an ideal metal to dempen vibrations and prevent resonances, because it's relatively soft nature.

It is also used for the same reasons for heavy machinery between the floor and the machine's feet.
Whether it will really suit it's purpose with such a relatively light load as a mount and telescopes is hard to tell, but it won't harm. Just a little bit of extra work while I was at it anyway.

[SimonIRE]

Hi All, 

 

So here is an update:

 

My fabricator can build a square pier 200x200mm (10mm thick), 100cm high (as I specified) and on top I will have a 300mm diameter top plate which I will bolt the mount plate directly too. I will also have holes for through the mount cabling and access to the inside of the pier in case I want to add bags of sand etc. 

 

My question to you all - would you think 200x200mm at 10mm thickness would be ok? Obviously it has the strength to hold the weight easily (total weight will be up to 250kg - 60kg mount with capacity of 100 kg gear and 100 kg of counterweights) but I am wondering about rigidity/flex. 

 

What do you think of square piers. I can see huge advantages for mounting things to the pier walls. Currently I am taping things to my round pier and its pretty awkward. 

 

What do you all think?

 

Simon

Edited by SimonIRE, 01 October 2020 - 06:16 AM.

[iwannabswiss]

Hi All, 

 

So here is an update:

 

My fabricator can build a square pier 200x200mm (10mm thick), 100cm high (as I specified) and on top I will have a 300mm diameter top plate which I will bolt the mount plate directly too. I will also have holes for through the mount cabling and access to the inside of the pier in case I want to add bags of sand etc. 

 

My question to you all - would you think 200x200mm at 10mm thickness would be ok? Obviously it has the strength to hold the weight easily (total weight will be up to 250kg - 60kg mount with capacity of 100 kg gear and 100 kg of counterweights) but I am wondering about rigidity/flex. 

 

What do you think of square piers. I can see huge advantages for mounting things to the pier walls. Currently I am taping things to my round pier and its pretty awkward. 

 

What do you all think?

 

Simon

If you see mine in the post above, it's a square pier. I think it's perfect; I've got all my stuff mounted using zip ties.

[macdonjh]

If you see mine in the post above, it's a square pier. I think it's perfect; I've got all my stuff mounted using zip ties.

Yeah, but you probably loaded your pier with only 240 kg, so it won't work for SimonIRE's manly load. 

[SimonIRE]

Yeah, but you probably loaded your pier with only 240 kg, so it won't work for SimonIRE's manly load.

Yes. Manly

[my-spot]

I keep seeing folks with these very large diameter top plates. If you are using a GEM, My concern is that these could interfere with tracking at the meridian as the scopes, cameras, dovetails, saddles, or whatever hit the top plate and/or the pier. I would at least make sure you size things so you can still track a few degrees past the meridian. (I wonder how many folks have ended up not being able to reach the meridian because their pier and/or top plate was too big?) 

[Waldemar]

I keep seeing folks with these very large diameter top plates. If you are using a GEM, My concern is that these could interfere with tracking at the meridian as the scopes, cameras, dovetails, saddles, or whatever hit the top plate and/or the pier. I would at least make sure you size things so you can still track a few degrees past the meridian. (I wonder how many folks have ended up not being able to reach the meridian because their pier and/or top plate was too big?) 

I myself made the pier the same diameter as the mounting plate of my mount. Using a tripod like a Berlebach Planet would give me less room for going past the meridian. In other pictures of piers with mounts, I mostly see the largest part is the mount's mounting plate. Most of the time the pier is thinner. The problem you mention mostly arises with the counterweights and tripods I think.

If that happens, people put a short pier extension on top of the tripod to resolve that problem.
These kind of problems mostly arise in higher latitudes, because of the RA angle.

Besides that most mounts if not all, have an option to set a value for going past the meridian, exactly to prevent that kind problem.

Edited by Waldemar, 04 October 2020 - 03:14 AM.

[macdonjh]

When I installed my latest mount, I made the plate just big enough to allow me room to tighten the mounting bolts to my pier.  It's bigger than the base of my mount, but just a bit.

 

Another, more basic, reason to keep a pier plate small (but not too small) is you may bump into it while moving about in your observatory.  A friend had that trouble, compounded by his plate being square.  He ended up bringing a grinder out to remove the sharp corners of the plate.  A messy afternoon.