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Metal Pier ... Anybody thought of using an RSJ post ??

Craney

By Craney
in DIY Observatories

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Craney

Craney

Posted
Posted

Evening all,

I was day-dreaming at work today about a rock solid pier that could  replace my Heq5  and  NEQ6 tripods.  The tripods are fine as they are, but when I have the dual rig running (SCT and 100mm refractor) or the 10"F4 with guide scope, I do wonder about a bit of leg flexure going on here and there.     Off the  shelf metal piers that have weight and solidity to them come in at about £500 to £600.  Hmmm?... that's quite pricey.                                                                 

So is there a low cost solution out there ??    I like the Todmorden idea,  but would not feel comfortable with 30-40kg of scope and counterweights swinging about above what is essentially, two breeze blocks with some mortar imbetween !!.... that could end badly, especially considering frost.    Also, I would like to be able to remove the fixing easily and completely without too much hassle , possibly to relocate when I move house.  ie.  it's not in some way connected to the Earth's continental crustal plate or resembles a concrete bollard in a car-park.....

hmmmm??  that's when I thought about this.   An RSJ post...

Anybody tried one ??

ARMCO Bolt Down RSJ Post | Powder Coated Yellow

Ok, it will need a top plate welding on to it to produce a platform, but  consider this......

1) They come in different heights....     500mm to 1500mm.   That lends itself to most scenarios.

2) Has a universal base plate.  So you could have 4 studs embedded in a sub-surface concrete ballast block, and attach EITHER a low or a high pier to it depending on your scopes or sphere of interest at the time.  Changing the pier actually would be as much bother as setting the tripod from scratch. So this is  the right kind of flexibility  !!.

3) Has an anti-vibration side weld already attached.

4) Comes in white, black or....YELLOW !!...

5)   the 1200mm one is £72.....

Am I missing anything major here that would sink my argument ??

Cheers,

Sean.

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Wiu-Wiu

Wiu-Wiu

Posted
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A public observatory uses these "lifts" as a base for their mount, they can be repositioned for people in wheelchairs or children to reach the eyepiece.

I don't know why your idea wouldn't work, it has the same "base plate" idea:

 

 

 

 

mount.jpg

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Ibbo!

Ibbo!

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Yes I used one  many years ago for the 4" F13 frac I had at the time with the home made EQ mount.

Very solid it was.

Mine was great value as I scrouged it from work at the time (worked for Budge at the time) and we had demolished something and it was going for scrap.??

I still have the EQ in the garage.

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Craney

Craney

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10 minutes ago, Davey-T said:

how big is it on the biggest side ?

Here is some info I got for a 760mm high post (maybe not the exact same as my picture in the first post, but pretty similar) .  

The 'post' profile  is a capital letter 'i' design and if I read the dimensions correct, the top of the joist post is 80x 130mm.

 

Dimensions

 

Depth 130mm (post), 332mm (base)
Height 760mm (including base), 10mm (base only)
Width 80mm (post), 250mm (base)
Thickness 8mm (end sections), 5mm (inner section)
Weight

Per Unit

Hope this is useful.

 

Sean.

18.7kg

 

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Peter Drew

Peter Drew

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Box section as shown by Harry and Davy-T would be a better bet. Just to clear any misunderstanding regarding the "Todmorden" mount, the sections are connected via lengths of steel studding, the mortar is just for bedding. I use 2p pieces to provide three point of contact on mine.   ?

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Bukko

Bukko

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I am successfully using 20cm bore heavy walled pipe for my piers and the only issue is welding top and bottom plates. My MIG welder is not quite enough for the task and I needed to pre-heat the steel before welding.

I don't see a problem using a length of RSJ, the rolled type is very heavy in section so if you can weld it, it should be fine.

Good luck,

Gordon. 

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Astrokev

Astrokev

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59 minutes ago, harry page said:

Hi

a Tak 180 ed - A tak 106 ed and a celestron 11" rowe      cant get the 14" newt on there as well :)

 

Harry

Maybe a stupid question - why the dogleg in the pier? The OTAs look pretty central to me over the base plate, but I can only presume it's for balance?

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harry page

harry page

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7 minutes ago, Astrokev said:

Maybe a stupid question - why the dogleg in the pier? The OTAs look pretty central to me over the base plate, but I can only presume it's for balance?

Hi

well I already had a conc base from my old scope which is off centre so needed a bend to get round this , also it is a  "flip a bit less pier enables the full range of the mesu200 :)

Harry

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JamesF

JamesF

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To return to the topic,  I see no reason why a section of RSJ wouldn't work either.  I imagine it shouldn't be too hard to get specs giving the deflection under load just to confirm that it won't be too bendy if required.

In my observatory I have three Todmorden piers partially constructed.  I have used four lengths of 12mm studding with large washers each side to fix the lower blocks to the foundation block (a cube of concrete roughly 500mm on a side from memory) combined with the foaming type of Gorilla Glue.  I intend to use the same method to fix the upper blocks.  Once they're done I'll either screw or glue some ply to the outside.  I don't think they'll be going anywhere in a hurry.

I bought a couple more blocks than I needed in case of errors with the tape measure, but I think they were only about £3 each.  I intend to have two and a half blocks for each pier, but in many cases just two might be sufficient (mine start about 250mm below floor height).  Whether you go for slabs (as Peter does) or a concrete block (as I have) I reckon you can still have a perfectly serviceable pier in the Brutalist style for perhaps as little as £40 to £50.

James

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IanL

IanL

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We use one at our society observatory, concreted in to the ground rather than bolted but don't see why bolting would make any difference. It's relatively tall and not that chunky, no particular issues with vibration or deflection but it isn't that heavily loaded usually. If you're using it solely for imaging you can keep it fairly short to minimise such issues, but obviously for visual it would need to be taller.

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Anthonyexmouth

Anthonyexmouth

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I was looking at steel before i went concrete overkill, round or square pipe with triangular fins would be your best option, If you're getting the welder out anyway, just copy a commercially available one with scrap metal. even if you're not welding it yourself you could gather the scrap from a yard and cut the pieces and present it to a friendly welder with a handful of beer tokens

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Yawning Angel

Yawning Angel

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I've gone for the 'pipe full of concrete and rebar' option. I have about 3m of this stuff left over (had to order 6m minimum!) and some 1.5m lengths of rebar - you're not a million miles away and would be welcome to them if they'd be of use?

IMG_1441a.thumb.jpg.c9621417a32f75e193355cc06469ee09.jpg

It's 150mm id, "Naylor Metro Twinwall Solid Pipe" smooth bore

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Craney

Craney

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Thanks for the offer @Yawning Angel  I'm going for the removable bolt down option that could be replaced with a taller/shorter 'twin'  pier if my scope collection/ imaging needs change.

I like the absolute solidity of this design, but alas I would have to site it in the middle of the patio.  This will undoubtedly unleash a force of nature not quite seen since the formation of the Solar System.... if you get my drift.

 

Thanks again for the kind offer.   BTW,  did you find a good cheap source of  'L' shaped rebar ??.....maybe M14  or thereabouts ??

SEan.

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