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Pier advice.....

GazOC

By GazOC
in DIY Astronomer

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GazOC

GazOC

Posted
Posted

I'm trying to get things clear in my head before I dig the garden up.....can anyone offer advice/ critique this plan?

1) Dig 3-4 foot hole

2) Fill bottom with hardcore/ broken bricks

3) Insert 14" sonotube sleeve (not sure what this is for but they seem to be in plans on the 'net)

4) Insert 10" steel tube

5) Pour concrete and a couple of rebars

6) Fill tube with sand

As far as Ive got (ie not fixing the plates or the mount) is this correct? I already have the sonotube, the pipe and the broken bricks to hand which is why I'm using them, is there any reason I shouldn't use these? Are there materials significantly better for the job?

I'm also torn in between welding a bottom plate to the tube or filling the tube with concrete and setting the bolts directly into that? Also given that I'd like the pier to be 4 foot high and able to take a 12" SCT/ EQ6 with extension piece, is 10" pipe overkill? I have access to 6" pipe would that be up to the job? I suppose over engineering is never a bad idea.

Sorry for all the questions but I really need to get this right first time as I'm sure you can appreciate. :D

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CELESCOPE

CELESCOPE

Posted
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Well Gaz,

as you know i made my Pier, the difference with my set up is , i will have a Dome soon , this is fixed on a 6/7 inch base of concrete, the Pier will sit in the middle bolted to the floor, my pier is an 8 inch square tube with the base plate mig welded and then bolted to the base, now i think this is good enough for my operation,as i dont intend to sit in the Dome , i will control it all from my other obervatory, so vibrations if any will not happen ,

So getting back to your set up , i would go for the 10 inch tube, and connect it to the lower concrete section, this is a far better way, as you will no doubt be hovering around the pier, yu have a big beasty there, so any over kill is great .

Rog

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barkis

barkis

Posted
Posted

I'm trying to get things clear in my head before I dig the garden up.....can anyone offer advice/ critique this plan?

1) Dig 3-4 foot hole

2) Fill bottom with hardcore/ broken bricks

3) Insert 14" sonotube sleeve (not sure what this is for but they seem to be in plans on the 'net)

4) Insert 10" steel tube

5) Pour concrete and a couple of rebars

6) Fill tube with sand

As far as Ive got (ie not fixing the plates or the mount) is this correct? I already have the sonotube, the pipe and the broken bricks to hand which is why I'm using them, is there any reason I shouldn't use these? Are there materials significantly better for the job?

I'm also torn in between welding a bottom plate to the tube or filling the tube with concrete and setting the bolts directly into that? Also given that I'd like the pier to be 4 foot high and able to take a 12" SCT/ EQ6 with extension piece, is 10" pipe overkill? I have access to 6" pipe would that be up to the job? I suppose over engineering is never a bad idea.

Sorry for all the questions but I really need to get this right first time as I'm sure you can appreciate. :D

Why Sonotube and a Steel tube Gaz?, I am a bit puggled over that.

Ron. :D

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GordonCopestake

GordonCopestake

Posted
Posted

The sonotube is used for a solid concrete pier with no steel. If you want to use a steel pier then you just put a base down (about 3 foot deep)

The idea with the concrete pier is to fill the tube with concrete then set bolts in the wet concrete in the top. You dont need BOTH the concrete AND the steel, one or tother

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geppetto

geppetto

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Another way might be to just use the sonotube? I have a 6 foot by 14" length of sonotube, could I just fill that with concrete and pop the bolts in the top

That sounds a better plan...

Rebar the tube concrete to the base concrete and it will stop a tank 8)

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GordonCopestake

GordonCopestake

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Another way might be to just use the sonotube? I have a 6 foot by 14" length of sonotube, could I just fill that with concrete and pop the bolts in the top?

Thats the idea. You'll need a footing though. Fill the footing and the inside of the sonotube with rebar before you pour. I'll knock up a quick (poor) sketch

post-12885-133877327134_thumb.jpg

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GordonCopestake

GordonCopestake

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The J-bolts are the most important part, the rest is a piece of cake (even if it's concrete cake!)

You'll need to get 2 plates made (see Phils thread for his wooden version) to allow adjustment. The base plate has to match up with the j-bolts and the top plate holds your mount head (although im sure you know all that)

A trip over to the CN obs forum will reveal the basic sort of thing most people are doing and bill arnets website has LOADS of examples

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George

George

Posted
Posted

The sonotube is used for a solid concrete pier with no steel. If you want to use a steel pier then you just put a base down (about 3 foot deep)

The idea with the concrete pier is to fill the tube with concrete then set bolts in the wet concrete in the top. You dont need BOTH the concrete AND the steel, one or tother

Like this only I used stainless 10 inch ducting instead of sonatube:

pierboot.JPG

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  • 2 weeks later...
Chubster

Chubster

Posted
Posted

Cheers for he thread Gaz...im planning exactly the same at them mo, so hope you dont mind me adding a few Q's

I think im OK with the actual concrete bit, in fact im going to use postcrete...cant be doing with all that mixing :D Any reason why I shouldnt apart from cost. The bit im struggling with is the making off the mounting bracket...can you buy these anywhere and why are they always square. I want a round one?

Upgrader...where did you get the stainless steel tube from and have you just filled that with concrete?

Cheers Gaz...and all :D

Chub

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George

George

Posted
Posted

Upgrader...where did you get the stainless steel tube from and have you just filled that with concrete?

Cheers Gaz...and all :D

Chub

I rescued the tube from a skip at work :D

I cast in 2 parts first the hole was filled with concrete then I set the tube in while still wet and set some steel bar in the tube in the wet concrete this was all set square, I left this a day then filled tube with concrete.

If casting in 2 parts its important that the first pour is left to firm up or else the second pour will just slump out the bottom.

Hope this helps.

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philsail1

philsail1

Posted
Posted

Hello Gaz. Have you dug the hole and concreted in the post yet? If you have, I hope it went OK for you. If you haven't, then may I give a little advice.

1. Ensure there is plenty of space around the 10" post you are installing - perhaps allowing 6" of space around the post.

2. Try and dig the sides of hole so they are either dead vertical, or preferably "dovetail" shaped (with the widest part at the bottom. This shape will give the greatest solidity and security - especially if the surrounding ground is soft.

3. With regard to the concrete mix. You can use "post mix," or mix your own (a 1:2:4 mix would give you a strong enough mix)(1:2:4 = 1 of cement, 2 of washed sand (not builders red sand) and 4 of lime stone chippings). give it a thorough mix

"dry" then add water sparingly. The wetter a mix is, the weaker the finished concrete. (Ideally concrete should be as stiff as to make just about workable - if it slides off your shovel when you pick it up, it's way too wet. As your post is meant to be holding up a heavy instrument - and will be doing the job for many years, the initial job (as you well know) wants to be rock solid. (If you wet concrete up too much, yes it will make it very easy to work with, but during filling the hole, all the stone in the concrete will sink to the bottom and the sand and cement will float. This will drastically weaken the whole job). I have seen this done when I worked in the concrete industry (as a batching plant foreman) in the 1970's - 80's.

4. I would not use rocks or anything else to wedge around the post. There is nothing wrong in using rocks, but if you do, you will have to make your concrete on the wet side, so it will pour between the rocks and avoid air pockets (which will reduce the solidity of the job). I would tend to get someone to hold the tube steady, whilst you feed the semi dry mix around the bottom of the post - securely ramming the concrete all around the post using a length of 3" x 2" timber. Try to do the job in one "pour." If you leave a part to "go off" you could get a "cold joint" where the first lot of concrete has not securely bonded to subsequent additional concrete.

Well, there you have it. As I said earlier, if you have already done the job, I hope it turned out OK. If not, and you are still looking for advice - I do not know much, but I would try and help all I could.

Regards,

phil edwards. (philsail1)

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GazOC

GazOC

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No I havn't dug the hole yet so you're advice will come in very handy. Many thanks.

BTW what part of North Wales are you from? I live just outside Chester in a place called Buckley.

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  • 3 weeks later...
SteveA

SteveA

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Posted

I'm considering a permanent pier with some sort of cover to keep the mount protected. I',m just looking around at the moment at various methods of construction.. Where can I get hold of Sonotube and the rebar mentioned in this thread ?

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