Fordos' Observatory Build

[Fordos Moon]

Work in progress. Roof covered as not completed yet and there is still a lot of rain about!

[SnakeyJ]

Looking very neat and tidy - nothing like my own bombsite during my build!    Nice to have the tarp on to keep the water - might allow you to do some bits inside even if the weathers foul.

[Fordos Moon]

Anyone know anything about bolts and concrete?

Have I got the right bolts here to fix my pier?

Do I squeeze some stuff in, twist the bolts into the holes (2mm wider) put pier on then tighten nuts or wait for resin to harden before putting on pier and nuts?

[Tinker1947]

The Raw Bolt looks like a self anchoring type, what normally happens, you put the bolt in the hole place the pier over the bolt, then tighten the nut this pulls the end on the bolt through the metal section on the end and this opens up and is self tightening in the hole, it wouldn't normally require any resin to hold it, i think you could squeeze resin in the hole then push the bolt into the resin and leave it to set....

Just make sure the bolts are upright and in the right position for the pier holes....

[ollypenrice]

I woudn't have used expansion bolts, I'd just have used a size of threaded bar that was a firm fit in the holes and put the epoxy in. As it stands I'd pack in the epoxy first, then the bolts, and tighten them before the epoxy goes off. If the epoxy goes off first you won't be able to tighten the bolts or you'll weaken the bond or both. I think your system of bolts and epoxy will be fine but tighten before it goes off. Not a professional opinion by the way!

Olly

[Tinker1947]

I think Olly's way may be better, tighten them with the pier in place, but on the other hand if the hole is oversized it will just pull the expanded up the thread , so it really a case of try tightening if it doen't grip just leave it to set, If you go for studding to fit the hole you may well need the holes in the bottom of the pier enlarging.....

[SnakeyJ]

Drill the holes, third fill with resin, put the pier in place and insert threaded bar (through pier holes to keep them centred and parallel).   Remove any excess resin before it's fully cured.    Once cured you can tighten the bolts down.

Provided you have resined 250mm plus in to good concrete I'm sure the bolts will shear before resin/concrete gives.

[Fordos Moon]

Gents thats fantastic advice thank you very much indeed!

[Bizibilder]

I think Jake has it about right - the expansion bolts you have there are not necessary.  It may well be worth investing in some stainless steel studding (threaded rod) as the last thing you want is for the steel to rust itself loose!  The plating will prevent rust but the sawn ends are the weak point and will rust.

[Fordos Moon]

I think Jake has it about right - the expansion bolts you have there are not necessary. It may well be worth investing in some stainless steel studding (threaded rod) as the last thing you want is for the steel to rust itself loose! The plating will prevent rust but the sawn ends are the weak point and will rust.

Thanks Bizi - can I buy the studding at required lengths so I don't make my own sawn ends?

[Tinker1947]

Normally comes in 1 metre lengths.....cuts ok with a hacksaw just have a nut on there to undo over the cut thread....

[leelee970]

You should be fine with what you've got. So don't worry.

I've erected dozens of aerial bracket systems at work and none have rusted and failed in +30 years. (except one, but that was the brick that came out, the rawbolt was fine !!!)

Lee

[Fordos Moon]

You should be fine with what you've got. So don't worry.

I've erected dozens of aerial bracket systems at work and none have rusted and failed in +30 years. (except one, but that was the brick that came out, the rawbolt was fine !!!)

Lee

Thanks Lee. No option to dig more holes really so need to get it right! The holes are full of water - i must get them completely dry before I start! ps your picture scares me lol

[Tinker1947]

A industrial hoover will suck the water out, normal hoover might go up in a puff of smoke, you could if you have the bits make a cold frame up to place over the hole once the waters out the extra warmth through the glass will help dry them out, as the weather is at the moment it could take a long time if unaided......

[leelee970]

Thanks Lee. No option to dig more holes really so need to get it right! The holes are full of water - i must get them completely dry before I start! ps your picture scares me lol

hahaha, yes my image does scare people - including my next door neighbour who nearly hit me with his dustbin one night ( I had gone to get something from my car and forgot I had the balaclava on).

Lee

[Fordos Moon]

A industrial hoover will suck the water out, normal hoover might go up in a puff of smoke, you could if you have the bits make a cold frame up to place over the hole once the waters out the extra warmth through the glass will help dry them out, as the weather is at the moment it could take a long time if unaided......

I've been using cotton wool swabs at the moment but it just keeps coming! I take it I should make sure it is totally dry before I think about fixing things into it? I will try our hoover, we need a new one anyway and my other half will be delighted if our hand is forced!

[Tinker1947]

You hire a hoover, use a thin piece of tube taped into the end of the hoover, insert tube in hole, stand well back if its your house hoover...., yes the concrete should be dry unless it says different on the resin, i have a tube of glue that works under water....when you replace the home hoover tomorrow,,,,a Dyson is very good..

[Fordos Moon]

You hire a hoover, use a thin piece of tube taped into the end of the hoover, insert tube in hole, stand well back if its your house hoover...., yes the concrete should be dry unless it says different on the resin, i have a tube of glue that works under water....when you replace the home hoover tomorrow,,,,a Dyson is very good..

Really chuckling over your response! Lol

[Fordos Moon]

I forgot to ask, I havent filled the gaps yet between the pier base and the shed base. Should I? And if so - with what?

[SnakeyJ]

I put foam around my plinth before casting the floor slab. Others have poured polystyrene beads around then caulked with flexible sealent - sikaflex or grey silicon should do the job.

typed on my mobile with Tapatalk

[Fordos Moon]

I put foam around my plinth before casting the floor slab. Others have poured polystyrene beads around then caulked with flexible sealent - sikaflex or grey silicon should do the job.

typed on my mobile with Tapatalk

Thanks Jake, i did same to form it but took it up as got well messy/wet/concretey and i hate mess! I do have a bit of the foam board left so may fuzz some of that back down there!

[Tinker1947]

A can of expanding foam would work, just a squirt all round at the max depth of the tube on the can it will expand and come out the top, slice it off with a saw or knife.......

[SnakeyJ]

A can of expanding foam would work, just a squirt all round at the max depth of the tube on the can it will expand and come out the top, slice it off with a saw or knife.......

Great idea and the foam likes it wet, but might this be too firm/hard a bond and transmit vibrations between the slab and pier footing?     I was thinking of a mainly cosmetic gap fill that maintained the isolation between the two.

I noticed yesterday that mine still gets some vibration when I walk around the mount.   I'm hoping this will be a point of contact from the raised wooden floor and pier itself, though it was too dark and I was too busy to investigate last night.    I do have 20mm gap all around my pier footing, with a compressed foam (like neoprene filler) between the two casts.   

[Tinker1947]

May be it might be better to just fill the gap with beads, if the foam did go to hard and wasn't flexible it would be a real bitch to get out.......

[Fordos Moon]

Advice required please. I've got this nice adaptor plate to go on my mount. But I need to rig up some kind of nub for the adjustment bolts to push against.

An M10 bolt fits as you can see but it needs to have no head so it fits inside the HEQ5 mount.

I do not have one from my tripod as that one was welded on.

Help!