Secret fixings

[Welderpaul]

Anyone got any good ideas? We need to fix quite a bit of 300x100x8 RHS onto a 300mm thick slab edge. The top of the RHS sits 110mm above the top of the slab. The SE has specificied the dreaded resin anchors (no doubt frightened of splitting the slab edge), but the fixings also need to be csk. We suggested stud with dome nuts, but no
The hole through the box section also needs to be sleeved at the fixing location to stop the RHS crushing.
Was pondering knocking in a 'bullet' (Wedge anchors) into the hole, giving a female fixing, then using a long csk bolt to fix into. Not really a resin fix though

 

[KTMMICK]

I dont quite get how you use resin anchors with countersunk bolts! Call me stupid.....
Why cant you use plugs? We use them here to fix things into brick and they dont split.
Failing that why not use studs as you say and weld it to RHS and flat it back.

 

[Welderpaul]

I dont quite get how you use resin anchors with countersunk bolts!

Yeah, that's the problem

 

[Paul.]

These might do the job, I've made them in the past by drilling and tapping through a piece of studding

 

[wyn]

I've only ever used resin once, but used the internal threaded sleeve, like TIG paul's link, with csk bolts.

 

[Hitch]

Is it for a car park by any chance...?

Used em on crash barriers, handrails etc where even dome heads are unacceptable.

Just like Paul's linky, i think Precision Profiles do em...

 

[Justme]

Not sure if I can describe this right but here goes.

Cant you resin bond some short bits of studding in the hole. Make them stick out shorter than the box by enough to clear the counter sunk head on an internally threaded bolt. Make the internal threaded bolt the right length to prevent crushing of the box section but short enough to slightly clamp it. Similar to the bolts you get to put the ends of flat pack bed on to the side runners Not the cross bolt type. But the ones like this.

Just make them counter sunk

 

[Tigman]

Dont they do csk thunder bolts you could drill the hole add some resin then screw the thunder bolt home get extra grip then !

 

[Welderpaul]

Not sure if I can describe this right but here goes.

Cant you resin bond some short bits of studding in the hole. Make them stick out shorter than the box by enough to clear the counter sunk head on an internally threaded bolt. Make the internal threaded bolt the right length to prevent crushing of the box section but short enough to slightly clamp it. Similar to the bolts you get to put the ends of flat pack bed on to the side runners Not the cross bolt type. But the ones like this.

Just make them counter sunk

I know the ones you mean, although not sure these will cope with the imposed loadings

 

[Welderpaul]

The other problem of course, is countersinking the (8mm) face of the RHS. Not much to stop the fixing pulling through the steel.

I'm wondering whether to drill a hole on the outside face of the RHS large enough for a socket to pass through, and use a normal nut inside the box section. Either weld a patch in and flush up, or knock in a plastic cap to tidy up.

 

[pedrobedro]

Do you mean fix studding in with the resin anchor then put a nut inside the RHS ? That sounds like the way to go and cap the outside hole after.

 

[Welderpaul]

Do you mean fix studding in with the resin anchor then put a nut inside the RHS ? That sounds like the way to go and cap the outside hole after.

Yeah, thats what i'm thinking

 

[Hitch]

Resin and thunderbolt wont work, youll have no way to final tighten it. You'd be lucky if you managed to screw it in anyway.
What size fix have they requested, m16,m20?

 

[snowcat]

The other problem of course, is countersinking the (8mm) face of the RHS. Not much to stop the fixing pulling through the steel.

I'm wondering whether to drill a hole on the outside face of the RHS large enough for a socket to pass through, and use a normal nut inside the box section. Either weld a patch in and flush up, or knock in a plastic cap to tidy up.

thats the way I do quite a bit of the Eng stuff, works well for me tho I rarely have to cap the box as I'm always thinking about future dismaltment...

 

[Tigman]

Resin and thunderbolt wont work, youll have no way to final tighten it. You'd be lucky if you managed to screw it in anyway.
What size fix have they requested, m16,m20?

The thunder bolt would give you the final tighten and the resin would go off for an even stronger fix !

 

[Hitch]

But the resin wouldn't get between the shank of the thunderbolt and the concrete....

 

[Welderpaul]

Probably M16. hmmm screwing the stud into the resin-filled hole through the box section would be a problem. Looks like the threaded inserts (as TP's link) would be best, just not a lot of meat behind the csk head. Don't think they are likely to accept button heads either.

 

[Justme]

I know the ones you mean, although not sure these will cope with the imposed loadings

Well yeh not those ones but you could make some up larger.

I'm wondering whether to drill a hole on the outside face of the RHS large enough for a socket to pass through, and use a normal nut inside the box section. Either weld a patch in and flush up, or knock in a plastic cap to tidy up.

That wont be as strong will it?
Especially if any loads are twisting the box away from the wall.

I guess it will depend on the angle the loads are at.

 

[Justme]

just not a lot of meat behind the csk head.

Even with a welded in spacer tube to stop the crushing?

 

[Tigman]

hehehehe just a smidgeon of resin !