Review of "Through Bolts"
I'm a miserable old git. I'm ashamed to say it's been a **** very **** long time since I reviewed my "trusts", have sought to rectify this by going through every review I've written in the past couple of years, if you feel hard-done-by, drop me a note.
Let us sing the praises of the humble ‘through bolt’ – if you have something big and heavy to attach to a flat concrete surface, these are the chaps for you.Also known as “anchor bolts” or “Wedge bolts” the through bolt is ideal where you need to fix to a solid surface which you wouldn’t be able to drill ‘right through’ to use a conventional bolt.
Through bolts are typically used in concrete to support or restrain high loading, where a conventional plastic plug would be insufficient – loading factors of around 1000Kg are not untypical, but this is dependent on the substrate 9what you’re mounting it into) being strong enough.Therefore, this wouldn’t be used to hang a small picture on a plasterboard or stud partition wall!
Typically this would be used to mount gate posts, handrails, garage doors, or high load racking to concrete floors or uprights.Take care that when using you don’t compromise the strength of whatever you’re mounting onto – beware beams, reinforcement rods etc.
The bolt consists of a machined steel shaft with a thread (screw) cut at one end, a washer and nut are typically supplied. Sometimes the shaft comes with a steel sleeve – which is the exact diameter of the hole it is intended to be inserted into.The far end of the shaft spreads out as a cone, around which are a couple of pieces of metal which mirror the profile of the cone. The outside of the metal pieces are the same diameter as the sleeve.
(It’s far easier to understand when you look at the picture)To fit, you drill a hole *exactly* the same diameter as the sleeve, ie for a 10mm bolt, you need a 10mm hole.
It’s important to get the diameter right – too small and your bolt won’t fit, too big, and it won’t grip tightly.It’s also important to make sure the hole is exactly at right angles to the surface being drilled, if it isn’t the bolt will become deformed when you try and tighten it, and it may well shear off.
The piece of work you are trying to attach should have a similarly sized hole to accept the bolt.To fit, drill your hole to the required depth using a masonry drill, and try not to let the drill bit wobble too much, as you won’t get a proper hold once the bolt is tightened up.
Remove any concrete dust either by using a commercial blower, or something like a bicycle pump. If you leave any dust inside, your bolt won’t hold tight (blowing into it won’t really help!)Through bolts are intended for use in solid concrete – bricks may crack, wood will almost certainly split. Don’t try to use through bots too near a concrete edge, as it will simply split the outside edge off.
To fit, simply hold the item to be attached up to the hole, tap the bolt through both holes until home, and then tighten the nut , it’s relatively easy to tell when the correct tightness has been achieved as the bolt goes solid.Costs are (depending on size) typically 50p to a couple of quid each.
The great benefit of such a system, even if it is a bit more expansive than ‘conventional’ bolts and anchors is the strength, and speed of fitting – you don’t need to wait for resin or mortar to harden, and the fixing is permanent.Some thought should be given to the environment the bolt is to be used in, moisture could compromise the strength of the fixing, so make sure any coatings are deemed suitable.
Through bolts are a generic fixing term, manufactures incluse, but are not limited to Rawlplug Fischer and Molly, and can be bought in teh usual DIY or trade places such as B&Q, Wickes and online.
Product Information : Through Bolts
Manufacturer's product description
Listed on Ciao since: 03/03/2009