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Threaded bar pull strength
scutter - 26/1/12 at 02:45 PM

Ok people, does anyone know what the pull strength of a 5/16" threaded bar would be?

Working on 1 1/2 Dia thread engagement, I'm thinking of using it for my anti-rollbar droplinks.

ATB Dan.


tegwin - 26/1/12 at 02:49 PM

How long is a piece of string?!

It all depends what grade of metal it is made from and what process has been used to form the thread (rolled, cut etc)


If you are just talking abut off the shelf studding... I would not! Better off with a piece of suitable steel with suitable rod ends screwed in/on to it.


daviep - 26/1/12 at 02:49 PM

Depends on grade and thread pitch.

Davie


Litemoth - 26/1/12 at 04:10 PM

Grade 8:8 steel would be 800 Newtons per square mm.


For example ...here's a metre of M12 for four and a half quid-ish

LINKY


britishtrident - 26/1/12 at 04:26 PM

At 5/16" thread dia you really need internally threaded drop links as a length of 5/16" threaded rod will buckle in compression

McGill Motorsport shop on eBay will sell you ready made adjustable drop links in various sizes for very little money.


Alternative get a couple of long drop links for a tintop and set to work with a suitable thread cutting die (look at Rover 75 front drop links on ebay but beware poor quailty ones the rubber dust boots are crap.


To join a RH male thread to another RH male thread you can use a special very long nut called a Studding connector you can buy them fom Wickes Stores or off ebay. These days you can only get them in standard metric threads.


MikeRJ - 26/1/12 at 09:52 PM

quote:
Originally posted by Litemoth
Grade 8:8 steel would be 800 Newtons per square mm.


For example ...here's a metre of M12 for four and a half quid-ish




The typical "all thread" that you get from B&Q etc is nowhere near 8.8. It's actual grade is somewhere between Brie and Camembert.


britishtrident - 26/1/12 at 10:13 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by Litemoth
Grade 8:8 steel would be 800 Newtons per square mm.


For example ...here's a metre of M12 for four and a half quid-ish




The typical "all thread" that you get from B&Q etc is nowhere near 8.8. It's actual grade is somewhere between Brie and Camembert.




Well below Stinking Bishop on the Wallace & Grommit tensile test scale then :-)


hillbillyracer - 27/1/12 at 12:00 AM

Yeah, we keep it at work & some folk say it's expensive, it's cheaper from so & so, but it's 8.8 grade & the others likely aint.
As said it's not the tensile strength you need to worry about, the same force will be in compression on the other link & the bar will bend under far lower compression loads than stretch/snap under tension.


scutter - 27/1/12 at 10:57 AM

Cheers folks, I'd forgotten about compression for some reason, looks like a piece of hex bar is gonna get some attention.

ATB Dan.


britishtrident - 27/1/12 at 12:12 PM

Hex bar is relatively expensive then you have face it off drill and tap it as already said you can buy in ready made but also you weld or braze threaded inserts in to plain tube. Both ready made links and inserts are easily and cheaply available off ebay.

Also I would sugest 3/8" UNF as 5/16" would only be suitable for short links and softer anti-roll bars.

Link toMcGill eBay shop.


scutter - 27/1/12 at 12:31 PM

Cheers, I'm playing with 5/16 as i've already got the rose joints.

What do we think of running some good quality studding inside a piece of steel tube and welding it in situ?

I'm only looking at 1 1/4" between the ends of the 2 rose joints.

ATB Dan.


DIY Si - 27/1/12 at 03:24 PM

If it's such a short length, could you not just cut the head off a bolt?


britishtrident - 27/1/12 at 03:47 PM

No I understand, you have female threaded rose joints ? At such a short length you will probably get away with threaded bar, but I would cut down a fully threaded Grade S set screw rather than iffy tensile threaded bar.
Grade S is a close equivalent of metric HT grade 8.8

Don't weld to high tensile bolts it is just asking for failure.


Namerick will sell you decent quality 5/16" dia 3" long UNF machine set screws http://www.namrick.co.uk/acatalog/Home_U_N_F__HT_Hex_Set_Screws_17.html


scutter - 29/1/12 at 04:51 PM

Hmmm, I wonder if the aircraft has any 5/16 screws Looking at 2 1/2" in total so it's an idea.

Cheers folks.