Making a high tensile bolt.

[Cato]

I'm not sure where this questions fits, so if there's a more appropriate section my apologies for not putting it there.

It seems to be the case that if you need to make a long bolt taking a length of bar, turning a thread of an inch or two at one end and then welding a nut to the other is a common approach. The weld on/around the nut is then neatened on the lathe. Presumably this avoids faff on the lathe with turning hex bar a bit at a time, spring cuts etc.

My question is, does welding the nut on affect the strength of the EN24 or whatever at the point it's welded? Given that it's a fairly common approach it would appear that if it does it's not enough to cause a problem or worry about. On the other hand being a common technique doesn't mean it's the right way.

 

[gaz1]

from what ive seen its all made out of one item and certificated

put it this way would you expect what you have said with a plane part bolt as its been done and its brought a plane down due to inferior bolts been used just to save money

care to say what your application for the part is for as it might help

 

[Cato]

from what ive seen its all made out of one item and certificated

put it this way would you expect what you have said with a plane part bolt as its been done and its brought a plane down due to inferior bolts been used just to save money

care to say what your application for the part is for as it might help

It's not my application or something I've done, it just seems to be the 'go to' method that people use for things like swing arm spindles, through case engine bolts and the like where motorcycles have been modified. In terms of loads then the pressure on the weld would be when it's tightened to hold in place.

 

[Kram]

That is how you bodge a rubbish bolt, I would not trust it for any high loading.
Hex bar is rare and expensive in short lengths. On a lathe it is farly easy to mill a hex or rotary broach as a cap head.

 

[hotponyshoes]

You will mess up the heat treat/temper to some degree by welding a nut on.
Small tacks with the tig and allow to cool between each tack might not be a problem.
If you blast it with the mig and end up with 2" of thread glowing red it might...

High Tensile studding and nuts are available.
Why not just use a mechanical interface like a pair of jamb nuts, a single knut, or center dot lock rather than weld?
Surely anything you do will be just as good as the nut you put on the other end...

 

[Cato]

You will mess up the heat treat/temper to some degree by welding a nut on.
Small tacks with the tig and allow to cool between each tack might not be a problem.
If you blast it with the mig and end up with 2" of thread glowing red it might...

That was what I was wondering about TBH.

Some seem to be bar threaded at both ends then a nut spun on to one and welded, others use braze. Harris used to use bar with a nut welded on one end.

That is how you bodge a rubbish bolt, I would not trust it for any high loading.
Hex bar is rare and expensive in short lengths. On a lathe it is farly easy to mill a hex or rotary broach as a cap head.

Just to reiterate, it's not something I'm doing or have done, just something I was curious about. The last time I had need of anything like that was for a lower rear engine mounting bolt 300mm long. I used 17mm hex bar and turned it down to 10mm.

 

[Old Dog]

In the places that you said the bolt is under shear forces not so much in tensile loads so even though its not good practice it would be a surprise if it broke. If the forces were tensile then it would be a problem.

 

[Erie Fred]

Somewhere...I saw a vendor offering headed plain bolt blanks, with long lengths avail.
Maybe Portland bolt.

Headed Anchor Bolts - Portland Bolt

Headed anchor bolts are used to anchor steel to concrete in place of a rod with a bottom nut.

www.portlandbolt.com

 

[Hitch]

And also take into consideration that high tensile male threads are usually rolled instead of cut.

 

[oldbikedavey]

Made some special A.10 Super Rocket head bolts recently in EN.24, and machined the whole edifice from solid, then used a 5C hexagon collet block to nip the hexagon head out on the shaper.
Worked very nicely, but cut the threads on the Colchester to the majority of their depth, and then finished off to clearance with an appropriate split die.
Some joker had helicoiled the cylinder barrel in an SAE thread on the front two outers, which was what caused the whole debacle to need sorting out....

 

[oldbikedavey]

I'm not sure where this questions fits, so if there's a more appropriate section my apologies for not putting it there.

It seems to be the case that if you need to make a long bolt taking a length of bar, turning a thread of an inch or two at one end and then welding a nut to the other is a common approach. The weld on/around the nut is then neatened on the lathe. Presumably this avoids faff on the lathe with turning hex bar a bit at a time, spring cuts etc.

My question is, does welding the nut on affect the strength of the EN24 or whatever at the point it's welded? Given that it's a fairly common approach it would appear that if it does it's not enough to cause a problem or worry about. On the other hand being a common technique doesn't mean it's the right way.

You could always just knock up a stud, with a decently engaged nut on each end...

 

[Rrobson]

You could always just knock up a stud, with a decently engaged nut on each end...

This, or just buy a suitable 10.9 fastener or cap head that fits.

 

[RaceDiagnostics]

I once welded in an Allen key, afterwards it turned to cheese.

 

[Milkybars]

Don't know if you have a mill and a hex collet block ?
If you do, use round bar and put on the hex using the above.
In most cases this saves a fortune when trying to buy the hex ..unless you have to make loads and can use an entire hex bar

 

[Brad93]

Making a high tensile bolt, start with a bigger high tensile bolt.

Forged, heat treated, stress relieved.