Engineers stud or just studding

I am having trouble locating engineers studding in 1/4" BSF with the right proportions of thread at the ends to plain shaft in the middle. Is there any reason I shouldn't just use a 1 1/2" piece of 1/4" BSF studding or will it do? The studs hold down the head stock on the Myford ML4 and screw into cast iron with nuts at the other end.

Why not thread a bit of 1/4" stock to what you require.

With BSF getting less and less demand since we went metric 50 odd yrs ago and the permutations of different lengths to keep in stock you can hardly blame suppliers for not keeping what you may want on the shelf. Though Namrick list 1/4 x 1.5

Edited By JasonB on 09/08/2017 15:35:34

Hi Nige,

This ebay seller lists them... **LINK**

Never tried them but HTH

Jon

If you need any level of strength, studding is not usually the way to go. Most studding is grade 4.6, ie 400 N/mm^2 breaking strength, yield 60% of that (240N/mm^2)

High tensile bolts are grade 8.8 (800/640N/mm^2) and cap head bolts are 12.9 (1200/1080N.mm^2), so you can see there is a significant strength difference.

It is possible to get grade 8 studding, but it's harder to find. The default is weak.

Regards,

Richard.

JasonB: Thanks but I don't have any 1/4" stock. As I would have to order it in I might as well order studs. I would make my own if I had stock but with the lathe in bits I didn't fancy risking the wobbly thread syndrome

Jon: Thanks, I have looked at those guys already and they don't do studs with the right amount of thread on each end.

Might have to order studs too long and continue threads down,

Beware of studs that have rolled threads if you want to modify them, the shanks can be undersize as rolling a thread increases the diameter of the threaded part.

Mike

Is it essential to get your lathe working? Get your lathe working , then you can make your own stud - much more satisfying. In the mean time use a bit of studding.
BobH

1-1/2x1/4 bsf set screw then cut the head of ?

Do Myford list these as a replacement part ? They may have been made speacial order for Myford with long threads on each end .

If you buy longer high tensile studs and try to cut longer threads it can be difficult and usually the thread comes out rough as they are heat treated after the thread is cut .

Are they high tensile to start with ?

Ian

BSF thread into cast iron isn't the best, for reasons eloquently explained in ME recently. However you are stuck with it. I'd be very surprised if a grade 4.6 stud snapped before pulling the thread out of the casting. Go for it, just be careful not to overtighten.

If you really want traditional studs these men have a wide range, but expect a big minmum order charge.

**LINK**

Get in touch with a supplier of Austin Seven parts such as **LINK**

Brian

Try here **LINK**

Usual caveats.

Enough of the excuses already!

Easy enough to make; as it happens these are mostly ¼"BSF:

Andrew

For studs subject to varying loads, it's best to make the unthreaded portion the same size as the thread's core size.

This is because if the central portion is thicker, varying loads cause the greatest distortion on the threaded portion which has more stress raisers and is more vulnerable to fatigue.

Doesn't apply to studs bearing static loads.

Neil

P.S. sorry Andrew

Andrew: What sort of steel do you use to make your studs please?

Unlikely - Myfords stopped supplying parts for the ML4 in the late 1960s. Even if it's also a standard part for the ML7, the present owners of the Myford name only stock a restricted range of spares.

George

For goodness sake, it's an old lathe headstock not a tractor wheel stud. Brass is plenty strong enough. As said above you will trash the cast iron before a stud breaks.

You might think that a stud holding on for instance a cylinder head is subject to a varying stress. For reasons too arcane to go into here, if a stud is properly designed and properly preloaded, the stress varies very little during load cycling. My interpretation of necking studs to the core diameter is to make them stretch more, so that slight relaxation from whatever cause has less effect on load. Big end bolts on Merlin aero engines had a short full diameter bit at each end and level with the join twixt rod and cap to centralise the bolt and locate the cap, but were necked down in between. In this instance it would also very slightly reduce the weight

Similar reasoning had quality motorcycles like Velocette have long studs going through te cylinder into the crankcase to hold the heads on, inferior brands like Triumphs used separate short bolts. Having now put the cat amongst the pigeons I'll take the dog out

Edited By duncan webster on 10/08/2017 00:15:57

The smaller, ¼" BSF, studs are EN1A. The larger, partially finished, 5/16" BSF studs are EN3B as these will be holding the cylinder block to the steel boiler.

Andrew

Studs or theaded rod?

As usual (like the current woodruff/straight key thread), I suspect it is 'horses for courses'. Likely each situation requires a little thought, at least before changing the designed item.

For instance, in the case of cylinder head fittings the studs usually have different threads on each end. A coarse thread into the cast iron and a finer thread for the nut (for extra clamping force at a given torque setting). Studs like this remain in situ when the item is dismantled, thus no clamping is done by the thread in the cast iron.

Waisted studs can be used where the material is stronger than the metal to which it it is fixed? Clamping nuts on these can also achieve the required force with less stress on the items, along with better fitting location.

For what you want to do, studding should be adequate. The tensile load in commercial studding, to yield it, will, be more than you need to clamp the Headstock. If you tried pulling the studding to yield, the cast iron will probably crack first.

Studs are "necked" between the threads to produce an even strength over all the length of the fixing. It can be argued that the radius between thread and core diameter removes a stress raiser, and the risk of fatigue failure

Through bolting from cylinder head into crankcase means that the cylinder barrel is only in compression, and is not distorted by the loads applied to bosses near to the top of the cylinder. With bolts going into bosses near to the top of the cylinder, a round bore won't be, once the head fixings have been tightened. It is quite possible to produce 0.004" ovality in a 4 inch bore this way! And that shows up with poor oil control and higher blowby.

Howard