Appropriate use of studs vs. bolts

[Mainer]

To be "authentic," is there an accepted guideline for when to use studs and nuts vs. bolts on an engine?

My current working hypothesis is that studs and nuts are used for blind holes, while bolts are used for through holes. Does that seem plausible?

 

[Stan]

Frequently, it is because the block material requires a coarse thread and a fine thread on the other end for better torquing.

 

[Cedge]

Mainer
Your hypothesis is pretty much spot on.

Steve

 

[mklotz]

Studs also have the advantage of providing in-place alignment guides for supporting and guiding heavy structures as they are attached. (Imagine the difficulty of mounting a wheel on your car if it were held with bolts as opposed to the simplicity of mounting with studs.) Ok, this isn't that much of a consideration in our small models but it may be a good realism guide.

On a pedantic note, I was taught that, if a threaded fastener is used to secure an object by passing through a hole in that object and into a threaded hole in some parent piece, the fastener is termed a "screw". If the threaded fastener secures two pieces by passing through holes in both and then being locked with a nut, the fastener is termed a "bolt". I don't know if anyone still adheres to this distinction but it makes for good tech-talk when you're trying to impress folks at a cocktail party.

 

[Loose nut]

In full size practice studs are used because they "stretch" differently than bolts do, in many applications bolts are not allowed. For realism in old time machinery models, studs are not threaded in the middle section, usually, and using a bit of threaded rod will look out of place if you are going for realism.

 

[Maryak]

My current working hypothesis is that studs and nuts are used for blind holes, while bolts are used for through holes. Does that seem plausible?

Mainer,

Not necessarily, think of the head bolts in your car engine, (bolts into a blind hole). As loose nut says, it has everything to do with the stretch achieved on the bolt/stud when the torque is applied. This is so that the correct tension in the system is achieved when the operating temperature is at its designed level. In full size practice sometimes, the bolts/studs holding joints in HP steam lines are tensioned by measuring the stretch of the bolt/stud when cold. Again, as loose nut says bolts are not permitted in some applications, be they blind or through.

Hope this helps. ??? ??? (Its designers choice)

Regards
Bob

 

[Mcgyver]

In full size practice studs are used because they "stretch" differently than bolts do,

the do? how?

For realism in old time machinery models, studs are not threaded in the middle section, usually, and using a bit of threaded rod will look out of place if you are going for realism.

agreed, but that would only show when it was disassembled. I like the section in the middle because acts as a stop, keeps them all to the same depth

 

[kf2qd]

I like to use studs in applications like bolting a head to an aluminum block - the studs will be installed and the nut will be steel on steel and the threads in the aluminum will experience very little wear over a few cycles of assembly/disassembly.

 

[Lew Hartswick]

Mainer,

Not necessarily, think of the head bolts in your car engine,

Regards
Bob

Except they are not "bolts" the are STUDS.
...lew...

 

[Maryak]

In some cases they are studs in others bolts, some even have special spline drive heads requiring a special socket head for the tension wrench, (eg Ford Escort).

Best Regards
Bob

 

[Cedge]

Yo Mainer
While these guys try to get more angels into doing the Watusi on the head of a pin, you can stick with your hypothesis and you'll do fine as far as authentic appearance goes..... : . I use the same basic rule of thumb, most of the time, myself.

Steve

 

[Maryak]

Mcgyver,

the do? how?

Don't know how to do the Watusi : :

A stud has a thread at each and which makes it weaker at each end compared to a bolt which only has a thread at one end. Hence a stud will stretch more than a bolt.

Hopes this helps ??? ???

Best Regards
Bob

 

[Mcgyver]

A stud has a thread at each and which makes it weaker at each end compared to a bolt which only has a thread at one end. Hence a stud will stretch more than a bolt.

I see what you're getting at, but I'm not so sure....the length having strain for both is the same, granted the stud has a section of threading under the nut, but chances are the bolt has the same entering the fixed piece, that's taking the strain past the nut and fixed piece as negligible.....if the bolt had a longer section of threads not engaged than the stud, it would stretch more

 

[Maryak]

Mac,

I totally agree with your hypothesis. ;D ;D

Where the stretch is used to measure the tension applied then the correct bolt or stud must be used, i.e. one of the specified length with the specified amount of thread(s) and of the correct material. Also the specified nuts, washers, lock washers etc.

Perhaps I am getting a little outside the object of the topic, but a very interesting exchange.

Thank You and Best Regards
Bob.

 

[Mainer]

Thanks Cedge. My main concern is authentic appearance for a model, so that's basically the confirmation I was looking for.

As far as the "stretch differently" hypothesis: seems to me that by slightly adjusting the stud design you could make it match whatever stress parameter you were looking for. I doubt it's a reason for choice of studs vs. bolts, although I'm certainly no authority.

For example, there are the waisted-down studs, where the center portion is turned down to the thread root diameter, to adjust the stress characteristics of the stud.

 

[Mcgyver]

Perhaps I am getting a little outside the object of the topic,

on the contrary, the discussion was quite relevant. Not because differing bolt tension is every going to be a factor in our models, but because the hobby is model engineering - what could be more germane than the discussion and learning of engineering; what goes into understanding a bolt in tension are the same engineering principals where ever forces are acting. The application of that learning is broad, bolts vs studs is just a somewhat academic (for modelling anyway) instance....the more i understand and learn engineering the more obvious prototypical design becomes and the less mystery there is in designing and building my own items. No angels dancing on pins in my shop, but if you want to improve, which for me is a fun parrot of it, it only comes through learning.

 

[Tin Falcon]

CD:
What does that OT rant have to do with the proper use of studs vs bolts or screws ?? Please confine such OT opinions to the break room or other forums that allow it.
Tin
Mr Compound driver 2's post on the metric system was moved to the appropriate thread in the break room.
Tin

 

[Cedge]

Me thinks CD missed his targeted thread. It would appear he's lamenting in response to Tmuir's therapeutic metric rant. Nice shootin' Kevin....LOL

McGyver....
Decaffeinated for the rest of the day.... grin. The poor guy just wanted to know how to make his work look authentic.

Steve

 

[Tin Falcon]

steve you are likely right it happens.
Tin

 

[Mcgyver]

Decaffeinated for the rest of the day.... grin. The poor guy just wanted to know how to make his work look authentic.

poor guy? I think he got a lot great content around his question

"teach a man to fish....."

advancing an understanding of why things are as they are IS the best way to make model work look more authentic. When you look at the shape and form of a prototype, its not often by accident, its engineered. The more one understands of this, the more likely one is to make things that look prototypical, materials, design, proportions etc...in other words it just looks right.

Also, discussions internet or otherwise do tend to wander...might be dull if they didn't