# Appropriate use of studs vs. bolts



## Mainer (Nov 21, 2008)

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?


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## Stan (Nov 21, 2008)

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


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## Cedge (Nov 21, 2008)

Mainer
Your hypothesis is pretty much spot on. 

Steve


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## mklotz (Nov 21, 2008)

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.


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## Loose nut (Nov 21, 2008)

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.


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## Maryak (Nov 21, 2008)

Mainer  said:
			
		

> 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


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## Mcgyver (Nov 21, 2008)

> 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


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## kf2qd (Nov 21, 2008)

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.


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## Lew Hartswick (Nov 21, 2008)

Maryak  said:
			
		

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


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


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## Maryak (Nov 21, 2008)

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


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## Cedge (Nov 21, 2008)

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


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## Maryak (Nov 22, 2008)

Mcgyver,



			
				Mcgyver  said:
			
		

> 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


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## Mcgyver (Nov 22, 2008)

> 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


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## Maryak (Nov 22, 2008)

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.


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## Mainer (Nov 22, 2008)

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.


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## Mcgyver (Nov 22, 2008)

> 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.


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## Tin Falcon (Nov 22, 2008)

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


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## Cedge (Nov 22, 2008)

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


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## Tin Falcon (Nov 22, 2008)

steve you are likely right it happens. 
Tin


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## Mcgyver (Nov 22, 2008)

> 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


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## Cedge (Nov 22, 2008)

Jeez Louise... the guy asks for a water fountain and gets a fire hose....LOL . I thought I was back on HSM or PM for a moment. Not quite sure why one would need three volumes of esoteric technical data to simply look authentic, but then we all have our own idiosyncrasies. However, I'll also agree.... a new and dedicated thread, given to fastener information might make a nice addition to the board.

Yup... decaf is in definitely in order..... :bow:

Steve


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## Mainer (Nov 22, 2008)

Progress...
Here's a picture of the "Unicorn" cylinder head, with studs and nuts. The nuts aren't quite thick enough, but they're better than Allen-head capscrews.... ;D


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## Mcgyver (Nov 22, 2008)

I seem to be attracting a lot of negativity from you. in this thread you've said....



> I thought I was back on HSM or PM for a moment





> Not quite sure why one would need three volumes of esoteric technical data to simply look authentic





> Yup... decaf is in definitely in order





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





> While these guys try to get more angels into doing the Watusi on the head of a pin



that's a lot of bandwidth just criticizing what someone else says and I not sure why it bothers you so. I find you often making cracks or criticizing the content of other posts... In this case I tried to explain why I think there is value in the direction it went, but hey, if there's not for you or you don't understand why peace....but why the criticism and snide remarks? .....If its not for you, walk on by....maybe others do get something out of it.


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## tel (Nov 22, 2008)

Play nice, chill'un!


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## wareagle (Nov 22, 2008)

Gentlemen, let's go easy here!


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## Tin Falcon (Nov 22, 2008)

Ditto lets keep the friendly banter friendly
Tin


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## Maryak (Nov 22, 2008)

OK Guys,

Lets keep it friendly, we are all entitled to our opinions. : :

Mainer the head with the studs and nuts looks pretty damn authentic to me. :bow: :bow:

Best Regards
Bob


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## Cedge (Nov 22, 2008)

Nice work Mainer. The head studs/bolts/screws look great.

I'll think let Mc's observations stand on their own....  :big: :bow:

<as Cedge checks to see which forum he's really on>

Steve


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## compound driver 2 (Nov 22, 2008)

OT rant! thats interesting. All I talked about was my dislike for the metric system and how its being forced on us.
The guys in Oz were talking about finding bolts and such I just gave my thoughts on finding bolts here and the reasons why its become hard work.
Poor old Cedge you seem to get up tite way too fast I never ment to upset you.

Its always friendly on here least thats the way i view it, and its why I stay on here.


Point is studs were used on valve chests and end covers partly to aid in fitting them. Its easier to fit the covers onto studs than offer up and put in bolts. That said there are lifter bolts fitted on a lot of valve chest covers to hep in removing them once teh foliac has gone hard.
Its also worth remembering that washers were very rarely used, rather the nut would be seated down on to a spot facing.


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## Cedge (Nov 22, 2008)

CD
I have no arguments with you. In fact my post was basically to Tin Falcon in reference to his comment about it being off topic. Tmuir had a thread just above this one that was expressing a similar metric discontent. For all the world it looked as if you'd posted to one thread while meaning to post on the other. As Tin said... it happens. Far from being upset, I was actually intent on mentioning you were unduly warned for being OT. 

Your comments on stud usage is the same information I've always been given, so again... I completely agree with your premise. It even further answers Mainer's original question concerning making things look authentic. 

"Poor old Cedge" was simply amazed that the question got all sorts of technically correct but non applicable responses, without ever actually addressing his original inquiry concerning authenticity. Thus the shades of HSM comments.

Thanks Kevin
Steve


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## T70MkIII (Nov 26, 2008)

Voice of inexperience here, but I would have thought something to be wary of if using studs that are threaded all the way to hold large thicknesses of soft material (ie aluminium cylinder head to block on a multi-cylinder engine) is the potential sawing effect the thread would have on the hole during assembly and disassembly - I imagine the small filings could potentially fall into the motor and cause untimely wear.


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## Loose nut (Nov 26, 2008)

I regards to the original question about what is better studs or bolts, if you want realism you have to do it the way the original was done.

Look up the work of Cherry Hinds on the web or in Model Engineer magazine, she (yes a woman model builder) is one of the best model builders that there ever was and it's all in the details. She doesn't use "close enough" bolts, studs, rivets, nut and other parts, she makes her own to the proper scale along with the rest of the models that are near perfection. That's why she has won so many awards for her work, her models just looks more like the prototype .

As for studs, old equipment studs didn't have threads in the middle, I don't know if it was for strength or just to eliminate extra work or something else, and the ends of the studs need to be finish properly usually with a radius, called a Higby end I believe, look it up on the web. Nuts aren't just a bit of hex bar cut off and threaded, they need to be as close to scale size as possible, the right thickness and finished like the real thing (proper period look which can be a square nut not necessarily a hex and rounded over or chamfered if applicable). You can't model nuts on modern types, they may not be the same.


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