SHCS vs Hex head

[Herbiev]

Hi all. I've been a bit inactive on this forum and in general lately. In the last few weeks I've been diagnosed with emphysema, a growth in the oesophagus, a severe acid spill on my leg and just for good measure spent the last 4 days in hospital with pneumonia. Anyhow my question is, I have noticed a strong preference for hex head screws over socket head cap screws by many builders on this forum and was wondering if there was an engineering principle behind this or purely aesthetic reasons.
Tia
Herbie

 

[mklotz]

My thoughts on the subject...

The SHCS is a relatively recent addition to the fastener arena so you're not likely to see any in period steam engines. My guess is that, if the industrial revolution pioneers had had them they would have used them. (Hepplewhite would have used a router too if he had had one.)

Heavy machinery bits are typically held on with studs and hex nuts. (Studs bear the weight of the part and provide alignment while the nuts are fitted - imagine mounting a tire to your auto with bolts!) So, the mechanics had a set of wrenches to hand already. It would be natural to use hex head bolts when a bolt was required - no need to have an extra set of (Allen) wrenches that would be required had SHCS existed.

Personally, I think SHCSs add a touch of 20th century tech look to a piece. I wouldn't use them on an historic model meant for display but on a non-representative model (e.g. Elmer's engines) I think they're sort of kewl.

Now to hear what the experts have to say on the subject.

 

[Omnimill]

Yeah, I reckon Marv's got it right again. Caps just wouldn't look right on a period model.

Vic.

 

[Mainer]

As far as I know, it's purely aesthetics. SHCS are a relatively recent innovation, so why should they be used on an alleged scale model of an historical engine?

 

[Jasonb]

Yes I'm with Marv on this one, in my opinion socket heads just look wrong on a period engine, the only thing worse are slotted roundhead screws where they should not be If it's just a bar stock engine then I don't have an issue with their use.

And while we are at it I don't go for excessive brightly polished brass/copper, it's fine to use it in our sizes because its easier to work but look at the original it would likely have been steel/iron and painted. Just a few smaller pipes & fittings in the bright metals which may have been polished by a caring engine man.

Jason

 

[bentprop]

I note that on some really early engines,square headed bolts and nuts were often used.
Model supplies are few and far between,and if you can get them,a horrendous price.I much prefer the look of hex anyway,but am using shcs on my version of Jan Ridders simple 2 stroke.Mainly because I had no hex bolts in the required size.In any case,2mm hex bolts have a head a few sizes larger than scale,so they don't really look right.My0.02c worth.

 

[Maryak]

Digging into my childhood, from memory my Meccano set had 1/8" brass square nuts and a fancy bent spanner to hold them.

Anybody else remember this ???

Best Regards
Bob

 

[Herbiev]

Hi Bob. My Meccano nuts were square also but iron. The bronze age hadn't been invented yet ;D

 

[Stan]

About seventy years since I saw my Meccano set but I think the bolts were slotted fillister head with square steel nuts. A worn sharp screwdriver to hold the head and a stretched sheetmetal wrench to tighten the nut.

An early introduction to pierced palms and skinned knucles that started a love of things mechanical that has never left me.

 

[Swede]

One other touch I appreciate is the use of studs and nuts where appropriate, rather than simply screws. They are a royal PITA to make, but the cool factor is off the charts! This front cover wouldn't look nearly as nice with screws, nor would the cylinder skirts.

I've still got some SHCS on the front bearing cover, and other parts of this engine. I do need to eliminate the SHCS where I can, but they are such handy fasteners. Lately, I've been buying TORX (star drive) screws as well, as these work better than SHCS in the smaller sizes, like 6-32 and below.

 

[pete]

Some more trivia, They also make SHCS nuts. I'm guessing for very tight areas. The stud length is critical and their REALLY expensive. Last time I saw them was in the MSC big book.

For historicly correct fastenings, A lot of equipment came with a large heavy nut and a thinner one for locking purposes on the studs. I remember years ago long running arguements in the M.E. post bag about which way the nuts went on the studs. Large one on the bottom, Small one on the bottom? I don't believe it was ever solved as to what nut went on the stud first to be historicly accurate.

I'd agree, Engine models made to represent a full sized engine that was built before SHCS look terrible with them. Sometimes you have no choice due to very tight areas.

Pete

 

[steamer]

My thoughts on the subject...

The SHCS is a relatively recent addition to the fastener arena so you're not likely to see any in period steam engines. My guess is that, if the industrial revolution pioneers had had them they would have used them. (Hepplewhite would have used a router too if he had had one.)

Heavy machinery bits are typically held on with studs and hex nuts. (Studs bear the weight of the part and provide alignment while the nuts are fitted - imagine mounting a tire to your auto with bolts!) So, the mechanics had a set of wrenches to hand already. It would be natural to use hex head bolts when a bolt was required - no need to have an extra set of (Allen) wrenches that would be required had SHCS existed.

Personally, I think SHCSs add a touch of 20th century tech look to a piece. I wouldn't use them on an historic model meant for display but on a non-representative model (e.g. Elmer's engines) I think they're sort of kewl.

Now to hear what the experts have to say on the subject.

Volkswagon Beetle. had them.....and yes they were a PITA!

 

[Tin Falcon]

I use a fair number of shcs on my models but mine are are not anywhere near historical representations of anything/.
Tin

 

[ajaxboltco]

They are both used very frequently in different industries, however hex bolts have more production standards including DIN933 Full threaded, DIN931 Partially threaded, DIN6914 high duty, A320 L7 for lower temperatures down to minus 65 degrees centigrade , etc. this gives technicians more specific choices and reliability.

You can get further information about bolt and nut here

 

[bazmak]

My Tuppence.I love hscs,because they are readily available in small sizes in metric
Hex hds look better on historical models but the heads are not to scale
you have buy non std with reduced heads.Hscs are better than high tensile
I reduce the head dia on CSK for scale and use a std drill to csk and they are far superior to slotted
even on historical models. For a flush finish you cant beat a counterbore
and a caphead.I use a std drill as a cbore and undercut the head on the lathe
to 30o this also gives accurate location with repeatability almost a dowel fit
You all use grub screws, far better than slotted grub screws Dome button hd also look good in certain applications.I now use mostly metric down to 2mm in hscs instead of Ba etc etc etc
Overall they have many uses but are not ideal in all applications
I also like studs and nuts but again you have to buy or make nuts with hds to scale but for true historical models its worth the effort. Regards Barry

 

[tornitore45]

Digging into my childhood, from memory my Meccano set had 1/8" brass square nuts and a fancy bent spanner to hold them.

Same here.

1/8" thick, the bolt were 5/32 same as all the shaft.

 

[vederstein]

...
- imagine mounting a tire to your auto with bolts!...

A few years ago I had an '82 Fiat Spider as my road going toy. It did have bolts for mounting the wheels.

Those crazy, lousy engineered Italian cars.

...Ved.

 

[tornitore45]

Those crazy, lousy engineered Italian cars.

Such as Ferrari, Maserati, Lamborghini or even an Alpha Romeo.

 

[modeng2000]

Not forgetting Mercedes

 

[hasankh96]

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