Farmall Cub bolts vs screws

[Rick Prentice]

While replying to the dogleg post, I stumbled when describing the small fasteners used to attach the dogleg to the casting. I called them small bolts but they are screws. I thought I knew the answer to this until I found several articles explaining the difference. Here's one article;

Criterion Four – Screw – If the fastener is designed to be torqued by its head into a tapped or preformed hole, then the fastener is a screw. Again, knowing the intended function of a part can be tremendously helpful. Any part designed to be torqued by the head into a tapped hole is a screw.

"

Something just doesn't seem right with me. By this explanation all the (bolts) that hold the many different attachments to the cub finals and torque tube are not bolts but screws. All the parts attached(bolted) to the engine, such as the head, starter, coolant elbows, front engine cover, etc. are all screws instead of bolts. Every article I searched explains the difference the same.

Jim, do you have a better explanation

[Don McCombs]

Maybe the answer to this quandary lies in the difference in definition between a cap screw and a hex bolt.

[radioguy41]

As far as I'm concerned, a screw requires a screwdriver, a bolt requires a wrench (including an Allen wrench). A perfect example of the nutiness involved is pictured below. Why is a Flange Bolt called a bolt and a Cap Screw called a screw? The only difference is the shape of the wrench used. Makes no sense.

Click on image for a larger view.

[inairam]

I think if there is a nut involved it is a bolt.

It goes into something like wood, sheet metal or a threaded hole and secures itself it is a screw in that application.

Now this does not cover well things like machine screws or using a hex head in a threaded hole or "socket head cap screws" Just my understanding.

Early in my engineering career when I was detailing assemblies we used "socket head cap screws" all over the place. Called them bolts once and got in trouble.

[SamsFarm]

In the trades, the simple definition is bolt has a nut, and a screw goes in a tapped hole!

Some of the typical abbreviations are;

HHCS, hex head cap screw

These below typically require a hex key!
SHCS, socket head cap screw (the allen bolt)
LHCS, low head cap screw
FHCS, flat head cap screw

https://en.m.wikipedia.org/wiki/Bolt_(fastener)

[Jim Becker]

I think we all have a long history of misusing the terms. Most of us grew up around others that misused them, thus the distinctions are often lost. Having a tool called a "screwdriver" adds to the confusion. It leads to the conclusion that a screw is what a screwdriver fits, even though there are more types of screws it doesn't fit than it does. A similar tool with a hex end is called a "nut driver", not a "bolt driver", but is probably most often used on screws. I'm not sure what to read into that.

If you go buy a box of hex "bolts" that aren't packaged including nuts, the box will usually say "cap screws". A proper cap screw should have a washer face. Thus the corners of the hex will not contact the surface of the part. With a common bolt, the hex will contact the surface. Oddly enough, the Wiki page pointed to above tries to explain the difference but their picture of a "bolt with a nut" is a cap screw with a nut on it.

If you look through the Cub Parts Catalog, I think you will find correct use of "cap screw" in most references. This includes the "head bolts" that are called "cap screws". It even includes the "cap screws" that hold the final drive housings on. There are a few "bolts" that look like they should be screws. They seem to mostly (all?) be specials that carry an IH "R" part number. They include flywheel bots, and wheel and drawbar bolts.

I guess it is just easier to say "bolt" than "cap screw". We generally get along fine without precision in what we say. However, I did see a relevant comment on the site of a fastener company (Earnest Machine):

Typically, in our industry, if someone orders a hex bolt you can always supply a hex cap screw. If a hex cap screw is ordered you cannot just supply a hex bolt without first getting the customers approval.

[Urbish]

I am a mechanical engineer and took a class on Bolts and Bolted Joints when I worked for the US Army in the Tank Automotive R&D Center. Jim Becker's description above matches the definitions illustrated in that class and the textbook, along with my Mech Eng education/experience prior and since. But I admit I continue to use the two terms interchangeably to avoid arguments about semantics.

[tnestell]

Just occurred to me that a stud is both a bolt and a screw at the same time

[tst]

there is much confusing info on hardware, when I order hardware and I buy too much of it, A bolt has partial threads while a cap screw has threads the entire lenght

[SamsFarm]

A bolt has partial threads while a cap screw has threads the entire lenght

Uhhhh.... Thats not true! If you order some 12 inch long hex head cap screws, you will only get about 2 inches of threads!

https://www.mscdirect.com/product/details/86502333

I've used hundreds, probably thousands of socket head cap screws and after a certain length for the specific diameter, they will be partial threaded!

[tst]

this can turn in to a mess, I think the manufactuers call them what they want with different names just so everyone is confused

[SamsFarm]

Lol

[Gary S.]

this can turn in to a mess, I think the manufactuers call them what they want with different names just so everyone is confused

Or depending on what they want to charge for replacements

[Jim Becker]

this can turn in to a mess, I think the manufactuers call them what they want with different names just so everyone is confused

There is probably some truth to that. It is probably more common that distributors ship what they have. One distributor web site that I checked earlier in this discussion said that they could substitute cap screws in place of bolts if they didn't have the bolts in stock. However, that said they would need to check with the customer for an OK to substitute bolts in place of cap screws.

[Stanton]

this can turn in to a mess, I think the manufactuers call them what they want with different names just so everyone is confused

There is probably some truth to that. It is probably more common that distributors ship what they have. One distributor web site that I checked earlier in this discussion said that they could substitute cap screws in place of bolts if they didn't have the bolts in stock. However, that said they would need to check with the customer for an OK to substitute bolts in place of cap screws.

Sounds like a cap screw has a washer face:


...and a bolt does not: