Hex head cap screw dimensions

[theoldwizard1]

If you do nor know the difference between a hex head cap screw and a bolt or between a hex head cap screw and a tap screw, please express your opinions elsewhere.

The charts on the web that I have found say that a ½" diameter hex head cap screw < 6" overall, only has 1¼" of thread. That would mean that a ½"X1½" hex head cap screw would have about ¼" of unthreaded shank, correct ?


Any one have a 1½" hex head cap screw handy and can verify this ?

 

[Doug Arthurs]

1/2-13 x 1-1/2 I have are fully threaded

 

[theoldwizard1]

1/2-13 x 1-1/2 I have are fully threaded

"Tap" screws are fully threaded regardless of length.

 

[lotsoftools]

I just measured one, 1/2-13 x 1-1/2 and it had about a 1/4 shank. It was JH branded, I think from Fastenal. I was carrying it in to snap a shot, dropped it in the yard and can't find it now.

 

[MP&C]

The 1-1/2 should have 1/4" or slightly less of shank. I have some that are MS35307, they appear to be about 1/8" off, the 1-1/2 shows about 1/8 of shoulder, the 1-3/4 has about 3/8 of shoulder..

Thread details per Mil Spec 35307E

Minimum thread length shall be twice the diameter plus .250 inch. The tolerance shall be plus​

.188 inch or 2.500 threads, whichever is greater. On screws that are too short for minimum thread lengths, the distance​

from the bearing surface of the head to the first complete thread shall not exceed the length of 2.500 threads for sizes up to​

and including 1.000 inch and 3.500 threads for sizes larger than 1.000 inch.

 

[theoldwizard1]

The 1-1/2 should have 1/4" or slightly less of shank. I have some that are MS35307, they appear to be about 1/8" off, the 1-1/2 shows about 1/8 of shoulder, the 1-3/4 has about 3/8 of shoulder..

WOW !! Thanks a million !!

I knew the shank length was not a "controlled" dimension. That is the exact picture I needed.

Thanks again.

 

[APEowner]

For what it's worth McMaster-Carr has cad drawings (and 3d models) of all their fasteners on line. I often use them when I'm designing a part based on a modified fastener.

 

[theoldwizard1]

For what it's worth McMaster-Carr has cad drawings (and 3d models) of all their fasteners on line. I often use them when I'm designing a part based on a modified fastener.

Thanks ! Good to know, if it does not fall out of my short term memory !!

 

[MotoDave]

WOW !! Thanks a million !!

I knew the shank length was not a "controlled" dimension. That is the exact picture I needed.

Thanks again.

For what its worth, most MS or NAS (Mil-Spec) fasteners have controlled grip length as well as overall length dimensions, and much shorter threaded sections than commonly available 'Grade 8' hardware. They're typically available in 1/16" increments. They are NOT CHEAP.

You'll find that sources like McMaster list a pretty large tolerance on the length of threaded section since they use multiple sources of supply and they can vary somewhat from source to source.

 

[laser3kw]

screw data link
I use this site ALOT!

 

[theoldwizard1]

... most MS or NAS (Mil-Spec) fasteners have controlled grip length as well as overall length dimensions, ...

I will not likely buy a MS or NAS fastener, but I know that large fastener companies are like to manufacture to those specs, but with loser tolerances.

For my project, I just need to buy some 1/2-13x1-3/4 cap screws to get adequate shank. The thread portion will like be cut shorter.

 

[theoldwizard1]

I am amazed at how many "professionals" don't know the difference between a "cap screw" and a "tap screw".

 

[APEowner]

You'll find that sources like McMaster list a pretty large tolerance on the length of threaded section since they use multiple sources of supply and they can vary somewhat from source to source.

I'll be dipped. I never noticed that before.

screw data link
I use this site ALOT!

Cool site. Thanks.

 

[bgarrett]

I am amazed at how many "professionals" don't know the difference between a "cap screw" and a "tap screw".

google shows nothing called a cap screw but offers this---> A tap bolt is (typically) a fully threaded hex bolt, while a cap screw is (typically) a hex head bolt that will be installed by turning the head of the bolt (screw) instead of tightening it with a nut. Usually cap screws are being threaded into something (a piece of machinery for example), rather than being used with a nut

 

[EarniesGarage]

Here is a couple of link you mind find of interest if you haven't already seen them:

https://www.boltdepot.com/fastener-information/Bolts/US-Thread-Length.aspx

https://www.boltdepot.com/fastener-information/Default.aspx