Hub set screws. Head type matter?

[ebinmaine 68,303]

Is there a particular reason why the hub set screws have a male square head?

 

Is there a particular reason why NOT to use a different style head such as a female 6-point Allen which is readily available to me...?

 

The only thing I could think of is the torque rating may be different? Or increased chance of stripping out an Allen head later?

 

What say you, fine and dandy Redsquare folk?

 

[pacer 3,174]

8 minutes ago, ebinmaine said:

reason why the hub set screws have a male square head?

 

I have posed that question to myself .... and I arrived at the conclusion of -- I've got numerous conventional grade 5 & 8's aplenty, so I use em!

 

When I have a hub needing attention, I take and add TWO more set screws. I use the method of taking my angle grinder and flattening a place on the axle and gently rounding the thread end of a bolt for the contact point and do use a back up nut.

[Achto 27,751]

I have a couple of tractors that I used Allen head bolts on. No issues.

[WHX?? 49,154]

Long as they have a cup point. I think it's more important to check them for tightness every now and then.

[Maxwell-8 4,290]

Allen here as well. but also Hex. put a socket on that, you can put more then enough torque on those bolts

 

My luck with Allen isn't great, they always tend to get dirt, water and rust in them. making them vulnerable to stripping. But that is my experience.

[pfrederi 17,866]

Only reason they are square is so jam nut can fit over them

[8ntruck 7,082]

I think the point contour is more important than the head type.  The square head is more tolerant of the dirty environment they operate in than a hex socket head.

[Jeff-C175 7,203]

14 minutes ago, pfrederi said:

Only reason the are square is so jam nut can fit over them

 

Citation Paul?

 

[pfrederi 17,866]

8 minutes ago, Jeff-C175 said:

 

Citation Paul?

 

 Common sense.  3/8" set screw would have a 9/16 head how are you going to get a jam nut over it....

Edited January 10, 2022 by pfrederi

[Jeff-C175 7,203]

21 minutes ago, pfrederi said:

how are you going to get a jam nut over it

 

Put the jam nut on before you thread it into the hole?

 

To say that's the only reason is a sweeping statement and probably not accurate.  

 

I might also think that there could be safety considerations.  A square head is less likely to 'hook' a piece of worker's clothing than a hex head because there's no 'step'.  Maybe that is the 'only' reason?

 

 

Edited January 10, 2022 by Jeff-C175

[pfrederi 17,866]

17 minutes ago, Jeff-C175 said:

 

Put the jam nut on before you thread it into the hole?

 

To say that's the only reason is a sweeping statement and probably not accurate.  

 

I might also think that there could be safety considerations.  A square head is less likely to 'hook' a piece of worker's clothing than a hex head because there's no 'step'.  Maybe that is the 'only' reason?

 

 

 

 

Lets think about strength  There is not much metal around the hex well in the set screws on the left.  They are usually used in a hole that completely surrounds the whole set screw ..think all the pulleys on our horses the threaded hole supports the set screw.  On hubs you want a jam nut so the head would be above the hole in the hub and not supported 35 ft/lbs or more might just crack the set screw.  Look at eh amoujnt of metal available in the square head to take the stress. 

Edited January 10, 2022 by pfrederi

[Snoopy11 5,714]

30 minutes ago, Jeff-C175 said:

Put the jam nut on before you thread it into the hole?

WHAT???

Are you actually suggesting that the jam nut be put on before threading it into the hole?

 

 

 

Don

 

 

 

 

 

Edited January 10, 2022 by Snoopy11

[pacer 3,174]

1 minute ago, Snoopy11 said:

jam nut be put on before threading it into the hole?

 

 

Thats the way I do it .....and since I have a mill I set the hub in it and mill a flat spot so the jam nut will have full contact.

[Maxwell-8 4,290]

15 minutes ago, Snoopy11 said:

Are you actually suggesting that the jam nut be put on before threading it into the hole?

yes, but tighten at last

[Jeff-C175 7,203]

1 hour ago, pfrederi said:

Lets think about strength 

 

No, I'm out... not diverting.

 

But let me say this:  I would NEVER, EVER use an Allen head set screw on a hub.

 

And technically, I believe that they are more correctly called "Grub Screws".

 

I would have no qualms about using a HEX HEAD set screw though, but looking at McMaster, it doesn't seem like those are a 'thing', they  don't list them.

 

These are what I would use:

https://www.mcmaster.com/set-screws/alloy-steel-square-head-cup-point-set-screws/

 

 

 

 

Edited January 10, 2022 by Jeff-C175

[roadapples 6,983]

I don't like Allen head. I've had too many strip out....

[RetroMower 349]

 I'll toss my $0.02 in. I think square head set screws are a thing of antiquity that were used before Allen set screws were available and/or cheap enough to use and things dont phase out of use quickly because "if it works why change it". Both have their advantages and disadvantages. Square head vs Allen type grub screws square heads can take more torque if the exposed portion isnt an issue where allen usually go flush or below it. I'm nearing the end of restoring a ģŕèèñ tractor ..... and the axle hubs have a square set screw with jam nut where the main drive pulley off the motor has an allen and no jam nut.  I think think personal preference plays a part here. 

[Jrain 276]

Square head set screws also known as Jack bolts  with most commonly having a cup point end , They are always manufactured of alloy steel for maximum strength  as well as high resistance for galling , wear and fatigue ,the square head provides for positive gripping for hand wrenching . they are Ideal for holding pulleys. collars and other machinery shafts when fine adjustments are necessary .

[SylvanLakeWH 25,924]

No one has said the obvious…

 

I mean…

 

duh…

 

square head / round hole… 

[Jrain 276]

Hex head set screw used commonly for fastening mated parts such as shaft and collar  they are quenched and tempered alloy steel ,these screws are intended for compression applications only and or not subjected to embrittlement tests , the headless design allows the fastener to sit flush or insert in to a threaded part.

[kpinnc 12,418]

I've used regular grade 8 bolts (3/8x16 thread) with a jam nut many times when needed. I've also used stainless square head/ jam nut combos as well. Both work equally well, one looks better than the other. 

 

Allen head? Negative sir, I would not except in a "limp back home" emergency, and I'd swap for either of the two previous options immediately upon arrival.

 

...Maybe if the allen bolts were stainless or plated differently than traditional black oxide. They corrode like crazy, no matter how clean you keep them.

 

Edited January 11, 2022 by kpinnc

[kpinnc 12,418]

23 hours ago, ebinmaine said:

Is there a particular reason why NOT to use a different style head such as a female 6-point Allen which is readily available to me...?

 

I should clarify my previous response Eb. I've seen nothing that corrodes quicker than black oxide here in NC. I've seen them rust so fast that the socket itself rounds out to the point that you strip them out very easily- and I always grind my allen wrenches bottom flat if they slipped previously. Might just be bad luck on my part, but it's reason enough to avoid them, especially on a hub. 

[Snoopy11 5,714]

MONEY @kpinnc...

 

Don

[Jrain 276]

I do not use any threaded hardware ever made of stainless ,because 99.9 percent of the time galling will occur on stainless threads , and this can lead to future extracting issues, and I consider any threaded stainless fasteners for one time use only ,I treat stainless like aluminum  One time use throw it away .and yes Allen hex head type bolts do rust and corrode fast , and I do have a few tricks for extracting a bad one  , but mainly here is something I learned a very long time ago and when I do this to my Allen type bolts I never have a issue when extracting them ,I coat the entire bolt and pack the Hex head with Mylanta, I also use it really on any bolt that I would have corrosion concerns on, such as exhaust Manifold and muffler systems , the Mylanta will give you a very good coating of A aluminum oxide and B zinc  witch is the main ingredient in Mylanta and gives some of the best protection as far as threaded coating go and you thought it was only for heartburn 

[ebinmaine 68,303]

12 minutes ago, Jrain said:

I do not use any threaded hardware ever made of stainless ,because 99.9 percent of the time galling will occur on stainless threads

 

Same here. I love the look of stainless in certain applications but over the last several years I've completely stopped using it because I'm not overly fond of the issues when trying to remove it later.