Project of the Month built by driller1432

Help Support Home Model Engine Machinist by donating using the link above or becoming a Supporting Member.
Home Model Engine Machinist > Building Them > General Engine Discussion > Why so many socket head cap screws?

Reply
 
Thread Tools
Old 08-01-2008, 01:58 PM   #1
SmoggyTurnip
 
Join Date: Mar 2008
Posts: 106
Liked 4 Times on 4 Posts

Default Why so many socket head cap screws?

Seems like 90% of the machining projects i look at use socket head cap screws. They are also used on most lathes that I see, and on tool holders etc. On my lathe the carage lock screws are socket head cap screws and they are always filling up with swarff making it hard to get a hex wrench in there. It is easier to strip the socket head on a socket head cap screw than it is on a Robinson head and a normal Hex head doesn' get filled up with dirt. I had to replace the screw on my screwless vise and on several of my quick change tool holders for this very reason. I replaced them with normal hex Heads. So why are they so popular?


SmoggyTurnip is offline  
 
Reply With Quote
Old 08-01-2008, 03:35 PM   #2
LCT
Guest
 
Posts: n/a
Default Re: Why so many socket head cap screws?

Quote:
Originally Posted by SmoggyTurnip
Seems like 90% of the machining projects i look at use socket head cap screws. They are also used on most lathes that I see, and on tool holders etc. On my lathe the carage lock screws are socket head cap screws and they are always filling up with swarff making it hard to get a hex wrench in there. It is easier to strip the socket head on a socket head cap screw than it is on a Robinson head and a normal Hex head doesn' get filled up with dirt. I had to replace the screw on my screwless vise and on several of my quick change tool holders for this very reason. I replaced them with normal hex Heads. So why are they so popular?
We use them in injection molds because they can be counterbored in the plate so they don't stick up past the surface. The heads don't take up as much room as a hex head either.


 
 
Reply With Quote
Old 08-01-2008, 03:51 PM   #3
cfellows
Project of the Month Winner!!!
 
cfellows's Avatar
 
Join Date: Aug 2007
Posts: 3,877
Liked 758 Times on 486 Posts
Likes Given: 3

Default Re: Why so many socket head cap screws?

I use them in model work because they are cheaper and easier to obtain than hex heads in the small, numbered sizes such as 2-56, 4-40, 6-32, etc. Also, allen wrenches are more prevalent than sockets and wrenches in these small sizes.

Chuck
cfellows is offline  
 
Reply With Quote
Old 08-01-2008, 04:16 PM   #4
Mcgyver
 
Join Date: Oct 2007
Posts: 496
Liked 15 Times on 14 Posts
Likes Given: 1

Default Re: Why so many socket head cap screws?

because they are so easily recessed - you never see them proud of the surface.

I don't put them on models though as most things i make are representative of an era or type of machine that didn't use them. going hex or better yet studs on a model is an easy way to improve the look with zero additional skill or chips required....unless you a masochist and make your own . i hear you on the cost Chuck, but I take forever to build so it doesn't add up to much.
Mcgyver is offline  
 
Reply With Quote
Old 08-01-2008, 04:42 PM   #5
Jadecy
 
Join Date: Dec 2007
Posts: 246
Liked 17 Times on 17 Posts

Default Re: Why so many socket head cap screws?

I don't know if this is still the case but cap screws used to be grade 8 by default. Some of the smaller hex head bolts found at the hardware store seem like they are made out of cheese. I also like the look of them.
Jadecy is offline  
 
Reply With Quote
Old 08-01-2008, 05:54 PM   #6
nemt
 
Join Date: Apr 2008
Posts: 61
Liked 6 Times on 6 Posts
Likes Given: 7

Default Re: Why so many socket head cap screws?

One very important reason to use cilindersockethead screws, is that they need less space compared to a hexagon head. Specially when using the wrench to tighten them on a hex bolt needs a lot more space then a socket head screw. And if you use the good grade, for bolt as for the key, you don't have to expect trouble!
I myself prefer sockethead screws for models as well for other engineering problems.

Nemt
nemt is offline  
 
Reply With Quote
Old 08-10-2008, 02:44 AM   #7
PolskiFran
 
Join Date: Dec 2007
Posts: 61
Liked 8 Times on 8 Posts
Likes Given: 2

Default Re: Why so many socket head cap screws?

I tried locating some 6-32 hex head screws when I was building my Upshur gas engine. I couldn't find any locally or in the standard supply catalogs so I decided to try my hand at making a few. I tried to follow the dimensions of a heavy head 5/16-18 bolt as a guide. These are common on the old gas engines. I started with making 8 pcs. to end up with 5 good ones, I needed 4pcs for the engine. After 2 nights of turning, threading and hex milling to fit my nut driver, I replaced the socket head screws with the hex heads. I snapped one head off with the nut driver. The screw was replaced with the spare and it really looked good. After about a year of running at shows I had to disassemble the engine for a cleaning. I found that two of the screws had snapped during operation. I went back to the allen cap screws and have had no trouble.

A few factors could have caused failure.
1) Using 1018 CRS for material was probably a bad choice for such a small screw
2)Having cut threads instead of rolled threads reduced the strength.
3) Milling the hex probably put some stress in the screw even before it was installed.

I will use allen screws where there going to be any amount of force. The purchased screws are stronger than anything I can make easily.

Hope this helps,
Frank
PolskiFran is offline  
 
Reply With Quote
Old 08-10-2008, 05:42 AM   #8
Bogstandard
Guest
 
Posts: n/a
Default Re: Why so many socket head cap screws?

We are very lucky in the UK, hex headed bolts are fairly easy to come by, so it is just not necessary to make your own.

If I make a 'period' model, I tend to use hex head with a lot of stud/nut work, just because that was how it used to be done on such engines.

If it is a model I have designed and made, I tend to use cap screws, but hide or recess the heads as much as possible, because to me they tend to look ugly.

One thing I can't stand to see is philips head domed screws on a finished model. I use them during the build to save having any damage to the final screws, but swap them out when the engine comes to completion.

John
 
 
Reply With Quote
Old 08-10-2008, 12:55 PM   #9
Stan
 
Join Date: Jan 2008
Posts: 994
Liked 31 Times on 31 Posts

Default Re: Why so many socket head cap screws?

Both socket head and hex head bolts are relatively modern inventions. When making models of anything made a hundred or more years ago, the standard was square head bolts with square nuts.
North American manufacturers tended to make their own fasteners with no standard size. In fact, as their punches and dies wore, the size changed. They solved both of these problems by supplying a set of wrenches with each machine. Even early automobiles came with wrenches to fit their particular size of fastener.
__________________
Stan in Leduc, Alberta, Canada. 53.40NĀ* 113.5W
Old, but still on the right side of the grass.
Stan is offline  
 
Reply With Quote
Old 08-11-2008, 02:25 PM   #10
SmoggyTurnip
 
Join Date: Mar 2008
Posts: 106
Liked 4 Times on 4 Posts

Default Re: Why so many socket head cap screws?

Quote:
Originally Posted by Stan
North American manufacturers tended to make their own fasteners with no standard size. In fact, as their punches and dies wore, the size changed. They solved both of these problems by supplying a set of wrenches with each machine. Even early automobiles came with wrenches to fit their particular size of fastener.

lol - This must be what they are doing in China now because my milling machine and my lathe both came with a 17mm wrench, But the one for the lathe is too small for the nuts on the milling machine. Both wrenches are stamped with the number 17 and look identical.
Each wrench fits the machine that it came with but not the other.


SmoggyTurnip is offline  
 
Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for Hex Head Brass Screws enginemaker1 General Engine Discussion 8 09-21-2010 12:10 AM
Small socket wrenches ghart3 Tools 9 03-24-2010 04:20 PM
Piston Rings, Socket Head Cap Screws, Set Screws HughT General Engine Discussion 17 03-18-2009 02:55 AM
Countersinking flat head machine screws Philjoe5 General Engine Discussion 14 04-30-2008 12:53 AM
Needed to counter sink a 4/40 socket head cap screw deere_x475guy Tools 15 02-02-2008 10:45 PM



Newest Threads






- Top - Member List