[modeleng] Re: Allen heads

I've seen the same trend Clif, and I think they are using basket spec mild
steel rather than a medium carbon steel as you would expect for torquing
grade spec bolts and screws. Reason is probably the softer steel  gives them
more screws per heading punch than if a better steel was used.

I'm sure with the fine detail and ribs on a Torx screw header punch, to make
the Torx socket on screws, the punches don't last long. Surely not as long
as a header for a hex head bolt, which has NO fine detail, or Allen head
which has only a hex shaped punch and no fine ribs.

The name of the game in making parts for car manufacturing is to make the
parts as cheap as you can and charge as much as you can to the car maker for
them. Typically suppliers will supply first parts in best materials, then
gradually cheapen the raw materials used until the car maker's QC department
starts yelling about it, particularly on fasteners and plastics.

Did you lube the screws when torquing? Nowadays the car manuals say to use a
good grade of lube compatible with the system you re working on while
torquing. If you don't, and torque the screws dry, the torque applied will
be higher than intended.

Cheers Jeff Dayman


----- Original Message ----- 
From: "Clif Walker" <clif.gwr@xxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Thursday, January 25, 2007 3:16 PM
Subject: [modeleng] Re: Allen heads


> Hi All,
> A couple of years ago I had to do a job on my Vauxhall ( part of the GM
> group for  our American and Canadian cousins) )car which meant removing
the
> Camshafts, the bearings of which were held down by 6mm Bolts with Torx
> heads.
> When replaced, these bolts had to be tightened down to a maximum of 6 Ft
lbs
> Torque.
> When putting the Camshafts back with a special Torque Wrench that I had to
> buy just to get down to such a low setting one of the bolts sheared off.
> After drilling out the remains I tried another bolt and found that started
> stretching at 5 Ft lbs. I went to the  local car dealer and ordered two
> complete new sets of bolts. When I eventually got them, on putting them in
> once again I could feel bolts starting to stretch at 5 ft lbs. In the end
I
> had to make a little test rig that enabled me to test each bolt before I
put
> it back into the engine.
>
> My thing is that a 6mm Steel bolt should be able to take far more than 6
Ft
> lbs torque and these were failing at 5. What sort of rubbish steel are
they
> making things out of these days?
>
> Regards
>
> Clif
> ----- Original Message ----- 
> From: "Jeff Dayman" <jeffdayman@xxxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Thursday, January 25, 2007 12:51 PM
> Subject: [modeleng] Re: Allen heads
>
>
> > Hi Jesse.
> >
> > I'm a Torx hater too.
>
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