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Posted by Tim Leech on August 10, 2006, 3:20 pm
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I've got to do the final tightening of some cylinder heads tomorrow.
I've been using a torque multiplier but for some of the bolts there's
no good way to secure the reaction arm & it's been getting damaged.
(it's the type designed for waggon wheel nuts which uses a second
socket on another nut)
My big torque wrench has lost the 3/4" square shaft which connects it
to the sockets, they're a special order item so I can't just buy one
off the shelf tomorrow.
If I square up a piece of mild steel bar, will it take the 500 lb-ft
torque, or just twist off? I could find a bit of stainless or EN8 if
that would do better.
I would just try it & see if the job was here, but it's 30 miles away,
it must be finished tomorrow, & I'd struggle to find something here to
test it on. OK, I could weld a big nut to the side of a boat on the
dry-dock and use that, but we've just finished painting it and the
owner is coming to collect tomorrow!
TIA
Tim
Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service
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Posted by david.sanderson@bem.fki-et.com on August 10, 2006, 4:09 pm
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Tim Leech wrote:
> I've got to do the final tightening of some cylinder heads tomorrow.
> I've been using a torque multiplier but for some of the bolts there's
> no good way to secure the reaction arm & it's been getting damaged.
> (it's the type designed for waggon wheel nuts which uses a second
> socket on another nut)
> My big torque wrench has lost the 3/4" square shaft which connects it
> to the sockets, they're a special order item so I can't just buy one
> off the shelf tomorrow.
> If I square up a piece of mild steel bar, will it take the 500 lb-ft
> torque, or just twist off? I could find a bit of stainless or EN8 if
> that would do better.
>From manual of machine design castle,1944:
T = 0.208fS^3 for a square shaft, T = twisting moment, where a safe f
for MS is
given as 9000 psi.so:
0.208x9000x0.75^3 = 789.75, but im not sure what the units are, or if
this helps....
values are for generic 1944 MS, alloy steel isnt covered, but the sheer
strenght is listed as
15000 psi safe working stress.
hth a bit
Dave
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Posted by Tim Leech on August 10, 2006, 5:12 pm
Please log in for more thread options On 10 Aug 2006 13:09:43 -0700, "david.sanderson@bem.fki-et.com"
>
>Tim Leech wrote:
>> I've got to do the final tightening of some cylinder heads tomorrow.
>> I've been using a torque multiplier but for some of the bolts there's
>> no good way to secure the reaction arm & it's been getting damaged.
>> (it's the type designed for waggon wheel nuts which uses a second
>> socket on another nut)
>> My big torque wrench has lost the 3/4" square shaft which connects it
>> to the sockets, they're a special order item so I can't just buy one
>> off the shelf tomorrow.
>> If I square up a piece of mild steel bar, will it take the 500 lb-ft
>> torque, or just twist off? I could find a bit of stainless or EN8 if
>> that would do better.
>
>>From manual of machine design castle,1944:
>T = 0.208fS^3 for a square shaft, T = twisting moment, where a safe f
>for MS is
>given as 9000 psi.so:
>
> 0.208x9000x0.75^3 = 789.75, but im not sure what the units are, or if
>this helps....
>
Well I suppose logically they ought to be lb-in, as the pressure is in
psi & you've done the shaft size in ins, but I can't believe the
figure would be as low as that!
>values are for generic 1944 MS, alloy steel isnt covered, but the sheer
>strenght is listed as
>15000 psi safe working stress.
>
>hth a bit
>
Well it would if I knew the units <BG>
Thanks
Tim
Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service
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Posted by david.sanderson@bem.fki-et.com on August 11, 2006, 3:17 am
Please log in for more thread options <Snip>
> >>From manual of machine design castle,1944:
> >T = 0.208fS^3 for a square shaft, T = twisting moment, where a safe f
> >for MS is
> >given as 9000 psi.so:
> >
> > 0.208x9000x0.75^3 = 789.75, but im not sure what the units are, or if
> >this helps....
> >
> Well I suppose logically they ought to be lb-in, as the pressure is in
> psi & you've done the shaft size in ins, but I can't believe the
> figure would be as low as that!
>
Me neither, which is part of the reason Im not sure, but lb/sq inch x
inch^3 does imply lb ins
789lb in doesnt sound like a lot, however the book is about safe, and
longterm machine desing, not a do the job for 5 mins at the edge of its
envelope...
Dave
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Posted by Peter A Forbes on August 10, 2006, 5:10 pm
Please log in for more thread options wrote:
>I've got to do the final tightening of some cylinder heads tomorrow.
>I've been using a torque multiplier but for some of the bolts there's
>no good way to secure the reaction arm & it's been getting damaged.
>(it's the type designed for waggon wheel nuts which uses a second
>socket on another nut)
>My big torque wrench has lost the 3/4" square shaft which connects it
>to the sockets, they're a special order item so I can't just buy one
>off the shelf tomorrow.
>If I square up a piece of mild steel bar, will it take the 500 lb-ft
>torque, or just twist off? I could find a bit of stainless or EN8 if
>that would do better.
>I would just try it & see if the job was here, but it's 30 miles away,
>it must be finished tomorrow, & I'd struggle to find something here to
>test it on. OK, I could weld a big nut to the side of a boat on the
>dry-dock and use that, but we've just finished painting it and the
>owner is coming to collect tomorrow!
>
>TIA
>
>Tim
The 3/4" Britool Torque Wrench here has a hardened drive piece, you might get
away with MS but you'll have to keep an eye on it in case it starts to go when
you are finely balanced on top of the pots! :-))
Peter
--
Peter & Rita Forbes
Email: diesel@easynet.co.uk
Web: http://www.oldengine.org/members/diesel
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> I've been using a torque multiplier but for some of the bolts there's
> no good way to secure the reaction arm & it's been getting damaged.
> (it's the type designed for waggon wheel nuts which uses a second
> socket on another nut)
> My big torque wrench has lost the 3/4" square shaft which connects it
> to the sockets, they're a special order item so I can't just buy one
> off the shelf tomorrow.
> If I square up a piece of mild steel bar, will it take the 500 lb-ft
> torque, or just twist off? I could find a bit of stainless or EN8 if
> that would do better.