Of bolts and fasteners in space

One would have thought that in space, where mainly temperature cycling
occurs, that this would make fasteners and bolts less of a problem to undo
after long periods, given that different materials expand and contract
differently. However, time and time again it seems this is far from the
truth. I hope someone is researching this, as if humans do want to go a long
way away, and need to undo some clever fastener or push a button to release
a mechanism, and it gets stuck they can hardly wait for someone on earth to
come up with a tool or some fancy lubricant to fix it.

Brian

Brian Gaff wrote:

truth. I hope someone is researching this, as if humans do want to go a long
way away, and need to undo some clever fastener or push a button to release
a mechanism, and it gets stuck they can hardly wait for someone on earth to
come up with a tool or some fancy lubricant to fix it.

They know how to fix this already: some heaters and coolant loops around
every external bolt in the station to keep them warm and comfy all the
time. :-)

Couldn't they use components for screw/bolt that react differently to
cold in such a way that spraying liquid nitrogen or some other liquified
gas onto the bolt would make it looser and easier to unscrew ?

I was thinking about the screw contracting more than bolt under cold,
but doing so might shorten the screw and thus bring the bolt down even
tighter against the surface it is bolted on , making it harder to remove.

"John Doe" wrote in message
...
Brian Gaff wrote:

truth. I hope someone is researching this, as if humans do want to go a
long
way away, and need to undo some clever fastener or push a button to
release
a mechanism, and it gets stuck they can hardly wait for someone on earth
to
come up with a tool or some fancy lubricant to fix it.

They know how to fix this already: some heaters and coolant loops around
every external bolt in the station to keep them warm and comfy all the
time. :-)

Couldn't they use components for screw/bolt that react differently to
cold in such a way that spraying liquid nitrogen or some other liquified
gas onto the bolt would make it looser and easier to unscrew ?

I was thinking about the screw contracting more than bolt under cold,
but doing so might shorten the screw and thus bring the bolt down even
tighter against the surface it is bolted on , making it harder to remove.

Don't forget about vacuum. It can cause problems with lubricants and the
like. That said, vacuum welding is a myth, according to Henry Spencer:

http://groups.google.com/group/sci.s...09b7136c1206f5

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Given all that with heaters etc, there does still seem to be a lott of bolts
and fasteners that misbehave from the normal. I just wondered why this
should be, or is it in fact much the same as we have here on the ground,
except that given the way people have to wear awkward suits in space, its
harder to simply put a large pair of mole grips and wd 40 to work?

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Jeff Findley" wrote in message
...

"John Doe" wrote in message
...
Brian Gaff wrote:

truth. I hope someone is researching this, as if humans do want to go a
long
way away, and need to undo some clever fastener or push a button to
release
a mechanism, and it gets stuck they can hardly wait for someone on earth
to
come up with a tool or some fancy lubricant to fix it.

They know how to fix this already: some heaters and coolant loops around
every external bolt in the station to keep them warm and comfy all the
time. :-)

Couldn't they use components for screw/bolt that react differently to
cold in such a way that spraying liquid nitrogen or some other liquified
gas onto the bolt would make it looser and easier to unscrew ?

I was thinking about the screw contracting more than bolt under cold,
but doing so might shorten the screw and thus bring the bolt down even
tighter against the surface it is bolted on , making it harder to remove.

Don't forget about vacuum. It can cause problems with lubricants and the
like. That said, vacuum welding is a myth, according to Henry Spencer:

http://groups.google.com/group/sci.s...09b7136c1206f5

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Brian Gaff wrote:
Given all that with heaters etc, there does still seem to be a lott of bolts
and fasteners that misbehave from the normal. I just wondered why this
should be, or is it in fact much the same as we have here on the ground,
except that given the way people have to wear awkward suits in space, its
harder to simply put a large pair of mole grips and wd 40 to work?

I recently got a carbon fibre bike frame. I was warned that with such
frames, it is very important to not over-torque screws. And I came to
better understand why NASA developped those multi-billion dollar power
tools where you dial in a torque number and it promises to not exceed
that limit.

When you are in a space suit with those gloves and a fair pressure
differential that "inflates" the suit, I suspect that an astronaut would
have even less tactile feedback on how the wrench/bolt is behaving under
a certain amount of force.

I suspect that many problems are due to the bolt having been tightened
with that power tool under specs of say 5 newtons, and when they do the
eva to unbolt it, they program the tool to not exceed 5 newtons and the
took is then unable to uncrew it. If a very critical bolt that holts the
whole truss to the station has been rated at 5 newtons, are you willing
to risk breaking the screw when you overtorque the bolt to unjam it ? If
that screw breaks off with the bolt, you're going to need lots of
space-rated duct tape to hold the station together.

Perhaps NASA needs to spec all bolts to a minimum torque needed to
tighten it, and a maximum allowed torque to unscrew it. This way, they
could tighten bolts at say 5 newtons, and they could go up to say 8
newtons to unscrew it if it appears to be stuck.

John Doe wrote:

I suspect that many problems are due to the bolt having been tightened
with that power tool under specs of say 5 newtons, and when they do the
eva to unbolt it, they program the tool to not exceed 5 newtons and the
took is then unable to uncrew it.

You suspect incorrectly.

As usual.

D.
--
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Derek Lyons wrote:

You suspect incorrectly.
As usual.

And insult instead of answering the question.
As usual.

Not to mention mating connectors. Luckily they were not allowed to use the
hammer.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"John Doe" wrote in message
...
Derek Lyons wrote:

You suspect incorrectly.
As usual.

And insult instead of answering the question.
As usual.

John Doe wrote:

Derek Lyons wrote:

You suspect incorrectly.
As usual.

And insult instead of answering the question.

You didn't ask a question - you made a statement. Learn to tell the
difference.

D.
--
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Derek Lyons wrote:

You didn't ask a question - you made a statement. Learn to tell the
difference.

Your professional attitude is refreshing. Bound to welcome people to
this newsgroup.

And in your rush to respond to my post, you conveniently forgot that the
OP had asked a question.

Since you appear to be one of the few who are allowed (by whom ?) to
make statements while us mere mortals can only ask questions, perhaps
you could asnwer the OP's original question ?