Machining some aluminum help!
These threads where there is not enough information to define the
problem can grow forever, because they are based on speculation, not
facts.
Corby, you have decided what you need based on what you know, but the
rest of us need a more general statement of the problem.
Unless, of course, that is something you do not choose to reveal.
Bill Hawkins
To tell the truth I had not worked this out. But I wonder of the screws
fail first on
they are in aluminum holes with only 1/4 of thread.
Which fails depends on the material and the number of engaged threads,
But if what you say is right for this case. It strengthens my case for
using self threading screws. I try and use these when I can.
What you do is center punch the screw location around the end plate. Then
glue the end plat in place using blue lock tight. (or even two tiny daps of
"Super Glue") then go to the drip pressed drill through the endplate into
the edge of the wall and insert one screw. The right size the type screw
will cut its own thread as you screw it in. Then drill neither hole and
put in another screw. It is imported to place the screw as you drill to
keep alignment, even when using the glue. Later take out the screw and
break the glue, reassemble.
On Thu, May 18, 2017 at 5:13 PM, jimlux jimlux@earthlink.net wrote:
On 5/18/17 2:36 PM, Chris Albertson wrote:
It would be easy to re-design the job for cheaper machining.. Do you
really need to tap the holes? You might use self taping screws. Id the
would work then you can do the work yourself with just a hand drill.
OK it you must use machine threads and they must be #4 size try "rivets"
these work like pop rivets but leave a hollow thread insert in the hole
that will take screws. Takes all of 5 seconds to install a thread hole.
Think again about threading aluminum. It is not very strong, it would be
easy for an end user to strip the #4 threads. Better to use the rivet or
other steel thread insert. Even native nuts installed with flush
rivets
is better
Interestingly enough, for 4-40 hardware, the screws fail before the
aluminum does. The area of the thread engagement is quite a bit larger
than the cross section of the fastener that is not thread.
For large fasteners, where the thread depth is a smaller fraction of the
fastener diameter, this may not be the case (as anyone who has stripped the
threads on an aluminum cylinder head with a steel sparkplug will know, in a
deep and visceral way).
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Chris Albertson
Redondo Beach, California
There are a lot of variables involved. Run the screws in and out of the aluminum a number of times and
the holes will fail first ….There are other gotchas as well.
Bob
This is where helicoils come in to play. They are used a lot on the CVD furnaces that I used to make parts for. They are not just for un-buggering a thread. They would be installed form the get go and could be replaced should something gall.
Link
We also used helicoils in titanium frames of the supercomputer I used to work with. Meant we could use relatively standard fasteners without fear of falling.
On a time nuts related note, I have a u blox GPS-1E that seems to be stuck spewing out in ublox format. With no development sw available (that runs on my Mac), I'm looking for the correct string to send its way to change it back to NMEA. Anyone point me at some docs or know the appropriate string?
Thanks!
Bob
On May 19, 2017, at 15:51, Lincoln lincoln@ampmonkeys.com wrote:
There are a lot of variables involved. Run the screws in and out of the aluminum a number of times and
the holes will fail first ….There are other gotchas as well.
Bob
This is where helicoils come in to play. They are used a lot on the CVD furnaces that I used to make parts for. They are not just for un-buggering a thread. They would be installed form the get go and could be replaced should something gall.
Link
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Yes, threaded inserts. There are many kinds but they are used almost
universally for cases where the material to be threaded is soft, like
aluminum. They also eliminate or reduce galvanic corrosion which is an
issue with steel screws in aluminum. (that said, as long as you keep water
away you are OK.) Still these inserts are the "class" way to go and will
save some broken taps.
As for a seal, it is hard to beat o-rings. A proper designed o-ring seal
does not need much clamping pressure as it depends on the pressure inside
to force the ring in place and hold it there.
On Fri, May 19, 2017 at 12:51 PM, Lincoln lincoln@ampmonkeys.com wrote:
There are a lot of variables involved. Run the screws in and out of the
aluminum a number of times and
the holes will fail first ….There are other gotchas as well.
Bob
This is where helicoils come in to play. They are used a lot on the CVD
furnaces that I used to make parts for. They are not just for un-buggering
a thread. They would be installed form the get go and could be replaced
should something gall.
Link
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
Hi
On May 19, 2017, at 5:35 PM, Chris Albertson albertson.chris@gmail.com wrote:
Yes, threaded inserts. There are many kinds but they are used almost
universally for cases where the material to be threaded is soft, like
aluminum. They also eliminate or reduce galvanic corrosion which is an
issue with steel screws in aluminum. (that said, as long as you keep water
away you are OK.)
There are some interesting internal studies out of places like Boeing that suggest the “keep moisture
away” includes some pretty modest levels of humidity …. It then becomes a question of if you do
or do not accept their methods.
Bob
Still these inserts are the "class" way to go and will
save some broken taps.
As for a seal, it is hard to beat o-rings. A proper designed o-ring seal
does not need much clamping pressure as it depends on the pressure inside
to force the ring in place and hold it there.
On Fri, May 19, 2017 at 12:51 PM, Lincoln lincoln@ampmonkeys.com wrote:
There are a lot of variables involved. Run the screws in and out of the
aluminum a number of times and
the holes will fail first ….There are other gotchas as well.
Bob
This is where helicoils come in to play. They are used a lot on the CVD
furnaces that I used to make parts for. They are not just for un-buggering
a thread. They would be installed form the get go and could be replaced
should something gall.
Link
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.