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Posted by Joseph Gwinn on December 22, 2009, 11:15 pm
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A few days ago, a foot broke off of my wife's favorite colander. I was
going to replace the colander, but she has had for at least 30 years,
and likes its now uncommon wide and shallow shape. So, I must repair it.
The colander is completely made of stainless steel, the bowl being about
12" in diameter and 5" deep. Alloy unknown, but it is not magnetic.
Fabrication was a bit sloppy. Each foot is spot-welded to the bowl in
three places, at least in theory. The foot that came off instead had
one weld plus two good-intention dents, and the one weld eventually
fatigued and broke. The other two feet were each missing at least one
weld, but it was hard to tell without pulling the joint apart.
I don't have a welder, and silver brazing was going to leave a very
large and ugly heat-affected zone, which could well rust. (Not knowing
the alloy, I have to assume that it is one of those that can rust if
raised to red heat.)
So, I drilled foot and bowl to accept three stainless steel 2-56 machine
screws and nuts, with the screwheads inside the bowl. I also put one
screw apiece in the other two feet, replacing the most obvious missing
welds. The bits of screw shaft protruding from the nuts were then
peened over with a ball peen hammer to form a rough rivethead.
So far so good - it will not fail in my lifetime. But it does look a
bit crude, and the peened thread ends are a bit sharp (as I didn't form
a real rivethead), and I think real rivets would have been better.
Copper is probably too weak, ordinary steel rusts, so the rivets should
be made of stainless steel.
The question is what alloys are best for making SS rivets. This is two
questions, actually, as one may wish to cold rivet (as I did with the
2-56 screws), or hot-rivet.
Whatever alloy those SS 2-56 screws are made of certainly would work as
a rivet. These screws were intended for use on airplanes, as the
flat-head screws have 100-degree heads, so they were probably made to
some MIL-SPEC.
Googling on "stainless steel rivet" yields that lots of rivets are made
of 304 and 316 alloys, so perhaps that's the best answer, at least for
cold riveting. But then there is hot riveting, where the rivet is
heated red hot before hammering into shape.
Joe Gwinn
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Posted by Bob La Londe on December 22, 2009, 11:26 pm
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> So, I drilled foot and bowl to accept three stainless steel 2-56 machine
> screws and nuts, with the screwheads inside the bowl. I also put one
> screw apiece in the other two feet, replacing the most obvious missing
> welds. The bits of screw shaft protruding from the nuts were then
> peened over with a ball peen hammer to form a rough rivethead.
>
> So far so good - it will not fail in my lifetime. But it does look a
> bit crude, and the peened thread ends are a bit sharp (as I didn't form
> a real rivethead), and I think real rivets would have been better.
> Copper is probably too weak, ordinary steel rusts, so the rivets should
> be made of stainless steel.
All stainless pop rivets. I get them from an outfit in Phoenix for marine
work. I've got several bags of them in various length 1/8 inch diameter
hanging from the pegboard in the shop. No clue what alloy they are. They
pop in easily enough. I suppose for "finish" work I could knock out the
stub of the stem, and then used a center punch and then pin punch to spread
and flatten the pull side.
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Posted by cavelamb on December 23, 2009, 3:26 am
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Bob La Londe wrote:
>
>> So, I drilled foot and bowl to accept three stainless steel 2-56 machine
>> screws and nuts, with the screwheads inside the bowl. I also put one
>> screw apiece in the other two feet, replacing the most obvious missing
>> welds. The bits of screw shaft protruding from the nuts were then
>> peened over with a ball peen hammer to form a rough rivethead.
>>
>> So far so good - it will not fail in my lifetime. But it does look a
>> bit crude, and the peened thread ends are a bit sharp (as I didn't form
>> a real rivethead), and I think real rivets would have been better.
>> Copper is probably too weak, ordinary steel rusts, so the rivets should
>> be made of stainless steel.
>
> All stainless pop rivets. I get them from an outfit in Phoenix for
> marine work. I've got several bags of them in various length 1/8 inch
> diameter hanging from the pegboard in the shop. No clue what alloy they
> are. They pop in easily enough. I suppose for "finish" work I could
> knock out the stub of the stem, and then used a center punch and then
> pin punch to spread and flatten the pull side.
>
>
>
Smallest pops I've seen are 3/32" diameter.
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Posted by Jim Wilkins on December 23, 2009, 7:01 am
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> ...
> All stainless pop rivets. =A0I get them from an outfit in Phoenix for mar=
ine
> work. =A0...
Stanley does or did make stainless pop rivets. 1/8" dia X 1/2" long is
part # PTT48, bar code 45731 13090. The store where I found them sells
imports, closeouts and overstock so I don't know a good quick source
elsewhere.
jsw
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Posted by Joseph Gwinn on December 23, 2009, 10:54 am
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>
> > So, I drilled foot and bowl to accept three stainless steel 2-56 machine
> > screws and nuts, with the screwheads inside the bowl. I also put one
> > screw apiece in the other two feet, replacing the most obvious missing
> > welds. The bits of screw shaft protruding from the nuts were then
> > peened over with a ball peen hammer to form a rough rivethead.
> >
> > So far so good - it will not fail in my lifetime. But it does look a
> > bit crude, and the peened thread ends are a bit sharp (as I didn't form
> > a real rivethead), and I think real rivets would have been better.
> > Copper is probably too weak, ordinary steel rusts, so the rivets should
> > be made of stainless steel.
>
> All stainless pop rivets. I get them from an outfit in Phoenix for marine
> work. I've got several bags of them in various length 1/8 inch diameter
> hanging from the pegboard in the shop. No clue what alloy they are. They
> pop in easily enough. I suppose for "finish" work I could knock out the
> stub of the stem, and then used a center punch and then pin punch to spread
> and flatten the pull side.
I didn't consider pop rivets because they yield this big sharp thing on
the blind side, and are weak relative to bolting or solid rivets. There
is actually a lot of force on these feet, given the leverage and general
banging around any kitchen implement receives.
The drive the stem out and upset with a punch approach will improve
strength and appearance but sounds like as much work as upsetting a
solid rivet, and yields something not as neat looking.
Joe Gwinn
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> screws and nuts, with the screwheads inside the bowl. I also put one
> screw apiece in the other two feet, replacing the most obvious missing
> welds. The bits of screw shaft protruding from the nuts were then
> peened over with a ball peen hammer to form a rough rivethead.
>
> So far so good - it will not fail in my lifetime. But it does look a
> bit crude, and the peened thread ends are a bit sharp (as I didn't form
> a real rivethead), and I think real rivets would have been better.
> Copper is probably too weak, ordinary steel rusts, so the rivets should
> be made of stainless steel.