I am doing some rebuild on my aluminum river jet boat. Going to weld closed
some old bolt holes in the gunnel and dash. What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. If I had a TIG outfit, might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

On Apr 22, 10:51*pm, "Califbill" wrote:
*What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. *If I had a TIG outfit, might
be easier, but only a spool gun. *1/4" steel plate? *Stainless plate?

I like copper.

Dan

Califbill wrote:
I am doing some rebuild on my aluminum river jet boat. Going to weld
closed some old bolt holes in the gunnel and dash. What is a good
backing plate to prevent a big gob of aluminum slump on the backside,
where I can not get the grinder after I use the spool gun on the top.
If I had a TIG outfit, might be easier, but only a spool gun. 1/4"
steel plate? Stainless plate?

Copper sheet

--
Steve W.

wrote in message
...

On Apr 22, 10:51 pm, "Califbill" wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get
the
grinder after I use the spool gun on the top. If I had a TIG outfit,
might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

I like copper.

Dan


Reply:
I thought about that, but since this is 50xx aluminum for corrosion
protection, I was thinking that would add copper to the weld.

On Fri, 22 Apr 2011 20:04:51 -0700 (PDT), "
wrote:

On Apr 22, 10:51*pm, "Califbill" wrote:
*What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. *If I had a TIG outfit, might
be easier, but only a spool gun. *1/4" steel plate? *Stainless plate?

I like copper.

Me too.

Califbill wrote:

wrote in message
...

On Apr 22, 10:51 pm, "Califbill" wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get
the
grinder after I use the spool gun on the top. If I had a TIG outfit,
might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

I like copper.

Dan

Reply:
I thought about that, but since this is 50xx aluminum for corrosion
protection, I was thinking that would add copper to the weld.

I recall Ernie noting not to use copper to back aluminum for that
reason.

"Don Foreman" wrote in message
...
On Fri, 22 Apr 2011 20:04:51 -0700 (PDT), "
wrote:

On Apr 22, 10:51 pm, "Califbill" wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get
the
grinder after I use the spool gun on the top. If I had a TIG outfit,
might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

I like copper.

Me too.

me too for stick & MIG

On Fri, 22 Apr 2011 20:04:51 -0700 (PDT), "
wrote:

On Apr 22, 10:51*pm, "Califbill" wrote:
*What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. *If I had a TIG outfit, might
be easier, but only a spool gun. *1/4" steel plate? *Stainless plate?

I like copper.

Dan

Same here

Gunner

--
"If I say two plus two is four and a Democrat says two plus two is eight,
it's not a partial victory for me when we agree that two plus two is
six. " Jonah Goldberg (modified)

On 4/22/2011 23:04, wrote:
On Apr 22, 10:51 pm, wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. If I had a TIG outfit, might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

I like copper.

Dan


I like bacon. G


--
Steve Walker
(remove brain when replying)

"Pete C." wrote in message
ster.com...

Califbill wrote:

wrote in message
...

On Apr 22, 10:51 pm, "Califbill"
wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the
backside, where I can not get
the
grinder after I use the spool gun on the top.
If I had a TIG outfit,
might
be easier, but only a spool gun. 1/4" steel
plate? Stainless plate?

I like copper.

Dan

Reply:
I thought about that, but since this is 50xx
aluminum for corrosion
protection, I was thinking that would add
copper to the weld.

I recall Ernie noting not to use copper to back
aluminum for that
reason.

Right. Use stainless to back up aluminum. Ceramic
works too.
Steel and copper are a no-no......
phil k.

On 4/22/2011 7:51 PM, Califbill wrote:
I am doing some rebuild on my aluminum river jet boat. Going to weld
closed some old bolt holes in the gunnel and dash. What is a good
backing plate to prevent a big gob of aluminum slump on the backside,
where I can not get the grinder after I use the spool gun on the top. If
I had a TIG outfit, might be easier, but only a spool gun. 1/4" steel
plate? Stainless plate?

I have always been told stainless steel plate. Ernie on the welding
group would give you the best advice probably. Even though those are
relatively small welds you are going to on them for a while to fill the
holes, or going on and off them. One trick I have used to help control
heat is to put sopping wet rags behind my backing plate. You aluminum
still have to be cleaned and brushed and cleaned to be sure of getting a
good weld.

Steve Walker wrote:

I like bacon. G


Cannibal!!! ;-)


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

On Fri, 22 Apr 2011 19:51:24 -0700, "Califbill"
wrote:

I am doing some rebuild on my aluminum river jet boat. Going to weld closed
some old bolt holes in the gunnel and dash. What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. If I had a TIG outfit, might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?
Copper plate.

On Sat, 23 Apr 2011 12:00:48 -0700 (PDT), whit3rd
wrote:

On Friday, April 22, 2011 7:51:24 PM UTC-7, Califbill wrote:
I am doing some rebuild on my aluminum river jet boat. Going to weld closed
some old bolt holes in the gunnel and dash. What is a good backing plate

Copper contamination would be bad (it accelerates aluminum corrosion),
so I'd consider... ceramic. A brick, a coffee cup... something like that.
You don't melt the copper. All the aluminum welders I know use copper
backers when welding gaps in aluminum.

wrote:
On Fri, 22 Apr 2011 19:51:24 -0700, "Califbill"
wrote:

I am doing some rebuild on my aluminum river jet boat. Going to weld closed
some old bolt holes in the gunnel and dash. What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get the
grinder after I use the spool gun on the top. If I had a TIG outfit, might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?
Copper plate.


graphite or ceramic plate.

wrote in message
...
On Sat, 23 Apr 2011 12:00:48 -0700 (PDT),
whit3rd
wrote:

On Friday, April 22, 2011 7:51:24 PM UTC-7,
Califbill wrote:
I am doing some rebuild on my aluminum river
jet boat. Going to weld closed
some old bolt holes in the gunnel and dash.
What is a good backing plate

Copper contamination would be bad (it
accelerates aluminum corrosion),
so I'd consider... ceramic. A brick, a coffee
cup... something like that.

You don't melt the copper. All the aluminum
welders I know use copper
backers when welding gaps in aluminum.

Awl riight.... just dug out an old welding
reference book:

Welding Kaiser Aluminum second edition copyright
1978 page 19-3.

Carbon or stainless steel backup bars, contoured
to fit one surface
are recommended, especially in repair of thin
materials, or where
poor accessibility makes welding from both sides
impractical. Such
bars should have a groove of suitable dimensions
immediately under
the joint or opening to be welded.

And on the next page:

Copper is sometimes deposited in a weld bead from
a
copper backup bar where penetration is too great,
or from a
burnback from the contact tube in MIG welding. The
presence of copper may be deduced from the
presence of
cracking and may be confirmed by radiography.

So, for most work it may not matter much but for
work on marine
equipment this could be serious. I found this too
important to not
say anything about it. Be safe out there, eih?
phil k.