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kilns, melting aluminum and heating granite!?!?

updated fri 14 nov 08

 

cec on tue 11 nov 08


I had a friend come to me with an aluminum router plate that was torqued slightly. After checking the price of a new plate he has come to me with a plan.
He would like me to heat the plate to 900 to 1000 degrees F with wieght on it. The wieght he has provided is two grantite slabs.

There are many of you that have chemistry and metal knowledge that might be able to advise me before I try this.

My friend has stated that the plate is a loss anyway so he is willing to try with no guarantee.

Thanks!
Celia in Virginia

pdp1@EARTHLINK.NET on tue 11 nov 08


Hi Celia,



He could straighten it at room temperature.


If it bent 'cold' to begin with...it can be straightened 'cold'.


Trying to straighten it with heat and static weight in a Kiln, would not be
a good idea...for several reasons.


Heating with a Torch as one applies force to straighten, might be alright,
sine one could then see and feel how things are going.


By 'Router plate'...do you mean the edge of the 'base' of a Woodworking
Router? Or...?


Usually Router plates ( which attach under the Base,) are Lexan or Micarta
or Masonite...




Phil
l v


----- Original Message -----
From: "cec"

>I had a friend come to me with an aluminum router plate that was torqued
>slightly. After checking the price of a new plate he has come to me with a
>plan.
> He would like me to heat the plate to 900 to 1000 degrees F with wieght on
> it. The wieght he has provided is two grantite slabs.
>
> There are many of you that have chemistry and metal knowledge that might
> be able to advise me before I try this.
>
> My friend has stated that the plate is a loss anyway so he is willing to
> try with no guarantee.
>
> Thanks!
> Celia in Virginia

pdp1@EARTHLINK.NET on wed 12 nov 08


Hi Larry,



Good point...


Though if a Casting, it'd of course depend on the particular Aluminum Alloy
as for it's
malleability-resilience...and definitely, some are
brittle-ish...frangible...they'll bend 'once' but crack when straightened.


I did a fast 'google' to see what these sorts of Routers were
about...none appear to employ any Castings or Forgings...unless
injection-moulded Plastics count.


Those having metal bases-platens, looks like the bases/platens are made of
fairly hefty
sheet-Aluminum Alloy, or as Celia'd mentioned somewhere, looks like 'CNC'
stuff....machined from thickish sheet.


Kind of interesting...


I've been to places where this sort of work is done - ie: cutting, moulding
edges, polishing - of Stone thin-slab things for Bathrooms and Kitchens, but
none of the times I'd visited such places was anyone working, for me to see
the Tools, other than the large stationary Wet Saws standing idle.




Funny 'straightening' story - some years ago I won a little e-bay Auction,
for an early,
large, 'Rockwell' Industrial Router for Wood Working... 1960s era.


Anyway, I dunno, 2 horse? A very large one anyway...the 'Fire Plug' sort...


It arrives, I spin the Collet-end with my fingers, Bearings feel mellow and
nice...plug it in...hit the switch, and it would have outdone most Paint
Shakers or old time Weight-Reducing-Machines.


Yeeeeeeeesh! Oh was that nasty...horrid!

I could hardly dare let one hand off of it to turn it off..!


Anyway...shaft was bent, just under the collet...just outboard of the
Bearing...not much, but 'enough'...

Probably someone had dropped it with a Bit in it.

Grabbed a Dial Gauge...decided and marked the apogee of the
eccentricity...gave
it good whack with a large Hammer, on the flat of the screwed-down Collet
nut, but with a heavy Brass drift mediating...checked it with the Dial
Gauge again...did one more little 'tap' and it read-out nice...plugged it
in...hit the switch...'Smooth as Silk'...


Probably that little-bit-o' work-hardening will not occasion any sudden
catastrophic failures under-load...or, time'll tell anyway...


Lol...




Phil
l v




----- Original Message -----
From: "larry"

> Possibly the base is not from machined aluminum but from cast metal,
> machined metal is much stronger and able to handle some manipulation but
> pounding on cast aluminum will result in many pieces of metal. I'd buy a
> new one. Larry

pdp1@EARTHLINK.NET on wed 12 nov 08


Hi Celia,




Ohhhhhh...


Well still, I'd straighten it cold...maybe on an Anvil or other
support-platen...or over bags of Shot, with a mediating Wood Block, if dings
were to be avoided...or in a large Vice...and or depending on the bend.


I don't think heating between Granite slab-pieces would work well...even in
heavy reduction where dangers of oxide-decompositions to the alloy would be
lessened.


Heating the Granite would be very iffy, to avoid having it explode, and the
thermoplastic 'window' of an Aluminum alloy would probably be quite narrow,
possibly past where you'd planned to take it anyway.


Usually there is 'Spring Back' also, for anything 'bent', so efforts to
straighten between flat-pressing surfaces would not achieve a 'flat'
result...which is to say, a bent platen of an alloy having any springyness
at all, would have to be over-bent in proper reverse of it's injury, at
least very slightly, to straighten...to end up straight-flat.



Phil
l v




----- Original Message -----
From: "cec"


> Phil- This is a router plate for a stone router, it looks like a aluminum
> cnc die to me. about 14" x 16". Airplane grade aluminum made in italy.
> One of his employees dropped it and he is one PO'd boss right now.
> Thanks for the help.
>
> cleia

larry on wed 12 nov 08


Possibly the base is not from machined aluminum but from cast metal,
machined metal is much stronger and able to handle some manipulation but
pounding on cast aluminum will result in many pieces of metal. I'd buy a
new one. Larry

----------------------------------------
From: pdp1@EARTHLINK.NET
Sent: Wednesday, November 12, 2008 10:32 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: kilns, melting aluminum and heating granite!?!?

Hi Celia,

Ohhhhhh...

Well still, I'd straighten it cold...maybe on an Anvil or other
support-platen...or over bags of Shot, with a mediating Wood Block, if
dings
were to be avoided...or in a large Vice...and or depending on the bend.

I don't think heating between Granite slab-pieces would work well...even
in
heavy reduction where dangers of oxide-decompositions to the alloy would
be
lessened.

Heating the Granite would be very iffy, to avoid having it explode, and
the
thermoplastic 'window' of an Aluminum alloy would probably be quite
narrow,
possibly past where you'd planned to take it anyway.

Usually there is 'Spring Back' also, for anything 'bent', so efforts to
straighten between flat-pressing surfaces would not achieve a 'flat'
result...which is to say, a bent platen of an alloy having any springyness
at all, would have to be over-bent in proper reverse of it's injury, at
least very slightly, to straighten...to end up straight-flat.

Phil
l v

----- Original Message -----
From: "cec"

> Phil- This is a router plate for a stone router, it looks like a
aluminum
> cnc die to me. about 14" x 16". Airplane grade aluminum made in italy.
> One of his employees dropped it and he is one PO'd boss right now.
> Thanks for the help.
>
> cleia