[TheForge] Welding Platen Question

[Peter Fels And Phoebe Palmer]

Dave:
Might it be that a weldment  welded when clamped to that table  would 
come out flat when unclamped, given the  taper of the weld champher 
tending to contract at the wider top side  on cooling?...........Pete F

David E. Smucker wrote:

> I just recently bought a used welding platen.  I have no idea how old 
> it is or it's history.  It is 48" by 60" inches with 1-1/2 square 
> holes.  I was told it at one time was used in a gulf coast ship yard.  
> Best I can tell it has never be reground.
>
> What is strange to me is that it has a uniform crown of about .060 
> inches in both directions.  This is based on a somewhat quick check 
> with a good (not perfect) 5 foot straight edge.  (And yes I turned the 
> straight edge over and checked using both sides.)
>
> I would not be surprised in a old welding platen to find dips or other 
> "non flat" areas but am surprised to find a quite uniform crown.  It 
> would seem that it was machined in at time of original manufacture.
>
> Any one ever hear of this?
>
> I have seen crown put into items that are going to be under very heavy 
> load so that the will be "flat" when loaded but not in a welding 
> platen that is 3 inches thick over most of the surface and 6 inches at 
> the edges and a center support rib.
>
> I can improve a lot on this by hand grinding and checking and hand 
> grinding and checking etc.  I am too far back in the woods and too 
> cheap to send it somewhere to be blancher ground -- weight without the 
> stand is about 2100 pounds.
>
> Dave Smucker _______________________________________________
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