Haven't bought heavy steel lately, can't help you on prices. But you may
need to rethink what you plan to buy:

When you weld, you warp. You can mitigate that in various ways but not
stop it. So any cold rolled plate would have to be bolted on to your
base frame. A good way to do get accuracy on a one off machine is to
build your frame, weld on 2" square blocks with the mounting holes
drilled in the center. You can use a hand grinder to get all these pads
EXACTLY the same height, then bolt the top plate on.

Beware that cold rolled has a hardened and stressed skin. If you machine
that surface off the opposite side will pull and put a nice bow in the
plate. For dimensional stability, you want hot rolled.

Bernard Arnest wrote:
Hi,

I'm going ahead with building a rose engine. I won't be the last,
and I think I'm prepared now. I'll be working full time for the next
week or two, and pay a visit to someone who built one himself, to
develop my own plans.

A friend recommended a rather large local supplier,
centralsteelsupply.com. I'm interested in buying 1/2 to 1 ton of
steel, mostly plate steel of varying thickness from 1/2" to small
amounts of 2" thick. I'm going to work full time over the next couple
weeks to get specifics. I haven't yet gone to them for a quote.

I was just wondering before I do so, what should I expect,
price-wise? Another classmate told me that in a mechE class they
predicted $.30/lb in various scenario problems. Granted, I'm buying
less than a ton and I'll need steel plate of greater dimensional
accuracy than I-beams, which is going to be more expensive. $.60/lb?
$1.00/ lb? It makes a difference to me; I'm rebuilding a machine
typically built to weigh 1000+ lbs. The stand should merely be stiff
and heavy and can be of innaccurate, rusted stuff welded up, but from
the base up things will need to be smooth, flat, and of reliable
dimensions to get the tolerances I want. If cold-rolled plate steel
can be had for under $.60/lb in quantities of half a ton or more from a
bulk supplier like that, I'll go wild and overbuild it with 1" plate
everywhere :-) If more like $1.00 a pound, as I design it next week,
I'll need to exercise more discretion and ask myself "do I really need
3/4" plate there, or will 1/2" be stiff enough for the final precision
I want?"

Secondly, they offer cutting service, both by bandsaw and by flame
cutter. It took me 30 minutes to cut through 2' of 1" thick plate. I
value my time at $9/hr, and as a student, equipment maintenance is not
a factor. What might I expect for both bandsaw and flame cutting
service? Would a cut like that cost me over $4.50, or maybe I could
get it done for $1?
And, with flame-cutting, is it easy to grind enough of the scale off
the surface to then machine with a mill? Whether flame cut or
bandsawn, I will almost always need to mill to more precise specs. I'm
guessing a flame cutter is much, much faster, and thus cheaper, than a
bandsaw to operate? Should I assume that I'll get everything flame
cut, and then grind off the scale and mill from there; and factor in
appropriate tolerances when I design how to cut things out? Or,
because a bandsaw has an autofeed but is not CNC, will that cost as
little or less than flame cutting services?
Will flame cutting warp the plate at all, causing it to no longer be
flat and no longer slide properly as a part of a slide rest, toolchuck,
or workpiece vise, etc.?


thanks for the advice!
-Bernard Arnest