Striegel: Scotty Howell is the Vice-President and General Manager of Robinson Iron and guides
the day to day operation of the firm and the assessment of conditions to the removal, engineering,
and installation of restored materials.
Scotty launched Robinson Iron in 1975 as a spinoff of the Robinson Foundry Inc.
A graduate in engineering from Georgia Institute of Technology, Scotty holds a Masters in Business
Administration from the University of Chicago and is part owner of Robinson Iron.
He learned the foundryman's craft from the bottom up so that he could be familiar with
the requirements of each demanding job.
Over the past thirty-three years, his resume of distinguished projects has included such
iconic landmarks as the Raffles Hotel in Singapore, the White House in Washington D.C., Vulcan,
and Birmingham, Alabama and others too numerous to mention.
Scotty.
Howell: Good morning.
It's a pleasure to be here with you today.
So first things first.
I would like to introduce (walked away from mike, unintelligible).
How do I advance it?
Okay.
Need you back.
So I'd like to talk to you about pattern making.
For most all foundrymen, the pattern is the beginning of the process and everyone pretty
much knows that the casting that you make can never be better than the pattern you use
to make it with.
Something is always lost in the process.
So the pattern making part is crucial to pattern makers.
This goes way back to the late nineteenth century and you can see from this woodcut
from Badger's Foundry, the molding going on in the lower portion of the foundry operation.
So the process has not really changed much in terms of the sand molding process.
This is an early image taken from the Robinson Foundry floor in 1975, and the gentleman on
the far left in the pork pie hat, his name is Mr. Aubrey Brown, was my pattern maker.
Mr. Aubrey carved most of his patterns with a pocket knife.
He was an amazing man but he was seventy years old at this point and time and there was no
one behind him to take up the craft.
So I knew I was going to be in trouble pretty quickly unless I did something to preserve
the patternmaking craft.
So what I did was I managed to apprentice some people to Mr. Aubrey and those people
learned the patternmaking craft starting off with just wood and so forth.
Now how do you begin the patternmaking process?
Well in many cases you'll start with a drawing or sketch.
That drawing or sketch then would be carved into wood, like these very old wood patterns
in our storage.
I see that we don't really do a good job of our housekeeping but these are original wood
patterns from the nineteenth century.
How do you do that?
Well, originally we just carved them by hand.
We used hand chisels and white pine, sometimes mahogany.
We made our patterns by hand carving.
This is an image of some nineteenth century wood patterns also carved by hand on the wall
in my office.
Later, foundries began to make patterns out of metal because the wood didn't last very
long, it got burned up in the process.
So they began making metal patterns like these.
These are loose metal patterns, again, quite old.
Many of these date to the 1860's and 1870's.
Later, they developed metal patterns that would be mounted to boards like this.
These were called match plates.
It was about in the late eighties, early nineties that we began to introduce plastics into the
world of pattern making and we used hard plastics, urethane based, to create our patterns.
We found this to be very efficient to make urethane based patterns like this collar here
without loss of detail, and also the urethane patterns were less expensive than the metal
patterns.
It's used by the creation of a mold and then you pour the positive, which a pattern is
always a positive, the mold is the negative, and we used, again we'd mount plastics to
wood boards like these.
Just for a very brief moment, I'd like to talk about the parting line which is a very
crucial part of a pattern.
There are a couple of things that are very important about patternmaking.
One is the parting line is the point at which the pattern is separated, the halves of the
molds are separated.
It has to be clean.
You can see how the parting line is established here on this particular type of pattern.
Also, the shrinkage factor is very important because iron shrinks.
All metal shrinks as they are poured into a mold.
This is a shot of a typical, what is called green sand mold, and I don't know why they
call it green sand because it's definitely black and it gets its black color because
it's recycled in the foundry over and over and the sand is burned but that's the two
halves of the mold.
The upper half is called a cope and the lower half is called a drag.
Now of course, molten iron would be poured into the void created by the pattern.
The pattern is compressed in sand, the two halves of the mold is separated, the pattern
is removed leaving a hollow cavity in which the molten metal is poured.
You can see the parting line is again a very important part of the casting work and it
creates what we call plus metal which has to be ground away.
As I mentioned, the shrinkage is important and the foundrymen
patternmakers tend to use a lot of instruments such as oversized rulers so that they make
their patterns bigger than they need to be.
Iron shrinks 1/8 of an inch per linear foot.
Other metals shrink at different rates so the pattern has to be bigger.
And then of course, there are lots of quality considerations.
The development of the pattern is very important because again, the casting that you make can
never be better than the pattern used to create it with.
Also, if the pattern and the gating is not setup properly, you can have casting flaws.
There are lots of ways to go wrong in a foundry, this happens to be a crack in the casting,
created by stress in the mold.
So what we really want is a nice clean detailed casting and again, the pattern is crucial
to that.
We have a lot of coordination issues.
The sizes of the pattern with the creation of the flask in this case, is a wood box,
which you would use in airset type sand.
This is an ancient flask and yes, that is kudzu.
We have that in Alabama.
Again, an old style steel flask with trunnions, it's just a very large one with a large cope
and large drag.
The gating is very important.
This is the way the metal flows into the casting.
In this case, you have a very large (unintelligible) even that little finial there.
The riser acts as a way for the metal to shrink as it flows into the casting so that there
would be no voids created inside the casting.
Again, a gating system here shown so that you have the down screw and then the feeder
is going into the hollow cavity created by the pattern, small rosettes.
This is a multiple type pattern where six rosettes would be made per mold.
Again, a down screw, feeder, the little gates or runners feeding to the larger rosettes.
So this is kind of a speedy way of getting me into the topic at hand and that is the
use of laser scanning for pattern making and this, we think, is our next step.
We do have a scanner.
The scanner that we use is small enough to go in an overhead bin on an airplane, so it
travels very well.
We can scan objects, we're scanning the same leaf today just as you've seen it and create
a model and the great thing about the model making is that with the press of a button,
we can account for shrinkage.
So, that's no longer a big concern to us.
We can also take the scanner, we can go to sensitive properties, let's say it's the US
Treasury Building in Washington, where they don't want messy molds being prepared on site
and they don't want to give up their iron work.
To be replicated, we can scan it on site, bring the model back to Alabama and then we
can create the patterns.
Once we have the model scanned, we can manipulate it using a program called Creaform and once
we have the model exactly like we want it, the right size, we can then convert it to
Mastercam and then use the Mastercam models to actually cut them using a three dimensional
router.
We have a Haus 3-D router, five foot by ten foot table, that we cut in this case, into
a material that we call [ ? ] which is tooling board.
Once we cut this individual shape like this in the router, we can then take that, prepare
a mold and then develop the pattern.
This is the router cutting a pair of patterns.
This is a fluted shaft . I think you'll see in a moment something happening with this
particular pattern.
This was cut in the [ ? ]. Since this is a deep fluted shaft, we would create the side
flutes using a side core, what we call a wing core on the outside of the pattern.
That's our core box that creates the deep fluting on the outside of this particular
lamppost.
We're getting pretty close to taking this to the foundry to be poured.
There we have a complete casting.
This happens to be in aluminum.
It's for a courthouse in Houston, Texas called Harris County.
There we have the completed lamppost and it would have a round globe on top of it in cast
aluminum, all made with routed patterns.
How much does all that cost?
Well, since we own our own equipment and the materials themselves are not that expensive,
it's not as expensive as say sending patternmakers to a jobsite and pulling molds and that sort
of thing.
So actually, we see it as a cost savings for us and also it is a much more cost efficient
process, meaning I have the scanning and 3-D routing turning out patterns faster than a
crew of men can get set up and taken to a foundry, so in terms of the way it's affected
us, it has been a very positive thing.
So that's my talk for today.
I'll be around all morning and so will Jane and if you would like to see more of the equipment,
we'd be glad to show you.