Re: Evergreen--hat section? And more?

Dennis Storzek

--- In STMFC@..., "Aley, Jeff A" <Jeff.A.Aley@...> wrote:

And leave an acceptably thin flange? That's the part that I can't imagine. I can't even imagine extruding a shape (from liquid styrene) that has flanges that are 0.010" or thinner.

I hope Dennis can comment, since my imagination is severely limited. :)



From: STMFC@... [mailto:STMFC@...] On Behalf Of Tim O'Connor
Sent: Friday, June 15, 2012 9:33 AM
To: STMFC@...
Subject: Re: [STMFC] Re: Evergreen--hat section? And more?

Dennis, you know a lot about tooling and such. Would it be possible
to make a "die" (or whatever it's called) that you could pull a styrene
strip (like a 2x4 or whatever) and it would "shave" the strip into a
hat section?

Tim O'
Let me star with this premise... I don't think Evergreen strips and shapes are extruded, I think they are milled, the same basic technique as Northeastern milled shapes, although not on the same machinery. Just as background, years ago Evergreen used to have the booth adjacent to Accurail at the Rosemont show, and while I never meant the owner, I did have dinner with their salesman a couple times. One night over dinner and drinks (lotsa drinks) I was reverse engineering what I thought their "secret process" might be, and the guy said, "well, of course I can't disclose our process, but you're close." Of course, as always, the devil is in the details, and so I don't feel bad making my next statements, because just because someone knows how something is done, doesn't mean they can do it without countless hours of experimentation to work out the bugs.

Anyone familiar with a horizontal milling machine? Basically a lead-screw driven table that passes under an arbor (shaft) that is accurately spaced above the table, and adjustable for depth of cut. The easiest way to cut a sheet of material into accurate width strips is to gang up a whole bunch of cutters (in this case slotting saws) spaced apart by accurately sized spaces, and run a sheet fastened to the table through. If you look at the thicker Evergreen pieces under magnification, you will see that two opposite surfaces have the "pebble finish" of plain sheet, while the other two have faint diagonal lines, basically saw swirls, except the saw is large in relation to the thickness of the sheet, so you don't see much curvature in the marks.

If you don't run the cutters all the way through the thickness of the sheet, you wind up with a sheet with a series of grooves, such as the base sheet for Evergreen standing seam roof. If you substitute milling cutters ground to a point, you'll get V groove siding; Cutters with an angular surface the width of the boards yields clapboard siding. If you stack up a combination of properly sized cutters, saws, and spacers, you can turn a sheet into a bunch of angle strips, or channels. Do a preliminary operation on the other side of the sheet, and you can make H section. As an aside, this is the same way Special Shapes brass shapes are made. So you see, there is really no reason they can't make Z section except either no one has suggested it, or they don't think it will sell.

There may be some practical consideration as to why the don't do smaller shapes than .060", but I really suspect it's more the perception that smaller than that strips are visually the same. It would be nice if someone would convince them to add shapes cut from .040" sheet, and maybe even .030" sheet. .030" Z would be 4-3/4" in N scale, maybe acceptable. .020" would be 3-1/4", but flange thickness might be a problem.

The same reasoning goes to flange thickness... their finest seems to be .009", and may have been picked as much because standard cutters work out that way than for any other reason.

Keep in mind that any new changes from what they are doing now will likely require several grand in custom ground cutters, so I'm sure they don't take the consideration of new product lightly.

I always wanted to see them make .010" X .010", to add muntins to Grandt Line windows, but I wouldn't be able to see it now anyway :-(

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