Large Scale Central

Hale & Norcross

Modeling Technical Modeling
#241

I’m toying with the thought of bagging all this, and 3D-printing the whole dang trestle. Would require maybe 20 or 30 sections, who knows, printed from a common parting plane of indeterminate location, upwards and downwards from that or those. Maybe bents can be printed vertically (as they stand), but would look much better built flat. So, another 40 sections. And probably with all the stringers as add-on bits of styrene or something.

Lots of benefits here, such as strength and flexibility of the PLA material, and easy replication of a section / part that gets stomped on. But lots of build time – which maybe doesn’t matter. Also, it violates a basic rule that I’ve learned the hard way: don’t 3D print what you can 2D cut.

Why do I say that? Because 3D printing is an ADDITIVE process where you spend lots of time seeing the tiny line of melted plastic laid down, and having to baby-sit the printer. Whereas 2D cutting is a SUBTRACTIVE process where you start with a piece of flat stock, and just cut it and glue it to something else.

Either way, I’m facing a fundamental design change in my present computer model. So that’s why I’m very glad we’re having this discussion before the computer model and patterns are done. And thanks everyone for helping me think this through.

===>Cliffy

[edit] When all is said and done, maybe a hybrid of 2DC backbone parts and 3DP details would have been best. Don’t know.

#242

Cliff Jennings said:

" Rooster " said:

Cliff Jennings said:

When I get to my train trestles, I’ll be using real wood, believe me. Just need to get this first mine done.

Re Read this twice as recommended by the experts and missed this post from the “OP” or original poster so I’m gonna go shallow and watch!

Just fantastic stuff Cliff and only trying to help along with others

Don’t go shallow Rooster, your engagement is vital here!!

But like Rick said, yeah, just pine.

[edit] Speaking of ‘shallow,’ you’ll appreciate this as a you are a history buff Rooster. For these waste trestles on the Comstock, and even some V&T trestles, yes, the tall pine bents would have been expensive to maintain. Their solution? Waste rock! So what started as a 40’ or 60’ high trestle became buried in its own waste rock, leaving only the stringers at the top. I could post many photo examples of this. On the V&T, also, there once was the “Belcher Trestle.” But with the filling in, it was no more. I have no photo evidence of that, but that’s what I’ve been told.

Making Fills with old trestles was very common…

A lot cheaper to maintain rock, than timber… bury the wood, it will help hold the shape.

John

#243

i don’t know about laser cutting. but if you are thinking about alternatives, i would recommend wood sticks over 3D prints.

long, fine printed pieces are not very strong. and wood looks more like wood.

#244

Hi John, roger that, and that’s a great pic!

Howdy Korm, I can’t argue with you. And if this were the only trestle & mine I need to make, I’d be more comfortable putting in the needed time. But thanks.

Still weighing options, and they’re getting more limited. McMaster answered my question re. outdoor use of (painted) ABS, and they said:

The ABS sheets we sell are smooth on both sides. However, these ABS sheets are not suitable for outdoor use because they have no added UV protection, and will degrade after prolonged exposure to UV rays. We do not have a paint or coating that we can recommend using on this material to address the UV exposure issue.

So I asked a plastics engineer ([email protected]), and he said:

For UV the best material would be Acrylic. Between ABS and styrene neither would last too long out in the elements. It helps that your going to primer and paint them, with that being said, maybe you should go with Acrylic… Most of my customers use acrylic or polycarbonate for models.

But I still say acrylic is more fragile. And Rick M. uses ABS, while Bruce C. uses styrene.

Like I said, still weighing options. Thanks all for putting up with this conundrum. At least I’m learning a lot about the negatives for each material.

Which is good. (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

===>Cliffy

[edit] Still keeping the real wood iron in the fire, as long as I can laser cut the pieces. The only source I’ve found is Green Valley Wood Products (link posted earlier), but I had to call them for the secret email address: [email protected]. So I emailed Dave with my questions, e.g., combining the shipping costs, other thickness availability, does he have redwood in addition to cedar, yada yada.

#245

if a lazy guy like me can do it, for you it would be nothing to make a wooden trestle.

a stapler, some nails, sticks and a minimalistic jig (seen in the first pic) and of you go!

http://www.largescalecentral.com/forums/topic/21015/a-trestle-bridge

#246

Yea jig and cutting all the parts to size/angle before hand, and the bents go together rather quick.

#247

I don’t think I’d worry about acrylic being too fragile. It’s not like all the squirrels are going to jump up and down on it on a regular basis. My styrene is pretty fragile as well, but it has held up with no problems. At least the acrylic will hold up!

#248

Good thoughts Bruce, thanks. And you can get colored acrylic (in 1/8" at least). I’m sort of settling on doing the bridge deck from acrylic, or at least its core, because that’s where the main complexity is.

I’m also coming back around to using cedar (from Northwest Precision) for the bents, as Korm & Dave are suggesting. That seems more straightforward, using 1 simple jig like you guys say.

#249

If you do end up using cedar for the bents, make sure to put a pad of some sort underneath so they don’t try to soak up water from the ground.

#250

Thanks Bruce, you bet. There will be some sort of cast concrete / plaster piers most likely, and am hoping to make the laser cutting help me with locating the forms.

I got some good news today that Northwest Precision can do 3/8" x 2" planks. Maybe wider, maybe other thicknesses. The email exchange hasn’t been exactly lighting fast, but I can work with 3/8 x 2". For example, here’s a bent with the main members cut from 3/8. This would be lasered from 3/8 “sheet”.

Adding the bracing, from 1/4 & 3/16 “sheet”.

I’ve simplified the bents to be of 4 heights, and here they are assembled into 3 distinct units.

The comes the superstructure, which is by far the most complicated element. I want something to tie all the bents together, and serve as the foundation of that superstructure. This shows a 2-ply 1/8" thick acrylic core, divided into the straight and curved main sections. I’d like the two-section deck to be removable from the “table leg” structures formed by the bents and bracing. But we’ll see.

The holes are for drainage.

Well, that’s today’s design approach, thanks all for viewing and putting up with all my back and forth.

===>Cliffy

#251

I hate to throw out yet another idea, but I’ve had VERY good service buying CEDAR from northwestprecisionlumber on Ebay. I suspect he will cut it to your own dimensions, but I have never even asked about redwood. The cedar I have purchased has held up very well, but I do put linseed oil on it…

Another thing to consider: I put horizontal stringers on my trestle when I built it…but I found out that the leaves could get in a LOT easier than my hand could to remove them. So, I ended up removing those stringers just so I could clean out the leaves. YMMV.

#252

Heh…and if you’re going to put a layer to tie the tops together, I’d probably have a bottom layer as well. Those bents are prone to move a LOT more that I’d like…

#253

Hi Bruce, thanks for your thoughts buddy. Roger that about NW Precision. As I mentioned at the start of my last post, today they said they can cut 3/8 x 2", but we’re still discussing widths and thicknesses. I’ve bought quite a bit from them, and am very impressed with their quality of cutting, and also their choice of wood: nice, tight, straight grain, perfect for our modeling needs. No redwood though, but I’m ok with cedar.

Good point about this being a leaf-catcher… ugh… If the sections (3 trestle, 2 deck) are strong enough by themselves, I’d like to be able to pick them up and shake out once or twice a year. But we’ll see how the joints work out.

Not sure about tying the bottoms together, being on different levels, but I hear your concern. I was toying with the idea of sockets in the piers (maybe acrylic) to help index the bents from below, but drainage (as you’ve mentioned) would be an issue. Unless there were slots in the socket walls perhaps.

#254

Cliff,

Don’t go the analysis/paralysis route. I just wanted to give you some of my experience, for what it’s worth - HEY - and not much at that. My cedar trestles are still doing just fine unless you look at them closely. I really don’t want to do any maintenance on anything yet my layout seems to have a different opinion.

I think my real problem is that I am fastidious when I’m building, but as soon as it’s done and outside I just let it slide.

#255

Cliff,
I wouldn’t worry too much about cedar rot. I built a cedar trestle and it sat in the ground for 6 years here in Seattle. After 6 years I tore the layout up and the trestle only showed minor rotting where the wood was in contact with the ground. If you put the trestle on a concrete pad that drains the water off you should be good for years.

Glad you found a source for cedar. Its so shocking to me to think that you would have to pay for shipping… An enterprising modeler could load up a truck with wood and head to the ECLSTS, sell the wood and load up with goodies for the drive back… :wink:

My local family hardware store has clear cedar for $1.35 a foot for 1x6…I wonder how much it would be to ship?

#256

I was wondering on wood buildings and trestles that contact the ground. If you painted the bottom and very lower edges with Plasti Dip or Flex Seal if that would seal them enough to prevent water damage where it contacts the earth. Maybe something to consider on your bents.

#257

Actually you and Rick stated that pine was the choice of lumber out that way for the bents. So if you want to be historically correct and don’t want to go the tree hugger route. You could cut your material from spruce (pine ) and soak it in old motor oil (kinda like the creosote affect). Should hold up quite well.

Loving the computer aided designs!

#258

Pine outdoors just doesn’t last no matter how much you “soak it”.

Any kind of impenetrable coating will keep water out but it will also keep water in! The water that soaks down through the wood from the top cannot escape and will rot the wood.

3/8 thickness seems a little thin for long lasting outdoor cross section no matter what the wood.

Seems like all the time spent designing, re-designing, dithering, questioning, and considering could have been spent finishing the tramways for half a dozen mine buildings(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-foot-in-mouth.gif)(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

Don’t take offense, just poking a little fun

Rick

PS.

Rooster, I agree. Old motor oil and diesel mixed 50/50 make a great preservative for wood, use it exclusively on raw wood structures, just not Pine(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-foot-in-mouth.gif).

#259

Spruce was the choice ,fir is the second …both from the pine family and when I stated pine I didn’t mean new growth stuff. I’m talking old growth stuff which is readily available.

Just a thought for Cliff

#260

Rick Marty said:

Don’t take offense, just poking a little fun

Rick

AGREED …Enjoying the hell out of all of this thread Mr. Marty. I’m young and still learning myself but sucking it all in!