Ed, that will be some impressive modelling!
Dave
Okay,
So I finally got my old and tired behind in gear. This morning I got up and made a cad drawing of the truss. I exported it as a .dxf file to a flash drive. I then took it in to work and loaded into the computer at the laser. I can work on projects at work, but I have to pay then for the steel usage. I cut it out of 12ga (.104") steel. All in all it took me less than 45 minutes for all processes combined and it cost me $3.06. I thought it came out pretty good.
As you will see in the photos I have attached below, the actual trusses are not flat, as my piece of steel in my last post above is. Each truss will consist of two of those pieces with diagonal cross braces on each side. I will just tack weld it all together with my tig welder. Not sure if this makes sense. I’m currently working on a jig to help that process go much faster.
Ed,
It’s great that you have an employer who allows you to use their equipment in this way.
I noticed that the trusses were actually double trusses with webbing in between and I was wondering how you were going to address that. Sounds like you have the answer!
Like any good steel worker, I’m riveted to this thread!![swg][(-D][(-D][(-D][:o)] Sorry, couldn’t resist.
Dave
Hi Dave,
As you suggested in an earlier post, I had to “beef” up the trusses a little in order for the laser to cut them well. They still look good
Ed
I agree! They look good, and given the overall incredible impression that the structure will make, nobody will notice how thick the beams are.
Dave
Yeah, I noticed that as well which is why I asked the OP just how nit-picky he was about details on this project. There are also trussed purlins between the bays and other fiddly bits as well. Not sure if I’m glad or amused how he’s gonna proceed . . . so we’ll just go with impressed for now. [bow]
I got interested in this thread when the OP asked how I’d fabricate these things. So, I pondered the idea and then did a little experimenting and cut out a couple and then pondered some more. I kinda gravitated to the idea of single trusses with members and chords and struts and whatnot with a cross-sectional area of 0.08" by 0.08". The idea was to capture the essence of the lightweight and lacey structure but still have it hold together while I constructed it with my crude equipment.
Cutting out the truss as a single piece would require a machine with larger capacity than I have. But even if I could fabricate such a piece, I don’t think I would. There’d be a lot of dead space and wasted material under the arch. Here’s a sketch:
My solution would be to design the pieces and parts so that they’d be easy to handle and assemble and make efficient use of the sheet goods.
[quote user=“ROBERT PETRICK”]
hon30critter
I noticed that the trusses were actually double trusses with webbing in between and I was wondering how you were going to address that. Sounds like you have the answer!
Yeah, I noticed that as well which is why I asked the OP just how nit-picky he was about details on this project. There are also trussed purlins between the bays and other fiddly bits as well. Not sure if I’m glad or amused how he’s gonna proceed . . . so we’ll just go with impressed for now.
I got interested in this thread when the OP asked how I’d fabricate these things. So, I pondered the idea and then did a little experimenting and cut out a couple and then pondered some more. I kinda gravitated to the idea of single trusses with members and chords and struts and whatnot with a cross-sectional area of 0.08" by 0.08". The idea was to capture the essence of the lightweight and lacey structure but still have it hold together while I constructed it with my crude equipment.
Cutting out the truss as a single piece would require a machine with larger capacity than I have. But even if I could fabricate such a piece, I don’t think I would. There’d be a lot of dead space and wasted material under the arch. Here’s a sketch:
Hey Ed-
I’ve only researched the past few days. Hard finding stuff in this Grand Central Station, but tons of stuff on that other one.
What era do you model? I’m asking to see if you’re gonna deface that elegant grandfather clock tower with B&O.
Robert
Yeah, sorry. It will be the 1950’s era. So I think it will have the B&O logo as well as the B&O billboard on the building roof. I have to make sure those were there then.
This is the main thing I struggled with. I went with .100" members with .104" thick material. I’m not totally happy with the looks, but it’s very solid. I might try to bring it down to .080" using .075" material.
Ed
No need for you to apologize for anything, but I’m a little embarrassed I didn’t notice the tag line in your signature. [:$]
Robert
Yeah. Just like the prototype trusses are extremely strong in only one axis, they are vulnerable to secondary stresses in the other axes. But once assembled and the last member is in place, the forces align and cancel each other out and the structure stands as a unified whole.
I model in styrene (well, actually, usually, ABS) and delicate spidery pieces and parts do come together and the assembled structure is remarkably sturdy and dimensionally stable.
I’d try to cut the steel as thin as possible, especially if you’re gonna assemble double trusses into a 3D space frame. But please don’t be too overly influenced by my ideas. You gotta go with what you got.
Good luck.
Robert
I’m just about finished with an experiment to determine how this structure might be built. The goal is to see how delicate and airy the framing trusses can be made and how stable and sturdy the finished shed can be.
I cut out the pieces and parts needed to form the structural skeleton of one complete bay . . . two double truss arches and four purlins connecting the composite arch ribs. Everything was cut from a sheet of 0.080" styrene, and the truss webs, struts, and chords have a nominal dimension of 0.080" by 0.080".
Then assembled the parts into the skeleton frame. The spacing of the arch ribs is 5.42" center-to-center based on drawings posted earlier by the OP.
I am amazed at both your works. Even more amazed that Robert is co-modeling.
That’s really cool Robert!
Dave
Robert,
Awesome work my friend!
I’m glad you are participating in this. I chose this railroad to model because of the fact I went to college just a few blocks where this station sat, the train station with clock tower, the bascule bridges, but most of all… the train shed! It was important to me that whatever railroad I modeled has a large train shed.
Unfortunately I’m tied up working on some stuff for work today and need to spend some time with the family, but I will get back on this soon. Thank you for the inspiration. I’m hoping you continue to model this. It seems to intrigue you and you certainly have the talent.
Ed
Following up from yesterday . . .
I did not have any 0.030" sheet styrene on hand like I thought, so I used 0.010" sheet instead. Being thinner, It pretty much shows the lumps and bumps of the skeleton frame and is a lot more flexible and kinda looks like a tent, but for purposes of this experiment it will be okay. The 0.030" sheet would give a smoother appearance and provide more rigidity to the structure.
Also notice that the eaves of the roof are about 1/4" short on each side. Apparently, the overall length of the curved arches is a bit more than I estimated. Dang. I suppose I could’ve measured [8-|] . . . but these are just the kind of things you discover by going through a pre-build mockup like this.
Here’s a photo of the load test. Success.
Here endeth the experiment.
Robert
Very impressive and very nicely-done! [bow]
Wayne