Any ME's out there?

ManofMystery · Feb 2, 2004

Re: Any ME\'s out there?

The CAD drawing of your proposed trusses looks just like the ones in the workshop I am building. I purchased mine as a complete kit (less lumber) from Miracle Steel. They use angle iron for the chords, and solid rod for the web.

You might give them a call -- their stuff is inexpensive, well-engineered, and they can supply all the right hardware.

phantom309 · Feb 2, 2004

Re: Any ME\'s out there?

Hey ManOfMystery-

Question for you. What size is the angle iron for the chords and what are the dimensions of your trusses? How far will they be spaced apart? Do your trusses have a "double" chord with two members, or only one? Can you measure or do you know the thickness of the angle iron?

I know that the 1" tubing I'm using is pretty small, but I plan to stick on the safe side of things by spacing my trusses much closer together than is common with Perka and MiracleTruss which will space trusses up to twenty feet apart. That's really something that they'll support that much roof area. A thirty foot wide building with trusses twenty feet apart has each truss supporting (30x20) 600 sq feet of roof. At a conservative 20lbs per square foot, that's 12,000 lbs on each truss! Amazing.

I'm playing with some modeling software which will calculate the loads on trusses. I could easily change the members of my truss to whatever size angle iron you are using, adjust the loads for your spacing and run the numbers. This would allow me what kind of compression loads per sq inch they are running and I'll stay below that level.

If necessary, I'll put up six or eight trusses instead of the three that is common with the pro's.

Thanks for the help!

Mark

Egon · Feb 2, 2004

Re: Any ME\'s out there?

Roof design isn't about maximum truss spacing. All that means is more purlin.

There is a sorta economical meeting of the two which the Engineer has to find.

Egon

Villengineer · Feb 2, 2004

Re: Any ME\'s out there?

I'm not trying to be a stick in the mud, but you need to be really carefull with FEA and modeling programs. While the equations and programs are not beyond anyone who can do math or figure out software, they are limited to proper application and the info put into them. All it takes is one constraint or loading to be wrong and all the data you get is wrong. We check all our computer simulations against experience and even other calculation methods. There simply isn't a substitute for experience and training. I'm really don't want to be a killjoy, I just don't want you to put a whole lot of work and $ into this project only to have it turn out poorly, or even worse fail and hurt someone.

phantom309 · Feb 3, 2004

Re: Any ME\'s out there?

Hi Egon-

I'm don't understand.

No matter if I go with MiracleTruss, Perka or a home-brewed truss, I'll use the exact same girts and purlins - 2x6's 24'OC for the roof and 2x4's 16'OC for the walls.

I'd like to use wood for this purpose because the insulation and decking options are better, IMO.

Thanks.

Mark

phantom309 · Feb 3, 2004

Re: Any ME\'s out there?

Hey Villengineer-

You are right RE the FEA models. I understand that any incorrect assumptions and/or errors could drastically throw off the results.

I'd like to have more personal experience in this area, but, well, I'm working on it. I built a 1400sqft storage barn two years ago using lightweight trusses (of a different design) that were designed by an ME (Structural) in town.

That said, I'm not exactly blazing new trails here. I'd like to stray from the fewer/bigger truss design that Perka, etc use to have lighter, easier to handle trusses. The pro's of course want to use the minimal amount of materials and labor to build the trusses and erect a building. I don't necessarily share that goal. To me, building the trusses and putting them up by myself is great fun. I want to do as much of the work as possible by myself. But if I can't convince myself that the trusses I'm using will work out, it'd be an option to build them using the same materials, etc as the big guys. I'm keeping my options open for now.

Thanks for the advice! Keep it coming!

Mark

Villengineer · Feb 3, 2004

Re: Any ME\'s out there?

I would suggest discussing this with the structural guy who designed your other trusses. Since you've already used his services, he might be willing to help guide a little. He will definitely know the allowable stress levels for your area. I doubt that he will be willing to help on the design itself for free, but he might be willing to help you with the parameters. Another option would be to discuss him designing the trusses using your material and desired constraints. I would at least attempt to "bounce" it off him. He might be intrigued and help you quite a bit.

Egon · Feb 3, 2004

Re: Any ME\'s out there?

Mark:

Uh- egg on my face! Misread your dimensions and became a little concerned.

My appologies for wasting your time.

Egon

phantom309 · Feb 3, 2004

Re: Any ME\'s out there?

Villengineer-

I'm thinking about paying him a visit. He designed the trusses that I produced last time. His company makes lots of metal buildings using these same trusses. Left unsaid in my previous note was how I "consulted" with him then. I did so by taking a tape measure, a camera and a note pad to a couple of the buildings he built and closely examing them so that I could carbon copy his design.

Is this a bad thing? Since the building I made was for my own use and I'm not in competition with him, I have no problem with it. In fact, I assume that "reverse engineering" as such is commonly done even within competing companies and is just the way things go. You tell me, can you patent or somehow secure the rights to the design of a metal truss? Food for thought I guess...

But he's probably the area expert in these lightweight trusses. If he'd take the time to sit down with me to talk trusses, I'd be happy to pay for his time.

Thanks again.

BTW: Egon - no problem!

Villengineer · Feb 3, 2004

Re: Any ME\'s out there?

You are correct in that reverse engineering is a very common occurance. Many companies purchase competitors models and disassemble them to see how they accomplished various tasks. The problem is that unless your application is identical to the one you are using for reference you can't just copy and apply. That's why companies use engineers to do this and not just guys who can measure and record. Additionally, most companies don't want to simply offer the same, they usually want to improve on the design to gain an edge.
To answer your question on patents, I doubt that most companies would attempt to pursue patents on most trusses unless it was radically different than anything that's been done before. Very few trusses fall into that catagory and patents are $, time consuming, and usually delay the release of the product. I would imagine that only a few truss companies have the resources to attempt this process as often you devote the resources only to find out that it's not patentable.