Seemingly basic drafting question

Before I became a welder/fabricator/draftsman and whatever else I do these days, I was a network admin (WinNT, Win2K) and a programmer (VB apps and DTS web components). When I was doing programming, I'd joke with my colleagues, "if it'll compile, it'll ship". Sounds like the same mentality about the trusses...if they'll stick together, they're good enough to go.

 

I think must be an interstate operation there...my house in Texas built in the 70's has a roof like that.

 

--HC

Hah, interstate indeed. It's just the nature of the beast. That same company also built prefab wall panels for the houses. Once you get all the lumber out to the field and get it ready to nail together, you may as well buy a tape measure with no units smaller than 1/4" on it. They just don't matter.

you may as well buy a tape measure with no units smaller than 1/4" on it. They just don't matter.

As I've said before, most of my drafting work is with commercial buildings. The concrete guys that do that stuff seem to think that if they pour the concrete in the right town, they got it right. I don't know how many times (well, yes I do...nearly every time) I've had a big rush job to get the curtainwall shop drawings done so they can fab the material, only to get an even rushy-er job a few weeks later for revisions to all that because they missed the openings. Not by some fraction of an inch, but by a foot, or two. Metal all has to be refabbed, glass gets scrapped and re-ordered because you can't cut insulated glass down if its wrong. Toss it in the recycle bin and start again.

One of the last chicken houses we worked on before he retired started out great, but as we stood the trusses and bolted them together, the farther we went down the house, the harder it got to assemble them. Ran a tape on all the trusses, they were with in +/- a couple inches. Couldn't figure it out for a bit till I said something about checking the footing. Found it...it was 50 feet wide at one end and 40 feet wide at the other. OOPS....we had to go work on another one while they jackhammered out one side and started over. What we had up already, we left, so they only hammered out the rest of that side.

Hey, Tankman, thanks for the reply. However, I can spell LISP if I look it up...I've never written code in LISP and never written any routines for AutoCAD. I wouldn't know where to start at this point.

 

--HC

I can't remember (), believe I downloaded this neat LISP routine right here at CadTutor.net.

dline.zip

I can't remember (), believe I downloaded this neat LISP routine right here at CadTutor.net.

Hey, Tankman, thank you for the link. I couldn't write that routine in a month of Sundays. I've been playing with it a bit but I need to read the file more (the comments) to undertand how to use it. But..just playing with it...that's pretty cool.

Thanks again.

--HC

--HC[ATTACH]31363[/ATTACH][ATTACH]31363[/ATTACH]

The extension of attached file shows dwg. I downloaded the file and extension says php?!?. What is wrong?

Same is true for the file ReMark uploaded.

Please ignore this post. a 2nd attempt solved the problem

From the FILExt website:

PHP

These are text files used on a server to generate HTML files sent to a browsing user.

Drawing1.dwg[ATTACH=CONFIG]31433[/ATTACH]

Hey, all, this may be stupid-simple but I cannot figure it out (I'm a builder, not a draftsman...so far). If I need to post this somewhere else, please let me know.

 

Attached is a file. I'm trying to draw a truss I'm going to build a number of. I want to throw in a diagonal brace between a couple of uprights on each side. I want the brace piece to have square ends, not diagonal cuts. I want the brace piece to fit into the space between two parallel vertical pieces and the horizontal and diagonal piece with, hopefully, all four corners of the rectangular brace piece touching the bounding pieces (I'm not sure this is possible). I'm not sure how to go about drawing the brace piece (shown in magenta in the file on the PurlinSupports layer). I've tried a number attempts but modifying the position/angle at one end mucks up the other end. If this is possible to draw it right in one try (without a bunch of hack work) then it's probably something sexy/simple (like bisecting a line with a compass) but I haven't figured it out. My hacking attempts are on the left in the drawing, my depiction of what I'm looking for as a final product are on the right in the drawing.

 

I'd love some help. Thank you.

 

--HC[ATTACH]31363[/ATTACH][ATTACH]31363[/ATTACH]

I tried to draw the requested diagonal member. Result is as follows:

As mentioned in one of prvious replies, centerlines of members should meet in one point (yellow lines in attached file). The reason returns to theory of modelling/analysing trusses where it is assumed that members doesn't bear moment and only present force is axial force.

So it is obvious that firstly the centerlines should be drawn. Then I offset the diagonal centerline to reach the thickness of other members (drawing is not precise. horizontal member is 102.13 and vetical one is 103.76). Then I connected the intersection point of diagonal lines with vertical and horizontal lines and trim rest. the lower end seams to be 90 degree and is acceptable but the upper end mmesses up.

Looking from geometric point of view, I don't think it is possible to find a diagonal member with square ends and passes through centerline. Then I think it will be a matter of try and error.

Solution for the problem

You don't need to have the exact length of diagonal to fit. Gusset plate can help to slove the problem. You can leave a tollerance in the diagonal member (brown color) and fill the gap with gusset plate.