[Farmers Machine]

If you draw a tube 6" square and 10 feet long with 1/4" wall and then use the tube to build a frame in an assembly, how do you trim the length to make a frame 8 feet by 9 feet and 6 inches, with out having to draw each part exactly perfect?
Thank You
The Farmer:tired:

[Caprirs]

As far as I know, the trimming would be done using the assembly boolean tool which can "add" solids together or "subtract" them from each other. So you would create your assembly allowing the 10' sticks to interfere, then choose the assembly boolean tool and cut/subtract. The catch is that the piece that gets "cut" or trimmed loses its design/feature tree. In other words, it becomes a dumb blob that cannot be edited.

For example, suppose the tubes had holes spaced evenly along their length. Those holes would not be editable anymore once the stick was boolean'ed.

[TomB]

I tried several ways to trim parts in an assembly and none worked acceptably. At the time I was thinking in terms of buildings and wanted to start with 2x4s, 2x6s and 2x8s plus I-beams then just cut them to the sizes I needed and place them, i.e. building the model like I would build the building. All the boolean things seemed to take a lot more clicks than the effort warrented.

What I found worked was to define planes, actually thin sheets, at all the surfaces that are boundaries. Then I defined catalog features that represented the cross sections. With that I could insert and place the catalog features in a part or assembly model and use the extrude to plane or feature to set the length. The only problem that I hit that was mostly insurmountable was the fact that Alibre does not support extruding to limits in two directions like what is needed to specify a rafter. (I could define a plane that was normal to the roof, import the feature onto the plane then extrude to the ridge beam. But then I could not extrrude the other end to the drip end. I ended up inporting two copies of the cross section then extruding both. It ends up looking about correct but there is a seam in the rafter and dimensioning in the part drawings gets messed up. When I got all the parts put in I hid the working planes and it looked like a framed house.

I asked about it on the Alibre forum pages but did not get any answers.

Tom

[MichaelHenry]

I've designed a few frames in Unistrut with Alibre and usually create all of the lengths of channel that I need as separate parts and then create an assembly of the fabricated frame from those parts. I'd think a similar approach would work for either Farmer or TomB.

Are you guys trying to design one 2x6 (or whatever) and then use it over and over again by making copies of the one 2x6 and then cutting it to size in the assembly?

Mike

[TomB]

I've designed a few frames in Unistrut with Alibre and usually create all of the lengths of channel that I need as separate parts ...

Are you guys trying to design one 2x6 (or whatever) ....
Mike

Thanks for commenting. Actually I have tried to model many different frames over the years, sheds with hip roofs, an A-frame house with dormers, ski lift terminal frames, and machine tool frames. Material has been lumber yard wood sizes and structural steel forms (angle, tube, pipe and channel). (I described the wood frame building in the example because it offered a standard set of terms, rafter, drip edge, hip rafter and 2x6 that most readers could relate to and the framing problem is really common between all cases.)

I’ve never had much luck with the idea of making drawings for every element as the end cuts are normally not simple. Because I was not satisfied with trying to calculate all the lengths and Alibre has really effective extrude capability I settled on that approach. It works ok, with minimal clicking and with very limited calculations I can model an irregular shaped frame. But it has some drawbacks: (1) If I need to put a member between two shapes that are at an angle to each other (for example a diagonal brace between two tower corners that are tilted in as they rise) I have to put a working plane between the two ends, insert a pattern then extrude until it hits one end. To go to the other end requires a second pattern and extrusion. But then I know of no way to join the two segments and eliminate the seam line in the model. (2) Frames built this way are parts and I know of no easy way to extract the added member so I can make a drawing with cutting dimensions for the part. One or two times I have isolated the working frame into a part then modified it by adding the new member and finally deleting the starting part. But when I do that I mostly make some sort of a keying or selection error and end up hanging the Alibre session. I’ve also tried extruding the part in an assembly with pretty much the same result, a hung session with undecipherable error messages. (Without cutting drawings the alternative is cutting something a bit long and square, holding it in place to add pencil marks then taking it down to cut. It’s typically a waste of time and material.) (3) Without piece part drawings of frame members it is hard to figure out how much stock to buy and how to best cut the pieces out of the long lengths purchased. I often find that I have enough short cutoffs left over to add up to one less purchase piece. Not too important when the purchase piece is an 8 foot 2x4 but way more bothersome when it is a 2”x2”x24’ angle iron that has to be carried to and from the top of a mountain.

However, I’m not complaining about Alibre. I realize that the SW is nothing more than a Man-Machine-Interface around some reasonably complete but unsupported academic rendering engine. Alibre can’t add significant features or actually understand the error messages because they don’t have access to the source code. But that is the cost one must pay for using somebody else’s free/low cost code and it is what makes Alibre’s produce affordable to the home user.

I have never heard of Unistrut. What is it? I’d sure like a more effective approach.

Tom

[MichaelHenry]

Tom,

It sounds like you are drawing a bunch of individual components for one assembly as a single part, rather than as a bunch of parts that then get constrained into an assembly. For example rather than model a simple wall frame as 2 horizontal pieces and 2 vertical pieces and then assembling those 4 pieces into one wall frame, you model the horizontals and verticals as one connected piece. Is that right?

Unistrut is U-shaped (some say C-shaped) metal channel that is used for building all sort of industrial structures. We use it for building frames for chemical process test equipment. The most common form is 1-5/8 to a side and available in up to 20-ft lengths.

Mike

[Farmers Machine]

I was at a sheet metal shop that uses solid works. I sat down with the owner to design a stainless steel box with large radius corners, it took about 45 minutes for 2 ends, the middle section and the top. we added legs simular to an old timey washing machine that were tapered from top to bottom and had a large rounded corner. we started with 14" tall legs and after assembly decided to go with 18" tall instead. Roy clicked on the dimension of the solid model leg, and changed it to 18". In 5 seconds the bottom base moved the legs got longer and the taper changed. When he opened up the leg drawing again the legs were modified and 18" tall. Does Alibre have this same ability?
Thank You for all of your help
The Farmer

[scudzuki]

What you are describing is direct editing (editing at the solid rather than the design elements level) and is available in AD Expert. I have not played with it much but what I have tried works as you decribe.

Joe

[MichaelHenry]

If a part design is changed and saved, then any assemblies that include that part will reflect the change in that part the next time the assembly is opened.

In other words if you modeled the same SS tool box in Alibre as an assembly from a collection of parts that you had designed and then changed the leg length and saved that changed part, the tool box assembly would have the new leg length the next time you opened it or printed a drawing of it. That would work in any version of Alibre.

Mike

[Farmers Machine]

When you are creating and assembly from individual parts, how do you edit your part while you are in assembly mode? I have expert but have not figured out how to dimension in the assembly mode, go easy on an old man, I can tear up a big chief tablet and a # 2 lead pencil.
Thanks
The Farmer

[TomB]

I was at a sheet metal shop that uses solid works. I sat down with the owner to design a stainless steel box with large radius corners, it took about 45 minutes for 2 ends, the middle section and the top. we added legs simular to an old timey washing machine that were tapered from top to bottom and had a large rounded corner. we started with 14" tall legs and after assembly decided to go with 18" tall instead. Roy clicked on the dimension of the solid model leg, and changed it to 18". In 5 seconds the bottom base moved the legs got longer and the taper changed. When he opened up the leg drawing again the legs were modified and 18" tall. Does Alibre have this same ability?
Thank You for all of your help
The Farmer

Everything you described can be done with Alibre in about the same time that it was done in Solidworks. When I posted at the beginning of this thread that there was a problem in Alibre that could not be addressed I was considering a model that was just a bit more complex than your washbasin.

I’ve never used the sheetmetal design tools in Alibre so I won’t speak to them but I could do the washbasin very quickly. (1) make a solid the size of the outside of the basin, then round over corners to radius desired. (2) use thin wall extrude to hollow out the basin. (3) define a flat plane at floor level and layout the foot print of the washbasin legs. (4) insert lines from the footprints to where the legs should intersect the basin. (5) extrude the footprints along the lines until they intersect the basin. The result would be exactly like what you drew in Solidworks and if I edited the location of the floor plain with respect to the basin the leg length would be changed immediately. The last step is really “parametric modeling” and it seems common to all of the high end CAD systems. If I needed to go further and make part drawings of the legs in Alibre it could also be done quickly. I can think of two ways to do it, editing in assembly drawing or duplicating and editing the working part model. Describing either process makes this paragraph too long. To make a part drawing of the basin would require learning how to use the sheetmetal tools but I'm quite sure they would work.

But there is a simple addition to the washbasin model that would make it impossible to draw with Alibre and that addition captures the shortcoming that I tried unsuccessfully to describe earlier. Just suppose the washbasin was to sit on a half egg shell shaped base. I just explained that if floor was flat it could be solved by extruding leg footprints to the basin curves. But with the problem extension involving the egg shell shaped base I can’t figure out how to draw the leg footprints on the base. I’d like to be able define a plane somewhere between the basin and the base, then draw the leg cross section on that plane, then extrude in two directions; toward the basin and toward the base. But Alibre does not allow extrusion in two directions to specified irregular surfaces.

I have no idea if Solidworks could manage that feat and I’d like to know.

Tom