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## Frame Generator Model

I have attached a frame that I created using frame generator using Inventor Pro 2012. I have played with frame generator for a bit and have used Mastering Autodesk Inventor 2012 by Waguespack and some you tube videos of Rob Cohee to help me create this frame.

If anyone has a bit of time and is interested, have a look and see if there is anything "wrong" or bad practice. We use this type of frame quite a bit here, so I would like to get a rock solid technique/process for creating these.

My questions are about the fork pockets on the bottom that intersect the frame width wise. In my sketch I had to separate the 2 longer tube sections because there is no trim function that would trim the 4x3 tube to both sides of the 10x4 tube.(can be seen in the sketch)

Also the 4 bottom ends that need to be cut on 45 degrees, I used sketch and extrude to achieve that. Is there a better way? Miter only seems to function if there is 2 intersecting frame pieces.

Thanks

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## Re: Frame Generator Model

The only possible simplification I can see is elimination of a few redundant dimensions by using construction lines, equal and symmetry constraints.

Well for some reason I can't attach an image today.

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## Re: Frame Generator Model

I forgot to add - that we can't make perfect parts, some are a little longer, some a little shorter - so it is often standard practice to trim mating weldment parts back with a bit of a gap so that they will always go together without causing the frame to be out-of-square.
http://forums.autodesk.com/t5/Autode...h/td-p/3644222

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## Re: Frame Generator Model

ok, thanks JD Mather,

thinking about the "leaving a gap" comment, so I should shorten my connecting tubes by ~1/32?
can this be adjusted with a min/max tolerance on the drawing?
I would find it confusing on a drawing; ex. have 2 pieces 24.9687" (25"-1/32") long then butt up against a tube 4". the drawing would state this to be 25"+4"+25"=54" but if you add up the actual length it is (24.9687"x2)+4"= 53.9374" which is a 1/16 difference than the length you actually want? Would this be clarified with a drawing notes, saying something like - "tubes are to be cut short to allow for squareness while being assembled use assembly dimension when building"?
Or is this kind of a given for most shops, they know to cut short to allow for fabrication to spec?

Sean

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## Re: Frame Generator Model

If you are sending for to an outside shop - I would give them only the finished dimensions.
It is there responsibility to generate the correct assembly and if the have the experience to do the job - they know what allowances need to be made.

If for inside the company work - there are two ways to look at this.
(but any way you look at it the assembly finished dimensions are the controlling factor)

1. Communicate with the shop floor guys similar to dealing with outside vendors and they should know what allowance need to be made - so you don't worry about accounting for gaps during design, you design as though we can make perfect parts.

or

2. Design for manufacturability where the digital model is the same as the manufactured results. Account for all variabilities including manufacturing tolerances. There are two major cases where I would do this. Case 1, this is not a one-off or small run job. Hundreds or thousands will be made. Case 2, the part ends will not be finished machined - only cut-off saw chopped. In my experience the person operating the cut-off saw is the least experienced person on the shop floor. Don't leave anything to chance with them. They should not be doing calculations.

It sounds like you will be getting the work done outside - communicate with the vedor and see what works best for them. Be sure the final contract states the finished dimensions as-assembled are controlling.

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## Re: Frame Generator Model

I use the FG a lot and there are quite a useful tips and tricks, most of which you just need to 'find'.

For this question/comment "My questions are about the fork pockets on the bottom that intersect the frame width wise. In my sketch I had to separate the 2 longer tube sections because there is no trim function that would trim the 4x3 tube to both sides of the 10x4 tube.(can be seen in the sketch)" I would say to just draw your lines so they intersect to remove some of the sketch constraints. The less complicated you make a sketch the easier it is to change when needed and not end up with unwanted/strange results. So you could remove the 3" gaps and just end the 25.375" and 54" lines at the endpoint of the 'fork pocket' lines. Then use the FG Trim/Extend command to trim the long side rails off at the face of the fork rail.

For this question/comment "Also the 4 bottom ends that need to be cut on 45 degrees, I used sketch and extrude to achieve that. Is there a better way? Mitre only seems to function if there is 2 intersecting frame pieces." I would use the Model/Chamfer tool. See the attached graphic. It doesn't change the length of the FG member. But do expand on the Chamfer tool options and select the single edge only.

chamfer.JPG

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## Re: Frame Generator Model

Thanks JD for the info,

Brendan, I am having trouble with both your tips, using the trim extend function to trim the tube that in "inside" the fork pocket in not working. I can only select one face to trim to, and the rest of the long side rail is removed beyond the trim face. Unless there is away I am not seeing to select both side faces of the fork pocket??

Also the chamfer function is giving me an error, do you manage to get this to work? It seems to work when I use smaller values like 2" or 3" but to chamfer the entire end of the tube which is 4", I get an error, see image.

Thanks

Seanchamfer_error.png

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## Re: Frame Generator Model

Sean, use Trim/Extend and not Trim To Frame. See below picture. Blue member is the Frame Member and yellow is the Face to trim the blue member too.

TRIM_EXTEND.JPG

As for the chamfer turn on Preserve All Features (I forgot that). See picture below.

CHAMFER_PRESERVE_ALL.JPG

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## Re: Frame Generator Model

Thanks Brendan, I realized my error, I would still need to have 3 lines representing the long bottom side rail and have the 2 lines intersecting as the fork pockets. I created one line representing the side rail, with 2 lines intersecting as fork pockets. So every time I trimmed, it deleted the remaining length of the tube. The chamfer worked,

Thanks Again.

Sean

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