topic Re: Flat pattern for twisted sheet metal in Fusion Design, Validate & Document Forum

Flat pattern for twisted sheet metal

ggray10 — Tue, 19 Dec 2023 17:27:46 GMT

I want to have a 90 degree twist in a 1/8" thick x 1/2" wide mild steel. The length of the twist is 1" and I have attached a file. I want to make a flat pattern out of the model. Most of the posts on the subject are two or more years old, but it is apparent that it can't be done in Fusion. Two of the suggestions were Autodesk Inventor and Mesh Maker. I don't want to invest in the Autodesk product. I looked at Mesh Maker and don't know which product is applicable. Since the twist is only 1" in length and the dimensions on the total length of the part are not that critical, my solution is to just model the flat pattern for the twist as a 1" flat section. Now that I have answered my own question, does anyone out there have any other thoughts?

Re: Flat pattern for twisted sheet metal

jhackney1972 — Tue, 19 Dec 2023 18:31:11 GMT

I am not responding to how to create a flat pattern of your file, I am responding because your Loft between the two bars has an issue. I attached a model with a better transition Loft.

Re: Flat pattern for twisted sheet metal

MichaelT_123 — Wed, 20 Dec 2023 00:01:41 GMT

Hi Mr GGray10,

In the first approximation, not taking into account a material yielding during the actual fabrication of the twist, the length of the outer edge is invariant during the process.

Thus, to recover a flat pattern, measure the twist spiral edge length and calliper the width, and you will have a rectangular pattern for the twist in its first approximation.

In most cases, it would be precise enough; I assume you are not fabricating braces for the Hubble Telescope.

The story might be quite different if you do, as accounting for material yielding during bar twisting operation ... is a very different pair of shoes not only from the point of view of patterning but also the modelling the bend is not so straightforward Mr. jhackney1972 licked the subject, but understandably, he did not bite it ... a modelling real twisting bar is tough.

Regards

MichaelT

Re: Flat pattern for twisted sheet metal

ggray10 — Wed, 20 Dec 2023 02:47:17 GMT

Thanks for catching the error. Looks like I inadvertently duplicated one of the twist points in the wrong position

Re: Flat pattern for twisted sheet metal

ggray10 — Wed, 20 Dec 2023 03:57:57 GMT

Yes, fortunately I am not working on the Hubble telescope so my margin of error is quite large in comparison. Measuring the edge of the bend indicates that compared to the gap between the flat sections, the bend shortened the material by less than 3/16". I will adjust the pattern accordingly and as they say, "it's close enough for government work". Thank you for your eloquent description of the issue.