3D spirals - How to generate cut sheet

[Anonymous]

So I drew a 3d spiral, and now i need to create a cut-sheet in sections (half or quarter) so I can sent to my shop for fabrication, and I have no idea how to do so. Please see attached photos.

I want to be able to provide a cut sheet template so i can print it out and they can trace it on the sheet metal, cut however many sections required, and weld it together to create the spiral. My concern is that the top view dimensions is not an accurate dimension when the piece is bent 8 inches from the start of the spiral.

Also, my next issue would be the side wall of the spiral, and how to properly create a cut sheet on the given dimensions.

I also tried to do this in Autodesk Inventor, using the sheet metal tool, flatten command, and I was unable to flaten the object.

[steve216586]

Your drawing isn't accurate at all. The bending of the metal to achieve elevation distorts what you have drawn in the top view to the point that it would be impossible to create what you drew in 3D.

Just one for instance, the center void area is circular in 3D. To achieve this from a cut piece of flat sheet metal stock, the center void area would have to be layed out as an elipse. When bent, to add the required elevation, the elipse would then be warped into a circle as seen from above.

Experiment with paper to earn a visualization, without wasting material.

[Anonymous]

Thanks for the response. I completely understand what you are saying, and I agree, the drawing I have provided is inaccurate, which is why i posted it for help on how to generate an acurate one. I realize that the top view of an cut sheet will be as you say, more of an eclipse, however I need to know how i would actually get there based on the dimensions given. Any ideas?

Like I said, i tried using the "flatten" command in Autodesk Inventor since i tried to replicate the part in that program as wekk and it didnt want to work... maybe I should post on that fourm as well?

Thanks!!!!

[SEANT61 · Accepted solution]

See the Excel sheet in Post #10 of this thread:

http://www.cadtutor.net/forum/showthread.php?31757-Screw-conveyor-flights

The information provided by the spreadsheet produced the flat geometry in the attached file.  Regarding validity; Compar all perimeter values as well as the area of the Surface and Region.  I don't think any elliptical curves are required.

Disclaimer:  The spreadsheet/DWG do not compensate for any neutral plane/K-Factor issues. 

[Anonymous]

Thanks for your help, and the spreadsheet! This is exactly what I am looking for. Thanks again!!!

[Anonymous]

One question, what does the angle "included and excluded" mean? I drew the angle on my drawing based on the variables i entered.

thanks.

[Anonymous]

Sean, I figured it out, and built a scaled model. THANKS!!!!!!

[SEANT61]

I'm glad the spreadsheet worked for you.  Thanks for the acknowledgement.

[Anonymous]

Hello again Sean,

I had another question and was wondering if you would be able to help me. Using your spreadsheet, I was trying to figure out how to calculate a side plate on the spiral as well as the spiral itself, so far I have been unsuccessful. Please see attached drawing. As shown in the "spiral view", there is a 4" side plate that runs along the edge of the spiral. Hopefully I can have a spread sheet like the one provided to be able to calculate the pattern on a flat surface, as you provided for the spiral itself.

Thanks in advance for your help.

~Julian

[SEANT61]

How is the 4" measured?  Is it int the vertical direction, or perpendicular to the helix surface? 

In either event, the side rail will just develop uot to a strip of material.  If the 4" is in the vertical then the strip width would be 4*Cos(InclineAngle).  I could include that formula in the speadsheet if desired.  If it is perpendicular to surface then it is just a 4" strip.  The length would equal the the ArcLength of the outer edge in the gememetry youve created for the helix surface. 

[Anonymous]

It is the vertical dimensions which runs parallel to the helix surface.


~Julian

[SEANT61]

I guess I'm still not certain how the dimesion should be interpreted.  See if this works.