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## Inventor General

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Registered: ‎10-12-2012
Message 1 of 6 (292 Views)

# 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this correct ?

292 Views, 5 Replies
10-12-2012 08:53 AM

Hello,

I would like to confirm the size is good or not, I built a 18" diameter Cylinder, 10 Guage SS (0.14). Inventor show me

the flat pattern is 55.915". I expect 2 x 3.1416 x 9 = 56.54". there is half inch different. is this correct ?!

thank you

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Message 2 of 6 (285 Views)

# Re: 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this cor

10-12-2012 09:08 AM in reply to: Carolus17

I'm coming up closer to what Inventor shows it should be.

I think your expected dimension is too big.

I'm thinking, when you figure the flat length on your calculator,

you are figuring the length along the outsid, rather than the

center of the material.

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Message 3 of 6 (270 Views)

# Re: 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this cor

Your hand calculation does not take into account the unfold rule that you have Inventor set to use. It defaults (somewhat arbitrarily) to a k-factor of .44.

You need to set up your unfold rules to take into account your manufacturing process.

At my shop we use the mean method for rolled parts (k-factor = .5), but we have a +/- .030 tolerance on sheetmetal parts.

Mike (not Matt) Rattray

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Message 4 of 6 (266 Views)

# Re: 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this cor

10-12-2012 09:39 AM in reply to: mrattray

flat patterns depend on the tooling and processes used.

I ALWAYS do a physical piece first to know the k-factor I should be using for that process/material thickness.

Down with IDW/DWG files..... Long live 3D PMI... Hurry it up already..
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Message 5 of 6 (263 Views)

# Re: 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this cor

10-12-2012 09:44 AM in reply to: mcgyvr

What I did here, for our occasional high precision press braked pieces, is to make test bends of all of our common materials (type and thickness) at various angles. I then charted all of the data in Excel and wrote equations to describe the way each material deforms as it bends more and more. I then set these all up as unfold rules in my template and wrote an iLogic rule to select the appropriate unfold rule based on the selected material type and thickness.

Mike (not Matt) Rattray

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Posts: 4
Registered: ‎10-12-2012
Message 6 of 6 (251 Views)

# Re: 10 Ga SS cylinder 18" diameter, the flat pattern is 55.915, is this cor

10-12-2012 09:55 AM in reply to: Carolus17

I'll check the bend table (excel) at the intenory. thanks a lot for the information and advise.

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