topic Mitered Rectangle Tube Bend, Flatten? in Inventor Forum

Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 17:33:38 GMT

Long time user (R4 days) it's been a while since I've had a good challenge...

We have a new toy, Plasma Tube Cutter, and I ran across a modeling challenge. This is not just tube bending or sheet metal solution.

Challenge: Determine OAL of rectangle tubing and the location of relief cuts.

The bends will be manual, then seems welded. The problem is the bends are essentially sheet metal bends but because bends are on opposing sides of the tubing profile I can not just flatten out the tube (aka "unwrap" part) or use Sheet Metal flatten tool. I did derive the model into parts that represent the "pieces" then grabbed the length of arc segment across the bend
(this doesn't take into consideration the bend factors) to space out pieces into an assembly with intent to derive the .iam into an .ipt but I'm curious if anyone else has a better idea?

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 19:13:57 GMT

Here's my solution after deriving the .iam (note the bridges are for support during plasma tube cutting operation)

Re: Mitered Rectangle Tube Bend, Flatten?

JDMather — Thu, 02 Dec 2021 19:53:15 GMT

Does the plasma cut result in beveled edges - or are they all perpendicular (the head does or doesn't swivel or only translates while tube turns (and perhaps translates))?

Does the manufacturer have a youtube video showing in operation?

Re: Mitered Rectangle Tube Bend, Flatten?

pcrawley — Thu, 02 Dec 2021 20:26:49 GMT

I wrote this a few years ago for exactly this situation. I like Frame Generator, so the solution goes on to use a frame generator model to achieve the same result.

Take a look here: Notch, bend, and straighten in Inventor - CADPRO blog

We're getting a tube laser in about 2-weeks, so can't wait to see this in action. Unless you have spent big $ for the 3d head, it's likely you'll only be able to cut perpendicular to the face, so the sheet metal tools in Inventor are the perfect answer to the modelling problem.

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 21:04:50 GMT

JD - It does not cut beveled, no swivel head. I also applied some surfacing/sheet metal tips from your AU class many moons ago...to get the arc length based on sheet metal = tube wall thickness...that class honestly has been one of the most applied courses in my 25yrs working with IV 🙂

Peter - ugh I'm no fan of Frame Generator...I've used them way before IV integrated their own...thank you for the link...cheers!

Re: Mitered Rectangle Tube Bend, Flatten?

pcrawley — Thu, 02 Dec 2021 21:07:30 GMT

I just spotted an error in the blog post - sorry 🤦‍♂️

In step 4 it says "In the derive dialogue box, output doesn’t really matter, as long as it’s a “solid” option (as opposed to surface or composite)."

It does matter. You need to derive the assembly into the part using the "Single Solid" option, otherwise adding the corner seam feature can take forever (on larger models) - and flattening doesn't work 🙄

These images were less than 5 mins work.

Frame gen:

Sheet metal with corner seams and bends:

Unfold:

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 21:11:19 GMT

...Not bad for the first try

Re: Mitered Rectangle Tube Bend, Flatten?

pcrawley — Thu, 02 Dec 2021 21:21:22 GMT

Great photos! Thanks for sharing.

You don't have to use Frame Generator - you can achieve the same thing with Loft to create the short "blunt" sections - then let Sheet Metal corner seam and Bend do all the hard work. Plus you get perpendicular edges on your model.

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 22:15:17 GMT

I need to dig into that tutorial, sounds like a great solution to me...1-2hrs of work vs 4min is a given.

Appreciate the feedback Sir 👍

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Thu, 02 Dec 2021 22:22:11 GMT

This is what I was hoping for 👍

I did manage to get within 0.06" to the modeled OAL vs old part design 😎

Re: Mitered Rectangle Tube Bend, Flatten?

pcrawley — Thu, 02 Dec 2021 23:04:24 GMT

I only hope my attempts are as good first time around with the new machine. Can't wait!

After thinking about the process, I suspect I was overcomplicating it - a lot!

Have a look at this part - I left it unfinished so you can add the remaining features.

The sketch is fairly simple and I used a sketch block for the section. Each section is extruded a bit (this makes the stubby blocks I previously made using Frame Generator). The rest is Corner Seam and Bend features from Sheet Metal. Drag the EoP marker up to see how it went together. Not sure why I didn't think of this 4-years ago!

Re: Mitered Rectangle Tube Bend, Flatten?

IgorMir — Fri, 03 Dec 2021 00:56:50 GMT

Hi Steve,

I hope - the attached example will give you some ideas how to handle your design. IV2010 format.

Cheers,

Igor.

Re: Mitered Rectangle Tube Bend, Flatten?

pcrawley — Fri, 03 Dec 2021 02:22:43 GMT

I like the simplicity of the design @IgorMir - but doesn't this process require you to unfold the design in your head, draw it flat, then fold it up? I'd need a bigger brain for anything more complicated than a square!

I should be more considerate of people not using the latest version... Here's a video of the process. It's about 2.5 minutes to model the part, then a bit more to add the stiffeners to prevent the part from folding up as it comes off the machine.

Re: Mitered Rectangle Tube Bend, Flatten?

SBix26 — Fri, 03 Dec 2021 03:59:01 GMT

Here's my attempt, which surprisingly worked all in one part in Inventor sheet metal. This is a 2022 file (sorry @IgorMir !).

Essentially, model the finished form of the tube, make miter/relief cuts as you did in your model, then flat pattern. The key is to make sure that the cuts coincide exactly with the thickness of the material.

Sam B
Inventor Pro 2022.2 | Windows 10 Home 21H1
LinkedIn

Re: Mitered Rectangle Tube Bend, Flatten?

IgorMir — Fri, 03 Dec 2021 03:59:26 GMT

Yes, it is a good way of doing it too.

Frankly - I have never had a request for making a design like that. I did the model three years ago (or there about) just out of curiosity.
I will keep your method in mind, should I get a need to make a real part. 🙂
Cheers,

Igor.

@pcrawley wrote:

I like the simplicity of the design @IgorMir - but doesn't this process require you to unfold the design in your head, draw it flat, then fold it up? I'd need a bigger brain for anything more complicated than a square!

I should be more considerate of people not using the latest version... Here's a video of the process. It's about 2.5 minutes to model the part, then a bit more to add the stiffeners to prevent the part from folding up as it comes off the machine.

Re: Mitered Rectangle Tube Bend, Flatten?

IgorMir — Fri, 03 Dec 2021 04:01:20 GMT

Thanks Sam,

I got the idea. 🙂
Cheers,

Igor.

@SBix26 wrote:

Here's my attempt, which surprisingly worked all in one part in Inventor sheet metal. This is a 2022 file (sorry @IgorMir !).

Essentially, model the finished form of the tube, make miter/relief cuts as you did in your model, then flat pattern. The key is to make sure that the cuts coincide exactly with the thickness of the material.

Sam B
Inventor Pro 2022.2 | Windows 10 Home 21H1
LinkedIn

Re: Mitered Rectangle Tube Bend, Flatten?

srobbinsZMA6L — Wed, 08 Dec 2021 13:11:16 GMT

Guys thank you! I was over complicating it, all because I didn't try the "bend" command LOL

Love how this group has been helpful over the years, no matter the experience level 🙂

Re: Mitered Rectangle Tube Bend, Flatten?

LuukDW — Wed, 02 Jul 2025 08:53:36 GMT

Hi,

I'm encountering an issue with using the corner seam feature on my rectangular tube model (50x25x1.5).

It appears the problem stems from the tube's radius. When I model the tube with a 5mm radius, the corner seam computes successfully, matching the example results. However, when I use my tube's actual 1.5mm radius, the feature consistently results in a computation error.

Has anyone experienced this before or know a solution? I've attached my model for reference. "LS-0100_1.ipt" is my reference model i am trying to re-create with slightly different dimensions. "Koker.ipt" is my attempt at solving the issue, it is built in a simular fasion as @pcrawley did in his model.

I have also tried the method @srobbinsZMA6L does. However i am unable to create a flat pattern.

Re: Mitered Rectangle Tube Bend, Flatten?

kacper.suchomski — Wed, 02 Jul 2025 09:47:52 GMT

A radius of 2.5 mm causes no rounding inside.
What profile standard has such parameters?

By default, the inside radius is equal to the thickness.

Re: Mitered Rectangle Tube Bend, Flatten?

LuukDW — Wed, 02 Jul 2025 10:46:38 GMT

Hi,

I am using stainless steel profiles, The inner radius is 0.5mm.

If i apply this inner radius it still comes up with problems. In the preview of the feature the result is shown but it wont actually create.