19 Replies Latest reply on May 28, 2015 6:48 PM by Dennis Bacon

    Sheetmetal v-bend

    Rob Haman

      I'm on a crash course to learn the sheetmetal tools and got stumped today. I need a v-bend that has flats on each side of the v, unfortunately the drawing I am working from doesn't give very good dimensions that can be used. The image attached shows what I need without the proper dimensions.
      The second one shows the dimension scheme I have to work with. This was created as an extruded sketch which is close but not close enough.

       

      How would an experienced sheetmetal modeler go about making this part?

        • Re: Sheetmetal v-bend
          Fraser Port

          Its a bit hard to see your picture but I would use a sheetmetal base flange. You can easily dimension to points or add construction lines where necessary.

            • Re: Sheetmetal v-bend
              Rob Haman

              Fraser,

              Thank you for the input. I didn't write down the actual dimensions before I left work yesterday, but in doing some experimenting last night it does seem that the base flange is going to work.

              I will try this today.

              • Re: Sheetmetal v-bend
                Rob Haman

                I worked on this some more today and after a great deal of fussing, got the bends very close. However, besides not having clear dimensions to work from it seems likely there is something incorrect on the clients end. My overall distance when folded is .010" off, but the flat pattern is .030" off.

                 

                They don't specify the bend radius and k-factor they used to get the part as drawn.

                 

                Thanks

              • Re: Sheetmetal v-bend
                Kyle Ng

                The extruded model you have can also be converted to sheetmetal if you want so that it can be flatten if you need to do a drawing.

                But as for the first image, you can start with the base flange as a flat surface then do an edge flange up at 45 deg (?) then down 90 deg (?) and then over another 45 deg (?). I am assuming those angles are 45 up 90 down and 45.

                • Re: Sheetmetal v-bend
                  Bernie Daraz

                  What is the bend radius and the material thickness? I'm just curious, Thanks!

                    • Re: Sheetmetal v-bend
                      Jackie Yip

                      Short cheat sheet on the math behind bending

                       

                      Source: Google images (bending k-factor)

                      image2.png

                      • Re: Sheetmetal v-bend
                        Rob Haman

                        The client drawings don't give me the radii they used so I have tried a few different ones (.060 - .080) in an attempt to make it work. They also give the material thickness in mm, which converts to .079". This is stainless steel so we will be using 14ga(.075) and a k-factor of .36. I tried using .080 as a material as well.

                         

                        Last night I modeled this as an extruded sketch and then "Insert Bends" on the sheetmetal tab and have the profile dimensions needed, but the bend angles are about 3 degrees off. I don't recall the actual flat and bent state overall dimensions so I will have to check them when I get to the office today to see how close they are.

                         

                        We may need to get some clarification on the drawings, something just doesn't seem to be correct.

                          • Re: Sheetmetal v-bend
                            Bernie Daraz

                            Rob,

                            They throw a loop into the figures as the bends are 2 place (45.00) and so are the others. Everyone knows for a 45 to work both legs have to be equal. It's my guess that the horizontal dimensions (.55) are incorrect.

                              • Re: Sheetmetal v-bend
                                Rob Haman

                                Bernie,

                                Good point. Even though the given dimensions don't lend themselves to an easy trig solution, a guestimate does raise a red flag.

                                 

                                Thanks.

                                  • Re: Sheetmetal v-bend
                                    Bernie Daraz

                                    Rob,

                                    Not an argument, but who does trig anymore? I draw the bends out and measure the results. In a case like this I could use the drawing too. Back in the AutoCAD days I would do the same and then create a 1:1 drawing for the brake guys (myself included) and use it to inspect the bends. I made the same drawings for manual countersinks to obtain the minimum hole size to be punched. Now in (parametric) SW I can keep a template and just update the numbers.

                              • Re: Sheetmetal v-bend
                                Bernie Daraz

                                Kyle,

                                Those are typically for air bending. In coining for production work in up to 13 ga steel we used Amada's and Wilson's .008" radius tooling extensively. Back many years we used American standard tooling that was sharp. We had to layout jobs with consideration for material grain many times. The .008 was our first choice in the programming and brake departments, we had a few of the other radius to 'pull in' jobs.

                              • Re: Sheetmetal v-bend
                                Bernie Daraz

                                It just occurred to me what the solution to this issue is, the .49 is reference. As brake guys we can control the position of the apex dimensions (.55). But considering the material thickness and 'our shop' standard bend radius it is what it is. If I had to I would present the customer with a drawing section of what they will receive (with tolerance) for a height dimension. Anything else will require special tooling or multiple bend setups greatly increasing the cost. I figure the job is in house and already quoted.

                                  • Re: Sheetmetal v-bend
                                    Rob Haman

                                    Bernie,

                                    Yes, I agree something in the given dimensions really should be a REF. dimension which would solve the issues. As I mentioned in the original post, I'm new to my company and therefore this client and how they dimension their parts.

                                     

                                    Thank you for the input, I will update as the solution presents itself.

                                      • Re: Sheetmetal v-bend
                                        Mike Pogue

                                        You should send the customer a screen shot and discuss it with him. It's clearly not an experienced designer, and you can help him (and yourself) by finding out what he meant, and educating him on how to get it next time.

                                         

                                        Feedback from fabricators is a big part of learning design.

                                    • Re: Sheetmetal v-bend
                                      Dennis Bacon

                                      Rob,, These kind of drawings can give you fits. The way this is dimensioned, if you change the thickness, the bend radius changes and vice-versa. I agree with Bernie (always  do) that you should nail down the bend radius to the tooling you are going to use and go from there. Most of the time a drawing will just indicate "minimum bend radius". It looks like .55 dim is to the inside mold line from your pic not to the center of the radius. This really should be clarified. I hate it when there is ambiguity.

                                       

                                      With the information given a brake guy would have fits and have to bend several parts and go by trial and error. I have included a drawing the way I would dimension this using OD virtual sharps (outside mold lines). That way the brake guy just plugs this information into his controller and most likely will get a good part on the first attempt.

                                       

                                       

                                      Oh Yea... Include the bend deduction!

                                        • Re: Sheetmetal v-bend
                                          Rob Haman

                                          Dennis, and all who have offered help:

                                          Based on what this bend pattern is likely for, a stiffener ridge, we decided to make the bend angles as the reference dimensions. Myself, a quick phone call or email would have been a time saver but only being employed for 3 days means going with the flow.

                                           

                                          So, I ended up creating a sketch of the entire profile including the inside/outside radii as needed, extruding the length needed and then using the Insert Bends feature. When all was said and done both the FPL and as formed dimensions met the design intent.

                                           

                                          While a great deal of time could have been saved with better dimensioning standards, it did give me a great opportunity to learn how not to do things and in turn learning better methods. And, get my foot in the door with some great mentors here on the forum.

                                           

                                          Thank you all!

                                            • Re: Sheetmetal v-bend
                                              Dennis Bacon

                                              Sounds like you got a good handle on this. I would like to point out that instead of extruding the length (from the features tab) then converting to sheet metal, you probably would be better off using the "Base Flange/Tab" on the sheet metal tab. This will extrude it and it becomes sheet metal without an additional step. On more complex parts converting to sheet metal can be difficult and sometimes impossible. My sketch in my previous post was used with the BF/T then added material thickness, bend deduction, and extrusion length in the dialog box. There are no faces and bends to select.