9 Replies Latest reply on Jun 20, 2017 6:32 PM by Bernie Daraz

    Include k-factor on drawing

    Chad Huleatt

      I'm trying to create a custom property for bend allowance and k factor. I am specifying k-factor using a gauge table.


      Bend allowance is automatically created as a  property of the solid body in the cut list folder, but I haven't been able to get that into an equation or the custom properties of the part.


      Thickness is one of the options on the drop down list for custom properties, and I can get radius by using an equation to create a global variable, and then make a custom property of the global variable.


      I can calculate k factor from bend allowance, thickness, angle and radius, so all i need to do is grab the bend allowance...


      Maybe Bernie Daraz or another sheet metal pro has some tips?


      Thanks a lot!

        • Re: Include k-factor on drawing
          Bernie Daraz

          Thank you for your reference of me but I'm sure there are others more experienced into putting this information into format as you desire. Most of my experience has been in actual fabrication, less so in communicating that information.


          While K factor is a regular topic here I am actually a numbers guy. I use charts from actual bends that were tested from actual bends. We typically used a router or work sheet that follows the job to indicate what values in the form of bend deductions and allowances as well as bend radii were used to program the job. If the benders were unable to obtain those values it was a programming error.


          Our benders would verify the values and 'complain' when the weren't correct or when, over time, the material thickness varied so much that it affected the standard values. It was easy for the programming department to change those values because we used a programming system that allowed for variables. Those variables were the bend deductions and allowances.


          If your discussion pertains to production outside or by a vendor to whom you would provide a print you need not be concerned with the 'correct' values and K factor is a 'quick' option. In some cases we have provided flats for reference only and these would only have outside dimensions marked "For Reference Only" on the print. Those outside dimensions allowed for quicker quoting and most likely nothing else.


          When I contracted or worked for fabricators it was important that flats generated by SW would able to be directly imported into programming systems but when I contracted it wasn't considered.


          I could offer some charts but they were 'our' charts, proven for use in our bending departments. I'll bookmark this discussion and hope that someone comes along to help.

            • Re: Include k-factor on drawing
              Chad Huleatt

              Thanks Bernie Daraz


              I have been sending the vendor PDF's of drawing and step file of finished part. They opened step file in inventor, created flat pattern, internal drawings etc. This worked great from my point of view. However, in an effort to reduce lead time, our vendor asked us to provide dxf of flat patterns, fully dimension-ed drawings with all bends called out etc. They provided us with the k-factors to use for specific materials/ thickness/ radii etc.


              I've added bend allowance as a note on the drawing, but was hoping to add k-factor so the vendor can do a quick check and see if we used the correct value for each situation.


              I think I can probably reverse calculate the k-factor from bend allowance, thickness, radius, angle. I was just hoping someone knew a secret trick to make it a bit easier....


              Our company is working on acquiring a brake, cutting equipment etc, so I'll keep what you said re charts in mind. I've found that a a bend deduction gauge table is a great way to store all that info, and also easy to maintain as bend deduction is so easy to measure/ calculate.


              Thanks again - I'll leave this as un-answered in hopes that someone has the secret to calling out k-factor....

            • Re: Include k-factor on drawing
              Dennis Bacon

              Chad,,  Like Bernie (brothers in sheet metal) I rarely use  a straight out k-factor unless I use it in a bend deduction formula but, as Bernie says it is a common topic here on the forum. I may not be understanding your question as you meant it to be understood. Are you looking for a table that displays both k-factor and bend allowance?.

              Does a bend table do anything for you? My k-factor column could be whatever I made it in my part file. If I use bend allowance on my bends that is what shows in that column. If I used k-factor on my bends, that is what shows in that column. If I used bend deduction that is what shows... I suppose it wouldn't be a good idea to mix them up in the part file though and your have to rename the column header to what you used. I don't use anything like this. Never have and never will but this may be what you are looking for. In any case we are keeping this thread going and perhaps someone who does this regularly would be able to shed some light on it. In my screenshot I used k-factor on my bends and just randomly altered a few to see how that would materialize in the column.

              Edit:.. I think where I was originally going with this is,,, Just because it says Bend Allowance in the cut list properties it doesn't necessarily mean it is a bend allowance. In this case it is a bend deduction.

                • Re: Include k-factor on drawing
                  Chad Huleatt

                  Thanks Dennis Bacon


                  In reply to your first question, the vendor is insisting on k-factor (don't know why, i always thought bend allowance or bend deduction where easier to use)


                  This afternoon (aus. time) I've been trying everything to make cut list or bend table work. The vendor has a rule: If radius = thickness, k factor is 0.27, if radius is 2x thickness, k factor is 0.44, if radius is bigger than 2x thickness 0.5.


                  I've built this rule into my gauge table, so i can use this as a shortcut, but I can't use if formulas in bend tables or cut lists....I could easily do it with equations or custom properties, but can't get that info into equation


                  For some reason I can't get k-factor to show up as an option in the bend table.....


                  I can make it work great for one part, but when I try to save as template, equations all greek out because dims no longer exist


                  I bet Deepak Gupta could make it work.......

                  • Re: Include k-factor on drawing
                    Chad Huleatt

                    Dennis Bacon, I'm really curious how you managed to get k-factor in the bend table. Could you post a copy of part & drawing?


                    Thanks, Chad

                      • Re: Include k-factor on drawing
                        Dennis Bacon

                        I did this in 2017 Chad. It looks like you are using 2016 according to your profile. Is that correct? Basically If I assign K-Factor to the bends or if it is assigned as default in the sheet metal feature (as default) that is the number you are going to get in the table. Cut-List or Bend Table. The problem with the Cut-List is (I think, like i said I don't do this often) it will only produce the default value of what is assigned in the Sheet Metal feature. In this case .5.. Remember that If you assign k-factor, or bend deduction, or bend allowance, that is what you get in the tables. I like the idea of the bend table because I can alter each bend value individually and it shows up in the bend table. Like I said before it is probably not a good idea to use combinations of Bend Allowance types if you want the table to populate and make sense. So if you use k-factor, or whatever, stick with it.

                        An example of altering an individual bend..

                        Double click on the header in the table and type in what you used in your model. I agree that it should automatically know what you used, but it doesn't. If you save that table after you altered that description (maybe call it k-factor), I'm pretty sure when you retrieve your table, on a new drawing, it will indicate k-factor.

                          • Re: Include k-factor on drawing
                            Chad Huleatt



                            I'm using the gauge table to set the k-factor. I guess that's why the bend allowance in the bend table isn't working.



                            When i manually enter the k-factor, it works like you said.



                            The reason I don't want to manually enter the k-factor is that I want that value to be stored in the gauge table, along with all the other info about available thickness/ radius/ etc.


                            I guess what I could do is calculate the k-factor using global variables, (create a global variable called k-factor) and use that for the k-factor instead of the gauge table.


                            Your're probably wondering why I'm making this so complicated.... reason is that my workflow involves a high number of very simple sheet metal parts (mostly folded panels, with a flat face and 2 or 3 edge flanges). My company makes fabricated signage, and it's not uncommon for me to design around 50 simple sheet metal parts in one day. So I need to make sure I can get the k-factor right every time without thinking about it too much....


                            Thanks again for the help - it never ceases to amaze me how much good advice I can get fro free.....I like what you said about bend tables and I think I'll start using them on my drawings - looks much nicer then having all the bend notes written on the flat pattern.


                            Next time your in Australia, swing past Inverell and I'll buy you a beer......

                              • Re: Include k-factor on drawing
                                Chad Huleatt

                                OK found a solution (sort of) to this issue. One of the guys here is handy with code and found a macro that runs through the features and prints values (i.e. bend radius, k-factor) to custom properties.


                                If you use a gauge table to spec k-factor, it still grabs the wrong k-factor.


                                I found a work around by using the macro to write bend radius to custom properties, then using a nested if formula in equations to specify the correct k-factor, based on the rules the vendor gave us. This returns a k-factor that matches that specified in the gauge table. Then I made a custom property called k-factor that takes that value.



                                This solution is far from perfect (i.e. if you have a part where bend radius differs, it won't work) but it should do the trick form most of what we do, as our parts tend to be fairly simple.


                                I'll leave this as un-answered in hopes that maybe someone will come up with a better solution. I think SolidWorks needs to sort out the issue of bend tables (on drawings) pulling the wrong value for bend allowance/ k factor etc. if you use a gauge table. Ideally the values from the gauge table would be more accessible - maybe they could auto-generate global variables?


                                Thanks again to Dennis Bacon and Bernie Daraz for the help on this - much appreciated!

                                  • Re: Include k-factor on drawing
                                    Bernie Daraz




                                    I'd like to thank you for your thanks but I would like to make it known that I believe others here did much more to help you through this and wish you luck to get this to where you need it to be. We all bend in press brakes and use different methods to get to a working bend allowance for our shops, so as conversation or advice in that regard I may have helped. It is up to you to develop this further if you have the time and the desire. I would like to commend you on your chase for this version of 'perfection'. Many would say it is just not obtainable, I would like to think it is. I've spent a lot of time to get to my version of perfection, I'm not done yet.


                                    If only bend tables allowed us to put in row-column data as opposed to one line listings I think we could be much further along. I have an Excel sheet from way back that works very well but for the last 25 years I have been using actual values developed from testing.


                                    Good luck!