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Bend Deduction Other Than 90 Deg

Question asked by Fred Vraj on Aug 25, 2015
Latest reply on Sep 18, 2015 by Bernie Daraz

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Hi Everybody,

I have been having some issues with getting the right flat patterns that have bends with other than 90 Deg.

I have my own database of BD for ALU and Steel Sheets.

I do manual testing on the floor with my press guy and my 90 Deg samples are quit spot on.

The BD is very accurate on my 90 Deg Bends.

I use this formula below to get NON 90 Deg bend deduction value.

BD for 90°/ 90 X Needed Angle

EX: ( in mm for ALUMINIUM 2.5mm TH, Bend Angle 36° )

4.09 / 90 X 36 deg

0.045 X 36

BD = 1.62 mm

I got this formula from this forum but I am not sure if it has worked for me.

It just seems to be too simple to be truth.

Thank you for any help that you can offer.

Fred

Bernie Daraz Aug 27, 2015 6:39 PM

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Hey Fred!

Using my own Excel based calculator I get the following:

Most every time I needed to calculate one bend angle it was returned back to parallel on the next bend so I added the complimentary angle to my Excel sheet. I know 'European' angles are different, are you sure you're entering the actual bend angle into SW? I'll bet you are.

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Vignesh S. Aug 27, 2015 7:03 AM
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Hi Fred,

Adding to your information.

Expected Flattened length= A+B+C-Bend Deduction.
SolidWorks Flattened length= A1+B1-Bend Deduction.
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- Fred Vraj @ Vignesh S. on Sep 18, 2015 9:38 AM
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  HI Vignesh,
  yes I know this basic formula. That was not the question actually but thank you anyway.
  :-)
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Dennis Bacon Aug 27, 2015 7:53 AM
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Fred,,, I get .95mm (.038") for 36deg with a minimum bend radius (I used .031") (for you .79mm?) I'm not sure What the "Expected Flattened length" is that Vignesh has there. Normally it would be A+B (measured at the neutral axis (which is the bend allowance))+C= Developed length.

You were correct saying that formula you use is too simple to be true.

There are bend calculators online that you can use which should get you pretty close. The only ones I'm aware of calculate inches only.

Edit:..
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- Fred Vraj @ Dennis Bacon on Sep 12, 2015 6:18 AM
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  Hi Dennis,
  and thank you. The Calculator sounds good and does very good job but I do hate:-) working in inches because we only work in mm. I know I can convert each figure but this would be very time consuming.
  I used it for one part that had 10 bends and it came very close to my needs but if I may say, not close enough to the required tolerance over those 10 bends.
  But thank you!!!!!
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  - Bernie Daraz @ Fred Vraj on Sep 13, 2015 10:01 PM
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    I know this will sound strange, we assume these calculators are dealing with inches but I just tried two of them entering mm figures for both the bend radius and material thickness and the answer was given in mm. I guess to the calculations the numbers are just units.
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    - Dennis Bacon @ Bernie Daraz on Sep 18, 2015 8:49 AM
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      Bernie Can you help me out here. Sorry to ask on this thread but this is important to me.
      can someone help me out? I need to find these. Do you know the supplier?. I've tried Harstswell (I maybe have misspelled that)but struck out. To be honest with you I have not spent the normal amount of time on this(24 hours) I'm just hoping that someone has seen thees before. I would really appreciate any help. Hinges , fasteners?
      
      Edit: I trust your judgment.
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      - Fred Vraj @ Dennis Bacon on Sep 18, 2015 9:32 AM
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        Hi,
        what exactly are you looking for? The link is not working.
        Can you upload pictures?
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        Dennis Bacon @ Fred Vraj on Sep 18, 2015 9:55 AM
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        Fred,, I'm a sheet metal guy but I have never seen these before. Any help would be very appreciated. I did this with snipping tool Hope your can view it. It's 6:30 here In California but my people are looking for answers and are bugging the heck out of me at this very moment. I have not ever been not able to provide them with information in the past. That is why I am reaching out.
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        Hinges..PNG145.2 KB
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        Fred Vraj @ Dennis Bacon on Sep 18, 2015 10:07 AM
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        Hi again from Australia:-) 1am here....
        yes I have seen them before but they are very hard to get.
        Check this supplier UES International:
        They sell one hinge that might be ok.....
        Photo: and Link:
        
        Concealed Door Removal Hinge – F6 | UES International
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        Dennis Bacon @ Fred Vraj on Sep 18, 2015 10:30 AM
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        Thank you very much. I have already past this information on. To be honest with you It looks pretty good. Let's see what the guy I trained will think. the sob is now running the place.
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        Fred Vraj @ Dennis Bacon on Sep 18, 2015 10:37 AM
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        My pleasure....
        OK perfect lets hope it will pass and make them happy.
        I have also sent you a message with another option.....
        Please let me know how how you go....
        Good day from Good night.....
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      - Bernie Daraz @ Dennis Bacon on Sep 18, 2015 8:49 PM
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        Dennis,
        Sorry I couldn't have helped but from reading all these emails I believe your issue is resolved. I had one of those drop dead ship builds that took me all day to complete.
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Bernie Daraz Aug 27, 2015 6:39 PM
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Hey Fred!

Using my own Excel based calculator I get the following:

Most every time I needed to calculate one bend angle it was returned back to parallel on the next bend so I added the complimentary angle to my Excel sheet. I know 'European' angles are different, are you sure you're entering the actual bend angle into SW? I'll bet you are.
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- Fred Vraj @ Bernie Daraz on Sep 12, 2015 6:22 AM
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  Hi Bernie!! I hope you have been well:-)
  Thank you for the table example. may I ask you what the 33% 44% 50% figures mean? Which one is the right figure for the 36 deg angle?
  Thank you and sorry about asking....:-)
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  - Bernie Daraz @ Fred Vraj on Sep 12, 2015 8:59 AM
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    Thank you for asking Fred, I've been well. I trust you have been too. The 33, 44 and 50% figures are the K factor. I use different ones depending on the tooling I have available. If I was using an .06 radius on .06 material I would use the 44. For a large radius, more than 4 or 5 times the material thickness I would use the 50. Most of my bending was a modified coin bend and I then used 33, typically then the top punch was .008 radius and the die was four times the material thickness. I could easily make the calculator show mm but it would be your responsibility to learn how to use it at your shop. We all bend with slightly different styles, that's why we have a variety of 'theories' (I do mean respect here) presented here. All of my bending was production, we didn't send work out except for infrequent laser cutting outside of our capabilities. The SW flat went to the programming system.
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    - Fred Vraj @ Bernie Daraz on Sep 12, 2015 9:52 AM
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      Hi again,
      Ahhhh it makes perfect sense. Thank you. I always ask my press guy to tell me what tool will be used for the job so I can use the right BD, BA or K factor.
      I have to say that I have very good database of BD which I got from my floor testing of 3 pieces for each material thickness with various bend radiuses and tooling. I convert this BD to K-factor like this: In Solidworks, I do create a simple one-bend model and play with it until the flat pattern for BD and K-factor are exactly the same length. Only than I can be certain that my calculations are accurate.
      
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Bend Deduction Other Than 90 Deg

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