Hello everyone,

Up until recently, we have been able to use SW's default K factor (0.5). I was not aware of the 1/2" or so discrepancies, since the shop guys could make it work. However, we are now making some interchangeable sheet metal parts, and they need to be closer than what we have been getting. We work mainly with 303 and 304 SS: 1/4", 10/12/14 ga. These parts, in particular, are 1/4", and we found that a K factor of .274 got us as close as 0.02."

This leads to me to my questions. I want to develop a chart to help prevent future mishaps like this, so I began searching the forums for sample K factor charts. I found Chad Moles's chart. Now, I understand that every shop's chart will be different, but Chad has a K factor of 0.4464 for the same material that I get 0.274. Is this typical? Can anyone post their K factor charts to give me some examples? Also, I used the formulas found here http://www.ciri.org.nz/bendworks/ to calculate my K factor.

Joe

Joe,

Please take no insult! I am a little confused as you speak of one leg at 2 5/16 and one at 2 3/16 which means the material stretched 1/2" Therefore your bend deduction would be 1/2 or .499 using exact decimal equivalents. A quick check of an old chart gave me a .432 bend deduction though we used a smaller bottom die I'm sure. Without knowing the resulting bend radius of your test bend I can't even speculate as to the actual k factor. What I'm reasonably sure of though, if the top bending die had a .015 radius, you did not actually achieve a .015 bend radius. Even that must be verfied to accurately determine your k factor. I would guess your brake guys could tell you what their bend deductions are? I would suggest using 'what they get' as opposed to k factors.