Bend Line Spreadsheet
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Background Summary As a scratch builder of the Zenith Zodiac CH601XL aircraft, I was fac bends in sheet aluminum with a bending brake. From my online convers alone. As an aside, the design for my bending brake came from Dave Clay, a T His plans for an 8' bending brake provide a straight-forward and cost metal in your own shop. For a copy of his plans, visit his website a "Tools." The only modification I made was to extend the length to 10 between rivets to add strength for the longer hinging action. After much trial and error, I picked up my copy of Tony Bingelis' exc Techniques" and read (and re-read) his section on "Making Fittings." describe the mathematical process needed to change a flat piece of sh and two flanges. This involves a 7-step process (shown on tab #4) th intensive if done manually. I decided that this was the perfect plac The spreadsheet labeled "Bingelis DL Calculator" is the result of tha accurate and works as intended. After going through that process, I then re-read the Construction Man design and his long experience in aircraft engineering is evident thr page 12 of that manual he writes: Starting with that much simpler formula, I then created the worksheet Calculator." With only slight modifications I was able to produce th
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Transcript of Bend Line Spreadsheet
Background SummaryBackground Summary
As a scratch builder of the Zenith Zodiac CH601XL aircraft, I was faced with the challenge of making accurate bends in sheet aluminum with a bending brake. From my online conversations with others, I learned I was not alone.
As an aside, the design for my bending brake came from Dave Clay, a Texas builder of the same type of airplane. His plans for an 8' bending brake provide a straight-forward and cost-effective means of making straight bends in metal in your own shop. For a copy of his plans, visit his website at http://www.daves601xl.com and look under "Tools." The only modification I made was to extend the length to 10 feet and to decrease the pitch (spacing) between rivets to add strength for the longer hinging action.
After much trial and error, I picked up my copy of Tony Bingelis' excellent book "Sportplane Construction Techniques" and read (and re-read) his section on "Making Fittings." This is where he goes into great detail to describe the mathematical process needed to change a flat piece of sheet aluminum into a piece with a flat web and two flanges. This involves a 7-step process (shown on tab #4) that is very precise but also quite time-intensive if done manually. I decided that this was the perfect place for an Excel spreadsheet.
The spreadsheet labeled "Bingelis DL Calculator" is the result of that effort. To the best of my knowledge it is accurate and works as intended.
After going through that process, I then re-read the Construction Manual for my airplane. This is a Chris Heintz design and his long experience in aircraft engineering is evident throughout the plans and the final product. On page 12 of that manual he writes:
Starting with that much simpler formula, I then created the worksheet tab labeled "ZAC Single Bend DL Calculator." With only slight modifications I was able to produce the "ZAC Double Bend DL Calculator" worksheet. By comparing that worksheet with the "Bingelis DL Calculator" it is possible to see how incredibly close the Heintz approximation is to the more-complicated Bingelis formula. Feel free to use whichever method works best for you.
A future addition I hope to make is additional tabs for triple and quadruple bends. On the 601XL there are several triple bends (center spar web, aileron stops, cross stiffeners and standard "z" angles). Two parts -- the gear channel and heel support -- require four straight bends. As time allows, I hope to modify the spreadsheets to accommodate those calculations. Any help from others in this area would be appreciated. If you would like to share your findings, I'll be glad to incorporate them with credit.
Of course, as with all matters pertaining to experimental aircraft production, you are responsible for all decisions regarding the advice you take and the parts you make. I'm not an aeronautical engineer, so these formulas and worksheets may contain errors. Use at your own discretion. For the sake of others, please report any errors you find and I'll be glad to make corrections.
Larry WingerTustin, [email protected]
2006-09-01
ZAC Single Bend DL CalculatorAssumptions:mminchesLength of Flange A18mmLength of Flange B18mmDegree of Bend90degreesRadius0.125inches3.17500625Thickness0.063inches1.60020315Formula:Results:32.81dl in mmDL = A + B - (R/2 + T)16.41Bend Line (sight line) in mm from A edgeBend Line = A - R/208-2006 Spreadsheet by Larry WingerFeel free to direct comments or questions [email protected]
ZAC Double Bend DL CalculatorAssumptions:mminchesLength of Flange A18mmLength of Flange B18mmLength of Web80mmDegree of Bend90degreesRadius0.125inches3.17500625Thickness0.016inches0.4064008Formula:Results:112.01dl in mmDL = A + B + C - (R + T*2)16.41Bend Line (sight line) in mm from A or B edgeBend Line = A - R/279.19Distance between bend lines (in web)08-2006 Spreadsheet by Larry WingerFeel free to direct comments or questions [email protected]
Bingelis DL CalculatorAssumptions:mminchesLength of Flange A18mmLength of Flange B18mmWidth of Web C80mmDegree of Bend90degreesRadius0.125inches3.17500625Formula:Thickness0.016inches0.4064008Setback3.581mmSB (Setback) = R (Radius) + T (Thickness)Step 1:Subtract Setback from Flange A14.42mmStep 2:Add Bend Allowance5.27mmBA (Bend Allowance) = ((.01743*R)+(.0078*T))*degrees of bendStep 3:Subtract Setback from both sides of Web B72.84mmStep 4:Add Bend Allowance5.27mmStep 5:Subtract Setback from Flange C14.42mmResults:Step 6:Add all figures to obtain developed length112.21dl in mmStep 7:Draw Brake or Sight Line16.51bend line (sight line) from edge of flange in mmDistance between bend lines (in web)79.19*Based on the process described by Tony Bingelis in "Sportplane Construction Techniques" (EAA, Fourth Printing 1998)in the section on "Making Fittings" (pp. 38-47)08-2006 Spreadsheet by Larry WingerFeel free to direct comments or questions [email protected]
Bend Allowance TableBend Allowance TableRadiusGage1/321/163/321/85/323/167/321/49/325/1611/323/87/161/20.0160.0160.0600.1090.1580.2070.2560.3050.3540.4030.4520.5010.5500.5990.6980.7960.0160.000670.001210.001760.002300.002850.003390.003940.004480.005030.005570.006120.006660.007750.008840.0250.0250.0670.1160.1650.2140.2630.3120.3610.4100.4590.5080.5570.6060.7040.8020.0250.000740.001280.001830.002370.002920.003460.004010.004550.005100.005640.006190.006730.007820.008910.0320.0320.0710.1210.1700.2190.2680.3170.3660.4150.4640.5130.5620.6110.7090.8070.0320.000790.001340.001880.002430.002970.003520.004060.004610.005150.005700.006240.006790.007880.008960.0400.0400.0770.1260.1750.2240.2730.3220.3710.4200.4690.5180.5670.6160.7140.8120.0400.000860.001400.001950.002490.003040.003580.004120.004670.005210.005760.006300.006850.007940.009030.0510.0510.1340.1830.2320.2810.3300.3790.4280.4770.5260.5750.6240.7220.8200.0510.001490.002030.002580.003120.003670.004210.004760.005300.005840.006390.006930.008020.009110.0630.0630.1420.1910.2400.2890.3380.3870.4360.4850.5340.5830.6320.7310.8290.0630.001580.002130.002670.003210.003760.004300.004850.005390.005940.006480.007030.008120.009210.0720.0720.1980.2470.2960.3450.3940.4430.4920.5410.5900.6390.7370.8350.0720.002200.002740.003290.003830.004370.004920.005460.006010.006550.007100.008190.009280.0810.0810.2040.2530.3020.3510.4000.4490.4980.5470.5960.6450.7430.8410.0810.002270.002810.003360.003900.004440.004990.005530.006080.006620.007170.008260.009350.0900.0900.2100.2590.3080.3570.4060.4550.5040.5530.6020.6510.7490.8480.0900.002340.002880.003430.003970.004510.005060.005600.006150.006690.007240.008330.009420.1250.1250.2840.3330.3820.4310.4800.5290.5780.6270.6760.7740.8720.1250.003150.003700.004240.004790.005330.005880.006420.006970.007510.008600.009690.1880.1880.4260.4750.5240.5730.6220.6710.7200.8180.9160.1880.004730.005280.005820.006370.006910.007460.008000.009090.010180.2500.2500.5680.6170.6660.7150.7640.8620.9600.2500.006310.006850.007400.007940.008490.009580.01067Radius Multiplier0.01743Thickness Multiplier0.0078Legend:x.xxxLight yellow = Bend allowance for 90 degree bendx.xxxxxLight green = Bend allowance per degree of bend*Based on the formulas described by Tony Bingelis in "Sportplane Construction Techniques" (EAA, Fourth Printing 1998)in the section on "Making Fittings" (pp. 38-47)
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