AVT 206 A&P - P2 - Developing Sheet Metal Flats

AVT 206 A&P - P2 - Developing Sheet Metal Flats - The Math Behind the Bends

Рет қаралды 432,976

Күн бұрын

This video is an explanation of the math on the FAA Airframe test. You can learn to bend metal without doing this math - but this video is about doing the math. It explains how setback, bend allowance, bend radius, and sight lines work when bending a radiused corner on the brake. Using the analogy of turning a corner in an automobile, all of the appropriate formulas are developed and explained. This is delivered classroom style, with my bad attempt at green screening. Sorry about the poor appearance. This fits in with my sheet metal series project 2.
For those interested in more details, I have a follow up video explaining how to apply these formulas to non-90 degree bends. I also have several examples showing the math.

Пікірлер: 200

@miruu28 3 жыл бұрын

Why is it so difficult to find such important info on the internet! Thank you so much.

@ismaeldelgado6615 15 сағат бұрын

The best explanations of where each thing comes from!!! Thankyou!!!

@rtwg605 2 жыл бұрын

Thank you!! This was a FAR better explanation than I'd gotten from my own class. I'll be watching more of your explanations.

@magedgaber7541 4 ай бұрын

from someone who's been in the service for more than 25 years in the Air Force this is by far the best explanation ever , thank you sir !!

@willw.birnie8446 Жыл бұрын

Keep it complicated! This is exactly what I have been looking for! Thank you so much. Keep up the great work!

@josafabass9670 6 жыл бұрын

I´d like say, thank you so much, your explanation help me a lot, I was worried about bend but your video take my questions away

@nyronm941 5 жыл бұрын

Best explanation available love how simple you made it, great job !!!!!

@TheEngineeringToolboxChannel 5 жыл бұрын

nyron matton agreed he did a great job!

@jeffchisamore1556 6 жыл бұрын

You totally made this easier to understand. I punch flats on a turret and often have to calculate bends out of the drawings. Good video. Totally worth watching.

@naboulsikhalid7763 4 жыл бұрын

great explanation, without a word. thank you for sharing your experiences and knowledge.

@scottyp.644 3 жыл бұрын

Thank you. When the company wants to know the procedure for how I do what I do. I will direct them to this video. I think my job is safe. You are brilliant. Excellent explaination.

@prateeksharma5124 7 жыл бұрын

concepts are very nicely put in a concise and interesting manner. good presentation style. thanks for uploading...

5 жыл бұрын

Omg man, I can't even begin to thank you for this. I didn't go to college b/c I started developing a software product which turned into hardware as well but now I'm on a "roadblock" since I lack some very specific knowledge like this. Thank you so much man!!

@pauljohnson1991 2 жыл бұрын

Even if you went to college you'd still be here watching with the rest of us lol

@1donagin 7 жыл бұрын

This video shows the theory behind making 90 degree bends. Here are links to more. For info on non-90 degree bends, see kzfaq.info/get/bejne/htSYo61yu7zFo5s.html. To see example calculations done by hand, see kzfaq.info/get/bejne/ja5iqJdkutbTgKM.html and kzfaq.info/get/bejne/jLCddrNqq92ucac.html. To see non-90 degree examples, see kzfaq.info/get/bejne/d9B4qsJjyMymoas.html and kzfaq.info/get/bejne/g7VlhNWWntjIZqM.html. To see the bends made in the shop, view kzfaq.info/get/bejne/rKqHjN1yybjOd4k.html. To see the same bends made in the shop without the math, view kzfaq.info/get/bejne/f56qgMeTnbLWgJc.html.

@insylem 3 жыл бұрын

Thanks for the refresher. A&P School was 12 years ago. Though, I've only ever done all that math in School. Even for my airframe test, we just guessed and bent it.

@r.mercado9737 4 жыл бұрын

This was quite stimulating! I enjoyed this teaching very much!

@zakaroonetwork777 Жыл бұрын

Thank you So much. So far the best Bend video on KZfaq. 😊

@elysha1980 5 жыл бұрын

I can't thank you enough for such amazing information video which you share with :)

@BrilliantDesignOnline 4 жыл бұрын

Absolutely excellent explanation with great analogies.

@pramodkinge8225 5 жыл бұрын

Thanks a lot for all of this knowlegde..looking forward to see more like this..!!

@tjvanderloop1686 6 жыл бұрын

Great sheet metal "Bend Allowance" based on thickness and MATH...Great Job! Thomas J. Vanderloop, Author, Technology Instructor & Manufacturing Consultant; CMfgE & LSME

@RPREYNO 5 жыл бұрын

I took Sheet Metal one year ago and I’m testing for my Airframe O&P this Saturday. Thanks man!

@1donagin 5 жыл бұрын

Good luck on the O&P.

@pradipacharya6794 4 жыл бұрын

I was in the middle of video and I just looked at T-shirt and saw SIU Carbondale... I am also in the same university for MS in Mechanical Engineering... Thank you for sharing knowledge

@michaelevans3307 6 жыл бұрын

Thanks for all the videos you have made for AMT instruction.

@1donagin 6 жыл бұрын

Thanks for both comments. Can you contact message me through my profile? I can't seem to get you a private message.

@paulmanhart4481 Жыл бұрын

This is exactly what I’ve been looking for. Thanks.

@throngcleaver 6 жыл бұрын

Many years ago, while working as a flight mechanic at a large aerospace corporation, I was tasked with building several complex parts for a flight test aircraft. The stack of drawings was daunting, with each part having multiple bends at various angles, but also multiple radii on some parts, and many of the flanges were at angles to the other flanges. Calculating non-standard angles wasn't fun, since the process at the time was to look up the setback in a table for that thickness and radius. (table was every 5°) I'd then have to do the math to extrapolate the answer for, say, a 37° angle. I knew how to calculate the bend allowance and do all the math, but it was taking too long and errors could definitely happen. I went to one of the computers in the shop, and basically put the bend formula in an Excel spreadsheet. I gave it enough places to add up to 4 bends, to make hat sections. To use it, all you have to do is type in the thickness, radius, and angle of each bend, and hit enter. It fills in all the info you need, and puts it in a drawing format with the thickness, radius, and angle of each bend in a table below the drawing. One click on the print button, and you're ready to cut your metal and head off to the press brake to bend your parts. Everyone loved it, and they are still using it today. Now I use Solidworks, but it took a bit of experimenting in the program to get the K factor correct (not .5) for aluminum correct. I knew my formula to be correct in my spreadsheet, so I drew a 1" x 1" flanged part, and kept changing the K factor until it measured within 0.0005" (half a thousandth) of what my formula said the flat pattern length should be. I've only used cornice brakes and finger brakes a few times, (A&P school mostly) but I always used a small hard square to align the sight line with the edge of the brake radius. Press brakes are where it's at though. Very nice explanation of what's going on in sheetmetal bending! Brought back a lot of memories. Thanks for sharing your expertise!

@trmechanic 6 жыл бұрын

thanks

@TheEngineeringToolboxChannel 5 жыл бұрын

Going through something similar at my company. Trying to streamline and standardize how we determine things like bend deductions, tool selection, die opening size, etc. Sheet metal bending has so many variables but once you standardize and control them it becomes much more predictable. Automated flat development processes and CNC press brakes make things a little easier too :).

@arniespace 5 жыл бұрын

I worked in sheet metal shops my whole life (retired now). I was a welder for many years and moved into calculating flat layouts for the last 13 years of my career. I did something similar but I developed my programs on a graphing calculator instead of excel. My programs would prompt for the necessary variables and then spit out all the dimensions needed to draw out the flat with autocad. We made a lot of cones and transitions so I had programs for those as well as other shapes you would come across in daily life. My cone program would calculate the chord, which was necessary to draw the flat in a CAD program, as well as all of the other information needed. The variables it prompted for where simply the two diameters and how tall the cone was. It was a lot like cheating, but I was never wrong, unless I made a really dumb mistake and entered a variable incorrectly. The variables for most other shapes where basically what are referred to here as the mold lines, plus the die radius, real world location of holes, etc. I never had to worry about sight lines, that was up to the press brake men, but they had computerized back stops, I only needed to give them the bend line and radius information. I also was responsible for nesting the parts on the sheet for laser cutting. At the end of my career we started using Solidworks, which took all the fun out of it.

@tulsihomes 3 жыл бұрын

Can you please share the formula you were using.

@throngcleaver 3 жыл бұрын

@@arniespace Great stuff! I've only designed and made a couple of cones, and they were related to bomb tails. Fun! I too, loved the challenge of it all, and really enjoyed that part of my career. The small department where I ended up making flight test components had a pair of Promecam hydraulic press brakes, one 4' and one 6'. They had DROs on their back gauges, making them super accurate. I ended up starting a business, (not related to sheetmetal fab, mostly machining) and eventually it morphed into sheet metal fab for U.S. Army helos. I had a pair of waterjets, (wish I had had a laser!) and bought a 4' Amada press brake. The hole location tolerances were 0.002", meaning that the center of the hole had to be inside a 0.002" circle. I put all the holes in the flat pattern full size, and once cut, deburred, countersunk for rivets, and bent, all the pieces Clecoed together and the rivets fit perfectly. (They also got conversion coated and primered, and a few got anodized black) Gotta love technology, at least for production parts. :D Saved a TON of labor. While I do love Solidworks, it sure took the fun out of figuring out the really difficult pieces. At least that knowledge got me retired at 46. I truly was lucky that I chose being an A&P as my career. Edited, because I forgot to mention, that in my spreadsheet, the little drawing included the 4 bend lines, (even if you only had one bend.......everything else would be zero) and also the material thickness, part number, bend angle, radius of each bend, and leg length, so you could mike the flanges without having to have the actual drawing at the brake.

@kfsrayjay7898 Жыл бұрын

thank you so much!! Explained it better than my teachers did!

@atalowais 7 жыл бұрын

Helped a lot to understand the differences 👌🏻

@johnreed4502 6 жыл бұрын

great presentation with application !!!

@nikhildasnm2808 5 жыл бұрын

Good work worth it actually can use these techniques to my projects also

@Engineers_Web 3 жыл бұрын

Your explanation is outstanding 👍

@michaelyoung698 5 жыл бұрын

Aok. Now I'll be visualizing those cars and drivers each time I get my bend allowance!

@rgsparber1 4 жыл бұрын

Excellent tutorial. I followed it very closely and found the following minor inconsistencies: At 7:02 you imply that the material thickness is 0.032 but at 11:20 you only get 0.165 if the MT is 0.040. At 15:40 you say "inner ones" as in the inner tangent lines but the diagram shows you are using the outer tangent lines. The text is consistent with the diagram. At 9:41 you say the actual neutral axis is at 0.455 but the equation says it is 0.447. As I said, I followed very closely. Thanks for the education!

@PG-qm5nk 3 жыл бұрын

Yes I agree, some big holes is his examples . I cant quite follow where he's pulling these numbers from?

@baklolHai 3 жыл бұрын

It's good to see this video . Useful for an engineer

@bearsrodshop7067 3 жыл бұрын

Can't learn this kinds knowledge @ your local jr collage,,,Great presentation, and at 68+, just getting into making more parts from sheet metal & aluminum. This will be most beneficial with the cost of materials soaring everyday. thx, New subscriber as of today, Bear

@eddievarela5691 2 жыл бұрын

This was very informative. Thank you

@vinayyadav9077 5 жыл бұрын

Great video for concept...thank you sir..

@AhmedXGhost007 4 жыл бұрын

best presentation i have ever seen

@Luis0J 6 жыл бұрын

My bend deduction formula for all materials and 90degree bends is 0.434(3MT + R) its always worked for me and never gotten me in trouble. I derived it the same way he explained in the video and I confidently would allow anyone to use it.

@TheEngineeringToolboxChannel 5 жыл бұрын

This is most likely a good estimation but I would always suggest bend samples for every combination of material type, thickness, bend radius, and even die size. This is the only way to know exact bend deductions/K factors for your process.

@lewisj856 3 жыл бұрын

Awesome video. Thank you!

@ZimmMr 4 жыл бұрын

Thank you sir, this video is VERY helpful

@Pradjaya 6 жыл бұрын

Sir, excellent explanation..👏👏 we need teachers like you in India..one with actual experience

@TheEngineeringToolboxChannel 5 жыл бұрын

Yes, he did a great jobs explaining these things!

@swamihuman9395 5 жыл бұрын

Excellent, simple explanation. Thx. BTW, I design in Autodesk Fusion 360 which supports sheet metal modeling.

@lewisngeno4789 6 жыл бұрын

thanks helped so much in my project

@bkkunalsharma233 4 жыл бұрын

Wonderful knowledge of sheet metal

@badboybootz8 4 жыл бұрын

Taking my O&P soon and this just scared the hell out of me lol

@davidbarrett7424 5 жыл бұрын

i like your teaching style. thanks!

@rkregers 3 жыл бұрын

Thank You so much for this video! If this was in metric system units it would be priceless, lol

@adamsisson5458 6 жыл бұрын

Thanks. Great video!

@EstechMagnetics 2 жыл бұрын

It’s more like 1/3 material thickness instead of 1/2 on the neutral axis. Metals are more encouraged to stretch than shrink, especially when the die is in static connection with the material.

@Portrayalpress 4 жыл бұрын

Super job - thank you.

@brahimabdelsadek5815 4 жыл бұрын

Thanx so much master.big respect to u.keep going

@sethgecko1972 5 жыл бұрын

Good work buddy!

@malcolmhodgson7540 2 жыл бұрын

Such great detail, put really well.

@richardbarnes3665 5 жыл бұрын

Such an excellent lesson!!!! Thank you for sharing this with us. Would you be willing to share this PowerPoint?

@D4rkS7der Жыл бұрын

Very usefull video, thank you very much.

@karanp5728 3 жыл бұрын

Wow, thank you so much sir 🙏

@justinsinkala Жыл бұрын

Nice work brother man

@jacobmassengill1553 Жыл бұрын

fascinating how much the bend allowances of glass and metal feel familiar. Ice only blown Boro glass though

@NoNo-dq4mc 3 жыл бұрын

if you follow the algorithms needed to produce the bend allowance and consider k factors, most metals that are commonly bent will hold true within tolerance if metal grade or tolerance of thickness is followed And the machine is dialed in. I only have trouble with a few alloy as far as I have encountered.

@nathansmith8183 3 жыл бұрын

This is fantastic.

@amrhussein951 6 жыл бұрын

in first example how you get the value of set back to be 0.165 (or you assumed it ). thanks for great explanation

@Ricky123g 4 жыл бұрын

GREAATT JOB! THANKS FOR THISS!

@ummyhorse7791 Ай бұрын

Indeed,, thank you very much sir.

@jameshenderson3867 2 жыл бұрын

Thanks brother more understanding

@lostcar2312 Жыл бұрын

Great video. I Need to convert to mm now.

@DennisZIyanChen 5 жыл бұрын

Take the concept to a deeper first principle level, and everything is super simple. All really rudimentary stuff honestly if you just understand how metal behaves in terms of its isotropic and kinematic hardening and how the yield surface may expand or translate and why a bend radius is needed becomes really clear. First principle thinking is never about explaining the real world, but it provides a foundation that's applicable to all problem types.

@MuckingMunt 5 жыл бұрын

" if you just understand ...." "...isotropic and kinematic hardening and how the yield surface may expand or translate and why a bend radius is needed becomes really clear." I think it's this bit you assume is already in a lot of peoples education or experience already. I doubt anyone learning a trade as an apprentice would need to go off on deeper theory..... but chances are the geometry comprehension is already there from basic previous schooling or education to appreciate this video.

@nealblackburn8628 3 жыл бұрын

i worked at a place where we did that stuff all the time but i don't remember it being that complicated, but what would i know everyone else in the comments says great job

@justinfrisbie2652 5 жыл бұрын

Great information, overall Great video, however I think completing and showing the work for all of the math used would be more beneficial. But I learned alot, Thanks!

@BA-wt1gl 6 жыл бұрын

Draw the part profile from the side in CAD, then offset 45% through the metal from the inside bend radius's, then add arc lengths and flat lengths together.

@1donagin 6 жыл бұрын

Only they don't let you have a CAD program when you go to take your A&P certification test - which is what this video aims to help you with - hence the title. If you want to do it the easy way in real life, find where the inside edge of the bend will be, and line it up on the brake as your sight line. You will gain a little length as you make the bend, but the bend will be in the right place. Cut off the flat you bent to the right length, and you are done. Who cares if you wasted 20-40 thousandths of material? But these ways won't work on the test - so you have to learn the math if you want to pass.

@themadmachinist8637 6 жыл бұрын

I'm not going to lie, that's how I've been doing it when I'm bending stuff by hand. My work just got CNC press brakes and because I'm a machinist the plant manager has decided that makes me a sheet metal expert too. Thank you for these videos, when I learn something new I like to know it by first principles so I can apply the technique universally.

@remiew45 4 жыл бұрын

Interesting, but you are making it too confusing for some. A much more simple formula for the length of a bend is......length = (radius x angle x 3.1416) / 180. That will give you the length of the bend in the middle of the material thickness if you use r+1/2t

@JimBob-lz1gy Жыл бұрын

Yeah, or Radius x 2 x Pi = Circumference, divided by 4 = arc length.

@Alex-ns8zn 8 ай бұрын

absolutely tremendous

@idreeskhan-zp5ey 3 жыл бұрын

I wanna design v-shape die and punch for bending at 90°,please anyone tell me what should be the width and thickness of the die and punch,the inner radius,the punch force.If I choose the the dimension of the plate (to be bent) is length*width*thickness=200*30*10?

@jackkb100 3 жыл бұрын

what is the thickness and bend radius did you consider?

@sahildharia2972 4 жыл бұрын

Hey mate , I am from Mumbai University (India 🇮🇳). Thanks for this video.

@wealthyboyrr5410 6 жыл бұрын

Excellent and after all i am able to learn bending from a practical point of view. Also the buzzword "K" factor, i searched many websites and difficult to figure out how they arrived this factor and now i am clear. If possible put up a video how this K factor is found out for different materials, becoz we have whole lot of tables around the internet but unable to find how it arrived. Thanks a lot

@1donagin 6 жыл бұрын

The problem with K factor is that the same term is used to refer to different things. In many industries, K factor refers to the location of the neutral axis as a percentage. (Example K factor of .45 would be a neutral axis at 45 percent of the thickness of the material.) My example are from aviation, and the USA's FAA uses K factor to refer to the adjustment of the setback for various angles that are not 90 - so this is what you will see in my videos.

@wealthyboyrr5410 6 жыл бұрын

Thankyou don. i saw u r example video and found some website with K factor tables and arriving methods. They are for general purpose application. Thank you, u made bending theory simple when i am confused with CAD tools and now realized that hands on calculation and understanding of the fundamental theory with difference to real world case is important for design and made simple by u. Keep your work "DON" many like me will learn and follow u r teaching. Thank u

@sanjay052 3 жыл бұрын

How did he achieve .702 value in bending allowance?

@rookie147 6 жыл бұрын

So much theoretical and real world switchbacks I forgot if I existed

@TheEngineeringToolboxChannel 5 жыл бұрын

HAHA....if everything is controlled properly theoretical values and real world values should closely align ;)

@lazertroll702 3 жыл бұрын

yeah, it gave me flashbacks of anime filler; i was loosing track of what was 'canon' ...

@varunkumarshankar1192 4 жыл бұрын

How do you know bend radius . Got set back

@dmmdmm5435 6 жыл бұрын

It's good to have plenty of scrap stock to quadruple check your backstop, die placement, travel, cleanliness. Sooo many variables have to be just right to have an unremarkable perfect part. Practice on scrap to lessen waste and take notes.

@rajeevdabra6625 6 жыл бұрын

Sir, very good explanation . But you did not tell what is material thickness (MT) in you example and from where you had taken value of bend radius (BR) ????

@1donagin 6 жыл бұрын

The example problem assumes a thickness of .040 and a bend radius of .125.

@angaraanirudh2606 2 ай бұрын

can anyone explain how did he get setback as 0.165 at 11:22

@racinford1 4 жыл бұрын

I ran a Amada Turret press for years and would get programs for new development and blank and punch the holes and shapes in the flat. I had to inspect the blank and all the hole locations plus other cutouts to a drawing that only showed you the completed formed part. Being able to calculate all the bend allowances made me look like a genius . Its not that hard.

@90vijayanand 7 жыл бұрын

how to find k factor?

@freemanfootball647 8 ай бұрын

How to control K factor on production ?

@thestralsound 3 жыл бұрын

I'm not exactly on time here, and I may lack context, but where are the 1.57 and 0.702 used to calculate the BA coming from?

@nived3211 3 жыл бұрын

Info not given.

@jeraldcajes7575 3 жыл бұрын

Is this applicable for 130 degrees bend?

@carfordelforero7122 Ай бұрын

How about calculating angles different from90?

@andrewbroussard4843 6 жыл бұрын

Is this Power Point file available for reference?

@swenstreed 4 жыл бұрын

Very good, noticed one small error and around time mark 15:13 when you are explaining where to layout "sight line" using "bend radius" You state that you are measuring from the inside but the diagram clearly shows you are dimensioning "site line" from the outside, correct?

@1donagin 4 жыл бұрын

The site line can be measured off either bend tangent line. You pick whichever BTL you are going to put under the caul on the brake. Measure one BR towards (and in some cases past) the other BTL.

@MeetJohnnyNg 2 жыл бұрын

How did you come up with 0.165 set back?

@felixvincent643 4 жыл бұрын

I didn't quite get how he got to the .702 value. Is this a constant? It must have something to do with the K factor?

@floryedable 3 жыл бұрын

I think he messed up. It should be 1.57* BR + .455*MT...where 1.57 is 1/4 the circumference, and .455 is the K-factor ( I believe he said he was using for Alum), and I come up with .19625+.00728 = 0.20353, NOT 0.224

@MeetJohnnyNg 2 жыл бұрын

@@floryedable what is the material thickness for aluminum?

@bkkunalsharma233 4 жыл бұрын

Good sir

@synrene 6 жыл бұрын

Awesome video Did anyone catch him say '3 things' but put up 4 fingers lol

@tuna6024 4 жыл бұрын

I just caught that xD

@lazertroll702 3 жыл бұрын

that, and he threw around unit-less scalars ... reckless ..

@automirrorguard8676 2 жыл бұрын

I have a issue with bending m.s. sheet metal at 90 degree. Can you help.

@TECH-fn6lk 6 жыл бұрын

thanks sir....it's helps me....but I didn't understood that sight lines

@dangerousdon7750 6 жыл бұрын

looking straight down you can't see the line that you have to line up with point of the punch where its going to impact on the part, because it's under the punch, so you move the the line out by half your radius size so you can see it when looking straight down and line it up. its easy and makes perfect sense once you get it. but hard to explain with text.