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Discussion Starter #1 (Edited)
I was making a hoop to go straight up from the floor, and angle it in/back along the windshield, then straight back over the window, and then straight back/down to the bed. I made the first bend at the top of the door post 25 degree's, and then went to the second bend. Set it up for the 65 degree bend, plus I lifted the piece I just bent 15 degree's to account for the kick in, but after I made the second bend, it only kicked in 8-9 deree's.
.Instead of rotating the tube 15 degree's, we should have continued rotating until it was 15 degree's from horizontal.

I would like to understand the math behind these compound bends. It seems as though we are not taking into account the "Z" axis, or something. Basically, I think we are setting the tubing up 15 degree's for the kick in, but after the compound bend, the tubing rotates, and now the top side has rotated over (which changes the angle). WOW, better read that one a few times.

I know I could bend some conduit until I got the right angle, but what is the fun in that! I read a thread started by STATION last August, but didn't really see a clear answer.
 

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Chubby Chaser
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Shoot a PM to Tin Bender or fatkid, better yet read Bending 101;)
 

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Yeah, a clear answer never really did come from that post. I ended up not being able to figure out how to do the math myself. I lay the peice of tubing out in autocad, and can easily use it to figure out the overall degree of bend needed to accomplish multi-plane travel, and how many degrees the tubing should be rotated from the previous bend.

Autocad has been a huge time saver in the construction of my buggy. There are only a few 90* bends on my buggy. Doing all of the math for travel in plane# and degree in plane# for every peice of tubing takes forever. I am not good enough at cad to construct my entire chassis on it, but I have the centerline of near every single tube layed out individually.

I got your e-mail...I will answer any questions not regarding the questions about this tomorrow, or will try to help with any more questions you have about this.

Sean
 

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Discussion Starter #4
Bending 101 got my to this point, but he didn't address compound bends (more then one plane). :flipoff2:

TINBENDER must be the bending guru, cause your the second person to mention him?
 

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Mustard Dog said:
Shoot a PM to Tin Bender or fatkid, better yet read Bending 101;)
Bending 101 is no help at all for what he is asking...... Bending 101 only covers single plane bends. It is also a big waste of time for me... I can have a peice of tubing drawn out on paper, cut, and bent in the time it takes to make a caveman drawing on the floor.


Sean
 

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Station said:


Bending 101 is no help at all for what he is asking...... Bending 101 only covers single plane bends. It is also a big waste of time for me... I can have a peice of tubing drawn out on paper, cut, and bent in the time it takes to make a caveman drawing on the floor.


Sean
Woopdedooo

What are you a conduit bending electrician:rolleyes:


Bending 101 has helped many people get the hang of their benders.
 

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Station said:


Bending 101 is no help at all for what he is asking...... Bending 101 only covers single plane bends. It is also a big waste of time for me... I can have a peice of tubing drawn out on paper, cut, and bent in the time it takes to make a caveman drawing on the floor.


Sean
Gee golly willikers, those caveman man drawings heve made things extremely fast and efficiant to the guys that bend for a living. How many cages was it that you've bent up again:rolleyes: :confused: :rolleyes:
 

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Monkeyboy said:


Woopdedooo

What are you a conduit bending electrician:rolleyes:


Bending 101 has helped many people get the hang of their benders.
I didn't mean to sound haughty , and I am sorry if I did. No I am no bending professional by any means nor do I ever claim to be.

What I meant is...
It is very innoying when people answer complex tube bending questions with " Go read bending 101" Obviously if a person is asking questions that are above what bending 101 covers then they are already familiar with it, or other techniques to use their bender.

I was no way intending to know Bending 101 or the the people who have provided it for everyone. But there are better ways to do things which people can work up to instead of just sticking to bending 101.

In August when I made a thread basically just like this one, I proposed that we come up with a more formula oriented Pirate special bending guide; A guide that not only covered bending formulae, but also geometric, and trigonometric principles?formulae. No one seemed too interested in it at the time. Hopefully this time around maybe we can get some people who want to put something better together.

Bending 101 is great for what it is....a very basic way to get acuanted with the operation of a bender. There are alot of people who are interested in more advanced technique, and Pirate should be the place to share that knowledge rather than continually pushing bending 101.

Sean
 

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Mustard Dog said:


Gee golly willikers, those caveman man drawings heve made things extremely fast and efficiant to the guys that bend for a living. How many cages was it that you've bent up again:rolleyes: :confused: :rolleyes:

I surely did not mean to turn this into an argument...

I am currently working on my first tubular space frame now, and the first few bends was enough for me to see that Caveman drawings are not the ticket. If you graduated from highschool(WHich is all the credential that I have which apply) then you should be able to accomplish laying out all of the bending situations that Bending101 covers on paper quicker than you can draw them on the floor.

Sean
 

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I worked this problem out mathmatically a few months ago, but lost the sheet. I had e-mailed it to someone on this board, hopefully they will speak up and post it. If I remember correctly multy plane bends:

Over all angle = X
Angle in one plane = Y
Angle in other plane = Z

X = arctan[sqrt( (tan (Y))^2 + (tan (Z))^2 )]

In other words, take the tangent of each angle, square those numbers, add them together and take the square root of that number, then take the arctan of that number, and that's your angle.

Chad
 

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You will find that bending tube can be more art than science. That is a tough piece to make for a beginner. Be sure to very carefully double check how you clock the second one to make a mirror image. I would be willing to bet that most pro fab guys on this BB would just eyeball it in the bender.
 

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bending is an art, i think too many people see awsome looking rigs/tube work and dont know the # of years experience thats behind the sceens.. Bending 101 guide is just enough to get you started and hopefully the light bulb goes off and you can see there is more to its....

But. for joe average tube kinker like me, everything is a 2d bend, I roll my junk out side and bend everything 1 bend at a time, with a helper or tack welds, to hold it as i go. I then measure the next bend, use a pumb bob to find/make a reference point for the die, ive since learned some stuff and can make better guesses as to what to do. Using an angle finder helps a lot...

-yag
(amature tube waster)
 

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sounds like we need somebody to write up a bending 102 article that covers more complex bending techniques.
 

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chadl said:
I worked this problem out mathmatically a few months ago, but lost the sheet. I had e-mailed it to someone on this board, hopefully they will speak up and post it. If I remember correctly multy plane bends:

Over all angle = X
Angle in one plane = Y
Angle in other plane = Z

X = arctan[sqrt( (tan (Y))^2 + (tan (Z))^2 )]

In other words, take the tangent of each angle, square those numbers, add them together and take the square root of that number, then take the arctan of that number, and that's your angle.

Chad
I believe that was me you sent that to, but I had a major computer crash since then and lost your diagrams. From your diagrams it appeared as though that is a correct formula for finding the compound bend angle. That is not all you need to complete the bends in question though. SInce each bend on it's own is in one plane you have to know how to phase it in relation to other bends in the peice of tubing. I do not know the formulas for finding this out, I use cad for that.


Sean
 

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camo said:
sounds like we need somebody to write up a bending 102 article that covers more complex bending techniques.
Thats what I'm saying....... I directly propsed that when I made my last thread, and nobody bit.

Sean
 

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Station, I'm sure I have a "formula" around here somewhere, And I'll try to dig it out...

As for what I use, there are much easy'r ways to go about finding the angles on complex dual/ trip plane bends...

This may sound kinda Fawk'd, but there ARE some things that I do keep to myself, After all this is what I do for a living..:flipoff2:

I caught a little shit from some of the other "tube guys" when I wrote 101, cause now everyone and their mom has a bender, and thinks that thier "DA SHIT" when it comes to bending...
True, Get'n a GOOD dual plane or Trip plane bend Right is ALOTTTTTTTT more involve'd than 101..
101 is for the BEGINNER and ment to be.

Again, I'll try to dig out the "paper" as soon as I can get off the "floor".....
 

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Discussion Starter #18 (Edited)
I read the tubing 101, and everything was rosie, but lastnight we just hit this brickwall. It's was totally unexpected and very frustrating. It would be nice if the tubing 101 article mentioned this.
After getting some sleep, things seem clearer today. What's happening in my example above is; we are measuring the angle before the bend on the front side of the tube, but after we put the compound bend at the top of the door (65 horizontal and rotate 15 degree's), the front side we measured initially has rotated to one side. Now when you measure the windshield angle, from the new front side of the tube, it's steeper.
So, even though we put a 25 degree bend at the door post, looking down on the axis of that piece of tube, we rotated it 15 degree's in the second bend. This axial rotation changes/decreases the sloop of the windshield portion when measured from the front and you get alot less slant at the side of the windshield.
 

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8 bends on the continuous front hoop...a friend does cages professionally (website pending), and he did an excellent job with mine...would have taken me a year for just the front hoop. We started this cage on a Tuesday evening, finished/painted it that Thursday evening. Clears the high-mount wiper on the windshield by less than 1/2". Even the pre-existing spare carrier landed exactly in the center of the rear X-brace...perfectly centered.

I'm a personal-fab kinda guy, but there ARE things best left to the pro's. He uses a hydraulic ProTools and their good notcher. All his sketch work is done on a chalkboard on the wall...do enuf cages and the measurements are second nature.
 

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Discussion Starter #20
Woody, he does excellent bends, but I don't see anything in three plains. It's more then just up/down/up and 90 degree hoop. Your right though, it's not easy, but it sure is fun! If I paid someone to do it, look at all the fun I would be missing out on. I'm learning a new skill, and appreciation for something I never understood before. Makes me a better, and less ignorant person then I was yesterday.
 
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