Illustration Number 1

What size dies do I need for my bender?  This seems to be the recurring question for many people looking to purchase a tubing bender and dies.  I do admit asking the same question many years ago with my first tube bender purchase.  Picking die sets is important for a couple reasons.  Perhaps the most important is you can not bend tube with the wrong size die.  1-3/4″ tube can not be bent with a 2″ die.  Many fabricators develop their on personal preferences when choosing tube bender die size including tube diameter and die center line radius (CLR). It is very important to understand how “Tube” and “Pipe” is measured.  Tube is measured by O.D. (outside diameter) and Pipe is measured by I.D. (inside diameter). See Illustration Number 1 for details.

Die size is not limited to material shape and diameter.  The die size also refers to Center Line Radius (commonly known as CLR).  CLR is measured from the center of the bend to the center of the tube. Center of the bend refers to the center line where the tube bender die rotates.  If you have access to someone with a tube bender and like the bends their machine produces ask them what CLR die they are using.

CLR can be important based on the job you choose to perform.  For instance over the years I have found a 6 inch CLR 1-3/4″ round tube die to be my choice for bending tube for a rockcrawler chassis and Jeep modifications.  My choice was made for a couple reasons.  The first reason is the 6″ CLR die does not stretch the outside of the 1-3/4 x .120 wall tube too much.  “Tighter” or smaller CLR dies for large diameter round tube can stretch the outside of the bend as it wraps around the bender die.  For rock crawler applications this can effect how easily the tube in your chassis can be dented.  Dented tube can lead to failure and should be replaced.   I am trying not to inject my personal opinion into this article but for some reason I feel the need to discuss my 6″ CLR 1-3/4″ die choice.  Another key reason I settled with this die size has to do with looks.  When working in and around sheet metal I have found a 6″ CLR die working for most projects.

Before purchasing a 6″ CLR 1-3/4″ round tube die I was using a 7″ CLR die.  The 7 inch CLR die was a good die size as well.  My main reason for switching to a 6″ CLR was bending tube for Jeep related projects.  When fabricating a rear wrap around tube or horizontal hoop around the back of a Jeep the 6″ CLR die matched up to the Jeep tube for a much better look.  I eventually sold the 7″ CLR die because I simply never used it.  Please keep in mind this is my personal experience and personal opinion on a CLR for 1-3/4″ round tube.  You may prefer a different CLR for larger tube diameters.

Things to understand when selecting a bender die:

  • CLR (Center Line Radius)
  • Round Tube (Measured by outside diameter or O.D.)
  • Pipe (Measured by inside diameter or I.D.)
  • Square Tube (just what it says square tube and is measure by outside dims)
  • 120 Degree Die (needed to make a 90 degree bend or slightly over)
  • 240 Degree Die (Used to bend up to 180 degrees.  Can be used to make shock hoops, driveshaft loops, and more)

Custom fabrication possibilities are endless.  After purchasing a tubing bender you will find yourself bending tube for a lot of different applications.  Depending on what you are building you can determine if you need a 120 or 240 degree die, the CLR, and tube diameter size.  The following might be a good choice of dies for most shops.

Die Sizes I have Used For Many Years:

  • 6″ CLR 240 Degree Die for 1-3/4″ Round Tube
  • 6″ CLR 240 Degree Die for 1-1/2″ Round Tube
  • 4″ CLR 240 Degree Die for 1-1/4″ Round Tube
  • 4″ CLR 240 Degree Die for 1″ Round Tube

Keep in mind you do not need to purchase 240 degree dies.  Most applications do not require a 240 degree die.  I the planning stages of your build you can design the project to work with the tooling you have.  I did not post the above statement to lead you to believe 240 degree dies are required.  Shock mounts can be designed into the chassis without the need for a traditional shock hoop.

If you have any questions or need help choosing a die size feel free to CONTACT JMR for assistance.