BENDING EXACT SHAPES

In this exercise we will show the steps required to bend these 2 table frames to exactly the same sizes. The distance between the legs of the table needs to be 900mm.

The key here is to know exactly where on the die and the material to start bending.

We start by drawing the design on a level surface.

Now we need to establish where on the die the tube will start to bend.

Spray the inside of the die (the area where the tube will fit) with engineers’ marking blue or a quick-dry spray paint.

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900mm

Lock the die with a stainless pin in thelock hole.

This prevents the die from rotating during bending.

Now insert a piece of tube and proceed to bend it to exactly 90º. It is essential that this bend is exactly 90º so take your time.

Remove the 90º bend. Remove the pin locking the die and examine the area of the die that you have sprayed.

By examining the scratch marks on the inside of the die it is easy to see where the tube actually started to bend.

Now take a permanent marker and mark this spot on the top of the die.

All subsequent bends will start at this point on the die.

Now pick up that perfect 90º bend you have made. It is a very important tool as it willbe the template for all your bends in 25 mm Round Tube

Examine the 25 mm tube that you have bent to 90º.

It will have the same scratch marks on the inside of the bend.

Mark the start and end of the scratch marks on the tube.These marks signify the start and endof the bend.

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Now place the template tube on the drawing of your design.

Place it so that the legs of your template tube align with the lines on your drawing.

Mark the drawing at the points where the start and end of bend lines on your tube template touches the lines of the drawing.

Do this for both corners of your drawing.

The arrows in the picture below shows where on the drawing these marks were made

These lines indicate the position of the bend. Note they are an equal distance from the centre of the drawing. (If not you have made a little mistake- perhaps your template wasn’t bent to exactly 90º?)

Cut a length of tube equal to the length of sides A+B+C.B = 900 mm that the table legs need to be apart.A & C = your own requirement for the height of the table.

Find the middle of the length of tube (ABC).

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340 mm 340 mm

A

B

C

Make a mark 340 mm to each side of the tube’s centre.

These 340 mm marks indicate where you will start bending the tube in order for the bent tube to match the drawing you have made.

When you load the tube into the bender -match the start of bend line on the tube, up with the start of bend line on the die.

The tube will now be bent in exactly the right spot to fit inside your design drawing.

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Tube Centre

Once you have made the 1st bend the setup should look like this.

With the second leg bent your results should look like this.

As the picture illustrate, leg A was bent first, then the tube was removed completely, flipped over andleg C was bent. This means that you start from the centre of the tube and bend towards the outside. The mid point of the tube should always be in the position indicated on the picture prior to bending.

These same principles apply to the bending of any type of material. If you are bending to an angle other than 90 º first make a template bend to the same angle and use that to find your start of bend lines on the drawing.

You will also need to make a template for every size of tube you use. Make them up and paint them a bright colour to prevent them from getting lost in the junk pile.

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2nd 340 mm bend line

Mid Point of Tube (B)

1 st bend line lined upwith start of bend line on die.

Leg C

Leg A

Leg ALeg C

Midpoint of tube