home made mandrel.

don't know what kind of interest there is in this, but this place has free plans to build a mandrel for bending tubes. just email them. got the plans this morning. haven't started in on it yet though.
http://www.pro-tools.com/200k.htm
and this has what looks to be one of these machines built and in action, as well as other peoples takes on the design.
http://www.blindchickenracing.com/To...bingbender.htm

Its just a regular tube bender.A mandrel tube bender is a whole different machine,as in large and expensive,that draws a mandrel thru the inside or the tubing as its being bend.Just trying to clear up the mandrel part in your title.

and mandrel bender draws the tubing around the die, unlike a standard bender that pushes inward on the center of the tube which causes wrinkles. even the the expensive machines do it this way, i can not see a tubing bender with something inside the tube as it bends. if they exists how do you get it out once it is bent?

i have a jd2 mandrel bender and it is manual.

sure seems like a low tech mandrel when you watch the video on that site. looks like the action of the jack on the lower die makes the upper die swing the same way it would if it was drawing a pipe or a tube through.

yea your bender is declared a mandral

Actually, as Ratdog mentioned this is not a mandrel bender. A true mandrel bender has an articulated mandrel that fits tightly inside the tube to keep it from collapsing on a tight bend. The protools / jd2 etc benders are actually known as rotary draw benders.

The difference in price? A manual rotary draw bender such as the protools costs a few hundred and the dies are a couple hundred a set. A mandrel bender that will bend the same size range is going to cost about $30,000.00 for starters and the tooling is going to be starting at around $4000 per size tube on up.



Above is a pic of a true mandrel bender (mine) set up to bend 4" OD x .125 wall tube on a 6" centerline radius for a frame project I once did. The bender would cost over $100,000.00 to replace and the die set in these pics was right around $7000.00.

For more pics of the bender and results: http://tubularfab.com/gal2/main.php?g2_itemId=1425

so how accurate is a rotary draw bender compared to a mandrel or a pipe bender?

i stand corrected, i was always told a "rotary draw" machine was consider and madrel bender. learn something new every day lol

I almost forgot to explain - the mandrel is retracted in the pic above. Prior to starting the bend it is advanced so the nose of the solid part after the 2 articulating balls is tangent to the center of the bend die. The balls then are in the bend area as the tube slides over it. Once the bend is made the machine hydraulically pulls the mandrel back out to where it is shown above. During the bending process it stays stationary as the tube slides over it.

This type bender is only needed for thin wall tubes on tighter bend radii - such as high-end exhaust pipes. With thicker wall tube on bigger bend radii - such as rollbar tubes, etc - you don't need the madrel to support the tube and a rotary draw bender does a nice job.