True Mandrel Benders

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so, i'm hearing a lot about tube and pipe benders and am getting a little confused here and have a couple questions that i can't seem to find answers to... hopefully someone can help me out...1.) what is the difference between a pipe bender and a tube bender? i understand (probably incorrectly understand) one is measured using OD and one is measured using the OD of the piece. which is which?2.) where is a TRUE mandrel bender and how much do they cost? obviously, this technology and convenience is not going to be cheap, but if one were to use it A LOT, it could pay for itself it seems like from being able to charge un-godly amounts of money for U and J bends.3.) is there a "Proper" way of using a "non-mandrel" pipe/tube bender to create a uniform bend with a consistant and re-produce-able ID/OD? i have heard about capping one end and filling it with sand, but this seems like more work than it is worth. is there a better/easier way?4.) if properly maintained, how long can a set of dies be expected to last? i wouldn't expect to have a set ever "wear-out", nor hae i ever heard of one, but if a set is used in a shop on a regular basis, could the metal-to-metal contact cause an issue in the long-term?5.) similar to #4, but what about the entire unit? once again, i have never heard of an issue, nor do i anticipate a length of time shorter than indefinate, but i'd like to know everyone's angle on the situation.6.) what are some good brands? i ahve seen countless "home-made" benders that seem to be of high-quality and craftsmanship, but are there certain features that are offered by only one manufacturer, such as a chrome-plated whatchamacallit, or a titaium doohickey?7.) and this is the last one (i promise), would it be a good idea to just order one online, or is it more valuable to try to get one thru a local supplier? it seems like this would be similar to most other welding/fab equipment in the fact that it should be tried, in one way or another, before the final purchase.Thanks!Later,Andy
Reply:Pipe is measured by Inside diameter.Tubing is measured by outside diameter.Usually, but not always, pipe has thicker walls, and takes bigger, more expensive machines.A mandrel is a piece of the die that goes INSIDE the piece that you are bending. Almost no bender that costs under ten grand, and more likely 50 grand, is gonna have a mandrel. Mandrel benders are used in high production tube bending mostly- stuff where they cannot have any collapsing of the tube at the bend.http://www.hornmachinetools.com/mand...be-bender.htmlPipe is usually bent one of three ways in production- either free in the air, with induction heating (no dies at all) like Wagner does- this is incredibly slick.http://www.wagnercompanies.com/site/...ticle&rpid=652Or rolled on a three roll bender- like one of these-http://www.eaglebendingmachines.com/index66.htmlThe third way is a rotary bend with matching dies- like these-http://www.jd2.com/Of the three, the cheapest, and most common in small shops, is the last, a JD2 style. Not necessarily the best, but its cheap to get started in.JD2 makes great benders, and, relatively cheap. I think they only sell online.Certainly, you can wear out both the bender and the dies, just as you can wear out any tool. Its unlikely, though, if you arent doing production bending 5/8, that you would do so. I did totally wear out the bending arm on my hossfeld, after 20 years, and I bet you could wear out a JD2 after ten or 15 years too. Real bending shops have to buy new dies, and get machines rebuilt.
Reply:WOW!  Excellent, informative answer!  I didn't know 1/2 that stuff, very cool! Thanks Ries!Have a Jeep Cherokee?  Click Here!
Reply:thanks Reis!!!! that helped out a lot. i really appreciate it... like Skwerly, i didn't know half of it, and the other half was still a little fuzzy. thanks again for clearing everything up.Later,Andy
Reply:Originally Posted by RiesPipe is measured by Inside diameter.Tubing is measured by outside diameter.Usually, but not always, pipe has thicker walls, and takes bigger, more expensive machines.
Reply:Yeah - Ries pretty well covered the topic!  And I'm guessing I am partly to blame for the title of this thread since I am the one that used the term "true" mandrel bender in another post.  I tried to explain back in that post (seems like it was titled "production job"?) why you'd need need a true mandrel bending machine for that job, but guess I wasn't very clear...  Let's try again:First of all as Ries mentioned above a "true" mandrel bender is a machine that uses a mandrel inside the tube to keep it from collapsing in the bend.  It actually goes further than that - a true mandrel bender completely contains and supports the inside and outside of the tube at the point where the bend is occurring.  This is a very large, heavy machine (mine that does up to 4" tube is about 10,000lbs!) because it has to be extremely ridgid.  For full mandrel tooling you have a bend die, a clamp die, a pressure die, a wiper die, and a mandrel.  You should be able to find pics and descriptions of these on the Horn website Ries posted above.  There are 2 important ratios to consider when bending a tube/pipe - the wall factor is the ratio of the wall thickness to the O.D. and the "D" of the bend is theratio of bend radius to the O.D.  For instance, a 1" OD x .125 wall tube on a 2" centerline radius would have a wall factor of 1/.125 = 8 and it would be a 2D bend.  You use this info to decide what tooling you need.  A higher wall factor means a more difficult bend, and a lower D makes for a more difficult bend.  There are tables to compare these 2 numbers and see exactly what tooling is required - in this case you could probably get away without using a mandrel or wiper die because that is a fairly low wall factor.Many people think a JD squared or Mittler Bros bender is a mandrel bender, but it is not because you cannot use a mandrel with them.  The reason I said you'd need a mandrel bender was more based on the extremely tight bend radius rather than the wall thickness.  You just aren't going to be able to use a 1 or 2" centerline radius bend die on one of those benders.  Another reason I said you need a true mandrel bender is because they actually clamp the tube very tightly so it cannot slip while making the bend.  A JD2 bender only uses a saddle to counter the bending forces at the starting end of the bend.  The tube can easily slip through that style clamp, and the tigher your bend radius the more likely it is to slip.  So, when I said you need to make the bends on a "true" mandrel bender it was not so much the mandrel part as the type of machine itself I was referring to.Oh, and I should also point out that you can bend either pipe or tube or even oddball shapes on a mandrel bender as long as you have tooling to match.
Reply:What about sand, or some other sort of media? i have heard rumors that if you were to cap one end, fill it with sand, cap the other end, bend it, then cut off the caps, you will not have a collapsing wall. is this true? it would not be prectical for very many bends, but if i only wanted to bend one or two pieces of exhuast tube, would this work?Thanks.Later,Andy
Reply:Filling the tube (or pipe) with sand -helps- to support the inside of the tube/pipe and thus may help to prevent kinking or collapsing the pipe/tube.  But is not quite the same as using a real full mandrel set-up.The fill-it-with-sand trick helps, and may allow you to go with a little thinner wall or a little tighter radius than 'normal'.  It is not a "fill it with sand and don't have to worry about kinking or collapsing anymore".
Reply:Originally Posted by grahamtheengineerGreat info Ries.I would also like to point out that "piping" generally refers to the material used  when moving liquids. And tubing is the material that is used for structural applications.  With that said, you would not claim that your roll-cage was built out of piping.  However, many people use the two terms interchangeably, but I have been taught and told by many other professionals that this is the correct terminology......just like the old motor/engine debate
Reply:Originally Posted by aczellerWhat about sand, or some other sort of media? i have heard rumors that if you were to cap one end, fill it with sand, cap the other end, bend it, then cut off the caps, you will not have a collapsing wall. is this true?