bending small bore copper pipe

Advert

bending small bore copper pipe

Home Forums Beginners questions bending small bore copper pipe

Viewing 15 posts - 1 through 15 (of 15 total)
  • Author
    Posts
  • #326372
    Sam Longley 1
    Participant
      @samlongley1

      I am about to start bending the first tubing for my traction engine. It seems a good point to fabricate a mini tube bender & i wondered if there was a rule of thumb for the minimum radius, or a typical working radius, that one would use for bending copper pipe from say 5mm upwards on a model traction engine.

      This would give me the size for the diameter of the primary wheels of the bender.

      I believe there has been mag articles on the subject but I do not subscribe

      Thanks

      Advert
      #8965
      Sam Longley 1
      Participant
        @samlongley1
        #326418
        Brian Wood
        Participant
          @brianwood45127

          Hello Sam,

          Head off down to your local plumbers merchant and look at their tube benders for micro bore copper pipe for central heating systems, these cater for 8 and 10 mm pipe, are well made and easy to use and may save you a bit of time instead of making a dedicated tool. At the very least they will give you ideas.

          The other alternatives are pipe springs that fit over the tubing which control the shape of the pipe as you bend it. They are tricky to use as you must over bend the pipe and then ease it back to the angle you want so that you can release the spring and judging that nicely is brought about by experience. They also need to be a close fit on the tubing to start with and may nor be available in all sizes.

          Regards Brian

          #326424
          Chris Trice
          Participant
            @christrice43267

            Go to a motor spares place and look at brake pipe bending kits too. Brake pipes are typically 1/4". It may be possible to machine wheels for smaller diameter tube you can incorporate.

            #326429
            peak4
            Participant
              @peak4
              Posted by Chris Trice on 10/11/2017 11:45:54:

              Go to a motor spares place and look at brake pipe bending kits too. Brake pipes are typically 1/4". It may be possible to machine wheels for smaller diameter tube you can incorporate.

              or more often 3/16" which is even closer to 5mm. The pipe itself is typically available in soft copper or Cunifer, depending on what colour you'd prefer on the engine.

              #326434
              Sam Longley 1
              Participant
                @samlongley1

                I already have pipe springs & a pipe bender, which goes up to about 40mm diameter. But not below half inch.& I know how to make a small bore bender – Dubro make one for model plane fuel pipe which is very small diameter.

                I just want to know if there was a rule of thumb for very small tubing. Many forumites must be bending pipes for their trains & traction engines & it seems odd that there isn't a rule such as – say- 3 times diameter as a guide line

                Edited By Sam Longley 1 on 10/11/2017 12:45:04

                #326457
                Brian Wood
                Participant
                  @brianwood45127

                  Sorry Sam, I misunderstood what you were trying to establish; I don't know but perhaps others have an empirical formula they use.

                  Regards Brian

                  #326460
                  Martin Connelly
                  Participant
                    @martinconnelly55370

                    There are rules for the tooling needed for CNC draw benders that allow selection of necessary tooling. The larger the OD to wall thickness ratio the more likely you are to need support inside the tube. Also the tighter the centre line bend radius is to the OD the more likely internal support will be needed. I have a cardboard computer (think slide rule made of cardboard) for this purpose. You find factor 1 which is wall thickness to outside diameter figure. Then factor 2 which is the centre line bend radius to OD. On the reverse side you set the slide to the factor 1 position and look down against a window to see what is against factor 2. This tells you if you need a wiper die, plug or ball mandrel and if a ball mandrel is required how many balls.

                    For example 3/4" 16swg tube has a factor 1 of 15 (they are coarse figures for the factors). With a bend radius of 3D (2.25&quot the factor 2 value is 3. The result is the table says this bend needs a plug mandrel but no wiper die. Reduce the bend radius to 3/4" and it says a one ball mandrel with wiper die.

                    This works for stainless steel but I don't know how applicable it is for copper tube, the bending tool selector does not say anything about material.

                    Martin C

                    #326464
                    Fowlers Fury
                    Participant
                      @fowlersfury

                      Re. your "It seems a good point to fabricate a mini tube bender" and "mag articles on the subject but I do not subscribe".

                      You could wose than look at David Carpenter's FREE ! website **LINK**

                      There have been two designs over the years, the first being **LINK**

                      But the easier one to build, producing accurate, tight curves in small Cu pipes was published by "Artisan". Unfortunately David seems to have moved the article to a DVD now (requiring payment) but I have the pdf and this image is from that, hopefully not infringing copyright:-

                      03_pipe bender.jpg

                      This is mine and have always felt it worth the effort of making in that my pet aversion is seeing poorly-formed bends in wavy pipes on otherwise excellent models.

                      tube bender_2.jpg

                      #326488
                      Martin Connelly
                      Participant
                        @martinconnelly55370

                        img_20171110_165519.jpgimg_20171110_165500.jpgPhotos of the cardboard computer I have for selecting CNC pipe bending machine tooling.

                        img_20171110_165435.jpg

                        Martin C

                        #326499
                        Sam Longley 1
                        Participant
                          @samlongley1
                          Posted by Fowlers Fury on 10/11/2017 14:36:57:

                          There have been two designs over the years, the first being **LINK**

                          This is mine and have always felt it worth the effort of making in that my pet aversion is seeing poorly-formed bends in wavy pipes on otherwise excellent models.

                          tube bender_2.jpg

                          Thanks for the second link. That is a lovely piece of kit & worth stopping the build just to make it. I did intend to make something more akin to yours but with a smaller fence to allow closer bends.Looking at the instructions there are quite a lot of bends to make in an engine & one can get better seating on the joints if everything lines up first time rather than being a tad out & trying to force something into line.

                          I also fly RC planes & bending piano wire etc is easier with a neat bender

                          Looks like I will have to make the bender & just make a few wheels & see how the first few bends go

                          Cheers

                          Sam L

                          #326578
                          John Ockleshaw 1
                          Participant
                            @johnockleshaw1

                            Hello Sam,

                            For copper tube a pipe centerline radius of two pipe diameters is fairly easily achieved. With smaller radii you need internal support and are likely to have tearing in the outside of the bend.

                            Martin's table illustrates the requirements.

                            If you Google this link you will find a mine of information http://www.pines-eng.com/pdfs/H&HBendGuide.pdf

                            Regards, John

                            #326582
                            Michael Gilligan
                            Participant
                              @michaelgilligan61133

                              That's an excellent document, John

                              http://www.pines-eng.com/pdfs/H&HBendGuide.pdf

                              Thanks for posting yes

                              MichaelG.

                               

                               

                              Edited By Michael Gilligan on 11/11/2017 07:22:09

                              #326609
                              mechman48
                              Participant
                                @mechman48

                                I​ made a small bore tube bender from a set of drawings, just can't recall from whom without looking in garage but …

                                mini tube bender (1).jpg

                                mini tube bender (2).jpg

                                The two examples are 1/4" & 1/8" copper tubing.

                                George.

                                #332702
                                David Carpenter 4
                                Participant
                                  @davidcarpenter4

                                  Re Fowler's Fury on copyright. If nothing else, it is good manners to ask before publishing anything from another website. As we say on modelengineeringwebsite.com:

                                  COPYRIGHT

                                  Everything on MEWS (and almost everywhere else) is someone’s copyright. Please ask if you wish to use any material from MEWS and we can normally arrange that.

                                  If you are submitting material for publication on MEWS, please make sure that you have permission where needed.

                                  Anything we publish on MEWS remains the copyright of the originator – simple.

                                Viewing 15 posts - 1 through 15 (of 15 total)
                                • Please log in to reply to this topic. Registering is free and easy using the links on the menu at the top of this page.

                                Advert

                                Latest Replies

                                Home Forums Beginners questions Topics

                                Viewing 25 topics - 1 through 25 (of 25 total)
                                Viewing 25 topics - 1 through 25 (of 25 total)

                                View full reply list.

                                Advert

                                Newsletter Sign-up