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What equipment do I need to TIG weld 4130 chromoly tubing?

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    What equipment do I need to TIG weld 4130 chromoly tubing?

    I am taking some framebuilding classes in 2018, but in the meantime I have two cargo frames made of 4130 chromoly steel that need some pretty extensive modifications. I need to do this myself before next year.

    I need to lengthen the chainstays, widen the dropouts and replace the 40mm head tube with a 44mm head tube. Because the frame has an integrated cargo rack, lengthening the chainstays/wheelbase involves removing a lot of smaller tubing. It looks like I will need some sort of tube bender to bend some 3/4" tubing. My goal is to fit Vee Snowshoe 2XL tires (5.05" X 31.5"), a 60T chainring and a 190mm dropout hub motor.

    The problem is that my only experience with welding is with a very cheap wire feed welder from Harbor Freight that I did use a lot on past automotive projects. The welding unit was a piece of junk, and my skills left me doing more grinding than welding.

    Can anybody please recommend a specific wire feed welder, tube bender, hole saw (if needed) and any other tools I might need for a proper framebuilding hobbyist shop? Or should I just go down to my local welding supply store and buy the stuff there? I think I can handle sourcing the tubing and instructional material. My budget for all the equipment is "under $4K".

    In the pictures, the red bike is the "Before" frame, and the last picture (of a bare black frame) is my goal. I have the frame in the last picture in my possession, so I will certainly use it for a reference.

    I realize that my old frames will almost certainly be stripped down to the "seat tube/top tube/down tube and BB" triangle, but that seems like more fun to me. The dropouts are already filed out for my 16mm Cromotor axles, and I already have the torque plates on hand for the rear. So the old dropouts will be reused.

    I have no interest in welding anything other than the aforementioned steel. I will never weld aluminum or titanium. Any other welding or fabrication tips are welcome, but please don't recommend selling the frames as is--they are my practice frames.

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    Last edited by commuter ebikes; 04-02-2017, 03:27 PM.

    Sounds like you need to get some scrap metal and learn how to weld and then work on the frame, you don't want the frame breaking in half going down the road. The best welder money can buy won't make you a good welder, only practice will do that.


      Originally posted by oledave View Post
      Sounds like you need to get some scrap metal and learn how to weld and then work on the frame, you don't want the frame breaking in half going down the road. The best welder money can buy won't make you a good welder, only practice will do that.
      Great advice. How could I have missed that? Maybe that's why I got such poor results on my automotive welding work.

      I won't buy it until I know what I need, but this welder looks like it might do the trick:

      Also, this website has great tools, but they are completely unaffordable to me:

      It seems I might need a miter, too. Obviously I am going to need to do a lot more reading on this.


        Sounds like we are on a similar journey :)

        I learned to weld a few years ago. It is frustrating, expensive, and time consuming to learn to TIG weld well enough to build a vehicle frame. That being said, after coming out the other side, with no more damage than serious doubts about my manual dexterity and a couple of scars on the back of one hand... It was worth it.

        If at all possible, take a night class at your local community college or tech school. You get to work with their equipment and materials before you have to start making purchasing decisions yourself. If that is not an option, I learned with the help of Jody at . As olddave said, welding is all about practice. The thin walled tubing and bizarre notching angles on bikes are beyond the skill of a lot of professional TIG welders.

        After wasting more time than I care to admit. The thing that finally tipped me over the edge was getting a couple of 20 foot sticks of thin walled square and round tubing. Using a cheap harbor freight bandsaw, I cut the tubing into 1 inch lengths. Every evening after dinner, I would head out to the garage for 30-45 minutes and practice a particular weld in some position until I could get 10 good quality welds in a row. Rinse, Wash, and Repeat.

        As for notching, I started with a harbor freight tube notcher . It was not perfect, but it got me started. Now that I have a mini mill, I use that for notching. It is awesome.

        What frame building class are you considering?


          Originally posted by funwithbikes View Post
          ...As for notching, I started with a harbor freight tube notcher . It was not perfect, but it got me started. Now that I have a mini mill, I use that for notching. It is awesome.

          What frame building class are you considering?
          Looking at the picture of the tube notcher, I can see how that would be perfect for framebuilding.

          I am taking and and in 2018, and in 2019.

          If I signed up for any class at the local Junior College, I would have to miss about half of the classes because of my job. The school linked above works well for my schedule because I can do it on my vacation. I can't recommend this school enough.

          What sort of mini mill do you have? Do you think is adequate for notching tubes? Or

          I had no idea that welding thin walled tubing was so difficult. I wouldn't mind spending hundreds of hours on practicing. I will hone my skills before modifying my frames.

          The welding tips and tricks website is a tremendously pertinent and helpful link. Thanks for mentioning it.

          Can you provide a link to a specific welder which is good for welding 4130 chromoly steel tubing? Miller looks like a good brand. How about this tube bender
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          Last edited by commuter ebikes; 04-03-2017, 10:39 AM.


            Whenever I do a search for a welder for this application, my search ends here: Does anybody have any arguments against this welder?


              As a home welder, I went with It can handle anything I want it to do. The miller is an excellent machine. It was just built to a higher standard than I need for occasional use.

              For minimill, I got All of the mini mill are made in the same seig factory.

              The Harbor Freight tube notcher, like so much other harbor freight stuff, takes a lot of tweaking and it cumbersome to set up a cut precisely. I usually ended up doing a couple of practice cuts to get the notcher set up correctly. Not exactly something one would want in a production facility... But as I was learning to weld at the same time, it was nice to have a couple of practice pieces.

              Yes, I like the welding tips and tricks site a lot. Jody switches back and forth between the practical how-tos and the theoretical pieces on how to cut open an weld and examine it for internal strength.

              Have you seen the pity bikes channel at . The guy is a total newbie... I found it really helped to get my gray matter going to listen to him think about a problem.

              These classes look pretty cool... ah so many things to learn :)


                It appears to be $140.00 cheaper here:
                You should decide on how thick of material and what type you plan to weld. That would help determine how powerfull of welder you need. You may want to call Miller and talk to them about what you want to do, and see what model they suggest.
                I started out with a table top mill & lathe a bunch of years ago. The only down side was capacity and speed. I sold them when we moved and replaced them with these: 11x27 vf lathe & pm25 mv mill. The price isn't that much more compared to the greater capacity and more versatility.


                • funwithbikes
                  funwithbikes commented
                  Editing a comment
                  Yes, I liked those tools. One of my major limitations is shop space. I have to fit everything into a single stall of a 3 stall garage :( Maybe if this ebike thing continues to work, I can expand into a second stall of the garage. :)

                I just did some research on setting up a "proper hobbyist framebuilding TIG workshop".

                I emailed a friend, who knows his stuff. Hopefully he doesn't mind me quoting him. He said "TIG welding is a high skill technique that requires years of experience to do well and stay good at, as well as expensive equipment. It is a rather difficult (even poor) choice for an occasional welder. Best to hire that skill when you need it. MIG welding is a better choice for the occasional welder. In any case doing quality welding is far more difficult than soldering, so when your soldering is up to professional grade then maybe welding is next. Welding is also messy and tends to make one collect a great quantity of metal tooling and scrap materials, so it takes a lot of storage...Might be best to join a shop group that has all the equipment and space, it is not compatible with your clean garage shop.

                If you do get welding gear then you can install 240V outlets in the garage.

                And it gets a little more discouraging from there. I talked to a gentleman at Anvil Bikeworks (linked above). He had obviously been asked the question many times ("How much would it cost to set up a proper hobbyist TIG framebuilding workshop?"). He was willing to answer all of my questions and the bottom line is that one would not spend more than (brace yourself) $20,000, and it could be done for less. $20,000 is the no compromises route. The mill is a large expense. He recommended a mill such as this:

                If one hasn't been taken out of the game with the purchase of the mill, then one will need a jig: Click image for larger version  Name:	1.PNG Views:	1 Size:	93.1 KB ID:	31962
                Last edited by commuter ebikes; 04-03-2017, 11:14 AM.



                  Once one has the welder, the large, stiff mill and the frame fixture, there are some tools needed on this page which I will not list because they are not catastrophically expensive.

                  There are four different frame mitering fixtures, but thankfully all of the frame mitering can be done with this single horizontal main tube mitering fixture:
                  Click image for larger version  Name:	3.PNG Views:	1 Size:	82.4 KB ID:	31964That mitering fixture goes on the mill.
                  Last edited by commuter ebikes; 04-03-2017, 10:34 AM.



                    After a few brake mount tools which are relatively affordable, we arrive at the last item needed: the tube bender for the chainstays. Click image for larger version  Name:	6.PNG Views:	1 Size:	82.5 KB ID:	31966
                    Last edited by commuter ebikes; 04-03-2017, 11:15 AM.



                      I am almost too discouraged to add it up, but choosing the expensive tools may end up being about $16,000. I don't think that I can afford that.

                      Certainly there are more economical choices in tools out there.

                      For my purposes, I would get one of the nice mills that David and Harold linked to and do my notching with that.

                      So now I will see about a more economical jig and tube bender.

                      I probably won't buy anything other than a welder before my first framebuilding class. There is obviously a lot of practicing to do.
                      Last edited by commuter ebikes; 04-03-2017, 11:10 AM.


                        I know one electronics technician who bought a harbor freight MIG welder and did some very good work with it. He compared to the Lincoln and there was little difference with regard to the resulting weld quality. You need to buy or rent a shield gas bottle of Argon or CO2, and get the appropriate wire. He said it was easier to learn than TIG and worked well on thin steel. The welds came out clean so there was almost no grinding. He was welding auto body panels so he needed to work with thin metal.

                        Here's a page on DIY welding and tradeoffs:

                        He uses ARC for general welding (heavy materials), MIG for thin metal and TIG only for aluminum. That's generally what I've heard.
                        Alan B