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Home made boring bars?

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  • Home made boring bars?

    I want to make my own boring bar with an insert but am stuck on what to make. It will be used to bore smaller holes,ie: 1/24 scale model wheels. I'm always amazed at the craftsmanship here, so please post your pics and description of your tool.

  • #2
    For small diameters up to about 3/4" most the time it's easier to drill and ream and make the shaft size to fit as needed. For short distances you can use a boring tool from a mill boring head and clamp it in the tool post or QCTP holder.
    It's only ink and paper


    • #3
      You say model wheels at 1/24 scale, but you don't say what you are modeling. Cars? Trains? Military vehicles? Monster machines? But lets assume a 6" hole at 1/24 scale. That would be a 1/4" hole in the model. A boring bar for a 1/4" hole would have to be quite small. I have never seen one. To make one with inserts, you would need an insert that is about 1/8" or smaller. Again, I have never seen such a small insert. And what size screw would you use to fasten it to the bar? A 0000-120?

      Drill and ream. Or use an end cutting end mill.
      Paul A.
      SE Texas

      Make it fit.
      You can't win and there IS a penalty for trying!


      • #4
        Yeah, we need to know the diameter.

        For 1/2" and smaller holes, inserts just get in the way. Solid bars rule, preferably solid carbide.


        • #5
          MTNGUN is right, iv never seen inserts that small, and for such small holes solid carbide boring bars are not gonna be expensive, And likey the only things rigid enough to bore any hole deeper then a few diamiters deep.

          Alternatively, if the metal is not super hard and the hole not excessively deep, rectangular or round HSS blanks can be ground (with much effort.. idealy some kinda rotating jig to make the relief of the shaft of the bar) for cheap... but well, much effort and grinding. the only good thing is that with 1/4" holes and smaller, your not gonna need a big blank.

          Iv heard of heating and bending HSS.. but that seems kinda questionable to me. I have seen 'prebent' HSS blanks, but they seem rare/expensive.

          something like these guys can be bought rather cheap for the small sizes, in solid carbide or solid HSS, and are resharpenable. Not sure if you'll find brazed carbide that small, but you could possabley make one yourself and braze carbide bits onto it.

          Still, this is one time where the higher rigidity of solid carbide would likey be nice.

          Of course. while small carbide boring bars are cheap, so are small precision reamers and the drills to go with them, especialy if you only have a few diffrent diamiters of hole to make, if you plan to make 20+ diffrent diamiters... well then a set of boring bars (Note, SET, you will find you need a few diffrent shaft sizes and lengths to 'idealy' match the job, one bar does not do all) might be better.
          Last edited by Black_Moons; 02-20-2010, 01:53 PM.
          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


          • #6
            Originally posted by Paul Alciatore
            I have never seen one. To make one with inserts, you would need an insert that is about 1/8" or smaller. Again, I have never seen such a small insert. And what size screw would you use to fasten it to the bar? A 0000-120?
            Here's a .230" min bore boring bar that uses WNMG inserts...


            • #7
              The wheels are made out of 7/8" diameter aluminum. I turn maybe a couple millimeters off the outside to clean it up. Inside I bore out nearly all for the inside diameter, leaving maybe a millimeter or two as you can see from the edge of the wheel. Here's a couple pics, but I'll take a better scale picture later.


              • #8
                Well, as Glenn pointed out, there are insert type boring bars available to do that, if you insist on an insert.

                However, since aluminum is so easy to work with, and since your holes are a modest size and depth, I fail to see the need for a high tech boring bar. In fact, the insert bars may work less well because they are not as sharp as a solid bar.

                A solid bar would work fine for your application.

                I have made small boring bars out of broken tool bits.

                Solid carbide boring bars are sweet for deep holes, but not necessary for what you are doing.


                • #9
                  I made a boring bar from a broken carbide burr, 1/4 inch diameter. Works really well. I'd have no problem using some smaller shanks for smaller work-

                  Take a piece of material that you can mount in the toolpost or whatever, and arrange to drill it with a drill bit held in the chuck. Use the tailstock ram to press the holder towards the chuck for the drilling operation. Then with a setscrew or two you can hold a piece of round carbide or hss, sticking out only as far as you need it to. Grind the business end into a 'D' bit, and you're pretty much there. My holder is drilled 1/4 inch in one end, and 3/16 in the other. I have some of those Boeing surplus long drill bits which I cut into suitable lengths to grind up as custom boring bits, etc. They are 3/16 diameter and hss. I have a full set of boring bars, but guess which one I use most- yeah, the homemade one. The 1/4 inch carbide bar is the one I use virtually all the time.
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                  • #10
                    I have successfully made and used boring bars made from Square Drill Rod. Heat red hot and form tool, then harden and grind business end of it.


                    • #11
                      This one can go straight in without a pilot hole.

                      " you not think you have enough machines?"


                      • #12
                        HSS does give a nice finish, but I like the ease of the ninsert and no sharpening. What type of insert would one use for this type of boring?


                        • #13
                          Circle makes a "C" series boring bar with a min bore of .180" and an "F" with a min of .275"

                          the inserts are pretty reasonable, and I would use an uncoated insert with a larger radius (like .015)

                          Last edited by EdC; 02-20-2010, 07:30 PM.
                          Experience is something you don't get until just after you need it. ..


                          • #14
                            As I said in post #2 drill and ream.
                            It's only ink and paper


                            • #15
                              Originally posted by Carld
                              As I said in post #2 drill and ream.
                              I don't think an 8inch long reamer is going to fit in a Sherline lathe. Even if it did fit, I can't imagine the shank would fit in the chuck.