Announcement

Collapse
No announcement yet.

Advice needed drilling long hole

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Advice needed drilling long hole

    wI need a hole about 11mm diameter right through a rod 1 foot long and about 1 inch diameter.

    Neither the inner nor the outer needs to be clean. This is effectively a long socket - one end will take a spanner and the other will be a 20mm square. The hole is to clear a 10mm rod, so it needs to be 11mm or so.

    I can source a set of drills from 4mm thru 10mm for a reasonable price, that will do the job up to 10mm, going in from each end. The meet in the middle won't be perfect, but I should think it would be acceptable.

    This is obviously too long for a boring bar, even a bar held at both ends. So I need some kind of self supporting bit to enlarge from 10mm.

    I seem to remember the gun barrel folk use a D-bit, but I don't like that idea. I'd rather have at it with this selection of commercial bits and then enlarge.

    Any suggestions ?
    Richard - SW London, UK, EU.

  • #2
    First drill from both ends with 10mm drill, no point using smaller than that.
    Silver braze or weld extension shaft to ordinary drill and use that to enlarge the hole to 11mm. Relief the drill shank so it wont bind in the hole.
    Or silver braze/weld the whole thing from 3 parts and you don't need to drill much anything..

    Or just buy Dormer A110 HSS 11mm Long Drill Bit, 195 mm Plain Shank. Abouts 15-20 pounds..

    Comment


    • #3
      Start with a piece of "3/8" iron pipe - its ID is about right. On one end, weld on a nut for the spanner and on the other your 20mm square socket.

      Oh, wait ... you're UK, maybe the 3/8 iron pipe is US. So, use whatever steel pipe works.
      Last edited by Bob Engelhardt; 09-04-2017, 10:40 AM.

      Comment


      • #4
        If you are going to drill it, use a lathe. I always had better results rotating the part for long holes.

        Mike

        Comment


        • #5
          Can you use DOM 1 inch OD by 0.5 inch ID?
          https://www.amazon.com/Rolled-Steel-...el%2Btube&th=1

          Comment


          • #6
            Originally posted by rohart View Post
            Any suggestions ?
            The only hard part about this is keeping hole aligned.....and this is easy if do what I describe in post 19 here http://bbs.homeshopmachinist.net/thr...drilling/page2

            I just put a hole through a foot long piece that will the shaft of a spindle, and it came out within 2 thou. Didn't take that long either.....ie process is not quite as tedious as it sounds.
            Last edited by Mcgyver; 09-04-2017, 11:39 AM.
            .

            Comment


            • #7
              Originally posted by Bob Engelhardt View Post
              Start with a piece of "3/8" iron pipe - its ID is about right. On one end, weld on a nut for the spanner and on the other your 20mm square socket.

              Oh, wait ... you're UK, maybe the 3/8 iron pipe is US. So, use whatever steel pipe works.
              X 2. Such a simple solution.

              BTW, a 20mm square is 28.28mm on the diagonal so you would need a considerable larger shaft than "about 1 inch diameter". How did you plan on finishing each end?
              Location: Saskatoon, Saskatchewan, Canada

              Comment


              • #8
                Originally posted by Bob Engelhardt View Post
                Start with a piece of "3/8" iron pipe - its ID is about right. On one end, weld on a nut for the spanner and on the other your 20mm square socket.

                Oh, wait ... you're UK, maybe the 3/8 iron pipe is US. So, use whatever steel pipe works.
                I was going to suggest a piece of pipe as well. I am sure its not strong compared to a one piece forging, but I have successfully done jobs by cutting a socket in half and welding a piece of pipe in the middle. Some such Frankenstein sockets have been used for sink drain nuts by hand or Harley clutch baskets with an impact. That's a big positive for owning some cheap import sockets. You don't mind destroying them.
                Last edited by Bob La Londe; 09-04-2017, 12:16 PM.
                *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

                Comment


                • #9
                  Deep holes are a historic problem. I've seen 3/4 pipe 5 ft long made from solid CRES 316L stock on a radial arm drill and hold wall concentricity so straight deep hold are do-able.

                  The trick for drilling deep straight holes is to have the center of the work on the thrust axis and concentric with the drill socket. If you can single point precision bore a starter hole 3 or 4 diameters deep, drilling straight holes becomes much simpler because you gave it a straight start.

                  I prefer to drill deep holes in barstock in the lathe where I can bore the starter holes and have that long centered tailstock travel to aid peck drilling. Are "aircraft extension drills" available to you? These are long drills with a short fluted portion.

                  http://www.irwin.com/tools/drill-bit...ank-drill-bits

                  The long stiff body aids in holding straightness. The short flutes are of no concern because you have to peck drill after 3 or 4 diameters hole depth. 11 mm a foot deep from one end or both is no big feat but drilling from both ends may be a bit lower in surgical risk.

                  My suggestion is to drill a size smaller from both ends using a concentric starter hole, then body drill once the through hole is established. The body drill taken to full depth will clean up any small mismatch at mid-hole to make a nice straight appearing passage for your bolt.

                  Easy-peasey.
                  Last edited by Forrest Addy; 09-04-2017, 08:30 PM.

                  Comment


                  • #10
                    Thanks for all your ideas. They'll all be archived for my future plans.

                    In fact I went the gas pipe route, and I lathed and milled up the end pieces before welding them on.
                    Richard - SW London, UK, EU.

                    Comment


                    • #11
                      Have you considered a socket extension? That's why they're made.

                      Edit: Never mind, I missed the rod part. Pipe would work.
                      Last edited by CCWKen; 09-06-2017, 09:13 AM.

                      Comment

                      Working...
                      X