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A good day in the shop

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  • A good day in the shop

    Spent time in the shop today working on a multi-stop carriage stop. It was a day of firsts:
    1. made would could charitably be called a mandrel
    2. drilled using the headstock. I didn't like it very much. Normally the drill is in the tailstock.
    3. tapped six 1/4x20 holes in .9" steel. Youch, now I know why people have power-tappers.

    No biggie, but knowing how to do something is a lot different than doing it.

    So I've completed the first part of the multi-stop, the spinning part. The fingers on this one are offset from the axis of rotation by 45* so they clear the carriage.

    I'm making this up as I go along. Tomorrow I'll design the clamp.
    Last edited by Tony Ennis; 02-24-2013, 10:13 AM. Reason: spelin'

  • #2
    Re. 3 "tapped six 1/4x20 holes in .9" steel. Youch, now I know why people have power-tappers".

    Use a bit less depth of thread - it probably won't matter most times if you reduce from 75/80% to 60% (larger tapping hole).

    Make sure your tap is dead sharp as there is more load on the tap (and the operator) if it is blunt and it will only get blunter (and more likey to snap) as the job progresses.

    I'd think about getting a "power" tap and tapping it under power on you pedestal drill (slow speed and lots of cutting oil).

    I'd have thought about drill clearance hole say 9/16" deep (no tapping there either) and you will have only about (0.90 - 0.5625 = 0.3375") to tap.

    It is all job-dependent of course.

    Comment


    • #3
      Originally posted by Tony Ennis View Post
      3. tapped six 1/4x20 holes in .9" steel. Youch, now I know why people have power-tappers.
      Bag the Walmart taps you have and get spiral point taps..... you do NOT have to back them up every 1/8 turn, and the chips get pushed forward. For a thru hole they positively RULE....


      And while that may sound bad for a blind hole, it does work, at least as well as an old-school Walmart 4-flute "back-em-up" type tap. So you get anything from a huge benefit, to at worst, a "wash" in the least advantageous situation.

      yes, DO drill to the 75% engagement.... that's normally what the tap drill tables show. For thick steel and long engagements, you may be able to go even a tad larger on the hole.
      1601

      Keep eye on ball.
      Hashim Khan

      Comment


      • #4
        They aren't from Walmart They're from McMaster or MSCDirect, I forget. They're 4-flute HSS and uncomfortably sharp. The brand is Interstate which I believe is ChiCom. I bought some #7 drills to use for these taps.

        Next time I buy taps I'll try some spiral points.

        Comment


        • #5
          Originally posted by J Tiers View Post
          Bag the Walmart taps you have and get spiral point taps..... you do NOT have to back them up every 1/8 turn, and the chips get pushed forward. For a thru hole they positively RULE....


          And while that may sound bad for a blind hole, it does work, at least as well as an old-school Walmart 4-flute "back-em-up" type tap. So you get anything from a huge benefit, to at worst, a "wash" in the least advantageous situation.

          yes, DO drill to the 75% engagement.... that's normally what the tap drill tables show. For thick steel and long engagements, you may be able to go even a tad larger on the hole.
          Bear in mind that they make spiral point taps for through holes and spiral flute taps for blind holes. My favoritte examples are the Blue Merlin and Blue Wizard taps.
          Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

          Comment


          • #6
            Carefully done, a spiral flute tap can be chucked in a low speed 3/8" or so drill for portable power tapping up to 5/16" UNC. Not exactly directly out of Machinery's Handbook of best practices, but practical and it works... BTDT.
            Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

            Comment


            • #7
              Look in Machinery's Handbook for tap drill sizes. The drill size varies by the depth of hole. I have found that 4 fluted taps in the small sizes are next to impossible to use. Long ago I switched to 2 flute spiral pointed taps, and tap breakage went way down, and ease of tapping went way up.
              The only Interstate tap I have is 14-24 for use in UHMW, or Delrin. That was the only brand that MSC had in that size. I generally stay away from that brand.
              Harry

              Comment


              • #8
                What brand do you prefer, Beckley?

                Are the spiral point taps intended for hand-threading? I poked around and saw 2- and 3-flute versions. Which appropriate in the general case?

                Comment


                • #9
                  "What brand do you prefer,"

                  That's a tough one. I stay away from the house brands, such as Interstate and Hertel, and opt for the higher priced ones, depending on the job*. CRS isn't so much of a problem, but the SS grades can be a problem, especially 316. Generally, I have had good experiences with the taps, and the other cutters in general, under the Greenfield umbrella.

                  2 flute, IIRC go up to about 3/8" and 3 flute for larger in the spiral ended taps. I use them in hand and power tapping. Blind holes can be troublesome, but if you're careful and don't jam the tap you should be OK. A crochet hook is a big help in getting the chips out of blind holes, as are pipe cleaners.

                  * Taps , and cutters in general, can get pricey. At some point a decision has to be made about cost effectiveness, but buying the cheapest has never worked for me. It's a false economy.
                  Harry

                  Comment


                  • #10
                    I put about a 2 inch wood screw on a short handle. It works great to remove the chips from a blind hole that can get packed in and don't blow out easily. This is especially true when using a spiral point tap (which I love). Just put it in the hole, twist a few times and pull the chips out.

                    Comment


                    • #11
                      Originally posted by camdigger View Post
                      Bear in mind that they make spiral point taps for through holes and spiral flute taps for blind holes. My favoritte examples are the Blue Merlin and Blue Wizard taps.
                      I did mention the blind hole issue.... In use, I find it isn't a problem..... the spiral POINT still works great FOR HAND THREADING.

                      Spiral FLUTE taps are HOPELESS for hand threading, they fill your hole with hard fractured bits of themselves, either on the way IN or on the way OUT.... luck of the draw which.

                      If you can drill the hole deeper than the threads need to go, it's easy to use the spiral POINT.... you can pull out the swarf, or not, just as you please. If the print has the threads to the bottom, well, that's what you do... but if you have a customer print that you MUST follow, you almost surely also have tapping heads, etc that will allow you to use a spiral FLUTE tap decently. if not, you are losing money fast.
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        Recently I have had good results from the OSG taps.
                        Byron Boucher
                        Burnet, TX

                        Comment


                        • #13
                          Originally posted by camdigger View Post
                          Carefully done, a spiral flute tap can be chucked in a low speed 3/8" or so drill for portable power tapping up to 5/16" UNC. Not exactly directly out of Machinery's Handbook of best practices, but practical and it works... BTDT.


                          I use normal taps all the time in the drill, just have to set the clutch right and you can really burn threw the holes.
                          Andy

                          Comment


                          • #14
                            Good day in the shop today- I needed to machine a seat for a flush socket head bolt. These do not have a 90 degree angle, more like 82 degrees or something. I found a broken 5/8 four flute tap, which I converted into a matching cutter. I ground the od to remove the threads, then tool-post ground the od for a smooth and accurate .5 inch diameter, followed by hand-grinding the four cutting edges and thinning the webs. It worked pretty well, but now I need to find a way to more accurately define the cutting edges. Looks like I need a tool and cutter grinder.

                            Anyway, this operation got my boring bar holder pretty much completed. The last part of this is going to be finding a way to hold the cutter to the bar. Since this first bar will be 1 inch diameter all the way, and the cutter is 3/16 sq, it should be easy enough to get it done before the day is up.
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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