Help tapping small threads, please

Discussion in 'Tips and Tricks' started by almega, Dec 22, 2018.

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  1. Dec 26, 2018 #41

    TRIPLE

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    All fine tread I cut I do with a Machine tap that is turn round in a box of bees wax, the grooves are filled with wax and when you turn back the tap and break the chips the chips will held in to the wax so it cannot cause damage the tread, after tapping clean the grooves with a brass brush for the next tapping.
    On this way of tapping I never have broken a tap in sizes from M1 , M1.2 M 1.5 M2 etc. And allways tapping by hand so you can feel the resistance an the moment the chip is breaking when you turn back the tap.
     
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  2. Dec 26, 2018 #42

    redhunter350

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    Almega, lots of good advice on here but here's my three penne'th use HSS ground thread taps, yes they are a higher price but worth the money -- they CUT ! one source I use is MSC and Lyndon taps, excellent value when on offer !
    Lubricants for mild steel / black iron [CRS & HRS ??] use coconut grease mixed with brake cleaner - we used to use Carbon Tetrachloride now banned; for aluminium use mentholated spirit [de=natured alcohol] everyone has their own favourite and there are lots of commercial concoctions available now, my lubes date from the 1960's. but always worked well.
    I see your material is 1/8" thick so really it should cause you no problems providing you use good taps and I would use hand tapping so you have the 'feel" and to keep it plumb a tapping block to start the thread.
     
  3. Dec 26, 2018 #43

    rodue

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    I have found that in brass or aluminum that I use a piece of drill rod and turn it to a little larger than you broken tap. Then drill a hole in drill rod large enough so the tap could turn inside. Then cut accouple of teeth on your drill rod. Then temper the end, The broken tap will act like a pilot and bore it out ,you should go deep enough that you can snap off your broken tap. Then you can re tap the hole with a larger tap and plug, you can re drill and re tap, using more caution, I haven't tried it in steel but this has worked for me
     
  4. Dec 27, 2018 #44

    Roger Pry

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    Valuable info for me. RMP
     
  5. Dec 27, 2018 #45

    goldstar31

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    I tend to use lard oil for general lubrication and usually add tallow mixed in for tapping.

    It's old but in the home workshop it works well.

    Regards

    Norm
     
  6. Dec 27, 2018 #46

    KMSK1

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    Tap Magic for aluminum Best I have found so far,,, Do have two back out tap and clean chips ,I tap a total of 8 holes in a .250 x .500 x .800 Alum block 6 are length ways through block 2 though the .250 . I use a drill buy hand , 3mm tap.
     
  7. Dec 28, 2018 #47

    john_reese

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    If using a T type tap wrench keep the chuck a bit loose. When your hands wobble that little bit of slack can keep you from snapping a tap.

    Instead of beeswax I use the wax stick intended for lubricating tools. There are many brands available. It is also a great lube for driving wood screws.
     
  8. Dec 29, 2018 #48

    mfrick

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    I have found that Goose grease works well with small taps it runs to the heat and not away like some cutting oils, just need to find a source. I have a friend who hunts and he gives me the fat and I render it down just for the purpose of taping holes. I used lard oil for yrs but get infections form it so industry went to the sulfur based cutting oils. Now everything is getting to be a synthetic based material.
    Mike
     
  9. Dec 29, 2018 #49

    john_reese

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    Use straight lard, Crisco, or bacon grease. None of those will cause an infection if fresh. Some use vegetable oil. All seem easier to get than goose fat. Actually, I have read that almost any animal fat or vegetable oil will work.
     
  10. Dec 30, 2018 #50

    Roger Pry

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    I want to learn how to drill and tap small holes for an undecided project so practice is what I want to do... so does anyone have an opinion on using an archimedes drill to help with my unsteady hands on a tricky bit of work? It would allow me to have two hands on the drill at the same time..
     
  11. Dec 30, 2018 #51

    Cogsy

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    You still have to hold the drill/tap straight so I don't see the advantage. Plus, for very small drills, you want very high RPM which you're not going to get by hand. Much better to have the work clamped so it can't move and utilise the chuck used to drill the hole to locate the tap in the same setup. Therefore everything stays in alignment and straight.
     
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  12. Dec 30, 2018 #52

    dazz

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    Hi
    I use a MT3 precision spring centre either in the drill or lathe tailstock. The spring centre keeps the tap properly aligned. Proper support and alignment significantly reduce the risk of snapping a tap.

    I had plans published in Model Engineer magazine a while back.
     
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  13. Dec 30, 2018 #53

    tornitore45

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    Something I would never do.
    If the alignment is supplied by a machine there is no problem.
    If the part can not be tapped on a machine use a small diameter driver between thumb and forefinger. The longer the driver the less wobble.
    I am sure that all the good techniques for tapping small holes have been found and described, there is no need to re-invent a wheel and make it square.
    After unavoidably breaking a 1/2 dozen taps and successfully tapping 100 holes you get the hang of it an never break one tap again. Breaking taps is the price of learning, since is not something one can learn from a book. However learning from others, books or otherwise is helpful.
     
  14. Dec 30, 2018 #54

    petertha

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    The only issue there is, many of the small taps we are talking about don't have a female centering dimple for the classic spring male center. The taps are typically a semi ground cone & not necessarily a consistent cone angle across manufacturers. So some folks propose another fix - a conical cup held in the spring center. But that is right adjacent to the squared lands where the wrench jaws go. Personally, I don't find the requirement for down force is an issue on fine, finicky threads. You can feel the first couple threads & then it smooth sailing. Consistent alignment with minimal axial variation is the goal IMO. Larger threads, for sure the spring center is very useful. I guess we all have our way of doing things.

    For fine threading aluminum, I find these style of taps do a good job. (Its just an internet picture, not necessary a brand endorsement). The flute angle and the reduced shank helps vacate chips over the classic taps. Blind holes should utilize chip ejecting style taps.
     

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  15. Dec 30, 2018 #55

    dazz

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    I hold the tap in a T tap wrench. That has a dimple that fits my spring centre.
     
  16. Dec 30, 2018 #56

    john_reese

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    For small taps with a male center on the top I grip the middle of the tap with my small Starrett tap wrench. The top of the tap is guided by the female end of spring center.
     
  17. Dec 31, 2018 #57

    Roger Pry

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    Is the idea behind the spiral ground (ccw) tap that the chips are worked back up and out of the hole with each reversal of the tap during the tapping action?
     
  18. Dec 31, 2018 #58

    john_reese

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    On spiral flute and spiral point taps reversing the tap periodically is not desirable. Spiral flute taps draw the chips out of the hole as long strings. Spiral pointed taps push the ships ahead of the tap as long strings. Just feed those types of taps continuously. If you reverse the tap to break chips the shorter chips may not evacuate properly.

    Even with conventional hand taps it is not always necessary to reverse the tap to break chips. I recently tapped 24 1/4-20 holes in cast iron about 3/4" deep using a tapping head. That gave constant rotation until I hit final depth and then reversed and backed out the tap at double the spindle speed.
     
  19. Dec 31, 2018 #59

    petertha

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    My post #38, right hand picture shows the chip ejecting style of tap in action. These taps are preferred in blind holes so chips don't go down into the hole cellar, bung up the tap & risk breakage. I've also heard you are not supposed to reverse these to break the chip like conventional taps & that makes sense. Blind holes shouldn't be substantially deep anyway. What I have done just to be safe on certain holes is wound the tap out completely, give it an air blow & then proceed in again. Personally I find the good quality taps of this style to work excellent. When you have a through hole, forward ejecting taps have an exit for chips to drop out. Or at least theoretically that's how its supposed to work.LOL
     
  20. Dec 31, 2018 #60

    Wizard69

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    Self tapping screws in my opinion are only good for holding sheet metal on a barn. I would not use them to many fine model or even a machine tool.

    This is prett much repeating what has already been said but here are my suggestions.

    1. Buy quality HSS taps. If not HSS the new super composite materials might work. For small threads we two flute taps. Never buy or use plain carbon steel taps as they seemingly are bottom of the barrel quality no matter who makes them.

    2. Always use plenty of lube suitable for the material being tapped.

    3. As others have noted tap alignment is critical. Most people need a tapping aid. However a taper tap can be helpful in unaided tapping.

    4. Contrary to many posts here do not use a drill press chuck for tapping of the extremely small tap sizes. It works fine for larger sizes but there is too much inertia in most drill presses for this to work well for small taps. The cut off for me and my drill presses is about 8-32, anything smaller is a problem. However a tap follower in a drill press guiding a tap handle is a good idea.

    5. Speaking of tap handles, most are way too big thus not allowing the feel you need. In many cases what you really need is a knob on the tap of one inch or less in diameter. Such a knob is a good lathe project! Make sure it is equipped to allow a tap follower.

    6. I’m not a big fan of drilling over sized holes for the taps. There is some leeway but I really don’t like going to far below 70% thus would tend to stop at 60%. Shave too much cut off and you can have issues with fasteners that may be at the lower limit. This especially with finer threads.

    7. By enlarge the majority of tapsive broken over the years are a direct result of being in a rush or trying to get more threads than the tap or hole allows. The real trick is to be able to stop yourself when you mind isn’t right for tapping. If dinner is on the table, go to dinner and leave that last hole for another day. Often it is the guy in the mirror and not the tap that is the problem.

    8. You mentioned Vermont American. I can’t speak to all of their products but the majority of the big box hardware store offerings are crap. Actually anything the big box store carry seems to be crap. Recently though some of the local stores seem to be putting in the effort to upgrade cutting tools with higher quality tools. For the most part though shopping at the big box hardware stores for taps and dies is a waste of money and time.

    9. If you are in a situation where a tap follower can’t be used consider tapping blocks. They can be wonderful as a tapping aid. Building a tapping stand is an alternative but it isn’t mandatory. From my perspective the real reason to build a tapping stand is to make it a platform for multiple uses. Otherwise tapping aids can be extremely simple, as simple as a V groove milled in a block of material. That material can be a piece of hardwood in a pinch. The goal is to support the tap square to the bore. The blocks with the V groove have a huge advantage in that you can see what you are doing, tapping blocks cover up the working end of the tap.

    10. Instead of using the chuck of a drill press or mill for that matter, consider using it as a tap guide. Adjust the jaws so that the tap shank just slips. Then use you fingers to spin the tap in started square. Very small taps will start with a finger grip on the shank while larger ones will require something to grip the shaft. This is a good place for those tapping knobs described above.

    Best of luck.
     
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