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I have a broken tap that is very thin M3(3mm) stuck in the hole that was drilled and I was trying to thread. Is there any way to get it out? This is in a table saw miter bar (9.39mm or 0.37in) for Ridgid TS3650.

As you can see it broke almost flush with the surface. It won't be a problem to leave it there after flattening the area with a file but I would like to use that hole if I can - I was almost done with what I wanted.

enter image description here

enter image description here

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  • Blind hole, or hole through a sheet of metal?
    – Huesmann
    Jul 10, 2023 at 12:04
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    Can you grind it flush and tap elsewhere? Jul 10, 2023 at 12:28
  • If the metal you are tapping is aluminium but the tap is steel you might be able to dissolve it with alum? Guessing that's not the case though.
    – user133831
    Jul 10, 2023 at 15:10
  • Give us more information on the part, "table saw miter bar" isn't Google-friendly. Since a tap is basically conical, anything which allows you to work on it from the far side will be a better bet- plus plenty of penetrating (i.e. very thin, not 3-in-1 or WD-40) oil. Jul 10, 2023 at 15:23
  • @MiniMe So presumably you've (in effect) tapped into that brushed surface visible in the first photo, with the hole being blind? What happened: did you bottom out? Jul 10, 2023 at 15:45

6 Answers 6

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CAUSES

I recognise those 1/4" shaft to drill to tap combos. They're very convenient for plastic or 3D prints, but in anything harder than brass or aluminium you'll do better to hand tap with a quality tap. Taps are absolutely somewhere that the cost and quality correlate, I've got one single M3 tap that cost as much as 20 of the combo bits.

enter image description here
She's a bit thin in the middle, exactly where your's let-go.

Since tap wrenches don't take hex bits, you were probably power tapping this, and got ever-so-slightly off axis. If there was a warning, it went past too quick to notice.

There's also a chance the tap bottomed out in your hole, or it got hung up on swarf/chips.

In the future, hand tap difficult tasks and those where there is no spare. Use an alignment jig and plenty of appropriate cutting oil, and take your time.

EXTRACTION

Start by examining the part for wear and damage. Is it otherwise worth saving?

You can use the part after flattening off the tap stub, but to use the hole it needs to come out.

  1. Start nice and gentle, with some warm air and penetrating oils. To get a grip on the tap, I'd use a couple of medium-heavy sewing needles pushed into the two visible gullets, and use an unscrewing motion. If there's movement, alternatively tighten and loosen edging it out. Keep the area wet with Kroil or CRC556 or almost any light oil. 3-in-1 or Singer oil would be better than nothing. If it comes out, the thread is probably okay.

  2. If there's no motion after 10-15 minutes, try shock. Mount part in a vise (make sure its not squeezing on the stub) Use a center punch and a hammer, or an automatic center punch to rock the stub in the hole.
    This will likely ruin any threads by making them a bit sloppy. Again, alternately tighten and loosen by tapping back and forth. Continue with hot air and oils, and even try remounting in vise so stub is horizontal.

  3. Welding won't work - its too small. Give up on this idea straight off.

  4. Drilling the stub won't work because its small and hard, and any drill will walk off into the surrounding metal. A carbide bit might work, but they're significant cost.
    At this point, I'd accept the hole is dead and a thread insert is in your future. Drill one small hole into the part parallel to the stub, so it's just touching the stub. You're trying to make a relief beside the stub so it can be knocked sideways by the punch and then grabbed with needle nose pliers.

After extraction, you'll have a trench large enough to fly an X wing down.

  • Fill it with weld, drill, and tap.
  • Fill it with JB Weld (the metal one) and drill and tap. Potentially weak expecially for fine threads.
  • Get a threaded insert like the 3D Printing people use and secure that in place with any good 2 part epoxy
  • You might also choose to epoxy in a M3 nut, or perhaps something larger if a larger bolt is acceptable.

ALTERNATIVES

Start by pricing up a replacement fence

  • What you had, and
  • The expensive one you'd like to own someday.

If you break the part unrecoverably, then the first is your get-back-to-go cost. The difference between the two is your opportunity cost to upgrade now.

Good luck!

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    thanks for the detailed and elaborated answer! You hit a nail there -damn, when I threaded the hole I had the bar in a vise -not very tighten up but yet it might have added some pressure to the bar right where the hole was which could explain why it all went so difficult. I last threaded/taped probably 35Y ago :-)) I could still remember the back and forth moves when you feel that the tap is stuck and it is not advancing. I used a screwdriver that takes hex bits to tap, not sure if I went off center with that (no drill used here, used a drill press for the hole)
    – MiniMe
    Jul 11, 2023 at 18:30
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Taps are very hard so drilling and an “easy-out” won’t work.

One possibility is to put pins down the flutes and turn with a bar - success depends on how stuck.

Spark erosion is possible but that small may be a problem.

If some is sticking out or close to the surface then welding a nut on may work.

Or you drill several holes around it to free it up then tap and fill with a stud, then drill the stud to M3 after.

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  • The last option can be a good time for brass studs.
    – Chris H
    Jul 10, 2023 at 6:58
  • not sure what you mean by brass studs ? Just to plug the hole ?
    – MiniMe
    Jul 10, 2023 at 13:05
  • @solar-mike I was wondering if I could get the tap out and reuse the hole, drilling around and doing all you said is going to weaken the bar, see the picture
    – MiniMe
    Jul 10, 2023 at 14:33
  • @MiniMe the idea is to drill out material from around the existing hole, to allow you to remove the tap. Then drill and tap the hole even bigger, insert a stud, and tap the right size hole in that - because you won't have anything left to run this size tap into. I just commented because brass is much easier to tap than the more common steel stud.
    – Chris H
    Jul 10, 2023 at 14:36
  • Agree but as you see in the picture there is not much room to play with that. I would rather leave the tap where it is and drill another hole if I can't easily reuse this one
    – MiniMe
    Jul 10, 2023 at 14:49
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M3 is quite small.

Depending on the nature of the hole, there's other means available. If it's a short hole (think 2-3x diameter, e.g. 6-9mm), a center punch and small chisel may be able to break the tap into pieces. which can be extracted. I've done that quite a few times with M3-M6 taps, but it requires access to both sides - and is likely to damage the surface around the hole.

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It's complicated by the fact that the twist will prevent you from putting something down the holes to get a purchase on the broken tap. Try /lots/ of penetrating oil left overnight, warm up (Al expands more than Fe) and see if you can persuade it to wind out using e.g. a very sharp punch. If you mess up the thread use a Helicoil to repair it. Carefully.

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  • This is mild/softer steel not Al
    – MiniMe
    Jul 10, 2023 at 17:05
  • Oh dear. Still, definitely oil and try cycling the temperature repeatedly: if you were cutting dry there might be a tiny bit of a pressure weld in there. I presume you don't have access to liquid nitrogen, but chilling in a freezer and then heating repeatedly /might/ help. Other than that see if you can live with it, or get a spare... or even get somebody to grind a replacement bar to size. Jul 10, 2023 at 17:22
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Sorry, images aren't loading for me right now, so I can't tell exactly what you're asking about. My guess, though is that the images shows the stock miter gauge that came with your saw.

If this is the standard miter bar that came with your table saw, just throw it in the trash and get a good aftermarket one.

Nobody, but nobody includes a decent miter gauge with their table saw not on a $2k+ Harvey, not on a $3k SawStop, not on a $4.5k PowerMatic. Nobody.

Of course, we don't know what you needed these holes for, but my guess is a DIY improvement to the miter gauge because what you've got is crap. (No offense to your Rigid, my Delta's stock miter gauge is crap, too.)

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    yes you guessed the purpose of my work. I do have an Incra HD miter gauge :-) but that is tied to the sled that came with it (because I want so) and the plan would be to have a go to miter gauge for quick rough work but at least decent because as is has like 1/16 or 1/32 play
    – MiniMe
    Jul 10, 2023 at 18:31
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A carbide drill in a drill press will likely drill this out, but you may have to drill/mill a flat with a small milling bit first to keep the bit from wandering.

To save the threads, size the drill a bit under tap drill size. The tap may crumble to pieces, or you may have to keep drilling with slightly larger drills until you can get one side clear.

Be careful, it’s hard to extract a broken carbide drill, and it’s more brittle and likely to break in a drill press than HSS.

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