O/T - help removing a broken tap

[jspangler]

Hi

I broke a 3/8-16" Tap in one of my fixtures ( 1" Thick 6061). I had already wanted to drill out the tapped holes, and heli coil these stud holes, but now i really need to do this. What can I use to fix this? The drill size for the heli coil tap is 29/64, so i can't co bigger than this.Any suggestions. I tried backing it out and chipping it out neither of which worked. I'd plasma cut it out, but then the hole will be toast.

 

Thanks

 

John

[Jayson Kramer]

Find someone with a EDM dunker to burn it out.

[J Coulston]

Try searching google in alt.machines.cnc there was a thread on chemicaly removing broken taps.

 

Subject: chemical tap disintegrator

Date: 2002-03-08 17:08:22 PST

 

The product was called Tap Out.

 

Good luck,

 

John

[iowajim62]

Hi,

Just a thought,ok? Bear with me if you haven't

heard this before. If you have an old 3/8" Carbide

Endmill not chipped or an old carbide regrind go to location X0Y0. Now bring your old cutter down

and set Z. Now turn spindle on at or about 5000

RPM and go into handle/hand wheel mode.

Now this is the fun part,set handle to Z and .0001

increments and start cutting down very easy. As you do this start blowing with your air gun right

on the hole and go down .100 and then back out and check. Keep going until your thru or you can dig out the remainder.

Remember this is emergency only method not Standard Practice.

HTH

Jim

[Guest]

I once removed a tap using a tap dissolving fluid. I think I got the kit from DoAll. Do All I can't remember the name of it though. Call DoAll and ask for the tap dissolving kit. It worked great. It did have some limitations on the type of material the tap was stuck in. But I think Aluminum was ok.

 

[ 10-02-2002, 05:17 PM: Message edited by: Marc Lindsey at San Diego CAD CAM ]

[MACHINEMASTERG]

iowa jim thats works but have also done this since you cant go past 29/64 take .437 mill grind bottom away on on side leaving one flutes corner enough that it clears tap dia when on center it will look like a bore tool off center then go down it will bore around broken tap cutting .437 dia hole and not hit tap?? after should come out with a little bit of alum around this woks takes some tring though got me out of big bind one night very late good luck!! edm is thebest way

[iowajim62]

Machinemasterg

Excellent idea !!!

Just love to hear new ideas.

Made me think of using old 1/2" em for this.

Learn somethin new everyday !

jim

[kyle]

Could also use a single lip carbide blank, works great on those odd size holes and is fairly strong. Just grind to needed diameter on your single lip grinder.

[MACHINEMASTERG]

yea kyle another good one keep then coming we had a problum with some guys always breaking taps but then we told then they had to drill the hole first !! no im not kidding

[MACHINEMASTERG]

another thought i had after reading this again ivhad taps bind and broke in aluminum could not move thenonly alittle bit then soaked then in aluminum tap magic and like the name said wala it backed right back out it must etch some metal and freed it up

[MACHINEMASTERG]

again just wondering how they keep the tap disolving fluid some have mentioned from disolving thru to containor its in??? man really getting my post count up now wont be long till 200 and i can get some free pst 's files

[iowajim62]

most of dissolvers eat the iron only

thats why it doesn't eat the parts

[cadcam]

quote:

---

we told then they had to drill the hole first !! no im not kidding

---

ROFLMAO

[TheePres]

Most mill tables are made of iron, so keep that stuff away from bed. Its Just Muriatic acid, you could probably get 5 galons of it, for same price as tap-kit.

[TheePres]

Jsplanger,

Could u use a Keen-sert in this app??

They are stronger than heli-coils and u use standard drills and tap. U can get 1 with 1/2-13 OD threads, use .453 instead of .422 drill, because they are not full profile threads on OD.

[jspangler]

Hi

Cool. I will try the end mill method since that's kinda what I had seen before. Thanks for all the quick answers.

 

John

[Glenn Bouman]

Since it is aluminum you can weld a steel bar to what is left of the tap and use it as a handle to turn it back out. Worked for me in the past.

[TimHollis]

If you have access to an EDM, form a Allen Hex, carbon, and sink it in. use a allen wrench and and try to back it out. This works really good if it a through hole.

 

 

The Expat

[Saultspics]

We have this problem from time to time.We use a carbide endmill the same size as the tap or bigger then use a steel thread insert (E-Z LOK)or heli coil.

Be careful, don't brake the endmill.

[Mick]

Sandvik make Hard Cut drills that will drill out a broken tap. I've seen them used before, and they work great. Call your Sandvik Coromant rep..

I'm sure he'll be glad to help...

[chris m]

All of these suggestions are right on.

 

Just a word in case you go a little oversize:

Helicoil makes a "Twinsert" which is generally used when something like this happens [or when the guys interpret "#6-32 Helicoil Tap" as "#8-32 Helicoil Tap"]. This is basically a Helicoil in a Helicoil which allows you to go bigger with the drill.

 

quote:

---

...but then we told then they had to drill the hole first !! no im not kidding

---

We had a problem here a few years back with a guy bending boring bars all of the time. The problem was solved when he was taught to drill a hole in the part first I'm not kidding either

 

Scary

 

[ 10-03-2002, 07:34 AM: Message edited by: chris m ]

[McRae]

Mick,

 

I also offer my testimonial here to the success of the Sandvik Hard Cut Drills. They are essentially the Single Lip Solution stated earlier on in the thread. Here also is an idea, since you have some good thickness, use something called a keensert which is a solid threaded unit and then drill and tap the hole in this "Steel" insert in the proper position.

[MACHINEMASTERG]

something funny ithough id share while we are talking about tapping my NEW guy called me over to see why his tapping op wasnt working ...good rpm to feed rate for pitch but when i looed at the tap i had a hard time not to laugh when i told him that its a.250 4fl ruffing mill??? no im not kidding!!

[Eric S.]

I have used an chemical in a kit called Tap Out. It is an acid that will SLOWLY eat away the tap and not aluminum. I have only used it on small taps and it still took quite a while so you might want to find another method for your headace.

[Roger Peterson]

Most of the time I have had to remove a broken tap in aluminum it wasn't neccesarily stuck that bad. The problem was you just didn't have a good way of putting any torque on it. Most of the time an easy out or if it broke off flush weld a smaller bolt to it. Try not to use shcs they get awful brittle when welded. Cobalt drills do a fair job of drill hss taps. Another trick is if it is broke a ways into the hole is to take a bolt of the correct size and chuck it up in the lathe drill a hole the size of the drill you want to use and spin it into the hole and now the hole you drill for you easy out is on center and if you apply a bit of torque when screwing it in you don't have to worry about the tap spinning and breaking your drill. Having a few sizes of left hand drill bits around isn't a bad thing either. The last time I tried the acid aproach it took a while.

 

my 2 cents

 

good luck

 

quote:

---

I have used an chemical in a kit called Tap Out. It is an acid that will SLOWLY eat away the tap and not aluminum. I have only used it on small taps and it still took quite a while so you might want to find another method for your headace.

---

Eric I agree SLOWLY is the key word

 

[ 10-03-2002, 02:50 PM: Message edited by: Roger ]