I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?

bud wrote:

I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?


Depending on the portability of the cast iron piece and how badly you
want to "get it done right", I'd suggest you look around for someplace
with EDM capability to "burn it out" for you.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

bud wrote:
I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?


On a high value piece, EDM is probably about it for safe and not like
to make a bad thing worse.

A carbide drill is like to wander to one side or the other, then snap
off. It's an expensive way to make a bad situation worse.

Depending how deep the part is, too, but sometimes a little judicious
work with a hammer and punches to rock the drill loose will do the trick.

If things are really ugly, or the cost is not there in the part, do
whatever is required to get the drill out, up to and including running a
carbide endmill straight in on a plunge cut, and sweat in, thread in, or
freeze in, a plug to start over on.

The old model engineers used to prefer carbon steel taps and drills
for this sort of thing, as they could be annealed quite easilly.

Your best course of action is really dependent on how deep it is, how
expensive the part is, and how ugly a fix you can afford to end up with.

As well as the tools at hand, too.

Cheers
Trevor Jones

bud wrote:

I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?

Rather than a drill use a carbide center cutting endmill, run it as fast
as you can and put a lot of coolant on it. If you drill it out with a
drill, make a drill out of a broken carbide endmill and grind a point on
it like a carbide die drill. Look in the catalogs for the shape of the
die drill. Its basicly a pointed spade ground onto a round carbide
shaft. EDM would be your last resort.. or maybe waterjet.

John

On Jul 25, 4:17 pm, bud wrote:
I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?


Where are you located?

I have a portable edm for such a task.

Wolfgang

Too many unknowns to pin a workable solution down. Here's mine:
drill an oversize hole down to the end of the broken bit. Large enough
to get a small needle nose jaw set into. Now, drill around the bit with
a suitable spot weld cutter to about 1/4" past the end. Break out the
remaining wall and pull the bit out with the pliers. Either continue the
drill procedure, or, if you need threads or hole size to the surface,
thread up a plug, tap the oversize hole, screw it in, and redrill/tap.
JR
Dweller in the cellar

bud wrote:

I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?



--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

On Jul 25, 4:17 pm, bud wrote:
I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?

I'd go with a smaller carbide drill or end mill. Machine out the web
of the broken bit and the rest will come right out. Unless the broken
piece is long enough or deep enough that the drill or end mill will
wander off center.

How about trying a 2-flute tap remover? Try tapping on the piece
first, maybe even try a bit of alum or acid to loosen things up?

John Martin

On Jul 25, 8:10 pm, John Martin wrote:
On Jul 25, 4:17 pm, bud wrote:

I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

On a drill that size I have had been able to use a carbide ball burr
if the drill is not too deep. Run the burr as fast as you can and
clean out the chips often.

I tried to EDM a busted tap once (4-40). No problem, I thought, I'll use use
my handy sinker EDM. Everything was going fine until the electrode shorted
to the workpiece, blew a chunk of metal out #^$^$!@*** and made a mess of
everything. It's not that easy to actually observe whats happening to a
submerged workpiece.

Even EDM is not always the anwser (unless your an experienced EDM sinker
operator which I'm not)


Tony


"bud" wrote in message
oups.com...
I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

Are there any tips to get it out? Would a #28 solid carbite bit drill
out the remains of a HSS bit? Would a Dremel tool work better using a
silicon carbide stone?

Any other suggestions?

I was trying to expand a hole in a cast iron piece when my #28 HSS
drill bit broke off while in the hole. There is no way to punch it
out from behind and nothing big enought to grap onto with vice grips
at the entrance to the hole.

The way I might try if the other suggestions don't work and if you can
get the hole vertical is to go to the spice aisle at the grocery store
and get a little bottle of "alum" (McCormick has it). It will probably
attack the cast iron some but I know it will eat the drill bit and
between the two it should loosen things up enough to work out the broken
bit with the tip of a pick. Use maybe PlayDough to make a little dam
around the hole slightly bigger than the hole and 1/4" deep, or a blob
of rtv. Take a teaspoon of warm water and dissolve as much alum in it
as you can, and then drip it into the hole. Every hour or two maybe
suck the old out and drip in fresh, or not. I soaked a broken bit in
stainless steel overnight and it was gone the next morning (shaking it
gently at 98F). I put a picture up at
http://mysite.verizon.net/vze4s345/id6.html

--
Regards,
Carl Ijames carl dott ijames aat verizon dott net
(remove nospm or make the obvious changes before replying)