Broken drill bit removal???

I've managed to fix this in a single sided applicaton by using a rotabroach - a holesaw kind of thing designed for cutting smooth, neat holes in sheetmetal. Come in sets. Useful tool. I managed to cut a deep groove around the offending broken drill and then was able to use a small chisel to smash away the stub which contained the broken bit.

This was on a body mount on a boxed '32 frame (thanks Matt and Dennis at IHRS) and i managed to save the day without any unwanted carnage.

Chris

 

I found a diamond tip core drill in 1/4" and gave that a try. It was making slow progress until the ****ty mild steel shank twisted off in the hole. Now two things stuck in the hole. Next came a 1/4" masonary bit with a tungsten carbide tip. It's slow but it works. Job done.

Thanks for all the advice. This thread turned into a pretty good reference for lots of related problems. The main thing is it got me sorted out.

thanks, Pete

 

I brake bits all the time. Mine are usually anywhere from 3/8" +

What I've found works best lately is a pair of needle nose pliers. Stick the tips in the void on the broken bit, squeeze, and spin it out in a reverse direction. Ofcourse, this only works if you can get the pliers in there.

 

Very different work application to be breaking 3/8 bits, but yes, at least at that size you have some options in terms of getting hold of them.

 

A carbide drill or end mill would have worked also. The idea being go slow and careful and let the bit do the work for you. Glad to hear you got it out.

 

I am not going to reiterate what good info has already been posted here. Not to be impolite here but I wonder why you are drilling a pilot hole for a 1/4" finished hole? I drill up to 3/8" without a pilot for general use brackets etc. If the holes require accurate locating then I would start with a 1/8 bit(or a center drill) and only go in about 1/8- 1/4" deep and then use the 1/4" bit to finish. Many people use several different bits to get up to the finished hole but if you have a drill press you only need a 1/4" pilot then you could go directly to a bigger bit, even 1/2", properly clamping the part to the table. As a 30+ general machinist (retired) I use this method all the time. I have even drilled a 1/2" hole without a pilot when just making a hole in a bar or plate.

 

I tend to agree with all of this, IMO, pilot holes are over rated.

I am speaking generally of course, there are exceptions.

But most of the time it seems like I get a "rounder" hole when I don't use a pilot, and while one of the reasons pilot holes are used is to save wear on drill bits, I am not so sure about that. In my mind, the use of a pilot hole concentrates the work a bit must do to a smaller area, causing the drill/work to jump and a more harsh existence for the bit...

 

I was visiting da tinman a while ago and he was installing the inside trim on the a-pillar of my coupe when he snapped the head off the machine screw he was tightening. After pitching the screwdriver across the shop, he grabbed a small visegrip and backed out the screw.

The threads had galled so he grabbed a tap and proceeded to dress the threads when SNAP!!, the tap broke off flush with the pillar. I kept real quiet. After a few choice expletives he grabbed his tig welder, quickly tacked a small washer to the tap through the center hole, then tacked a small hex nut to the washer and effortlessly backed out the tip of the tap. Took him less than five minutes.

Me? I'da been in the La-Z-Boy™, beer in hand, seconds after that "SNAP".

 

You mite try using an arc welder take a 1/8 rod turn the amps to about 140 put the rod hard against the bit and have someone turn on the welder long enough to make it stick then try pulling it out. I've done it to remove broken polts

 

I once broke a tap in a piece of work I was machineing ,I heated it up to cherry red and then packed the area with heat retaining putty and let it cool real slow which annealed the tap .It then made it possible to drill with a carbide.I also have holesawed an area where drill was broken ,then slugged and welded and dressed and retapped.These are ways you can use if you cant shock the bit with a punch and break small pieces off until you get it all out,some times patience works best.Joe

 

Done that before with good results^^^^^^But it's an all or nothing fix.

 

If its a small enough piece, lay it in the freezer (a container of dry ice is the BEST and quick too) over night. Next day punch it from the back side.......... has worked for me.

In college where a chem lab with dry ice was readily available we use it for getting retainer pins in our formula and baja cars. Also makes a pretty BANG when you mix it with water in a pop bottle.....

 

Today I broke a 10-24 screw in my backup light frame and welded( second try it stuck to the screw) a nut onto the bit sticking out and then unscrewed it. Didn't think of welding a flat washer on first, will have to keep it in mind for next time.