Drill/Tap newbie mistake! $#^%@!

[SledDog]

OK, I'm a newbie! Here's the issue. Most of the bolts on my M38 are original. I've been spraying them down with PB-Blaster on a regular basis since it arrived. I knew drilling and tapping was going to be an on-going project. However, I have never snapped this many bolt heads ever~!

The big issue, this is the first time I've snapped a drill bit in a pilot hole. How the heck can I get this sucker out and finish? It snapped flush with the frame (last hole of course), for the grill mount on the right side.

[wesk]

The only way is to use a new drill bit of a harder material then the one you broke. Read in "cost more money" bit.

The type and degree of fastener corrosion on these old vehicles generally dictates a need for a, Oxy-acetylene torch for heating the fasteners cherry red before you try to turn them. If this is out of your reach try a Mapp gas torch.

I prefer the torch over the drill and easy out routine. "Easy out" is a true misnomer.

A few points to remember when using the drill:
1-The cheaper the bit the faster they break!
2-The smaller the bit you try to use for pilot holes the easier they break!
3-Always use cutting oil with the drill bit. This will cut down on breakage.
4-When using very small bits for starter pilot holes keep the hole shallow. Not more than a 1/4". Then move up to the correct bit.
5-Invest in a Hi-speed air die grinder and cut-off wheels.

[oilleaker1]

There is a kit of socket-like extractors that has 4 pins or projections that slide into the 4 cutouts of a tap. It fits or snaps into a wratchet. Some mechanics have them. If you can't see the 4 low grooves on the end of your tap, it won't work. The other try is to take a center punch and hammer and try and reverse the tap out in a turning motion while hammering it. Some guys lay a hex nut over the end of the broken tap and weld it to the tap on the inside of the nut. Once it sticks, turn it out while still hot. That hardened tap is not going to like any drill bit you try. All the above is termed------" a peckeroid " John

[Bretto]

If I ever run into a questionable bolt anywhere, I always used heat. I have always had luck with just propane. My technique that I do is heat it pretty good then hit it with a mist of water. I'll do this a few times. The subtle movement between the bolts and threads from the quenching is enough to break the bond of rust. Then I hit it with some penetrating oil before attempting to back it out.

[RICKG]

I have resorted to this approach more than once.
If the slightest bit of broken stud is above surface
lay an appropriate size washer over it and weld it to the
stud from inside of hole. Take a 2 or 3 inch scrap of 1/2"
sq steel (or whatever size you can scrounge) and weld
it to the washer. Put a wrench on the 1/2" scrap and
gently work it out..

[wesk]

That hardened tap is not going to like any drill bit you try.

John,

It's a broken drill bit not a hardened tap.

[oilleaker1]

Well , Wes has seen that I can't read, but, half of the answer still applies. Drilling out a drill bit gives you the same problem. I usually make it to the tapping part and break off the tap though. Hope you get it out without too much of a fight. John

[SledDog]

Thanks for all the advice and great tips! Good news...the offending bit is now sitting in my trash bin and the hole has been successfully tapped! It only wasted 2 hours of my time

I'm now taking a different approach to un-siezing the remaining 4,000 nuts, bolts and screws. That should save me 8,000 hours...right?

[xheadnut]

Take a hardened punch and chip the drill away. have broken many drills in 30 years of machining. the drill is harder than what you are drilling but also more brittle, a piece of steel can bend but a drill will snap or shatter because of this.

[ocwd]

Try heating the bolts up with a tourch before you remove them. The heat will cause the bolts to expand and break the rust bond. Heat them up and let them cool a bit before removal. It works most of the time. Be careful if you have already put chemicals on the bolts. They may give off toxic fumes when heated. A small tourch from Home Depot is pretty cheap. This is for bolts that you have not broken yet. You'll go through about 3 cans of oxygen for every 1 can of map gas.

Dave

[ocwd]

I'll try propane as Brett mentioned above. It's cheaper than oxygen.

[wesk]

Propane will not usually heat to cherry red. Mapp gas will as will oxy-acetylene. I don't bother with the Oxy/Mapp system since I have a complete oxy/acetylene setup. The plain Mapp bottles are just a tad more than the propane and will reach much higher temps.