Drill Doctor

[chrisser]

I've been drilling and tapping my heads where the exhaust manifold bolts go.

All the bolts snapped off and I've been unable to extract them. I even tried drilling the centers and welding a nut on the stud - no joy.

I found that most of my drills dulled before I even finished the first bolt, which then took forever to get through the material. I was first going to buy a bunch of new bits, but the price of that adds up quickly. I have all 12 holes in the heads to redo, plus the 4 in the exhaust manifolds for the Y pipe, and the stud that holds the oil dipstick bracket.

So I got up early yesterday and ran to Lowe's before the black friday traffic got too heavy and picked up a Drill Doctor drill sharpener.

They're about $100, and I wish I had bought one years ago. As soon as the bit starts to dull, I walk it over to the sharpener and top off the edge. Takes less than a minute and I'm back to work. Sometimes I sharpen the same drill 3 and 4 times during the course of a single bolt. I got 3 of the broken bolts drilled out and then tapped in about 45 minutes - it took hours to do it before I got the sharpener.

I don't have any affiliation with Drill Doctor, but I sure like their product.

Edit:

I was also using Harbor Freight taps. They've worked fine for me in the past chasing threads and tapping aluminum, but they wore out quickly tapping the heads. Picked up a few taps from McMaster-Carr (they're local to me and were open yesterday) and the difference is like night and day. If you have to retap heads, the money spent for a quality tap is definitely worth it.

 

[Scy]

Yep, the Drill Doctor ended up saving me money in the long run. I thought it was all hype, but it just works.
Definitely worth the money, unless you can sharpen bits by hand on a grinder. I could never get the hang of that skill.

 

[chrisser]

I can never get a decent bit on the grinder either, especially on the smaller sizes.

I went out this morning around 10:00. I'm back in after cutting the bolts near flush, and drilling and tapping 5 bolt holes in one head. Less than two hours. Probably sharpened bits 25 times. I can't believe how much time is saved having sharp drill bits and good quality taps.

I actually bought 8 taps from McMaster Carr, since I wore out 2 Harbor Freight taps on two holes. Figured at that rate, I'd need at least 5 or 6 and got extra 'cause it's a 2 hour round trip back there and they close early today.

Nope. Used one McMaster Carr tap for 10 holes with no appreciable wear.

 

[Scy]

Mcmaster-Carr is one of my go to places as well.

As far as bits or taps go they are one of the few areas I won't go cheap on. I try to buy American made drill bits as I think we still make the best there is. I would only use Harbor Freight or any big box store bits on a wood project like a bird house or something. Anything to do with metal gets the good stuff.

 

[Spott]

Yes, harbor freight cutting tools are made of the cheapest steel, and are poorly hardened. Decent HSS bits from a good industrial supplier can't be beat, for the price.

The best sharpening machine I've ever seen is an old Darex M-series machine. They're a little spendy, but if you replace dull bits a lot, it will pay for itself in the long run. It's still not worth it to sharpen anything under 3/16" or so, however.

Spott

 

[RonD]

I have had good results drilling out broken bolts with reverse drill bits, and reversible drill.

Most broken ends start to unscrew before you are 1/2 way in, the rotational direction and vibration loosens them enough to break free and out they come.

 

[doorgunner]

Turn the drill (bit) about 1/3 to 1/4 as fast as the drill motor will run---if the metal is hard, turn the bit about 30-50 rpm to drill thru hardened steel.....the "bit" will last much longer....also use threading oil to drill holes and to tap threads to make everything go smoother.

 

[wildbill23c]

I've had my drill doctor for several years now, and it works great, you can also change the sharpening stone on it when it becomes worn out as well. I took my grandfather's dull bits and sharpened them, and he swore I bought a new bit set. It works great. Now that I have it, I find myself keeping my bits sharpened and ready to go. Drilling wood isn't much of a problem, but trying to drill metals is where the bits will become dull more quickly.

 

[Hammermechanic]

Yep.....What Doorgunner said! I have a friend who just doesn't "get it" and trys to drill metal with a non-variable speed drill. As a result,he burns up bits,and HATES drilling anything! Too much speed = too much friction,which equals too much heat. Bit loses it's hardness and dulls quickly.
I learned long ago (Dad was a Machinist!) to drill where the speed creates a long,single spiral "chip" and always ask yourself,"What color is the chip?" Too much speed = blue chip,and bit won't last very long.

 

[martin]

Most of the hand drills on the market are useless for a project like this as they turn way too fast. I know they have variable speed but to get them to turn at the speed you need (4-5 hundred rpm) they have no torque as that's probably the slowest they will go and as soon as you load them they stall. good hand drill will have a maximum speed of around seven hundred rpm.
Sharp, good quality tools are always the way to go, cheap (quality) tools are frustrating and dangerous.
My grandfather showed me how to sharpen bits by hand on a grindstone when I was knee high to a grasshopper and it's something I've never forgotten. I've tried using a few of the various bit sharpeners over the years and have never been able to get on with them for some reason.

 

[Dune Runner]

I have always used a freshly dressed grinding wheel for drill bits. I learned to do it in a machine shop class when I was going through a CNC course.

 

[Scy]

I have always used a freshly dressed grinding wheel for drill bits. I learned to do it in a machine shop class when I was going through a CNC course.

What about putting a split point on those bits with a grinder? Drill Doctor will do that as well as sharpening.

I'm not dissing the skill to use a grinder to sharpen bits, (I wish I had that skill), I just really appreciate the split point on some drill bits.

 

[adsm08]

Most of the hand drills on the market are useless for a project like this as they turn way too fast. I know they have variable speed but to get them to turn at the speed you need (4-5 hundred rpm) they have no torque as that's probably the slowest they will go and as soon as you load them they stall. good hand drill will have a maximum speed of around seven hundred rpm.

This.

The Triton engines pop manifold studs all the time, and we have to drill them after they have become case-hardened from heat cycles. We have a kit at work to make sure we get the pilot holes straight and it has this little chuck that goes on an air ratchet. I can turn the restrictor down on the air line and that bad boy just rips the studs up. I can get my air ratchet to spin at 10 RPM and not stall.

 

[Mark_88]

Turn the drill (bit) about 1/3 to 1/4 as fast as the drill motor will run---if the metal is hard, turn the bit about 30-50 rpm to drill thru hardened steel.....the "bit" will last much longer....also use threading oil to drill holes and to tap threads to make everything go smoother.

Most of the hand drills on the market are useless for a project like this as they turn way too fast. I know they have variable speed but to get them to turn at the speed you need (4-5 hundred rpm) they have no torque as that's probably the slowest they will go and as soon as you load them they stall. good hand drill will have a maximum speed of around seven hundred rpm.
Sharp, good quality tools are always the way to go, cheap (quality) tools are frustrating and dangerous.
My grandfather showed me how to sharpen bits by hand on a grindstone when I was knee high to a grasshopper and it's something I've never forgotten. I've tried using a few of the various bit sharpeners over the years and have never been able to get on with them for some reason.

Well, glad I read this again...great information...I have about 5 bits that I managed to get about 4 holes each just drilling 18 gauge steel...I was cranking the speed up as high as it would go...and I created many blue chips without realizing what the problem was...

Thanks for posting...

Not sure if I can afford a Drill Doctor but I will look into them next time I have some money in my pocket...

 

[frdtrknut]

Good quality drills and taps make working with metal a pleasure. Good quality stuff holds an edge much longer so in the long run pay for themselves. Build yourself a good set a little at a time and it won't seem so expensive. Also speed is important and some good cutting oil will cool and save the edge.