drill bits

[seattleboatguy]

I need to drill out a frozen bolt on my Westerbeke 4.4kw generator. It's the bolt that a bracket pivots around to tension the belt. I expect to go through several drill bits in the process, and I was wondering if you guys sharpen your old bits or just buy new ones at the hardware store? Thanks.

[OldDan1943]

I buy new but also keep the old for wood.

[PPandE]

I'd start the project by buying cobalt drill bits. Good luck.

[HopCar]

Try to find left hand twist drills. You may find the bolt turning out as you drill it.
Watch this video. It has some great ideas for keeping the drill centered.

https://www.youtube.com/watch?v=dJfkCj3FWBs

[Olebird]

Drill bit sharpener is one of most valuable tools on the bench. Keep em sharp, tempered, with a good cutting oil - much easier.

[BruceK]

Impressive video Parks. No BS, just "this is how it`s done". The OP won`t have the luxury of the job on a bench, but he`s off to a flying start. I had a friend who was a toolmaker on top of fitter and turner, watching someone with real expertise with metal is a treat.

[C lectric]

If there is enough thread in the hole to use another bolt then that bolt could be drilled to centre the bit long enough to start the pilot hole in the broken bolt.
I have made guide plates of 1/4 steel to align the bit properly so it drills on centre if there is/are another couple holes nearby to hold the guide plate.

I agree about the reverse twist bits and have had success with those on a number of occasions. Sometime even though broken the remained is loose or loose enough for the reverse bit to back it out.

There is a tool called a combined pilot and countersink tool used usually on a lathe but also in drill press operations. The pilot part is quite a bit smaller than the body . These a quite short tools, HARD, and if used carelessly can break.
High speed and coolant for the pilot part just to get the hole started in the broken bolt. Once done then the other bit can be used.

Try using a dremel with a small stone that can reach in to grind a flat spot so the drill bits, which ever you use has a flat area to start on. Otherwise the bit is going to wander.

I use new bits in cases like this. I am reasonably good at resharpening bits but no where near good enough for this. And yes a cobalt bit is just a little bit better than the usuall HSS.

And try to find a GOOD penetrating oil to hopefully help with the broken bolt part.
Kroil , is good.

[psneeld]

I broke a lot of drill bits like many.

Then I bought a small set of left twist, Irwin brand cobalt drill bits and they even drilled broken taps nicely.

Best I have used by far!

[FF]

https://www.lowes.com/pd/Drill-Docto...E&gclsrc=aw.ds

Makes a great present!

[Cigatoo]

Originally Posted by psneeld

I broke a lot of drill bits like many.

Then I bought a small set of left twist, Irwin brand cobalt drill bits and they even drilled broken taps nicely.

Best I have used by far!

I have 2 sets of Irwin’s.

[seattleboatguy]

HopCar's video and FF's bit sharpener were both pretty cool. Thanks very much. Fortunately, I don't have to worry about ruining threads deep inside a shaft. Both ends of my nut and bolt are visible, though not easy to attack. It is the shaft in the center that has welded itself with corrosion to the belt tightening bracket. I may have to move the generator to get at it, which will not be easy, but I think I can eventually get it off of there. Thanks for the feedback.

[ancora]

As an apprentice, I was told by my mentor to never refer to a drill as a "bit." It is a drill.

[FF]

While taking apart stuff will work with any drill that survives , some holes need to be structural.

A new bit will drill a round hole the size of the drill bit , but a hand sharpened bit will drill a larger hole as eyeballing the drill center is near impossible.

The drill bit sharpener system centers the drill, so it drill the size hole you planned on.

[Bacchus]

Originally Posted by ancora

As an apprentice, I was told by my mentor to never refer to a drill as a "bit." It is a drill.

I've heard that opinion before but have never seen anything to substantiate it other than " I knew someone".
Completely contrary to what my mentors told me and I find in "print" anywhere.
Got any confirming evidence?

[friz]

I have a Drill Doctor. Yes it sharpens bits but takes practice. Probably takes much less time to sharpen a bit than driving back and forth to the hardware store.

[twistedtree]

Originally Posted by ancora

As an apprentice, I was told by my mentor to never refer to a drill as a "bit." It is a drill.

If a bit is a drill, then what is the thing with the electric motor and chuck?

[OldDan1943]

Originally Posted by twistedtree

If a bit is a drill, then what is the thing with the electric motor and chuck?

Hmmm, how do you explain the phrase, " Brace and bit"?

[Island Cessna]

Originally Posted by twistedtree

the thing with the electric motor and chuck?

Like most trades, machinists have a lingo dedicated to the trade. The old time journeyman machinists I worked with called that thing a “drill motor”.

[Porgy]

Originally Posted by twistedtree

If a bit is a drill, then what is the thing with the electric motor and chuck?

That explains it! I know a very experienced guy who always called it a “drill motor.”

[Portage_Bay]

Originally Posted by Porgy

That explains it! I know a very experienced guy who always called it a “drill motor.”

I learned the correct terms are drill motor and drill bit. Shortened for convenience to drill and bit.