What size drill bit for lug stud.

[/pine]

There are plenty of times when professional machinists/millwrights cannot use an annular cutter and mag drill. And unibits suck for anything over 1/8". So to say it requires a unique situation to use a twist drill is far from accurate.

While opening up a hole 1/8" at a time sounds good in theory to a novice.....those who make a living making holes in metal know that is the worst possible thing you could do

LMAO....those that make a living boring holes in metal don't usually use hand drills and twist bits...go back and read what I said a little slower...!

And I hate to point it out but this thread was about enlarging an existing hole....likely a common occurrence in the millwright business...!

Quality unibits are commonly used on metals up to 3/8"...and they are fast...

 

[the old grind]

Millwrights (that I still hang with & talk shop) use(d) reamers to tweak holes working in our GM plant. Rotary broaches not in their kit & not always a place to attach a mag drill to a machine when setting it. May be different in other shops.

 

[LD1]

LMAO....those that make a living boring holes in metal don't usually use hand drills and twist bits...go back and read what I said a little slower...!

And I hate to point it out but this thread was about enlarging an existing hole....likely a common occurrence in the millwright business...!

Quality unibits are commonly used on metals up to 3/8"...and they are fast...

Yup, the thread was about enlarging an existing hole. And I gave my advise. But then somewhere on page 2 or 3 the conversation turned to stepping up drill bits vs a pilot and drill to size.

Unibits are different than stepping up drill sizes. Their cutting angles are not the same and they dont try to grab and twist the drill out of your hand like stepping bits.

But Id say most on here dont have a unibit.

And most that make their living making holes try to avoid using a hand drill. A drill press, mill, mag drill, etc are all much preferred. But there are times when a hand drill is the only option.

And yes, slightly enlarging an existing hole with no way to mount a mag drill is a very common occurrence in the millwright profession. And its dreaded by anyone that has any experience. It is much preferred to just drill a pilot then a bit to size. Unibits have too many limitations.

I am someone who has made a career making holes in metal. I have held many titles, some of which include industrial maintenance, machinist, and millwright. So when you reference "professional machinist or millwright", or "those that make their living boring holes"......you sir are talking about ME. I AM one of those you reference. And I stand by what I have said, and could hook you up with a dozen other "professional machinists and millwrights" that will say the exact same thing

 

[ROUSTABOUT]

Buzzing the hole out with a die grinder would also work. You don't need to remove much.

And ream from the back side. Leave the face near normal.

 

[lpakiz]

I’m with spyderlk and LD. You’ll never get a usable hole with a drill bit. Never.
Custom sized reamers are available and are the best solution, especially since you need to do several holes. Don’t wreck the hub, break the bit, or break your arm with a drill bit.
If it were just one thin hole, you could try a carbide burr and a high speed die grinder, but you should have some experience doing this.

What ‘“might” work is a tool called a “tapered bridge reamer.” You would need a 5/8”. This size reamer starts at about 7/16 (guessing here) and final diameter is 5/8. Your final, correct size will be somewhere along the length of the taper. Mark the shank or make a stop collar to limit the final depth that you need, to achieve the hole size you want.
Ream from the backside, so the hole gets smaller as it gets nearer to the hub face. Turn it as slow as you can, using a big OLD, slow speed 1/2” drill.
Someone above suggested practice. I HIGHLY recommend that too. Get a flat plate of scrap, about the thickness you are working with. Drill a 1/2” rough hole (or several) in the plate, then ream with the bridge reamer until the stud fits. When you get it right, head over to the hub. And as mentioned, freeze the stud and warm up the hub.

 

[SPYDERLK]

I had considered the bridge reamer route as well, but thought, perhaps wrongly, that the taper hole would be a deal breaker.

 

[the old grind]

Bridge reamer has a slow taper, not like the T-handle reamers many of us used for elec panels/boxes before unibits and cordless drills went into our kits. We're removing the hubs to open holes and install the studs, no? Once a hole is sized right for the interference fit I've used manifold nuts & deep-well impact sockets to draw wheel studs in, with anti-seize I'd use on threads anyway. Grease is kinda old hat for that but still works. btw, love hearing from other tradespeople, esp those with more OTJ experience than mine.

 

[SPYDERLK]

Bridge reamer has a slow taper, not like the T-handle reamers many of us used for elec panels/boxes before unibits and cordless drills went into our kits. We're removing the hubs to open holes and install the studs, no? Once a hole is sized right for the interference fit I've used manifold nuts & deep-well impact sockets to draw wheel studs in, with anti-seize I'd use on threads anyway. Grease is kinda old hat for that but still works. btw, love hearing from other tradespeople, esp those with more OTJ experience than mine.

Never stated, but Iv always thought this was to be handled in place. Otherwise the job is an essentially trivial drill press reamer task.

 

[ROUSTABOUT]

I'm just a yay hoo with a shop at the house, but I have a 30 ton press. I'm sure somebody you know has a press. Probably a die grinder also. And can make your dreams come true.