What size drill bit for lug stud.

[the old grind]

Drill bits are not reamers. DB needs a pilot hole to be only as wide as the bit's web. (AKA 'chisel' in the trade) The margin has no relief so doesn't actually cut when wobbled to enlarge a hole. Reamer also has no relief on the margin, removes up to .015"/side when hole is sized correctly.

Using a drill bit sized to slightly enlarge a hole is like reaming and puts all the load on the corners. (10+ yrs J-man toolmaker/tool grinder for GM engine & transmission plants, once 22k member UAW Local 599 is now just a retiree chapter)

Agree that a DP or better a mill is best to maintain hole size and location. Ream don't drill if hole is nearly to size. Carbide tooling (drills, reamers, burrs) can chip/break easily when used in hand drill & some (less rigid) DPs.

Anyway, back to what'll work this time.

 

[SPYDERLK]

Agree that a DP or better a mill is best to maintain hole size and location. Ream don't drill if hole is nearly to size. Carbide tooling (drills, reamers, burrs) can chip/break easily when used in hand drill & some (less rigid) DPs.

[[Anyway, back to what'll work this time.]]

Rat tail file and Loctite.

 

[pmsmechanic]

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

 

[LD1]

Drill bits are not reamers. DB needs a pilot hole to be only as wide as the bit's web. (AKA 'chisel' in the trade)

Trying to explain that on this forum seems a lost cause. Everyone thinks The proper way to drill a 1" hole is to start at 1/4, then 3/8, then 1/2 then 5/8, the 3/4 etc etc. I feel bad for the poor drill bits.

But split point bits up to 1/2"....no pilot. Over 1/2"...pilot only the size to clear the chisel. It cannot be repeated enough.

 

[SPYDERLK]

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

Yes, but extremely hard to control. You cant win the accuracy fight. Deflection forces from cutting on only one side of the burr cause it to want to orbit inside the hole. -- Very sensitive to the slightest loss of operator control, especially when the burr is not quite small compared to the hole. But then a small tool causes a need for more fine blending; a light touch situation that hampers tight positional control. And a burr nearly as big as the hole is out of the question. Such can generate orbital frequencies well up in the audio range [KHz] from a bit spinning just a hundred RPM !

 

[/pine]

Trying to explain that on this forum seems a lost cause. Everyone thinks The proper way to drill a 1" hole is to start at 1/4, then 3/8, then 1/2 then 5/8, the 3/4 etc etc. I feel bad for the poor drill bits.

But split point bits up to 1/2"....no pilot. Over 1/2"...pilot only the size to clear the chisel. It cannot be repeated enough.

Actually from a technical point of view the only logical reason not to step up in bits is about precision (not the wear on the bits)..because the lack of guidance of the point you can end up with a three sided or oversized hole...

...Yes, it does wear more on the outside of the lip face but no more than if the entire lip was cutting...it also takes less energy from the drill...it's a compromise but hardly a big deal...These days field machinists and millwrights use unibits in place of twist drills for enlarging etc...

 

[SPYDERLK]

Actually from a technical point of view the only logical reason not to step up in bits is about precision (not the wear on the bits)..because the lack of guidance of the point you can end up with a three sided or oversized hole...

...Yes, it does wear more on the outside of the lip face but no more than if the entire lip was cutting...it also takes less energy from the drill...it's a compromise but hardly a big deal...These days field machinists and millwrights use unibits in place of twist drills for enlarging etc...

Grabbing and chipping of the cutting edge. The spiral angle causes it to pull in/'screw' in. Even a drill press can suffer this as there is downward play in the spindle rack&pinion. Bits used for stepping should be brassed to a less aggressive angle.

 

[LD1]

Actually from a technical point of view the only logical reason not to step up in bits is about precision (not the wear on the bits)..because the lack of guidance of the point you can end up with a three sided or oversized hole...

...Yes, it does wear more on the outside of the lip face but no more than if the entire lip was cutting...it also takes less energy from the drill...it's a compromise but hardly a big deal...These days field machinists and millwrights use unibits in place of twist drills for enlarging etc...

Stepping actually takes more energy from both the drill and the operator trying to fight said drill.

The attack angle of the cutting edge gets more aggressive out towards the edge of the bit. And only trying to enlatge a hole 1/8" (1/16" each cutting edge) causes the drill to want to bite way too aggressive and you end ur chipping drill bits, bending them, or breaking them (or the operators arm if in a good drillmotor).

A pilot only as large as the web of the bit is all that is needed and prevents the bit from wanting to grab too aggressively.

A sure way to tell a novice machinist/millwright apart from an experienced one is how they decide to hand drill a 1" hole. IF someone grabs two bits, ~1/4" and a 1".....you know they know what they are doing. Someone that grabs 8 bits in 1/8" increments is a novice and I'll stand back and watch the show as they proceed to destroy half a dozen bits in the process of trying to hang on for the ride.

 

[/pine]

LoL...Depending on the thickness of the material being drilled...(room permitting) a professional machinist or millwright is most likely going to bore a 1" hole with a mag drill and an annular cutter....otherwise a drill motor, pilot bit and a unibit...
...it would only be in a unique situation where a regular twist drill would be employed...

Again, it's a compromise mostly based on precision...someone that only has battery powered drill motors and a set of twist drills.would usually give up the pointy head professional practice for the ease of getting a hole bored that will work for them...and they'll do it every time..(cutting less metal requires less energy)...

 

[LD1]

LoL...Depending on the thickness of the material being drilled...(room permitting) a professional machinist or millwright is most likely going to bore a 1" hole with a mag drill and an annular cutter....otherwise a drill motor, pilot bit and a unibit...
...it would only be in a unique situation where a regular twist drill would be employed...

Again, it's a compromise mostly based on precision...someone that only has battery powered drill motors and a set of twist drills.would usually give up the pointy head professional practice for the ease of getting a hole bored that will work for them...and they'll do it every time..(cutting less metal requires less energy)...

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