Safetying nuts

[bbb]

my urologist used an electric cautery and said to have them checked in 6 weeks.
 

[John Noonan]

my urologist used an electric cautery and said to have them checked in 6 weeks.
 

Brian,

After you walked out of the office did you come right back and demand a second opinon?.....

[JackD]

While the RPM suggestion is close, did you really mean 40 to 50 FPM ?
Isn't it more like 4 to 5 inches per min or way less ?

[bbb]

it was just wrong. the nurse was hot as hell. scottsdale blond, boobs, tan.
during my prep time, she got a gander of why my wife married me..
no, it isnt my looks nor my money  

i'll be here til thursday. dont forget to tip your waiters and waitresses...

[hotrod]

While the RPM suggestion is close, did you really mean 40 to 50 FPM ?
Isn't it more like 4 to 5 inches per min or way less ?

I think your mixing cutting speed (the relative surface speed of the drills cutting edge to the metal) with the feed rate.

Machinists use a cutting speed guide line for various metals and in my experience it is always specified in surface feet per min (SFPM or simply FPM ). Each metal alloy has an ideal best cutting speed and it is pretty uniform across a wide range of machining processes. It is the surface speed of the tools cutting edge with respect to the metal it is cutting.

In drilling they also specify a recommended feed rate, which is how fast the drill point advances through the material.

From the American machinist Handbook here are some recommendations for drilling certain metals.

Alloy ............................ surface feet per minute
Manganese steels ..................... 15
302/304 stainless ..................... 15 - 40
Stainless Hard ........................... 30 - 40
Nickle and Monel ....................... 40 - 60
Steel Annealed .......................... 60 -70
Steel Forged / tool ..................... 50 -60
Alloy steels ................................. 50 -70
Soft Cast Iron ............................ 80 - 100

Brass / Bronze (soft)................... 200 -300
Aluminum ................................... 600

Drill rpm required for 1/16 inch drill:

40 sfpm = 2,445 rpm
50 sfpm = 3,056
60 sfpm = 3,667
70 sfpm = 4,278
80 sfpm = 4,889
90 sfpm = 5,500
100 sfpm = 6,111

Suggested feed rate is to advance the cutting edge about .001 - .002 inches per revolution.

At 3056 rpm that would give a 3 to 6 inches per minuted feed rate.

Bottom line you can't get adequate drill speed (rpm for ideal cutting speed) with a battery operated drill on small diameter drill bits. You need to go to a 120v AC 1/4 inch drill with max 3000 rpm just to get in the ball park of proper drill speeds for 1/16 inch drills and in some cases a high rpm air drill would be better.

Larry

[JimW]

Wow.  I never knew this feed rate stuff.  For sure I am turning the drill 'way' too slow.  I'm going to try the McMaster Carr retainers, but if I have to go back to drilling, I'll definately step up the speed.  Will definately need some cutting oil to control the heat.

Thanks!

Jim.

[hotrod]

You can also help control drill breakage and heat by how you drill.

It helps a lot to use an intermittent pressure where you apply pressure, and let the drill cut for a second or 2 then pull it back a bit to help it clear chips and get cutting oil to the point then re-apply pressure and drill down another couple seconds.

This pecking process helps on the smaller drills because their flutes are so small it is difficult for them to clear the chips. If you pull the drill back out every couple seconds it will spin all the accumulated chips out of the flute and then it can cut easily again without clogging the flutes and getting super hot at the point.

Then you want to slow down your feed rate at the point that you just break through the back side so it does not Keyhole through that last little bit of metal and bind up and break. You can also help prevent breaking drill bits as they breakout the back side, by putting something behind the material you are drilling like a soft piece of steel so the drill point does not plunge through the back side unsupported.

Larry

[RICK]

My Dad used to say, "Theres only two things that will ruin a drill bit.
   1, Turn it at the wrong speed.
   2, Loan it to your buddy.


   RICK

[Eric S]

On my bike, the front axle clamp bolt sets in flush with the surface of the fork.  I could drill through the fork (about 1/8") and into the hex socket of the bolt,  but then I would have to line up these holes each time, regardless of torque setting.  Any ideas?

[JackD]

Different dialect . same language.
SFPM means cutter edge speed to us and FPM is the feed rate that tells us
 how fast to feed tooling into or across the material for best economy.

[pdubu]

If most drills had a power feed it would be moot. It does take paying attention and not feeding too fast thereby flexing the bit which leads to breakage. Sometimes you get in a groove and they drill like popcorn (pop, pop, pop). Other times it is the opposite groove and its snap, snap, snap with bits breaking left and right  

Now drilling by hand, especially those in odd locations where there isn't time or the hassle seems not worth pulling the fastener are the buggers. For those that do it all the time, it looks like nothing. To those of us that occasionally need to do the same, it seems a good time to buy stock in a bit company. In those cases I try to find a drilling guru (aircraft mechanics & motorcycle road racers usually hand drill enough to stay in practice) to get it done.

As hotrod noted, a bit of breakage does happen when exiting the material.  I've found those fasteners I drill on the drill press and can back up with a bit of something else do drill fairly well and the bits last longer.