I am new to the metal working world. However, I always thought that drill presses running through metal were supposed to run nice and slow.

Recently though, I have ruined a couplla drill bits and even a 20 dollar hole saw (made for metal). So, I open up the top of my drill press to slow up the speed (was drilling about the speed of a electric hand drill) and here I find a chart with types of metal and where to set the belts...

So, I set the belts for mild steel, check it twice and cut it on. This made the press FASTER than before.... BUT, I am exaclty where this chart says to be...

This confuses me seeing as how I always thought drilling throuugh metal was supposed to be snails speed with light pressure....

Was I to slow before or what???????

i'm no metal worker either Ty but i have found that if it's going to slow it work hardens the metal and makes it virtual impossible to drill through and ruins the bit. same thing happens with a chop saw when not applying enough pressure. the metal gets hot and hardens evidently and then no amount of pressure will cut through it. could it be that you're not applying enough downforce when drilling ?

- jack

It depends on the size of the hole, I can't remeber what the exact equation is but it's something like (1.5x circumference)/ diameter= rpm??? I can find out tonight for sure.

For a hole saw put it on super slow and use lots of oil. :D

Theoretically, RPM = (4 x Cutting Speed) / Drill Diameter

Cutting Speed:

Aluminum - 250
1020 CRS (Mild Steel) - 100
1045 HRS (Hot Rolled Steel) - 80

On my buddy's drill press we converted it over to use a motor and controller he got off something they threw away at work. The controller has a little number counter, so you can infinitly set motor speed from 001 to 999. I cannot tell you how nice this is instead of having to move the belt all the time on the pulleys on top.

David, does the motor have any torque at low RPM? I can't see how it could. I like the idea though!

for hole saws, I like to stay around 500 rpm. have a good fixture to hold the part firmly. As far as drill bits go, a factor in drilling is feed pressure. You know you are putting the right amount of force on when you get the big long curls coming from the work. Also, some type of oiler on your drill press is worth the dough in saved bits.

I have found that 2 stroke engine oil works great, and smells really good too. :D

Originally posted by MattS
David, does the motor have any torque at low RPM? I can't see how it could. I like the idea though!

electric motors have the same amount of torque at all rpms.

Umm no. Not if he is regulating the voltage to the motor. Ever use a variable speed drill? Try and drill a hole real slow or real fast? With slow speeds the drill has no power at all. Or I am missing something!!

Originally posted by zags
electric motors have the same amount of torque at all rpms.

Originally posted by zags
for hole saws, I like to stay around 500 rpm. have a good fixture to hold the part firmly. As far as drill bits go, a factor in drilling is feed pressure. You know you are putting the right amount of force on when you get the big long curls coming from the work. Also, some type of oiler on your drill press is worth the dough in saved bits.

Agreed. A properly sharpened drill bit makes a big difference also.

there are some charts in the Machinery's Handbook. basically, it depends on what material you are cutting and the diameter of your drill. hole saws are a little different. you'll have to figure out the Feet per minute and then convert it to RPM. if you don't have a Machinery's Handbook, i'd recommend getting one. new, they are around $80, but you can find them used for alot less. try college/campus book stores and used book stores. matt

here's a simple set of charts to follow from:

Precision Twist Drill (http://www.precisiontwistdrill.com/techhelp/article12001995.asp?image=help)

they have other tech info available also-

mostly, it's what works for you!!!!! it depends alot on your setup-
rigidity it the key, and as Tim Taylor say's:

MORE POWER!

on a 30 HP, 25000 lb horizontal machining center ya can make holes in a hurry! we use alot of insert drills in Titanium and Nickle based alloys w/ 1000psi coolant, 1-3/8 dia x 4.5" deep in less than a minute- movin' lots of stock :D

later

Matt - as far as I can tell, it has plenty of torque using it the way we do.

But I tell you what - I will ask my buddy the specifics about what we put on there, and maybe even get the all important picture to explain it better :p

Actually, electric motors exert 100% of their torque at 0 RPM, and (almost) 0% of their torque at max RPM.

This is why they're used to drive locomotive axles. Can you imagine how low the gearing would have to be to keep even a huge diesel from stalling right as the train tried to move? :eek: The diesel drives a massive generator, which powers the electric traction motors for the axles.

And you can get away with higher speeds on a drill press than with a hand drill, because you also exert MUCH more pressure on the bit. Think aobut it - you probably push just as hard, but it's multiplied because of the gearing used to maneuver the chuck.

Actually, electric motors exert 100% of their torque at 0 RPM, and (almost) 0% of their torque at max RPM.

This is why they're used to drive locomotive axles. Can you imagine how low the gearing would have to be to keep even a huge diesel from stalling right as the train tried to move? :eek: The diesel drives a massive generator, which powers the electric traction motors for the axles.

And you can get away with higher speeds on a drill press than with a hand drill, because you also exert MUCH more pressure on the bit. Think aobut it - you probably push just as hard, but it's multiplied because of the gearing used to maneuver the chuck.

DRM,

WHY DID YOU CHANGE THE PIC IN YOUR SIGNATURE?!

THE FORMER WAS COOL, THIS ONE S U C K S

BRING THE OLD ONE BACK!!!:p :p

It fit's him better!!

IT SUCKS!!!!

Originally posted by the frog
DRM,
WHY DID YOU CHANGE THE PIC IN YOUR SIGNATURE?!

THE FORMER WAS COOL, THIS ONE S U C K S

BRING THE OLD ONE BACK!!!:p :p

Originally posted by Dr. Evil
Actually, electric motors exert 100% of their torque at 0 RPM, and (almost) 0% of their torque at max RPM.

You will need to explain this one to me, I don't get it. :confused:

Remember torque is different than power, in that torque is the effort that may or may not result in motion, where as power (hp, for a unit of measure) is the rate, or speed at which work is being done.

working in metal you use whats called surface feet per min, when working in plan old steel with a drill bit your surface feet well be 110 ( that never changes)

so take the 110 and times it by 4 (it to never changes) and then you well have 440 , so on a heavy machine you would turn a 1" drill 440 RPM so to get the speed for a smaller or larger bit just divide it by its size... so for a 1/2" it would look like ** 110X4 =440 then divide by .500 and you well need a rpm of 880 RPM

But on a small drill press I would go with 60 surface feet on steel
300 on alum and about 20 on stainless.


so try 240 rpm for 1"
480 for 1/2"
and about 1000 for 1/4"

I now your limited on most drill presses on the low speeds so I would go slower than faster.

:roxy:

Originally posted by the frog
DRM,

WHY DID YOU CHANGE THE PIC IN YOUR SIGNATURE?!

THE FORMER WAS COOL, THIS ONE S U C K S

BRING THE OLD ONE BACK!!!:p :p


Wow... I didn't know anyone cared :D

I though gangsta DRM was getting old - decided on a change :p

Originally posted by d.d.machine
working in metal you use whats called surface feet per min, when working in plan old steel with a drill bit your surface feet well be 110 ( that never changes)

so take the 110 and times it by 4 (it to never changes) and then you well have 440 , so on a heavy machine you would turn a 1" drill 440 RPM so to get the speed for a smaller or larger bit just divide it by its size... so for a 1/2" it would look like ** 110X4 =440 then divide by .500 and you well need a rpm of 880 RPM

But on a small drill press I would go with 60 surface feet on steel
300 on alum and about 20 on stainless.


so try 240 rpm for 1"
480 for 1/2"
and about 1000 for 1/4"

I now your limited on most drill presses on the low speeds so I would go slower than faster.

:roxy:

"Try to keep up" Really? :rolleyes:

I think that info has already been posted twice.... Fawkin' Newbie


:flipoff2: Welcome:flipoff2:

Always get good results at 450 for metal, with most bit sizes under 3/4

Wow... I didn't know anyone cared

Was that an actual pic of you?

YES!! LOL He likes to take weird pics when he forgets to take his meds.

Originally posted by bgreen
Was that an actual pic of you?

here is an easy way to judge rpm on a drill.

If the chips are turning gold in any kind of carbon steel then you are right on the money for speed. If the chips are turning blue or dark brown then you are going to fast.

If the chips are turning gold in stainless then you are turning too fast and are asking for disaster.

:smokin:

YES!! LOL He likes to take weird pics when he forgets to take his meds.

:D :smokin: :D kind of looks like a gangster. he he :cool:

Yep - that was actually a pic of me :D



As for drilling, and chips.... I thought it was good when the drill was cutting out long spiraled wire type shavings when drilling?

Originally posted by DRM
Yep - that was actually a pic of me :D
As for drilling....

we do'nt gine a shoot about drilling....:flipoff2: :flipoff2:

WE WANT THE GANGSTER:cool: BACK AND THAT'S IT!!!

See, I always thought that the long spirals were pushing WAY to hard. I guess I am just gong way to slow and hardening the shit outta stuff.

Can anyone disagree with the spiral deal?

Thanks!

chips=shavings=what ever comes off the tool you are cutting with. the shape of the "chip" is going to be determined by several things such as: flute design, tool pressure, material, rpm, feed rate, and others. Mostly what you want to watch out for is that the chips / shavings are not plugging up the flutes of the drill. Generally in mild steel and the like spiral shavings would be better than small chips, especially if you have to drill very deep.

Determining how hard to push the drill into the material is also determined by many factors: Material to be drilled, Material the drill bit was constructed from, helix angle, relief angle, coating, ect. Most of the time I try to use moderate pressure and make a judgement call on wheter or not I need to add more or back off alittle.

If you asked an old timer how he figures out how fast to turn a drill he would say "Just as fast as it needs to go". meaning that over the years you will develope a feel as to what needs to be the rpm and feed rate.

There hard part for me is that I have developed a feel for the most part and when I go program our CNC's I have to get out the charts and calculator cause CNC's need exact numbers. You dont want the operator to have to be turinging the feed and speed up and down all the time. or to have to go back and do a bunch of editing. :D

Good info., but I am not programming a friggin CNC! All I wanna know is some BASIC guidelines on how hard to push. I just assume that spirals seem to be a good BASIC guideline...

Muchos Gracias!

Originally posted by bgreen/alaskaoffroad
chips=shavings=what ever comes off the tool you are cutting with. the shape of the "chip" is going to be determined by several things such as: flute design, tool pressure, material, rpm, feed rate, and others. Mostly what you want to watch out for is that the chips / shavings are not plugging up the flutes of the drill. Generally in mild steel and the like spiral shavings would be better than small chips, especially if you have to drill very deep.

Determining how hard to push the drill into the material is also determined by many factors: Material to be drilled, Material the drill bit was constructed from, helix angle, relief angle, coating, ect. Most of the time I try to use moderate pressure and make a judgement call on wheter or not I need to add more or back off alittle.

If you asked an old timer how he figures out how fast to turn a drill he would say "Just as fast as it needs to go". meaning that over the years you will develope a feel as to what needs to be the rpm and feed rate.

There hard part for me is that I have developed a feel for the most part and when I go program our CNC's I have to get out the charts and calculator cause CNC's need exact numbers. You dont want the operator to have to be turinging the feed and speed up and down all the time. or to have to go back and do a bunch of editing. :D

Originally posted by TyTy
Good info., but I am not programming a friggin CNC! All I wanna know is some BASIC guidelines on how hard to push. I just assume that spirals seem to be a good BASIC guideline...

Muchos Gracias!



I think he covered that pretty well - it is something you just have to get a feel for.

And I have found his other comment to be true as well - the drill should be turning as slow as you can and get the cut you are needing :)

Originally posted by MattS
David, does the motor have any torque at low RPM? I can't see how it could. I like the idea though!

Oh, David... does you buddy have any more of those. :D :D :D

The motors are typically three phase motors, the drives are changing frequency of the three phases to speed it up or slow it down.

WARNING: If you see one rated for 460V that seems like a great deal, but you want to run it off 230V single phase for a 208V three phase motor... Do NOT buy it. Typically microprocessor controlled, and they will shut down due to undervoltage! John (fellow HSM) made this mistake, so he has a couple of these boxes back on eBay VFD (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1725081806)

Also you have to "derate" them when using single phase power to the VFD box

I have one for my lathe & milling machine (both three phase motors). Nice addition!

Tom :usa:

Originally posted by TyTy
Good info., but I am not programming a friggin CNC! All I wanna know is some BASIC guidelines on how hard to push. I just assume that spirals seem to be a good BASIC guideline...

You didn't want to figure out feedrate now????

Feedrate = RPM x # flutes x Chipload? :D

Yes, those formulas work best for actually programming CNC's.

One more thing to consider tho when drilling larger diameter holes is to drill a pilot hole first..... Way easier overall, and not as hard on the bits.

Good info., but I am not programming a friggin CNC! All I wanna know is some BASIC guidelines on how hard to push. I just assume that spirals seem to be a good BASIC guideline...

I answered your question once already, no need to get testy.:eek:

Determining how hard to push the drill into the material is also determined by many factors: Material to be drilled, Material the drill bit was constructed from, helix angle, relief angle, coating, ect. Most of the time I TRY TO USE MODERATE PRESSURE AND MAKE A JUDGEMENT CALL ON WEATHER OR NOT I NEED TO ADD MORE OR BACK OFF A LITTLE.

If you asked an old timer how he figures out how fast to turn a drill he would say "Just as fast as it needs to go". meaning that over the years YOU WILL DEVELOPE A FEEL AS TO WHAT NEEDS TO BE THE RPM AND FEED RATE.

spirals may never happen if the drill bit is not sharpened to make them. also you may have a hard time getting spirals on brass or bronze and some types of cast iron. just make sure that you dont :smokin: the bit and you are good to go.