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View Full Version : Why are drill presses not flexible like hand held drilla



Hobbyinovator
03-05-2009, 07:03 AM
Pardon an ignorant new bee, I'm just wondering why drill presses are not as flexible as hand held motor drills? With most hand held drills you have variable speed, often hammer and screwdriving with right/left rotational options. With most drill presses you have to open them to change belt if you want to change speed.
Would it be so hard to have variable speed on most drill presses? Is there any technological/economical reasons why this option is not applied to drill presses?

Evan
03-05-2009, 07:48 AM
Cost. If you want that sort of convenience you can have it but it costs a lot of money. Hand held drill motors are low power devices and use a type of motor called a universal motor. Such a motor is easy to speed control with a circuit the same as a lamp dimmer. Howerever, it does not scale up well because a universal motor in larger sizes consumes enormous amounts of power if allowed. The starter motor on a vehicle is the same type in most cases and can draw peak currents on a mere 12 volts of 400 amps.

Using a speed control as on a hand held drill does not provide the low end torque required to use bits in the larger sizes. That takes mechanical torque multiplication which is what the changeable belt does on a larger machine.
Belts are cheap and so are pulleys. If you want convenience though you need gear transmissions and they are not at all cheap to make.

I have a large industrial drill press and shifting speeds is as easy as changing gears in an automobile. It runs forward and reverse at the flick of a switch which also provides high and low speed along with the 4 speeds available with the gearshifters for a total of 8 speeds forward and 8 backward. It also costs about $3000 when new.

Hobbyinovator
03-05-2009, 08:16 AM
So is there any new technology coming up that might change this in any foreseeable future?

BillH
03-05-2009, 09:12 AM
So is there any new technology coming up that might change this in any foreseeable future?

For an innovator, you don't seam to have a grasp on how things work.

Hobbyinovator
03-05-2009, 09:16 AM
That's why I'm here:) .

paulx
03-05-2009, 09:20 AM
I drilled a few holes the other day with a hand held electric and let me tell you it was work.The operative word in Drill Press is press.

digger_doug
03-05-2009, 09:24 AM
How I modify my drill presses.

1. I add a foot switch (constant pressure to run),
in series with the existing motor switch.
So I don't have to reach over to shut the motor
off. Also, so I don't accidentally step on the switch
during set-up, this enables me to "lock out" the motor.

2. I bring out the starting windings (single phase)
to a reversing switch, this allows me to tap.
Note: as it is single phase, you don't get the 3-phase
advantage of instant reverse, but with a little practice,
you will see how long it takes to slow down, before
engaging reverse.

3. I wire the light to a separate switch (if it isn't already)
to allow it to be on all the time, not just when the
motor is on.

These are just some basic things I have done to my drill presses.

Let's hear some more.

BillH
03-05-2009, 09:26 AM
That's why I'm here:) .
Look up VFD and 3 phase motors.
There are many applications to speed controls outside of the machinist world, like electric scooters. Radio Control electric airplanes use some pretty high powered stuff, treadmill motors, etc. Electronic speed controls for both brushed and brushless motors, rheostats, Variacs, etc.

HSS
03-05-2009, 09:28 AM
Stick you a 3 phase motor on there with a VFD. Then you got variable speed and forward and reverse. But for me that is just too much sugar for a dime.

Patrick


Edit: Dang y'all type too fast for me!! Ya beat me to it.

NickH
03-05-2009, 09:38 AM
I fitted a 3 phase motor and VFD to my benchtop drill press, the motor is capable of 0 to 200% rated RPM, I leave it in low gear most of the time & mostly use the VFD to get higher speeds when required,
Nick

Hobbyinovator
03-05-2009, 09:38 AM
This is one of the few variable drill presses I have come across so far:
http://www.micromark.com/MICROLUX-VARIABLE-SPEED-DRILL-PRESS-WITH-DIGITAL-DEPTHFINDER,8283.html

Anyone have any experience with it?

Willy
03-05-2009, 09:48 AM
For an innovator, you don't seam to have a grasp on how things work.

BillH, the man is here for the the same reasons the rest of us are....to learn and exchange ideas.
What may seem obvious to some is new information to others.
I'm sure as a fight instructor you have been on both sides of the learning curve often enough to grasp that concept. If not, you would soon find yourself alone in the cockpit.
Remember, others could berate and belittle you as well for asking what to them is perfectly obvious.
A little consideration for others, remember the person you talk down to on one level may if fact be the heart surgeon that saves your butt two weeks down the road.

J Tiers
03-05-2009, 09:48 AM
Howerever, it does not scale up well because a universal motor in larger sizes consumes enormous amounts of power if allowed. The starter motor on a vehicle is the same type in most cases and can draw peak currents on a mere 12 volts of 400 amps.


A universal motor is a series motor, but a series motor is not a universal motor.

Your example of the starter motor is flawed, since the starter has one job, and everything is subordinated to getting that one job done as cheaply as possible. The high current is due to the very high torques required in starting duty, it is not a requirement of the type.

And, a starter motor is NOT a universal motor...... it is a series DC motor. There is nothing whatever stopping the making of a reasonably efficient series DC motor, and in fact they are made up to the thousand HP range. Some other types offer more control, and possible higher efficiency, but that is relatively recent. And they come with compromises also.

A large "universal" motor for 60 Hz is more of a problem, since the winding inductance must be small enough to allow the currents required for the power level. But a 1 or 3 HP motor would be very possible.

The real reasons they are not made for machine tools are:

1) They would be more expensive than the other solutions

2) they require more maintenance

3) they have particularly poor inherent speed regulation, which is a serious problem

4) to gain the full benefits without the horrible speed regulation, external circuitry is required, which can be nearly as expensive as an induction motor with a variable frequency drive, but the induction motor requires less maintenance.

Other solutions offer performance similar to the series/universal motor, although they typically suffer from poorer torque at low speeds. The series motor can be made to develop close to 300% torque at low/zero speed*, which is why it has been used in traction applications, such as diesel-electric locomotives and the like, for 100 years.

* The torque is nearly unlimited, but in a practical sense about 300% is probably max.

Hobbyinovator
03-05-2009, 09:56 AM
NickH and Digger Doug, what was the price tag for your modifications?

BillH
03-05-2009, 09:59 AM
BillH, the man is here for the the same reasons the rest of us are....to learn and exchange ideas.
What may seem obvious to some is new information to others.
I'm sure as a fight instructor you have been on both sides of the learning curve often enough to grasp that concept. If not, you would soon find yourself alone in the cockpit.
Remember, others could berate and belittle you as well for asking what to them is perfectly obvious.
A little consideration for others, remember the person you talk down to on one level may if fact be the heart surgeon that saves your butt two weeks down the road.
Willy, I thought he was a Spammer from the far east. Still not so sure.

digger_doug
03-05-2009, 10:07 AM
"NickH and Digger Doug, what was the price tag for your modifications?"

A handy box, a bracket welded on it.
A toggle switch (DPDT), a blank cover plate (drilled for toggle)
A surplus foot switch.

My time...

Hobbyinovator
03-05-2009, 10:09 AM
No spamming, no trolling here. I'm from Sweden by the way not from China. I have most of my life been more ignorant than most people about technical matters, and not been a very practical person either. But in recent years I have started to get more and more interested, so I have a looong learning curve.
A few month ago I bought a small and cheap drill press.
I have hardly known the names of many of these technical things in Swedish, and there are few if any Swedish/English dictionaries that give a serious coverage of technical matters, so I simply have to compare Swedish and English pictures, or look in poorly translated manuals so I apologize if give you some technical incorrect terms.

Evan
03-05-2009, 10:15 AM
A universal motor is a series motor, but a series motor is not a universal motor.


Example?


And, a starter motor is NOT a universal motor...... it is a series DC motor

What makes it a DC motor?


1) They would be more expensive than the other solutions


I said that


3) they have particularly poor inherent speed regulation, which is a serious problem

They have no theoretical speed regulation. I implied that. (current draw)


The torque is nearly unlimited, but in a practical sense about 300% is probably max.

Nonsense. It's limited by the winding resistance and magnetic saturation.

Hobbyinovator
03-05-2009, 10:17 AM
The reason I asked about "new technology" was because there seems to be alot of things going on right now. The Li-on battery technology that came with cellular phones and portable computers has been effectively applied to hand held tools for example. So I wondered perhaps there is something else that anyone of you know about that will be used in future tools with in a ccouple of years?

A.K. Boomer
03-05-2009, 10:19 AM
I have most of my life been more ignorant than most people about technical matters, .


Ohh to the contrare my dear fellow, you just showed half the guys here that although be it small - VS drill presses do exist --- http://www.micromark.com/MICROLUX-VA...NDER,8283.html
Im guessing larger ones do too;)

Gotta admit - you got it allot more together than this guy; "For an innovator, you don't seam to have a grasp on how things work."

Lew Hartswick
03-05-2009, 10:25 AM
About 50 years ago Sears Roebuck sold a drill press that had a
variable speed motor on it. I have seen one a long time ago. That
was when electronics was just beginning to invade the tool business.
On reflection it may have been a little less than 50 but at least 30
or more.
...lew...

Hobbyinovator
03-05-2009, 10:29 AM
I was considering bying the Microlux drill press, but since it is American it's 110 volts and not suited to European 220 volts system, plus the shipping cost.
So I considered buying a similar from Proxxon, but they seem to lack variable speed.

A.K. Boomer
03-05-2009, 10:36 AM
There's also the possibility that a company adopted a type of mechanical VS (torque converter) type system like the ones on milling heads, That would solve the electrics problem as the motor remains constant speed:)

Bill Pace
03-05-2009, 10:48 AM
Another common modification to DP's over here is to adapt a treadmill motor to them -- I bet you got treadmills over there... people throw them away over here:D

If you can scrounge one, itll have all you need to make your DP variable speed -- there a little board in them that converts ac voltage to dc, and a potentiometer to vary it, so you get a motor, the control board and a potentiometer out of the tread mill. And if its sold in Sweden, then it should be constructed to handle your voltage.

Carld
03-05-2009, 10:50 AM
Hobbyinovator, you will find a lot of inovative offerings in the smaller drill presses and lathes. The larger machines rely on heavier duty stuff. Most the variable speed drill presses I have seen and used are belt driven with variable pulleys. Even the mills use variable pulleys. Some lathes came with variable speed motors and one shop I worked at had one. I liked it but when the controler failed it cost a fortune to replace the controler and it never worked as good as it did before the failure.

The biggest reason for the same old same old is COST and dependability. The bigger the machine the more expensive the inovation costs and small shops and home machinists can't afford it.

ckelloug
03-05-2009, 10:58 AM
Hobbyinnovator,

Keep up the well reasoned questions and people will get used to you here. We've had too many spammers here of late and so people are a little reluctant to help new posters with very general questions. You are obviously trying to get an answer to a real question so I hope this thread serves you well. Welcome to the zoo here!

I'd say something to help you but I don't have a drill press and don't use them regularly so I have no knowledge that will help you on drill presses.

Regards,

Cameron

JCHannum
03-05-2009, 11:01 AM
What makes it a DC motor?


The permanent magnets?

Evan
03-05-2009, 11:03 AM
Most starter motors have no magnets.

topct
03-05-2009, 11:30 AM
Most starter motors have no magnets.

What? Your testing us, right?

larry_g
03-05-2009, 11:31 AM
I'm going to have to say that if you look at the historical industrial uses of a drill press that most are sized for the job they are to do. Big machine for big drill bits that have to turn slow. Small high speed machines for the small hole drilling. A drill bit will have a wide range of operating speed so the drill press does not have to have a lot infinate range. If your needing reverse then your not needing a common drill press, your needing a more specialized machine. Have you looked at the Mill/Drill machine? It may have the features that you desire.

Can you tell us the what the intended use of the machine you desire is? Or is this a question in general?

lg
no neat sig line

JCHannum
03-05-2009, 11:34 AM
What? Your testing us, right?

It must be an Ixian [TM ]:rolleyes: thing.

Stu
03-05-2009, 11:55 AM
I have a Delta drill press with a variable belt drive. The pulleys change size with a dial on the front. Infinitely variable from 50 to 3500 rpm. Very nice for a small home shop.

Bill

Evan
03-05-2009, 12:03 PM
What? Your testing us, right?


No, just correcting Jim.

Most starter motors are series wound and have no permanent magnets. With no power applied they have no magnets. They have a wound armature and a wound stator and will run on AC or DC.

Stu
03-05-2009, 12:19 PM
Correction, speed is 500 to 3100 rpm.

Bill

2ManyHobbies
03-05-2009, 12:58 PM
Variable speed drill presses aren't that common for the same reason that quick-change tooling is uncommon on drill presses. The cost makes such a tool uncompetitive in the market. ~$70 gets you a workable tabletop press, ~$100 gets you a free standing machine. Less if you shop used, more if you are looking for industrial quality.

Speed is a function of diameter and material. If I need 20 holes of the same size, I get the appropriate bit, cross reference the chart, take the 5 seconds to set the belts and the 15 seconds to center the bit. After that, all of the work is clamping and popping holes in your material. 90% of your "lost time" on a drill press isn't swapping bits or setting speeds, but issues with work placement. Save the money for quick-change and variable speed setups and use it for jigs and fixtures instead. The performance difference is amazing.

JCHannum
03-05-2009, 01:05 PM
No, just correcting Jim.

Most starter motors are series wound and have no permanent magnets. With no power applied they have no magnets. They have a wound armature and a wound stator and will run on AC or DC.

Well, there you go putting words into my mouth again. I never said starter motor or that all starter motors have permanent magnets.

You asked a question that I quoted, and I assumed you sincerely wanted to know what would qualify it as a DC motor. In an attempt to add to your knowledge, I answered.

Many starter motors are indeed of the permanent magnet type. As a matter of fact, I recall someone on this board fooling around with such a motor to power a bicycle a few months ago.

Weston Bye
03-05-2009, 02:10 PM
Well, there you go putting words into my mouth again. I never said starter motor or that all starter motors have permanent magnets.

You asked a question that I quoted, and I assumed you sincerely wanted to know what would qualify it as a DC motor. In an attempt to add to your knowledge, I answered.

Many starter motors are indeed of the permanent magnet type. As a matter of fact, I recall someone on this board fooling around with such a motor to power a bicycle a few months ago.

Indeed, auto starter motors are getting smaller, operating at higher speeds with gearing added for torque. Evan might want to look at the starter in his PT Cruiser. It might have a permanent magnet field. Then again, I wouldn't blame him if he didn't want to roll around on the ground looking for it.

Hobbyinovator
03-05-2009, 05:35 PM
Larry_G: It was mostly a question in general, though the intended use of my current drill press is drilling in stainless steel. Since I hand tap(and I'm new to that aswell) the holes in some cases, it would have been interesting if I could get my drill press to move at very slow speed like a screwdriver.
It was partly my interest in scale modeling and stop motion armatures that made be buy my first drill press. I have been trying to make my own stainless steel stop motion armatures, similar to the ones you can see in the links:
http://www.scarletstarstudios.com/stopmo/
http://www.animationsupplies.net/standardarmature.php
http://www.armaverse.com/
http://www.animateclay.com/shop/index.php?main_page=product_info&cPath=8&products_id=87
http://www.stopmotionworks.com/drlballs.htm
http://www.stopmotionworks.com/ohspics.htm
http://www.stopmotionworks.com/ballbrz.htm

Evan
03-05-2009, 05:58 PM
Well, there you go putting words into my mouth again. I never said starter motor or that all starter motors have permanent magnets.

You asked a question that I quoted, and I assumed you sincerely wanted to know what would qualify it as a DC motor. In an attempt to add to your knowledge, I answered.

Many starter motors are indeed of the permanent magnet type. As a matter of fact, I recall someone on this board fooling around with such a motor to power a bicycle a few months ago.


Seeing that I did not even quote you it's pretty hard to say that I am putting anything in your mouth. I suggest you post what I said in the appropriate context and stop being intentionally obtuse as is your habit.

I repeat, most starter motors STILL have no magnets, the context being "permanent magnets".

Yes, some manufacturers are using permanent magnet motors, especially on small yard machinery where the torque requirements aren't the same as cranking over a V8. That is why I qualified my statement with the word "most". The series wound motor is still the motor of choice for starting automobile engines.

Since there seems to be some trouble on the part of a couple of members here understanding what I said I shall endeavour to use small words in complete sentences when I describe how something works or reply to intentionally instigative comments.

BillH
03-05-2009, 06:03 PM
Ohh to the contrare my dear fellow, you just showed half the guys here that although be it small - VS drill presses do exist --- http://www.micromark.com/MICROLUX-VA...NDER,8283.html
Im guessing larger ones do too;)

Gotta admit - you got it allot more together than this guy; "For an innovator, you don't seam to have a grasp on how things work."
Boomer Please explain this last post if you have the balls.

plastikosmd
03-05-2009, 06:07 PM
Hey, another thread highjacking. Glass houses and stones.

Thanks for the stop motion stuff. That was cool. If tapping is a major issue for you, slowing the motor is nice but you can also use a tapping head in your drill. Based on some of the links provided, it would seem that workholding is also an issue and may improve your production.

Evan
03-05-2009, 06:10 PM
If you are going to complain of thread hijacking how about coming out and saying who you think is responsible.

J Tiers
03-05-2009, 11:00 PM
Example?

it may be an inefficient AC motor......

if the winding inductances are larger, you can't get current thru it to increase torque without a voltage drop that limits power. It may "spin" on AC, but typically won't operate well unless made to be a "universal" motor.




What makes it a DC motor?


The fact that it runs on DC would be a very good clue......... while there ARE AC starter motors, they are not common, or werent until the Prius etc.

The typical DC motor is not made with the lower inductance etc required to use effectively on AC, although the differences between an AC universal and DC only motor can be subtle.




They have no theoretical speed regulation. I implied that. (current draw)


perhaps, if it matters, the point being that they are not good for machine tools UNLESS they have feedback and speed controls, in which case they can be quite acceptable.

Bythe time you add that, the thing is too expensive to produce, and an AC motor with VFD will probably be cheaper, and operate at least as well.



Nonsense. It's limited by the winding resistance and magnetic saturation.

Nonsense? Perhaps a little learning about motors and how they work would do you some good.... Winding resistance is low for any efficient DC motor....

Since the torque is essentially proportional to current in a constant field, a shunt motor would require 300% current.

A series motor increases torque by increases BOTH in the field AND the rotor current.... F=Bli, where the F is force, representative of torque, the B is the field, the l the winding length, and i the current. The l remains constant, but B and i change.

The current does not need to increase as much to improve torque.

Since the field increases at a similar rate to the armature (rotor) current, the effect of current is squared, and the torque increases faster and more than with a fixed field.

Interestingly, even AFTER saturation, which will obviously eventually occur, torque is even exerted by the now effectively coreless windings.....so field saturation does not prevent torque increases, for instance.

The OP will find that drill presses CAN have nice variable speed drives. Rockwell had a machanical system, and any 3 phase DP can have a VFD applied to it. Of course, when one has a DP that has a limited number of speeds and is a hassle to change, one often finds that whatever speed is set is perfectly acceptable for the next job also!

A.K. Boomer
03-05-2009, 11:37 PM
Boomer Please explain this last post if you have the balls.



Sure no prob. ---- Hobbyinnovator asked some questions about why shift on the fly variable speeds are not on drill presses --- Although Evan fixated on just one area of the way this can be achieved (electrically) he gave a very reasonable answer and concluded that generally it seemed to be an expense issue and a typical drill press is just not worth the pursuit --- Hobbyinnovator then ask the question if there were to be something new in technology that might change this in the foreseeable future -- very reasonable question as we do indeed live in amazing times ---- You then hit him with; "For an innovator, you don't seam to have a grasp on how things work."
This didn't only flabbergast me but also a few other members of the board, And I might add let him know that you don't really have a grasp on how to spell correctly,,,
Then later in the posts Hobbyinnovator indeed proves to us that there are "real" VS drill presses , then later someone confirms my theory of how I thought they might make a VS belt drive system like the ones on milling machines - thank you very much, To make a long story short -- you called somebody out on something and insulted them when they actually have a better understanding about how things work than you do ------ You cant do that around here -- it don't work that way and never has, you'll get your ass handed to you every single time:)

So there ya go ---- not only balls that i have to use a wheel barrow to carry -- but a nice hefty dose of reasoning and intelligence,,, any other questions?

Will this get me another nice nasty one word'er in my mailbox again? Grow a sac...

BillH
03-05-2009, 11:49 PM
Sure no prob. ---- Hobbyinnovator asked some questions about why shift on the fly variable speeds are not on drill presses --- Although Evan fixated on just one area of the way this can be achieved (electrically) he gave a very reasonable answer and concluded that generally it seemed to be an expense issue and a typical drill press is just not worth the pursuit --- Hobbyinnovator then ask the question if there were to be something new in technology that might change this in the foreseeable future -- very reasonable question as we do indeed live in amazing times ---- You then hit him with; "For an innovator, you don't seam to have a grasp on how things work."
This didn't only flabbergast me but also a few other members of the board, And I might add let him know that you don't really have a grasp on how to spell correctly,,,
Then later in the posts Hobbyinnovator indeed proves to us that there are "real" VS drill presses , then later someone confirms my theory of how I thought they might make a VS belt drive system like the ones on milling machines - thank you very much, To make a long story short -- you called somebody out on something and insulted them when they actually have a better understanding about how things work than you do ------ You cant do that around here -- it don't work that way and never has, you'll get your ass handed to you every single time:)

So there ya go ---- not only balls that i have to use a wheel barrow to carry -- but a nice hefty dose of reasoning and intelligence,,, any other questions?

Will this get me another nice nasty one word'er in my mailbox again? Grow a sac...
Your post makes no sense, filled with claims that can not be substantiated, and was nothing more than an insult. You can not logically determine how much I know, or my understanding of how things work based on my post. You are a stupid hypocrite, getting mad at me for being fresh to some one that I thought was a spammer from China. Your not handing me anything, I'll shove my size 14 up your ass.


Sure no prob. ---- Hobbyinnovator asked some questions about why shift on the fly variable speeds are not on drill presses --- Although Evan fixated on just one area of the way this can be achieved (electrically) he gave a very reasonable answer and concluded that generally it seemed to be an expense issue and a typical drill press is just not worth the pursuit --- Hobbyinnovator then ask the question if there were to be something new in technology that might change this in the foreseeable future -- very reasonable question as we do indeed live in amazing times ---- You then hit him with; "For an innovator, you don't seam to have a grasp on how things work." There is NO NEW TECHNOLOGY to control the speed of an electric motor, or any new mechanical device to control speed. Everything we've been doing for the past 20 years is rehashing the same old idea's. I am sorry but you and the OP had the last 20 years to study the different ways to vary speed. You are not smart for thinking up a VERY, VERY old idea. Geez, as a 13 year old kid I knew how a comet torque converter worked on a go-cart.


Then later in the posts Hobbyinnovator indeed proves to us that there are "real" VS drill presses , then later someone confirms my theory of how I thought they might make a VS belt drive system like the ones on milling machines - thank you very much, Oh MY GOD!!!! AN electric motor controlled by an electronic speed control that is connected to a drill press!!! OH MY GOD!!! WE LIVE IN SUCH AMAZING TIMES!!!!
Boomer, I had no idea you are such a simpleton. I mean geez, WHO ever thought of the idea of putting a DC motor on an electric powered tool, and also adding an electronic speed control to vary the speed must be an Einstein!!!



To make a long story short -- you called somebody out on something and insulted them when they actually have a better understanding about how things work than you do ------ You cant do that around here -- it don't work that way and never has, you'll get your ass handed to you every single time:) No, I thought he was a spammer from China. Now how can you determine that he has a better understanding of how things work??? You can't. Don't lecture me on what I can and can't do here, I've been here much longer than you. And further, after dissecting your post, I have determined that you are probably not as educated as I am since your logic has many holes in it.
Oh and being a spelling nazi on a web forum? A machinist forum?? Some of our best contributors on this forum make no effort to spell correctly, that is pretty petty of yourself.

A.K. Boomer
03-06-2009, 12:12 AM
I'll shove my size 14 up your ass.



This isn't that kind of site, You need to find that kind of "friend" someplace else -- I know this place is cleverly disguised most of the time but its really actually about machining and machinery and stuff, good luck with that though.

BillH
03-06-2009, 12:20 AM
This isn't that kind of site, You need to find that kind of "friend" someplace else -- I know this place is cleverly disguised most of the time but its really actually about machining and machinery and stuff, good luck with that though.
Lets see, you are trying to inject some kind of homosexual reference onto myself, that is typical from some one that is lacking points for a good counter argument. Second part of the post, trying to explain that in fact this is a machinist forum. So you are now trying retreat from this debate by stating the obvious...
And no response to the rest of my post simply because you are unable to argue it...

A.K. Boomer
03-06-2009, 12:27 AM
Yup --- damn yer good!

Its either that or I really don't want to upset the board with anymore of this crap:rolleyes:


Edit; I wont allow you new posts to further disrupt the board - however - your way off in your reasoning as you admitted yourself that "I thought he was a spammer from china"

So -- you insult him and tell him that he does not have a grasp on how things work (even though he knows more than you) He then reply's "that's why im here" and even puts a cute little smiley face behind it, So you end up being both wrong about the issue and wrong about him being a spammer and yet are the one acting like a total ass and then you never own up to it --- Like I stated -- that don't fly around here -- you will get your ass handed to you every single time -- don't like it? two options - change your tactics or deal with it. (keep it simple stupid). The jackal thought he could get away with insulting new members also -- lets just say that "he's not with us anymore".

BillH
03-06-2009, 12:29 AM
Yup --- damn yer good!

Its either that or I really don't want to upset the board with anymore of this crap:rolleyes:
Wow, you are already feeling resignation?
Whom is handing what to who?

J Tiers
03-06-2009, 12:39 AM
It occurs to me that a hand-held drill motor without a VS feature would be of limited use, now that most people have learned to use a VS type..... Who has not "babied" a hole saw so as not to burn it up, or some similar use of the VS feature?

But a drill press has never, in the popular types, had any on-the-fly variable speed combined with a control that is easy to work while actually drilling. It might be a very useful feature, but has not been seriously tried.

Yes, there have been speed foot-controls, etc, and some types can be varied under load mechanically as well, but most drill presses, probably the vast majority, are set for speed and then used, even if they CAN be varied on-the-fly. So we don't expect it.

There is no technical reason at all why it cannot be done.

There may be reasons why it would be less useful on a drill press, since the drill press is probably used for heavier-duty drilling, and there are fewer ways to 'finesse' the bit and speed with the drill press than with the hand drill motor. Stalling the drill press is likely to be uglier than stalling the hand drill, too.

Once you set the speed for the drill size, what more do you want? feed is the "other variable", but with the "sensitive" or lever-feed type it is infinitely vaariable, allowing many of the same sorts of "babying" to be done, just a bit differently with the drill press than the hand drill.

As for new technology, it isn't needed to do the task. And there really are not so many "new" ways to vary speed. There are "new versions of old ways".

gearedloco
03-06-2009, 02:46 AM
No, just correcting Jim.

Most starter motors are series wound and have no permanent magnets. With no power applied they have no magnets. They have a wound armature and a wound stator and will run on AC or DC.

Well, sorta-kinda. A series-wound D.C. motor does not require a laminated field structure, where an A.C. series motor does if it is to be reasonably efficient. This is why electric traction motors in railroad applications were most often D.C. motors, until quite recently. Yes, there were a few exceptions, but in those cases lower frequency A.C. current was used - typically 25 Hz or occasionally ~16 Hz. And in those cases, the AC motors had to be significantly larger than comparable DC motors in order to fit in the laminated field structure.

In either case the armature must be laminated. The reason for that is left as an exercise for the reader. Hint: see "eddy currents" and "hysteresis".

-bill

Evan
03-06-2009, 04:48 AM
it may be an inefficient AC motor......

if the winding inductances are larger, you can't get current thru it to increase torque without a voltage drop that limits power. It may "spin" on AC, but typically won't operate well unless made to be a "universal" motor.



In other words a series wound motor WILL run on AC and DC. They are inefficient in the best case so that isn't a good criteria for determining what sort of motor they are. Bottom line is that a series wound motor will run on ac or dc. It can be optimized to some degree for one or the other but it is the fact that it will run on either that led to the term "universal motor".


The fact that it runs on DC would be a very good clue.........

That is circular logic. It is a dc motor because it runs on dc except when it runs on ac which makes it an ac motor except when it runs on dc.


Since the field increases at a similar rate to the armature (rotor) current, the effect of current is squared, and the torque increases faster and more than with a fixed field.


You need to review basic electromagnetism Jerry. Perhaps a little learning about motors and how they work would do you some good. The current may increase in both windings but that does not result in magnetic moment increasing in square law proportion to the current. Dipole magnetic fields follow inverse third power law with distance. The magnetic moment interaction over a gap with permeability 1 is not current squared because of the u/4pi r^3 term.

What you propose is equivalent to so called "free energy".

NickH
03-06-2009, 05:08 AM
NickH and Digger Doug, what was the price tag for your modifications?

I paid 50 for a new inverter duty three phase 1/2 Hp motor & 30 for a second hand Mitsubishi Freqrol inverter drive.

(that's twice the price of the original drill press in upgrades :D ).

It does make a really sweet drill press, if you use the belt speeds as well as the controller the high speed will handle 1mm and less drilling into ally, stainless, titanium etc. and the low speed will drive a 22mm bit through steel very nicely.
Everything bolts on & I kept the old bits so I can downgrade the press again if I choose to replace it.
Regards,
Nick

Doc Nickel
03-06-2009, 05:57 AM
I have yet to run across an automotive starter motor that has permanent magnets. The style I'm most familiar with, late sixties to mid-eighties GM, are series-wound.

Fords of a similar vintage, and I believe up until even into the Ninties, use the field windings to actuate the bendix as well- obviously a permanent magnet won't work here.

I have no doubt there are probably some starter motors out there that use permanent magnets- as noted, likely the small and weight-sensitive things like yard machines or motorcycles- but generally speaking, automotive starters don't have 'em.

As for the variability on a drill press, there's more than a few models out there that have variable speeds- meaning, I assume, on-the-fly and/or infinite variability, not just step-pulleys. I have a Rockwell drill press with an infinite Vari-drive, and it works great.

The problem, as already noted, is cost. A good floor-model DP suitable for a decent home shop might cost you $200 if you get a few bells and whistles. A Vari-drive style like mine? Looking in my somewhat outdated '04 Rutland Tool catalog, shows the cheapest variable-speed drill press being a 15" Wilton for $1,700. Some electronic variables (I'm assuming using a built-in VFD and 3-phase motor) go from $3,200 to $4,700.

Now, the difference isn't just the variability- the Wilton, at least back in '04, was still an American-made industrial-quality machine. The $200 step-pulley press is a rebranded light-duty Chinese import.

The other reason is that for the most part, true wide-range or infinite variability isn't all that necessary or indeed all that important.

For the average home-shop user, a speed in the ballpark is fine. If the chart says you need 258 RPM, if the drill press gives you 185 or 320 RPM, you're fine. Besides which, the vast majority of the $200 import press buyers are just doing woodworking anyway, and other than perhaps a few spade bits or exotic woods, the actual spindle speed beyond "fast", "medium" or "slow" is all but irrelevant.

And last, if you mean variable-on-the-fly, as in a hand-drill's trigger, that's unnecessary on a press. The hand drill only has it because it doesn't have a set of belts to set speed ranges. Some hand drills do have planetary gearboxes to give similar speed ranges, but still, there's virtually no reason to need to vary the spindle speed on-the-fly in a press.

And finally, if you did want to, for example, convert a step-pulley drill press over to variable speed, as noted above, one of the best (though not the cheapest) methods would be to swap in a 3-phase motor and a VFD. A treadmill motor and it's DC controller would work- and working treadmills can often be had for free- but keep in mind that the motors usually have a very high top speed (6 or 7 thousand RPM) which will likely require adding at least one jackshaft. Also, the speed controllers typically aren't very sophisticated, and simply alter the motor speed by altering the voltage- meaning you'll have very little power at the spindle at low speeds.

Doc.

ptjw7uk
03-06-2009, 06:23 AM
To get back to the original posting most drill presses were used in a manufacturing environment where once the speeds were set then with the induction motor in place it would drill to its hearts content all day and everyday. Most of us end with one of these drills because they are so numerous and as we are not doing the same thing day in day out have to change its configuration its just the nature of the beast. You will always end up with machine tools that are better suited toindustrial environments ending up in the machinsts workshop.
Problem with most of us we at the outset will never know waht we will eventually ask the machines to do, just get the best you can afford you will always hanker for that little bit extra!

Peter

Willy
03-06-2009, 09:02 AM
Lots of permanent magnet motors are being used in automotive applications. They are popular because they are cheaper to produce, give the OEM designer more flexibility in component placement due to a smaller footprint, and offer higher power output.

They are usually gear reduction, and have been available in the aftermarket for at least the last twenty years due to the increase in clearances when using headers.

Just about all of the starters I've replaced in the last few years have been permeate magnet starters. The old direct drive series or series-parallel wound starters is rapidly disappearing.

Oh, and a word of caution to those who have in the past reached under to hood to give a stuck starter a smart smack on a cold day in order to loosen it up...DON'T!!. Ceramic magnets do not take kindly to hammer blows.


Just as an example here is a replacement starter for GM engines up to 502 ci., so they are not just for dinky motors anymore.

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=39735

Check out the weight and also the size of the actual motor. Don't forget the end closest to the flywheel is mostly the gear reduction unit!

Edited for grammer....OOOPS!

Evan
03-06-2009, 09:32 AM
They may be available as after market replacements but they are not common as OEM parts. My PT Cruiser has a series wound starter which is standard for Chrysler products.



Chrysler Crossfire Starter

The modern Chrysler Crossfire Bosch replacement starter motor is a series-wound direct current electric motor with solenoid switch mounted on it. Call us toll-free now to order a Chrysler Crossfire bosch replacement starters from our huge online catalog. We are the Internet's leading source for auto parts and our Chrysler Crossfire Starter inventory exceeds each of our competitors!



A good reason for NOT using a permanent magnet motor is that it will fail if overheated. Even if it doesn't demagnetize it will stop working until it cools down and will probably be permanently weakened.

Willy
03-06-2009, 09:57 AM
Evan, I just replaced a starter on a first generation 1998 Neon it is a permanent magnet motor. I have a second Generation 2001 Neon also permanent magnet motor. I sincerely doubt that yours is any different. Have you removed it and had a good look?
Most cars produced today come with permanent magnetic starters.
If you don't believe me ask at at an automotive electrical shop.
Or if you have a lot of confidence that yours is series wound, get about a 1/2"x18" steel punch and reach down past the induction tract and give it a good blow.:D Shouldn't do any harm to a series wound motor.

J Tiers
03-06-2009, 09:59 AM
In other words a series wound motor WILL run on AC and DC. They are inefficient in the best case so that isn't a good criteria for determining what sort of motor they are. Bottom line is that a series wound motor will run on ac or dc. It can be optimized to some degree for one or the other but it is the fact that it will run on either that led to the term "universal motor".

None of that "Evan logic" please........

(SIGH) A "universal motor is DESIGNED to work on the general AC system, as efficiently as possible. The motor type is typically chosen because of the speed-torque curve, and the ease of crude speed control, vs an induction motor which is speed-locked to the AC line input. If that means some compromises, that is accepted.

A "DC" motor is designed to work on the DC voltage of choice, EFFICIENTLY, and makes NO PROVISION for running on AC, even if it might "spin" on AC.

You totally ignore the entire concept of back EMF and how the back EMF, winding impedance, and the applied voltage interact in motor operation.

In your simplistic world, if it turns, it works..... In my world, the real one, it is supposed to work well, and provide defined operational specs.



That is circular logic. It is a dc motor because it runs on dc except when it runs on ac which makes it an ac motor except when it runs on dc.

(SIGH) Not really, it is a DC motor because it (the starter motor was the subject) is designed to operate on a specific range of DC voltages, and do a certain job. The designers had NO INTEREST in how, or IF it "works" on AC, and made NO PROVISION FOR that.




You need to review basic electromagnetism Jerry. Perhaps a little learning about motors and how they work would do you some good. The current may increase in both windings but that does not result in magnetic moment increasing in square law proportion to the current. Dipole magnetic fields follow inverse third power law with distance. The magnetic moment interaction over a gap with permeability 1 is not current squared because of the u/4pi r^3 term.

What you propose is equivalent to so called "free energy".

Bull.

The effect exists, it is important. it is illustrated in the fact that a series motor tends to "run away" speed wise. That is NOT affected by simplifying the issue to a "square" term.

Apparently you don't believe that the magnetic flux is affected by the ampere turns. or perhaps you think that turns are magically subtracted as the amperes increase....... or you believe that all magnetic action of the coils ceases when the steel is saturated.......

if you can give me a correct explanation of why a series motor tends to run away in speed when unloaded, and relate it to the torque increase I mentioned, then I may pay attention to your "interesting" opinions about motors and 'free energy".

If you can debug your own statement about "free energy" by explaining why the series motor POWER is not over unity despite the increased torque, then you may get extra credit.

This is your golden opportunity, Evan...... be a physicist for a day.


BTW, the answers have a lot to do with the various factors that make a series DC motor (or the related "universal" motor) less than suitable for machine tools, BUT VERY suitable for traction applications like locomotives.

J Tiers
03-06-2009, 10:01 AM
Well, sorta-kinda. A series-wound D.C. motor does not require a laminated field structure,

Except pole pieces........depending.

Evan
03-06-2009, 10:16 AM
Defining a motor as a DC motor because it runs on DC is self referential and is indeed circular logic. A series wound motor WILL run on either AC or DC regardless of how well or poorly it does so.

A series wound motor will "run away" but not to infinity, not even theoretically. If the magnetic flux was increasing as the square of the currents then not only would it run away but it would do so in theory at an exponential rate. That is obviously absurd, and incorrect. In real life AND in theory the magnetic flux interaction over distance increases at a lesser rate than the currents because of the third power term that describes the propagation of magnetic fields. Ampere turns etc have nothing to do with that principle, it is inherent in the fact that a magnetic field is a volume based dipole field.

Willy
03-06-2009, 10:17 AM
They may be available as after market replacements but they are not common as OEM parts. My PT Cruiser has a series wound starter which is standard for Chrysler products.

A good reason for NOT using a permanent magnet motor is that it will fail if overheated. Even if it doesn't demagnetize it will stop working until it cools down and will probably be permanently weakened.


Evan, if you get a starter motor hot enough to loose the magnetism in the magnets you are also going to damage a conventional series wound motor. It's one of the biggest causes of motor failure...people keep cranking until it's toast. Look in any owner's manual and it usually states not to engage the starter for more than twenty seconds without giving it a chance to cool off!

By the way my copy of the factory service manual says I have a six pole permanent magnet starter...which with my own two eyes I have verified. Have a look inside yours.

Edited to add: Don't trust online parts sources as a refernece unless they will pay for return shipping.

Evan
03-06-2009, 10:23 AM
I don't think I can see it. Hell, I had to pull most of the intake manifold just to change spark plugs. It's parked in the tent garage for the winter still. Thanks for reminding me though, I should start it today and let it run a bit. If it's geared that should be easy to tell if you are actually listening for it. I have never noticed it.

Willy
03-06-2009, 10:28 AM
They are not of the old style double reduction Chrysler type but have a planetary reduction system...vary quiet, as are most new starters. Much the same as the gearing on a cordless drill very compact.

DICKEYBIRD
03-06-2009, 12:34 PM
Meanwhile, back to the OP's question: For building your animation figures, why not move up in price range and get a Sieg X1, X2 or preferably an X3 mill-drill to do your work. You're going to need the milling capabilities anyway. They all have very nice speed controls that can be adjusted on-the-fly if needed.

ps: Welcome to the forum.:)

lazlo
03-06-2009, 12:59 PM
Hobbyinovator, you will find a lot of inovative offerings in the smaller drill presses and lathes. The larger machines rely on heavier duty stuff. Most the variable speed drill presses I have seen and used are belt driven with variable pulleys.

The biggest reason for the same old same old is COST and dependability. The bigger the machine the more expensive the inovation costs and small shops and home machinists can't afford it.

I think Hobby is looking at the current offering of inexpensive Chinese drill presses, and coming to the semi-reasonable (but incorrect) conclusion that variable speeds on drill presses are rare.

Like Carl says, drill presses have had variable speeds, whither from Reeves Drives (variable-width pulleys) or gearboxes (like a hand drill), since the early 20th Century. But those drill presses are in a whole different price point.

Delta does make a cheap Chinese copy of the benchtop Clausing vari-speed drill press, but Reeves Drives are temperamental under the best of conditions, so a poor Chinese copy is hopeless:

http://www.amazon.com/DELTA-DP350-Shopmaster-3-Horsepower-12-Inch/dp/B00006K00I/ref=sr_1_4?ie=UTF8&s=hi&qid=1236358697&sr=1-4

http://ecx.images-amazon.com/images/I/41FFMDVbEaL._SL500_AA280_.jpg

Spin Doctor
03-06-2009, 05:57 PM
Right now for a DP I am using a Ryobi (hey no laughing there) variable speed bench model. I forget the model # but is actually a pretty nice little machine. Low speed is a little high for metal working (500 rpm) but it was marketed for woodworking. Note the was. Ryobi comes out with something that isn't a complete POS and they drop it from their line

J Tiers
03-06-2009, 09:52 PM
Defining a motor as a DC motor because it runs on DC is self referential and is indeed circular logic. A series wound motor WILL run on either AC or DC regardless of how well or poorly it does so.

naturally, that is merely silly of you. "running" is a very elastic term, and you completely ignore any semblance of usefulness of the motor.

with that logic, an airplane is a submarine.



A series wound motor will "run away" but not to infinity, not even theoretically. If the magnetic flux was increasing as the square of the currents then not only would it run away but it would do so in theory at an exponential rate. That is obviously absurd, and incorrect. In real life AND in theory the magnetic flux interaction over distance increases at a lesser rate than the currents because of the third power term that describes the propagation of magnetic fields. Ampere turns etc have nothing to do with that principle, it is inherent in the fact that a magnetic field is a volume based dipole field.

Your statement proves that, as I suspected, you evidently do NOT understand how the series motor works. You apparently don't know why it CAN run away..... and therefore why its speed is so variable as to answer the original poster's question as to why the technology used in hand drill motors is not used in drill presses.

And, of course, nobody made any statement of the series motor running away to infinity. That is merely your straw man argument.

If you do NOT understand, as it seems you do not, you are better off to say so instead of going off on tangents.

lane
03-06-2009, 11:07 PM
I don`t even own a drill press . And when I did all I used it far was to run a wire brush.

spope14
03-06-2009, 11:35 PM
Delta has drill presses with a variable speed system - the cone belt type of thing found also on Bridgeports. They also had a drill press that had forward and reverse. The Fwd/Rev. must have been hard to find, I have seen only two in my life, one 25 years ago, and one in the shop next to mine and he sold it two years back.

J Tiers
03-07-2009, 12:06 AM
Delta has drill presses with a variable speed system - the cone belt type of thing found also on Bridgeports. They also had a drill press that had forward and reverse. The Fwd/Rev. must have been hard to find, I have seen only two in my life, one 25 years ago, and one in the shop next to mine and he sold it two years back.

Isn't Delta what absorbed Rockwell? Rockwell had that system both on their lathes, and on at least some drill presses.

For the forward/reverse, do you mean a mechanical system?

lazlo
03-07-2009, 12:09 AM
Delta has drill presses with a variable speed system - the cone belt type of thing found also on Bridgeports.

Like the one in the picture I posted above? :)

Evan
03-07-2009, 12:50 PM
And, of course, nobody made any statement of the series motor running away to infinity. That is merely your straw man argument.


Care to review this earlier statement?


* The torque is nearly unlimited, but in a practical sense about 300% is probably max.


Unlimited torque? What an interesting concept, closely related to running away to infinity.


naturally, that is merely silly of you. "running" is a very elastic term, and you completely ignore any semblance of usefulness of the motor.



Of course. So what? The point is that it will run on either AC or DC. That is what makes it a universal motor. That is also my only argument. I have made no other claims while you have been rocketing off in all sorts of directions with a combination of false assumptions and just plain wrong physics.

J Tiers
03-07-2009, 04:57 PM
Unlimited torque? What an interesting concept, closely related to running away to infinity.


Ignorant statement by you. Running away is, curiously, at the LOW TORQUE end of the spectrum..... It is virtually impossible to "run away" at the high torque (and therefore low speed) end of the range.




I have made no other claims while you have been rocketing off in all sorts of directions with a combination of false assumptions and just plain wrong physics.

You have made the claim that I have used wrong physics, which in this case shows you have no clue in the matter.

The series motor "runs away" specifically because of constantly decreasing current, and therefore decreasing field (and deceasing torque).

At some point the POWER becomes too low to spin it any faster, and it reaches a constant speed. hopefully the construction can take that speed.

This is because the back EMF constantly decreases with speed IN A SERIES MOTOR, due to a decrease of field current. It is interactive, because there is NO fixed field aside from remanent magnetism in the iron. the field comes from motor current, which decreases as back EMF increases

More speed is more back EMF, but more back emf means lower current, which lowers the field AND the back EMF, because the field current is the motor current.

To maintain back EMF it must spin faster, because if it does not, current will increase, providing torque to speed it up.

The net result is that the motor tends to increase rpm to a destructive point, if windage does not hold it back first.

At the LOW end of speed, despite your howls of protest, the torque curve IS parabolic (square of current) up until the point that the iron begins to saturate. then it levels off as a straight line increase until limited by available volts and resistance. Even with iron saturated, the coils alone still provide a field increase with current increase, just at a lower rate. The torque available is quite high, higher than with fixed-field motors, approaching 300% of nominal.

Naturally the POWER is not increased so much, because the SPEED is low.

I realise you wont believe it, and will quote more pseudo-science to "prove" it is wrong, but it is still this way no matter how much you howl and act as a "board bully".

And the above is why the series motor as used in a hand tool is virtually never used in a machine tool, which is one part of the original poster's question. The speed is so unstable that it is unusable without speed feedback and strong speed control.