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Why are drill presses not flexible like hand held drilla

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  • Why are drill presses not flexible like hand held drilla

    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?

  • #2
    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.
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      So is there any new technology coming up that might change this in any foreseeable future?

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      • #4
        Originally posted by Hobbyinovator
        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.

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        • #5
          That's why I'm here .

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          • #6
            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.

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            • #7
              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.
              Last edited by digger_doug; 03-05-2009, 09:27 AM.

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              • #8
                Originally posted by Hobbyinovator
                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.

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                • #9
                  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.

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                  • #10
                    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

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                    • #11
                      This is one of the few variable drill presses I have come across so far:
                      http://www.micromark.com/MICROLUX-VA...NDER,8283.html

                      Anyone have any experience with it?

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                      • #12
                        Originally posted by BillH
                        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.
                        Home, down in the valley behind the Red Angus
                        Bad Decisions Make Good Stories​

                        Location: British Columbia

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                        • #13
                          Originally posted by Evan
                          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.
                          Last edited by J Tiers; 03-05-2009, 09:54 AM.
                          1601

                          Keep eye on ball.
                          Hashim Khan

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                          • #14
                            NickH and Digger Doug, what was the price tag for your modifications?

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                            • #15
                              Originally posted by Willy
                              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.

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