Drill Press RPM's

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I received a drill press from a friend of mine. near as i can tell its a "no-name" import one with 5 speeds. Problem is that it does not have an RPM chart for adjusting the belt. I dont know which wheels are for what speed. I was able to find out which is the fastest and which is the slowest but beyond that I don't know what speeds they are. Is there any way to find out? I didn't see any make or model info on the drill itself but found the sticker/plate where it was most likely attached :) any ideas? Thanks
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snipped-for-privacy@gmail.com wrote:

Is it not on the inside of the pullys housing lid?
--
Sir Benjamin Middlethwaite




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snipped-for-privacy@gmail.com wrote:

A mechanical tachometer would give you a fairly accurate RPM reading.
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Jack Novak
Buffalo, NY - USA
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snipped-for-privacy@gmail.com wrote:

Measure the pulley diameters, work out the ratios for each combination, multiply by motor speed.
Chris
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snipped-for-privacy@gmail.com wrote:

Is there a speed plate on the motor?
Spindle speed = Motor RPM X Driver Diameter (divided by) Driven Diameter
Driver=wheel attached to motor driven= wheel attached to spindle
It doesn't matter what units you measure the diameter of the wheels in, as long as you measure both in the same units.
Most wheels I have seen are in whole inches.
If the drill uses gears, count the teeth on each gear, and use that instead of the diameter.
motors are usually 1425 or 2850 rpm unless they are internally geared
--
BigEgg
Hack to size. Hammer to fit. Weld to join. Grind to shape. Paint to cover.
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Well, I guess that depends on where you live. In the U.S., with 60 cycle current, they are generally 1725 or 3450 rpm.
John Martin
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Can you explain why that is? 60 cycles per second = 3600 cycles per minute. So how come motors spin at 95.8% or 47.9% of the frequency of the AC supply, instead of 100% or 50%?
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Doug Miller (alphageek at milmac dot com)
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wrote:

http://www.iprocessmart.com/leeson/leeson_singlephase_article.htm "Slip."
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On Nov 2, 9:12 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

It's called slip. I won't try to explain it, as I'm not an electrical engineer. If you really want to know about it, I'd suggest an EE textbook.
John Martin
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Doug Miller wrote:

'Tis so for induction motors, not synchronous. Stator windings induce magnetic field in rotor. Field in stator rotates, in effect, and line freq. With no load, rotor essentially does same. With increased load, rotor speed droops from no-load.
In engineering classes, arm-waving was used to explain why.
J
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snipped-for-privacy@sme-online.com wrote:

OK, thanks -- that helps.

Arm-waving is used to explain *lots* of things in engineering classes...
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Doug Miller (alphageek at milmac dot com)
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snipped-for-privacy@sme-online.com wrote:

To make a synchronous motor, the rotor is a permanent magnet (or polarized electromagnet). Permanent magnet has problems: it's weaker than electromagnets, and iron bits get caught in the works. Polarized electromagnet has problems: you have to provide current to the rotor, and it's harder to make balanced than a simple lump of iron.
So, you use a lump of iron (with some addons, lamination and conductive rivets), and it gets magnetized by the stator. When the motor is asked to do hard work, the magnetic field lags the stator field (if it didn't lag, there would be no torque), and when the motor is fully loaded (and about to reach thermal or other limits) it's typically five percent phase lag, i.e. 95% of the speed of a synchronous motor. A synchronous motor would also have a phase lag, but it doesn't re-imprint the magnetic field of the stator onto the rotor, so the lag doesn't remagnetize the rotor and it isn't usually the rotor part of a synchronous motor that burns up at stall...
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I'm going to oversimplify a bit here but here's the basic idea:
In a conventional induction motor, the stator creates a magnetic field that "rotates" around the rotor. As the field crosses the rotor, it induces a current in the rotor, which causes the rotor to develop its own magnetic field. The rotor field is attracted & repelled by the rotating stator field and causes the rotor to turn. Here's the part that you need to wrap your mind around: The stator field rotates or fluctuates according to line frequency. If the rotor rotates at the RPM that the line frequency would indicate, then the stator magnetic field would not cross the rotor windings, because as the stator field rotated, the rotor would be rotating right along with it. Since there would then be no induced current or magnetic field in the rotor, the motor would be operating at 0 (zero) torque.
Of course there is always some load on a motor, even when not connected to anything there is some drag in the bearings. So the load tends to slow down the rotor, which means that the stator mag field starts crossing the rotor more frequently, inducing more current, etc.
The speed listed on a motor data plate is the RPM at full load. A 1.5 hp table saw motor, for instance , might spin at "almost" 3600 RPM when it's just sitting there running. But when you start ripping some 8/4 maple, it slows down, draws more current and produces more torque. At it's full design load, it might be spinning at say 3450 RPM.
Now, there is a type of motor called a "synchronous" motor and it does rotate at synchronous speed. Unlike an induction motor, though, a synch. motor has DC current supplied to windings in the rotor to create fixed magnetic fields, relative to the rotor. Theoretically permanent magnets could be used. These synchronous motors are usually 3 phase, and the stator windings are arranged more or less the same as in an induction motor, causing a rotating magnetic field. Instead of depending on this field inducing current and a magnetic field in the rotor, though, the magnetic fields of the rotor want to chase the rotating stator field around. No induction is required to generate the rotor field, so the rotor doesn't "slip" like it does in an induction motor.
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Often wrong, never in doubt.

Larry Wasserman - Baltimore, Maryland - snipped-for-privacy@charm.net
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John Martin wrote:

oh bum
I fergot that bit
ta!
--
BigEgg
Hack to size. Hammer to fit. Weld to join. Grind to shape. Paint to cover.
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On 1 Nov 2006 14:32:27 -0800, snipped-for-privacy@gmail.com wrote:

Won't be exact since you're not using pitch diameters of the pulleys but will be close enough for practical application:
First measure (Dial or vernier outside calipers recommended) the overall diameter of each step in each pulley. You could use the diameters at the bottoms of the groove, but the ODs will be closer to the pitch diameter and, therefore, more accurate, especially for the smaller pulleys.
For each set of pulley steps, let:     A = Diameter of a step in the Motor Pulley     B = Diameter of the corresponding step in the Quill Pulley     M = Motor Speed - Probably either 1725 or 3450 rpm. Should be stated on the motor's nameplate along with voltage, etc.     Q = Quill Speed
Then, Q = M * A/B when the belts are running in that particular set of pulley steps.
With only 5 speeds, it's unlikely that you have two belts and a stepped idler pulley like that on my Jet. But, if you do, then it's slightly more complex.
Let everything be defined as before plus:
    I = Speed of Idler Pulley     D = Diameter of the Idler pulley step corresponding to the Motor Pulley A     E = Diameter of the idler pulley step corresponding to the Quill Pulley B
Then I = M * A/D And Q = I * E/B
Or, combining the two equations, and eliminating I,
    Q = M * (A*E)/(D*B)
Hope this helps.
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It wouldn't be too hard to make your own chart. Either measure the pulleys & calculate from that, or turn motor pulley by hand until quill pulley has made a full turn. repeat for each pulley step combination, a little division & multiplication, and there you are. The motor is almost definitely 1750 RPM ut it should be on the motor nameplate just to be sure.
If you need more detail post a question or you could find the explanation on the web somewhere I'm sure.
--
Often wrong, never in doubt.

Larry Wasserman - Baltimore, Maryland - snipped-for-privacy@charm.net
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My 12" Delta drill press speeds are from top pulleys to bottom and use in drilling hard wood. : 3100 bit size 1/16 to 1/8 2340 bit size 3/16 to 1/4" 1720 bit size 5/16 to 3/8 1100 bit size 7/16 to 1/2 620 used for metal
I'd think that yours are probably pretty much the same.
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On 1 Nov 2006 14:32:27 -0800, snipped-for-privacy@gmail.com wrote:

Put it on the second slowest speed and leave it there. If you're doing something exotic there's about a 95% chance your slowest speed isn't slow enough anyway.
-Leuf
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wrote:

Second that- though I leave mine on the slowest speed. It gets used for steel as well, so slowest is best in my case. Even though you could jack up the speed for smaller bits in wood, I've never seen a real advantage to that.
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Well, let's see... I opened Mozilla, typed "drill press speed chart" into the google search bar and came up with this and many other links.
<http://www.woodmagazine.com/wood/story.jhtml?storyid=/templatedata/wood/sto ry/data/85.xml>
Hope this helps.
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