Drill press question

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I have a trademans bench drill press and i would like to lower the rpm on it. The lowest rpm setting is 800. I was wondering if a put a larger pulley on the spindle shaft of the drill and kept the motor pully the same, would this work? I was thinking of putting on an 4'' or 4 1/4'' wide pulley on the spindle shaft. Anyone know around what rpm it would drop to?( The stock pulley is 3 inches wide on the lowest setting  Thanks. Also where a good site to buy pulleysYa gotta spend money to make money!
Reply:That one change is only going to take it down to around the 500-600 rpm range. Is that enough to warrant the effort?
Reply:Hello Shane  To answer your question would be with this simple formula. The diameter of the motor pulley multiplied by the RPM's of the motor equals a number. Take that number and divide it by the diameter of the driven (drill press spindle) pulley. That will equal the driven shaft (spindle) speed.  In other words, if your motor is 1725 rpm and the motor pulley is 3 inches diameter, and the spindle pulley is 4 inches in diameter, then.1725 X 3 = 5175--------------5175 divided by 4 (the spindle pulley dia)= 1293 rpm'sor if the motor's pulley was 3 inches and the driven pulley was 9 inches in diameter, then1725 X 3 = 5175--------------5175 divided by 9 (the spindle pulley dia) = 575 rpm'sor if the motor's pulley was 3 inches and the driven pulley was 6 inches in diameter then your driven (spindle) speed would be half the speed of the motor, because the driven pulley is twice the diameter of the drive (motor) pulley, Or1725 X 3 = 5175--------------5175 divided by 6 (the spindle pulley dia) = 862.5 rpm'sor if the motor's pulley was 6 inches in diameter and the driven (spindle) pulley was 3 inches in diameter then the spindle would be twice the speed of the motor because the motor pulley is twice the diameter of the driven pulley. Or1725 X 6 =10350-------------10350 divided by 3 (the spindle pulley dia) = 3450 rpm'sAre you getting the idea? I would give the algebraic formula, but a computer cannot do this, as a matter of fact, I just noticed that my computer does not even have a symbol for divide. It's got + & - & you can use a upper-case X for multiply, but none for divideFigureing gear speeds are done the same way, except, instead of using pulley diameters, you use the number of teeth.If youre still haveing trouble with figgureing out pulley speeds then send me a message, thru this site, with motor rpm's and pulley diameters and desired spindle speeds, and I will figgure it for you. OK?You could get pot metal pulleys at the foreign made junk stores like Lowes, Home Depot, Harbor Freight, ETC.  But if you go to an industrial supply house or an bearing / oil seal / specialty supply house. You can get almost any pulley (called sheve, pronounced shi-ve) in almost any configuration, and it will be American made!!!!!!  Your friend, Doggie Almost forgot to tell you that when figuring speeds you will get a driven speed number that is xxxx.xxx. I always disregard the numbers that are to the right of the decimal point. Because that is only the left over fraction of a rpm. Unless you want super accuracy, like in doing gears, trips to the moon, ETC. ha ha,  just thought that I would add that.Last edited by Doggie; 10-24-2009 at 12:02 AM.Reason: cause I could
Reply:You can use the slash by the ? key as well for the  ÷ symbol or steal a copy from this post using Ctrl-c.  Do you have 'Word' on it?  it can also stick a whole formula in it real nice.  Do... Insert--Object--choose Microsoft Equation 3.0 from the list then just choose what you want to do from the equation editor and  write it out.   Attached ImagesLast edited by 3 weelin geezer; 10-24-2009 at 11:06 AM.
Reply:Let me give it a try: Attached Images
Reply:Thanks guys, I can't find out how much my motor rpms are though. Its not in the manual or on the press anywhere? Also i checked homedepot and couldn't find any pulleys soo i guess i'll check on the web somewhereYa gotta spend money to make money!
Reply:If you know what the RPM settings actually are on the machine and the given pulley sizes that make them you can work backwards to get the motor RPMs. There should also be a tag usually on the motor that gives that info. A search on line for the model of the machine may yield a manual for it.There are also devices that will measure RPM's, I remember a post somewhere  that someone had just gotten one. I also have a vague recollection of an old motor head method of doing it, but can't remember exactly how right now..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You can take the ratio of the old pulley to the new pulley. Which is 3/4 or 3/4.25. 3/4 is equal to 0.75 So 0.075 times 800 rpm is 600 rpm3/4.25 is equal to 0.7058...... So 0.7058 times 800 rpm is 564.64 rpmYou can also do the same thing in reverse. 800 rpm's divided by 4/3, or 800 rpm's divided by 4.25/3 you will get the same answers.       Sincerely,             William McCormick
Reply:Most likely you don't have room in there to get the size pulley you'll need.You could try thishttp://www.docstoc.com/docs/2550001/...e-the-Big-Onesbut I would just get yerself a 16 speed Drill press-Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Originally Posted by 3 weelin geezerLet me give it a try:
Reply:Originally Posted by 3 weelin geezerYou can use the slash by the ? key as well for the  ÷ symbol or steal a copy from this post using Ctrl-c.  Do you have 'Word' on it?  it can also stick a whole formula in it real nice.  Do... Insert--Object--choose Microsoft Equation 3.0 from the list then just choose what you want to do from the equation editor and  write it out.
Reply:Do a search for "alt-numbers" keys and you'l find various tips and tricks for alternatives to place symbols in text. You hold the alt key down and use the numbers keys. Of course it depends somewhat on the text being used but here's a couple of examplesHold alt plus nums keys 0247 = ÷alt plus 0215 = × alt plus 0178 = ² alt plus 0179 = ³alt plus 0176 = °alt plus 0177 = ±alt plus 0162 = ¢and so-on. There are many more and many duplicates for some.
Reply:Originally Posted by wagingreat tip, I'm computer illiterate as well, Can you give more details about the Do..Insert--Object trick...all I could find on my key board is the insert key???