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Conference noted::woodworking_and_tools

Title:Woodworking and Tools
Notice:INDEX see 5.nn, BUY/SELL/SWAP see 7.nn
Moderator:BAMVAX::GOODWIN
Created:Sat Mar 01 1986
Last Modified:Wed Jun 04 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2113
Total number of notes:20008

2107.0. "Rheostat for speed control?" by AIAG::MILLER () Fri Feb 28 1997 18:34

    
    	I am considering purchasing a Delta 12 inch drill press.
    	The low end of the speed range is 620 rpm.  I believe
    	I will need lower speeds for some of my metal work.  It
    	has been suggested that I just put a rheostat device like
    	is used for some router applications in line to reduce the
    	speed.  Anyone have any experience with this technique ?
    
    	regards,
    	Walt
    	RAYNA::Miller
    	dtn 276-9062
T.RTitleUserPersonal
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2107.1problems with rheostatFIEVEL::FILGATEBruce Filgate SHR3-2/W4 237-6452Fri Feb 28 1997 20:3517
 Because the drill press has an induction motor, the rheostat will only
 reduce the torque.  The reduced torque, along with the drag associated
 with the pressure on the bit, will dictate the speed of the bit.  If the
 drag on the bit is constant, it might be possible to control the speed
 `close enough'.

 I mounted a pair of pillow blocks and a jackshaft on a plate pinched 
 between the motor and the drill press.  After turning the motor upside
 down and reversing its direction it drives the bottom end of the vertical
 jack shaft with pulleys and a belt.  The top end of the jack shaft gets
 the original stepped pulley from the motor installed on it and a
 someone longer than original belt is used to power the press.

 good luck with which ever,
 
 Bruce
2107.2HELIX::WELLCOMESteve Wellcome SHR3-1/C22 Pole A22Mon Mar 03 1997 12:5814
    re: .0
    
    You've almost certainly got the wrong kind of motor for that to work.  
    Routers and such have "universal" motors, but the drill press most
    likely does not.  Its speed is tied to the line frequency, so to change
    the speed electrically you have to vary the line frequency from 60 Hz
    to something else.  While there is equipment available to do this,
    the last time I checked the cost was in the $500 range, probably a
    bit much.
    Your best bet is probably to vary the pulley sizes, add a new
    countershaft, or get a slower-speed motor (you can get 1140 rpm
    motors, but they're a bit expensive too).  Or perhaps a gearhead
    motor.
    
2107.3jammer.zko.dec.com::JackMarty JackMon Mar 03 1997 13:445
Also, if you are talking about the "Bench" drill press,
make sure that the quill stroke is adequate for your needs.
It is only about 1 1/2".  I regret having invested in the
12" and should have gone for the 14", which has a quill
stroke in the 3 1/2" range.
2107.4Delta 14" likelyAIAG::MILLERMon Mar 03 1997 16:348
    
    	Thanks to all for the feedback.  It seems very consistent with
    	additional advice received over the weekend.  Appears the Delta
    	14 inch at Home Depot for, ouch, $287 is the best way to go.
    
    	regards,
    
    	Walt