What Motor to use, advice please.

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Cipher

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Hello,
I'm on rebuilding an old Chinese benchtop drill press. It came with a wrong type of motor.

What I would like to have is a advice on what power rating for the new motor to select.
I have 230V 16A 50Hz AC, single phase.
It is a 12 speed drill press with SPA 12,7mm profile V-belt. Column diameter: 80 mm, Spindle: MT2 with M22 screw size arbor, all bearings are replaced with new quality ones.
Some of these drill presses are sold with 0.37kw motors, others with 0,77kw and some with fantasy motors around 1kw - "nominal".
New motor will be a new industrial single phase one with starter capacitor.
Since this is my first drill press and at the same time the largest machine in my small work room, I have now idea on what to aim for. My target is to be able to drill up to 25mm / 1" holes in Aluminum and mild steel, using reground industrial HSS MT2 drill bits.

Any advice would be helpful.
 
My drill press is very similar to yours, but is a floor model. The factory motor draws 8.6A, (~1 kW) per the Chinese (edit: Taiwanese) manufacturer. That motor is adequate for everything I have done with it since I bought the drill press new in 1983. The bigger problem is with speeds. It has 3 pulleys, double reduction. With our 60Hz power, the minimum spindle speed is 215 rpm. At 50Hz, it would be 180 rpm. 215 rpm is too fast for 1 inch (25.4mm) drills in mild steel on the fairly light machine, aluminum drills well at that diameter.
 
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If you plan on drilling large diameter holes on a bench top drill press, you will probably need to slow the spindle down to do it.
A 25mm hole is pretty big for a drill press of that type and honestly, if I were planning on work like that I'd look for a bigger machine.
But, to answer your question, most drill presses of that type come with 1720 RPM motors. If you plan on drilling big holes you should
consider an 1140 RPM motor instead. This will bring the overall speed range of the machine down usefully. (I converted my own
drill press in this way and reduced the minimum speed to 132 RPM.). As far as power is concerned, at least 3/4 HP (.56kw).

Also, if you plan on drilling large holes (or any size hole really), be sure that the work is securely clamped to the table before you
drill. Large drills in particular will try to grab the work and spin it around which can break stuff or injure you.
 
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Thank you, so 1kw it will be.
I could up one pair of poles, cutting speed nearly in half, then it will top up at about 2000 rpm and about 100 on the low end.
Would that help with the cutting speeds or just be to heavy on the belts?
 
I don't want to drill 1" holes into steel all the time, it just should be able to do it once or twice before it sucks itself into a black hole...
Than it will be 1,1kw, 4pol (1400rpm) and, looking at the prices, it will be a 3 phase and vector vfd.
(Used, factory tested, still cheaper than the new single phase motor alone...)
Thank you very much, now I have an Idea on what to look for.
 
The charts show 215 rpm as about half of a typical surface speed recommendation in steel with a 25mm drill. Give it a try and see.
 
Hi, it's me again.

I ordered the new motor. In the end I went for a 0.77kw single phase one with nominal 1400 rpm. The 1.1kw motor would not give me any room for adjustments and the shaft diameter would not fit the pulley... VFD would have been a nice toy too, but they are not meant to be plugged in and out all the time, so not an option for me on the 2nd thought. At least the new motor can handle its load continuously - I'm used to the mini mill and mini lathe toys so this is a real improvement for me.

One more thing before I can close this project:

I would like to have a dead man's switch, but I haven’t seen any on a drill press yet. I have seen one on a packing machine, a “inverted” momentary footswitch – as long as you keep it pressed up, the machine runs. What do you think? Would that be overkill? Are dead man's switches even used on modern drill presses (maybe in a more industrial evironment)?

I do have added/planed so far:
  • central kill switch, seems it is going to be forehead operated if both hands are busy preventing a helicopter from taking off…
  • keyswitch (because children)
  • belt cover switch
  • new motor contactor
  • new momentray switches for on/off
  • fault-current circuit breaker
  • RPM-meter and motor temperature readout, just because I love arduinos.
  • Work light (yes, I consider a well illuminated workspace a safety feature :grin:)
  • Vise and clamps.

(The original setup was a Dahlander motor with one plug, no switch.)
 
Cipher said:
I would like to have a dead man's switch, but I haven’t seen any on a drill press yet. I have seen one on a packing machine, a “inverted” momentary footswitch – as long as you keep it pressed up, the machine runs. What do you think? Would that be overkill? Are dead man's switches even used on modern drill presses (maybe in a more industrial evironment)?
Click to expand...

I have a foot switch on my drill press along with the ''forehead'' switch. So if there is a problem all I have to do is lift or move my foot, but really just is good for convenient operation. Mostly my drill press is used for deburring and countersinking operations. It rarely drills holes.
 
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