Drill Press Speed Control

[Expat]

So here is a question I've been pondering for awhile but I can't get a good answer for.

I've setup my drill press (Delta 11-980 - Single phase 120V) to run on the lowest belt speed (600 ish RPM), but when cutting harder materials or for detail work it would be useful to further slow things down. So i'm wondering if I might be able to use an SSR to further control the speed of my drill press, similar to the setup for boiler element control.

Much appreciated for any thoughts.

[shadylane]

You would need a variable frequency drive

[Expat]

Thanks for that Shady, but i'm not sure if I understand.

If the SSR is truncating the waveform and providing less power, wouldn't it turn slower?

[shadylane]

The speed of a Single phase motor is dependent on the frequency of the AC current it's running on.
Trying to slow the motor down by lowing the voltage, will cause it to have almost no power and will overheat
If the drill press has a 3600 rpm motor, a 1800 rpm could be substituted

[Expat]

Much appreciated for the additional detail.

Glad I didn't try before asking lol

[Truckinbutch]

I'm totally ignorant about electricity as this post will show .
I use a router speed control on brushed motors to slow them below what gearing will provide . This will not work on motors that do not have brushes .

[Desvio]

Most drill press motors (brushless) were only designed to run one speed and that's it, you control your chuck speed by changing the belt on the variable pullies. The minute you cut voltage even the slightest, the torque instantly drops like a rock and with any resistance that sucker will get very hot. Best to review your pulley ratios.

[FuelMaker]

I've recently done this exactly thing: I used a ebay $30 1.5 horsepower treadmill motor (which are universally DC motors) and a ebay $30 KBIC-125 SCR DC controller with a external heatsink and a fan. The heatsink never even gets warm.

The KBIC-125 controller is a kickass controller and very configurable. It even has a soft start and you can set how long it'll take to get up to speed.

I had to do a little turning of the motor shaft to get the pulley to fit right but once I got it within a couple thousands I did a heatshrink interference fit and it's rock solid.

This was with a medium-large Harbor Freight drill press - it's exactly the same as the Grizzly drill press - same manufacturer and same parts. The spindle on its only has 2 thou runout and I'm really happy with it. However the chuck was a piece of crap and I replaced it with a good jacobs chuck.

I use it for a million things, not least of which is turning down gun barrels.

PS. I did the same thing for slowing down a Harbor Freight band saw so I could cut metal with it. Works like a charm.

[Danespirit]

I'd use an SCR for that.
I've similar in my mind as my drill press is made with belts and pulleys.
That doesn't allow the speed to go down to a point where I can use a reamer or a hole saw.
So a SCR similar to what I use for my still, would be my approach to it.
Something like this: http://www.ebay.com/itm/AC-220V-5000W-S ... Sw2gxYunTp" onclick="window.open(this.href);return false;" rel="nofollow
Edit: Of course, you'll have to get one for the correct voltage and wattage.

[FuelMaker]

FYI

The vast majority of the motors you see are synchronous motors - which means their speed is determined by the input frequency and their power output determined by the wattage (V x A) input.

On the other hand a "universal motor" speed is determined by the voltage input, these kind of motors are found in such things as routers, hand drills, etc. A universal motor can be either AC or DC input depending on the type. A true DC motors speed is determined by the voltage input and it's power by its amperage draw.

On the KBIC controller I mentioned earlier, it'll sense when it's under load and bump the voltage to maintain the same RPM. If you go the treadmill motor route I strongly recommend you DONT use a treadmill speed controller. Not only is it a PITA to hook up, you've got several extra leads to deal with and most importantly it has a safety feature that requires you to dial the speed down to zero and then back up to start rotating again.

[OtisT]

I'm not sure of you tool and material specifics, so my redneck solution may not meet your needs. I had a similar need when boring holes in SS pots, lids, and some hardened copper plate. I am using a 2 1/8" tc tipped tool. The tool suggested 80 rpm and my press goes down to 260. I went to a friend's home to use his mill the first few times I did this. I later found that I was able to use my hand held cordless drill to do the same job with as much success. Stainless pots, not thick, were a breeze. Those only take a few seconds. 1/8" hardened copper plate took more time and muscle, but was doable. I've had no issues with clean cuts and edges using this process but I am very experienced with using tools. i.e. Most of my friends would F this up.

I used sufficient cutting oil. I held the material secure with a vice. You really need a death grip on the drill motor to hold firmly in place in the correct position. I was even hugging the motor to my chest on that copper, to keep it steady. Do not over rev the motor; just gentle squeezes for slow speed. Let the tool do the cutting; Just enough pressure to cut, but no more. And when it gets hot, cool it before continuing. Good luck.

PS. Have you checked to see if there are alternate pullies for that equipment? Not likely, as a jump from 300 down to under 100 is a big jump, but it's worth looking into. You small pulley is likely 1", so you can't go down there, but if you have clearance for a much larger big pulls that Could do the trick.