[dpktm]

Why do it?
After having it for 10 years the 4 best uses for spending money and time to fit a 3 phase motor on your existing drill press:
-Improved cutting speeds for steel to cut a hole and preserve the drill.
-Actually being able to drill stainless 304 and 316- almost like steel.
-Use of a countersink to cut a clean hole without chatter.
-Better drilling for hole saws

I keep a drill doctor anyway for maintenance

VFD - Anywhere really - I used KB electronics in Florida $125 back in the day
Motor - Ebay $50 - century 1 hp motor from a Texas Grain mill.
Computer Fan - Internet - This one's 220v
The drill press was a 1973 floor mounted press when Taiwan started importing tools into the U.S.

Basics - Get the frame# off the existing 110 motor and 3 phase should match it for bolt pattern and shaft size. The fan offers motor cooling you loose with low motor speed drilling. I called KB and told them what I wanted to do, they gave me the unit best suited for it and what I needed in the replacement motor.

Options- Find something without a motor. Match the motor holes to get a frame size and replace the pulley with a step pulley (ZORO or Grainger) or get a 3 phase DP and power it with a VFD.

Far easier than getting a tread mill motor and building mounts for it. A VFD would be great for a lathe or band saw but I'm not looking for an excuse to quit dirt riding yet.

This is for Oscar if he hasn't pulled the trigger on buying a new unit.

[Oscar]

I've only read a little about VFD, but I haven't re-familliarized myself with them as of late.

[dpktm]

I got the idea from a machining forum years ago when treadmill motors were a dime a dozen. The motherboards cost more to replace than to replace the worn unit- so DC motors were easy to get. This is an easy way to get around the DC wiring to AC current and it works slick.The belt hardly ever slips. Same tech used today in cordless hand tools- multi phase switching of amperage for precise control.

Buy your new DP and use it, but bookmark this mod for future project work. If you get a unit with strong precise spindle, square and adjustable table options and a multi-speed pulley system, convert it later. If tool history is the same, the motors aren't that great on chinese bandsaws or drill presses anyway.

Ever bought a new dirtbike rode it, and got the suspension done? That kind of difference.

[Oscar]

You'll have to back-track as to why someone would want to use it on a drill press that already has adjustable speed? I'm not sure I follow you. Were you referring to an,old post of mine about a drill press?

[dpktm]

Yes the old post.
Changing pulleys for speed control is not half as good as twisting the POT on the fly. Just like welding with low too of an amperage- we start slow, and put a slow rate of down pressure on drill. It generates heat and ruins the bit.

Better if you can run a higher feed and pressure rate for cutting material to cut friction and heat.

Stainless best demonstrates this. On the small lathe I run as high a feed rate and speed I can to prevent heating and hard spots. Same with drilling stainless - especially stainless. Sure, you can pop the lid and move belts, but the VFD gives you way more speed options within the pulley configuration at your finger tips.

[Oscar]

Yes, I agree with the advantages. How would it be different from a drill press that already has infinitely adjustable speed (not stepped pulleys)?

[cj737]

Yes, I agree with the advantages. How would it be different from a drill press that already has infinitely adjustable speed (not stepped pulleys)?

Adjustable pulleys only offer a direct ratio of torque to RPM. A VFD allows you to maintain the higher torque most frequently associated with a slower speed, but operate at a higher RPM. Imagine drilling a 1/2" thick plate of stainless 316. You need speed to prevent galling, but you need torque for the thickness and pressure.

Some VFDs also allow you to power them with 110v, but operate at 3Ph power to the motor (inverter included). This is a significant cost savings.

[Oscar]

A VFD allows you to maintain the higher torque most frequently associated with a slower speed, but operate at a higher RPM.

How? (not saying I don't believe you, I honestly don't know how you mean).

So like in this drill press:

https://www.northerntool.com/shop/tools ... _200659141

How would it be set-up to take advantage of the property you mentioned?

[dpktm]

Yes, I agree with the advantages. How would it be different from a drill press that already has infinitely adjustable speed (not stepped pulleys)?

If it's the Klutch 17" floor model- I don't know what they use for speed control. The VFD is a bigger gain for users having to change pulley belts. I think CJ explained it well in a couple lines.

Anyone Interested:
KB electronics.com
KBVF 14
Chassis/ IP-20 AC drives
Operates a 1hp 3 phase motor 50-60 HZ

[Oscar]

The VFD is a bigger gain for users having to change pulley belts.

And for those who have one like I linked that doesn't have pulleys to make belt changes? It has a fully adjustable speed range, similar to a CVT.

Would the drill press be set to it's "highest" speed, but then the speed would be modulated by the VFD? It all just seems counter-productive to me when the drill press already has it's own infinitely adjustable speed control (it may not be a knob, but it's a simple lever, so it's essentially the same thing). I can see the advantages with 'traditional' drill presses, where one has to literally change the belt to get different pulley ratios, but I for the life of me cannot see how it would make one with a CVT-like pulley setup any better.

[cj737]

A VFD allows you to maintain the higher torque most frequently associated with a slower speed, but operate at a higher RPM.

How? (not saying I don't believe you, I honestly don't know how you mean).

So like in this drill press:

https://www.northerntool.com/shop/tools ... _200659141

How would it be set-up to take advantage of the property you mentioned?

A VFD allows you to spin the motor of the drive and the spindle at the exact same speed. Your pulley drives don't create the same 1:1 relationship. The motor will spin faster with your potentiometer, but the reduction to drive the pulley and in turn the spindle, you lose torque and velocity. With VFDs, you don't. In fact, you can spin the motor to its full potential by changing/tuning the frequency thereby producing higher spindle speeds.

For a drill press, its a bit overkill I will grant you. For a lathe, a mill, etc it can be a huge advantage. Also, most VFDs have braking, acceleration, and deceleration programming available. Spin up to full speed in 0.5 seconds, and decelerations in 2.5 seconds. All through electronics, not hydraulics or mechanical wear.

[Oscar]

With VFDs, you don't. In fact, you can spin the motor to its full potential by changing/tuning the frequency thereby producing higher spindle speeds. (Are you saying that I could spin the motor faster than it would normally be spinning when it receive it's power from it's rated input V/Hz? IOW: say I have a 1-Φ motor. It spins at 2000 RPMs (unloaded), via 120VAC/60Hz standard household input power. If I add a VFD, I can make it spin even faster than 2000 RPMs?)

For a drill press, its a bit overkill I will grant you. For a lathe, a mill, etc it can be a huge advantage. Also, most VFDs have braking, acceleration, and deceleration programming available. Spin up to full speed in 0.5 seconds, and decelerations in 2.5 seconds. All through electronics, not hydraulics or mechanical wear. (I do have a lathe/mill, it's a Smithy Midas 1220LTD 3-in-1, but it has two 3/4HP 1-Φ. Would the benefits still apply?)

Please see my questions above in blue.

[TraditionalToolworks]

A VFD allows you to spin the motor of the drive and the spindle at the exact same speed. Your pulley drives don't create the same 1:1 relationship. The motor will spin faster with your potentiometer, but the reduction to drive the pulley and in turn the spindle, you lose torque and velocity. With VFDs, you don't. In fact, you can spin the motor to its full potential by changing/tuning the frequency thereby producing higher spindle speeds.

This is partially true, we need to keep in mind that you can only reduce the frequency by about 50% before loosing too much torque on the motor as a result. You stated that the VFD won't loose torque, but that part is not true, it will. Raising the frequency is a different story, I don't think that will allow you to increase the torque, but it won't loose torque.

For a drill press, its a bit overkill I will grant you. For a lathe, a mill, etc it can be a huge advantage. Also, most VFDs have braking, acceleration, and deceleration programming available. Spin up to full speed in 0.5 seconds, and decelerations in 2.5 seconds. All through electronics, not hydraulics or mechanical wear.

I can see the advantage with a drill press. While it's true as stated above that the drill press is already multi-speed, it will only allow for the specific supported speeds, anything outside those speeds are not obtainable. With the VFD you can get a smooth control of a wider range, and if setup properly on the correct speed pulley it should provide most of the range needed. You can still change the pulley if needed as well. This would allow one to adjust to prevent a drill bit from burning the metal one is cutting in a more precise way, while the bit is doing the actual cutting. Is it absolutely needed? Probably not. Would be be desirable? I think it could be and can see the advantage.

That said, I pretty much agree that a VFD is more useful on a mill or lathe. Very useful on a belt sander also, like a 2x72 they seem to be pretty popular.

[cj737]

With VFDs, you don't. In fact, you can spin the motor to its full potential by changing/tuning the frequency thereby producing higher spindle speeds. (Are you saying that I could spin the motor faster than it would normally be spinning when it receive it's power from it's rated input V/Hz? IOW: say I have a 1-Φ motor. It spins at 2000 RPMs (unloaded), via 120VAC/60Hz standard household input power. If I add a VFD, I can make it spin even faster than 2000 RPMs?)

For a drill press, its a bit overkill I will grant you. For a lathe, a mill, etc it can be a huge advantage. Also, most VFDs have braking, acceleration, and deceleration programming available. Spin up to full speed in 0.5 seconds, and decelerations in 2.5 seconds. All through electronics, not hydraulics or mechanical wear. (I do have a lathe/mill, it's a Smithy Midas 1220LTD 3-in-1, but it has two 3/4HP 1-Φ. Would the benefits still apply?)

Please see my questions above in blue.

No, you can match the speed of the motor and the spindle. The motor spins to it's maximum (or variable thereof) but the spindle is not spinning equally. There is always a discrepancy to some degree between the two.

As for your Smithy, yes. In fact, you can get a VFD running on 120VAC and have it power a new, 2HP 3Ph motor if you want the added luxury. These are some of the benefits of VFDs; they're programmable and some have inverters onboard.

[cj737]

This is partially true, we need to keep in mind that you can only reduce the frequency by about 50% before loosing too much torque on the motor as a result. You stated that the VFD won't loose torque, but that part is not true, it will. Raising the frequency is a different story, I don't think that will allow you to increase the torque, but it won't loose torque.

You misunderstand what I wrote.

All motors will lose torque to a degree depending upon many factors, not just their speed. The point I made is that matching the motor RPMs to the true Spindle speed allows the torque to be linear in its path. And, you don't have the loss of speed, torque etc through reduction gears. This is why I stated a belt-driven drill press is not an ideal application for them. Because even with a VFD, you still have the belts transferring the power from the motor to the spindle.

Raising the frequency doesn't necessarily increase or diminish the torque. The change of frequency can be used for other purposes, like phase control, heat into the motor, power consumption, etc. What I did say is that increasing the speed via the VFD doesn't cause an absolute loss of torque the way belt driven equipment does.

Sorry for the confusion-

[Oscar]

With VFDs, you don't. In fact, you can spin the motor to its full potential by changing/tuning the frequency thereby producing higher spindle speeds. (Are you saying that I could spin the motor faster than it would normally be spinning when it receive it's power from it's rated input V/Hz? IOW: say I have a 1-Φ motor. It spins at 2000 RPMs (unloaded), via 120VAC/60Hz standard household input power. If I add a VFD, I can make it spin even faster than 2000 RPMs?)

For a drill press, its a bit overkill I will grant you. For a lathe, a mill, etc it can be a huge advantage. Also, most VFDs have braking, acceleration, and deceleration programming available. Spin up to full speed in 0.5 seconds, and decelerations in 2.5 seconds. All through electronics, not hydraulics or mechanical wear. (I do have a lathe/mill, it's a Smithy Midas 1220LTD 3-in-1, but it has two 3/4HP 1-Φ. Would the benefits still apply?)

Please see my questions above in blue.

No, you can match the speed of the motor and the spindle. The motor spins to it's maximum (or variable thereof) but the spindle is not spinning equally. There is always a discrepancy to some degree between the two.

As for your Smithy, yes. In fact, you can get a VFD running on 120VAC and have it power a new, 2HP 3Ph motor if you want the added luxury. These are some of the benefits of VFDs; they're programmable and some have inverters onboard.

Sorry but our modes of communication just don't jive together. Here you say you match the motor to the spindle, in the previous quote you say you get higher spindle speeds, then in another post you say motor of the drive and the spindle at the exact same speed. Sorry man, can't understand what you're saying the way you're typing it.

[cj737]

Your motor spins at a variable speed since you have a potentiometer. The spindle does not spin at the equal speed, no matter what you choose for a pulley or motor speed. The drive mechanism prevents that from happening.

With a VFD, you can tune the two to be equal. This will generally produce more torque. Even at higher speed, you retain more torque.

You cannot spin the motor faster than its designed limit with a VFD.

[Oscar]

Your motor spins at a variable speed since you have a potentiometer. The spindle does not spin at the equal speed, no matter what you choose for a pulley or motor speed. The drive mechanism prevents that from happening.

With a VFD, you can tune the two to be equal. This will generally produce more torque. Even at higher speed, you retain more torque.

You cannot spin the motor faster than its designed limit with a VFD.

I just realized, what is missing here is numbers. That's why I can't understand your explanation. It's not you, it's me. Also, I think we're talking/thinking about different machines.

[TraditionalToolworks]

All motors will lose torque to a degree depending upon many factors, not just their speed. The point I made is that matching the motor RPMs to the true Spindle speed allows the torque to be linear in its path. And, you don't have the loss of speed, torque etc through reduction gears. This is why I stated a belt-driven drill press is not an ideal application for them. Because even with a VFD, you still have the belts transferring the power from the motor to the spindle.

That's true, and a direct drive motor would be more ideal in that case. However, if the belt system is designed properly there shouldn't be any loss, AFAIK, and VFDs are commonly used on machine that do transfer power from a motor with a pulley through a belt.

What I did say is that increasing the speed via the VFD doesn't cause an absolute loss of torque the way belt driven equipment does.

I do have a number of direct drive machines, and ones that use 3 phase motors, but not something I would use a VFD on. One reason that belt drive motors are preferred is when you need to replace the motor, since you can always fabricate some type of mount rather than having to use the exact same frame type.

If I understand what you're saying the torque changes when the machine is operating with a belt, but wouldn't the torque fluctuate in both directions? I mean unless the belt is slipping. That's why I mentioned if the belt system is designed properly there shouldn't be any loss in torque. On some machines like a South Bend lathe which uses a flat belt, they're actually designed for belt slippage to become a feature when the machine becomes overloaded. At least that is my impression. Larger lathes with larger motors are not as forgiving when they get bound up, and more often than not something has to give, which means something will break.

It is true that VFDs can be used for other things besides speed, they can easily change the direction of the motor without having to swap wires on the motor, since 3 phase motors have the ability to run both ways and VFDs only work with 3 phase motors. Also they can be used as a brake to stop the motor without having a mechanical brake.

I'm not a VFD guru, but have a couple I use in my shop. They are quieter than running an RPC, but I find the whine they create on the 3 phase motor is also less than desirable, just not as bad as the idler on an RPC.

I had been planning to use a VFD on a South Bend lathe I want to put into service, but with my new shop I'll be using a Phase Perfect, which I think is preferred over either a VFD or RPC, but probably less than desirable than 3 phase coming in from the power company. Some people argue as the Phase Perfect is balanced and each of the legs are equal in output. That's not the case with the 3 phase power from the power company, so I'm told. I don't have any personal experience with that.

Anyway, this post is long, and my point previously was that I can see the advantage of using a VFD on a drill press, but don't think it would be possible to use it for the entire range of all speeds, so even in that case one may need to change the belt on the pulleys, however the advantage from my view is being able to adjust the spindle at any speed, so you could tune the drill bit to ensure you have the best cut on the actual material, that's all.

[Poland308]

If you have a good freq drive it can be tuned to get rid of the whine, (harmonics).