Converting Jet Drill Press to VFD

[brittf]

I've been considering this for about a year now. I have a Jet Model JDP-17MF drill press that has served me well for the past 13 or so years. It is a sixteen speed press but you have to move belts around on pulleys to change speeds. I regularly drills holes up to 3/4" in diameter in steel. I sometimes will use hole saws in steel as well. Since I start with a 1/8" pilot hole I'm constantly moving belts around to change to the appropriate speed for the material (usually steel) and drill size. Installing a variable speed drive will make this easier and I can switch to different speeds with the twist of a knob or the press of a key.


Jet Model JDP-17MF Drill Press


Pulley Setup to Allow for Sixteen Speeds

I'm posting this for two reasons: 1) I'm looking for comments and feedback from those of you that have gone before me; and 2) Hopefully this will serve as a how-to for those that follow. I've researched this on the Internet and never really found something that could help me. I did find a YouTube video where an individual installed a three phase motor and VFD on a drill press but he did not adequately deal with the torque issues in my opinion. I want to make sure I do not lose the torque necessary to drill larger size holes such as 3/4"

The current motor on the drill press is a 3/4 horsepower and turns at 1725 RPM. The torque necessary to drill larger size holes is developed when you reduce the spindle speed with the pulleys.


3/4 Horsepower Jet Motor

At first I thought I would be limited by the mounting plate that attaches the motor to the drill press. I thought the motor frame was a NEMA 56C. Thinking this, I was headed to use a 1 horsepower motor with a NEMA 56C frame. However, after measuring the bolt pattern I concluded it was not a standard NEMA 56C frame (could be a metric pattern, I don't know). Since I was going to have to fabricate a new mounting plate this opened up a new opportunity for motor sizing. I've now decided to go with a 2 horsepower motor with a NEMA 145T frame. This should fit as it does not appear to have that much bigger of a footprint than a NEMA 56C frame. With the 2 horsepower motor I've already increased my torque capability substantially.

The motor I'm looking at is the IronHorse MTCP Premium-Efficiency Cast-Iron Three-Phase AC Motor, model number MTCP-002-3BD36. I'm planning to use one with a base speed of 3,600 RPM. I will then reduce the base spindle speed 2:1 or 3:1 by the pulleys to 1,800 or 1,200 RPM. The motor will safely run at 5,400 RPM therefore, if I reduce the base spindle speed to 1,200 RPM by the pulleys I can increase it 1.5 times to 1,800 RPM by the VFD and not exceed the maximum safe speed; 1.5 times 3,600 is 5,400 RPM. The motor is advertised to have a 4:1 constant torque ratio. This means that I can run the motor at 900 RPM with a spindle speed of 300 RPM which should get me close to being able to drill 3/4" holes with maximum torque. If necessary I could use the pulleys to reduce the spindle speed further. The motor appears to be reasonably priced (cheaper than the prices I've seen on Baldors).

I'm looking at the GS2-22PO variable frequency drive. One feature I like about this drive is that the panel is detachable so I could mount it on the drill press and the have the controls much closer to me (rather than having them mounted on the wall). It also has a potentiometer that you can use to adjust the frequency (and therefore the speed) without having to press the up or down arrows repeatedly. I have seen a drive with the ability to program 16 presets. I may study that one further before I make the final purchase decision.

The motor has a 7/8" diameter shaft so the existing motor pulley will not work. I have found a Baldor four groove pulley that will work.

I have found the motor and drive available at AutomationDirect.com

For those that have interest I've attached the specifications for the motor (three .pdf files) and the drive (two .pdf files). I've attempted to highlight the motor and drive I've selected on these spec sheets. Sometimes my annotations show up; sometimes they don't. I have had problems seeing them on my iPad unless I save the files to iBooks.

Again, I desire feedback from those of you that have modified machine shop equipment to utilize VFDs. Given the holidays in December, and that out of town of a week this month, I won't be making my purchase until after the first of the year.

Thank you.


Britt

 

[exmaxima1]

I would use a motor with a base 1725 rpm instead of the higher speed motor you suggested. You can always run the VFD up to 120 hz and get more speed out of it, but if you start with the faster motor and always run it slower you are losing power.

 

[pete379]

I would use a motor with a base 1725 rpm instead of the higher speed motor you suggested. You can always run the VFD up to 120 hz and get more speed out of it, but if you start with the faster motor and always run it slower you are losing power.

X2 pete

 

[Farrier]

I vote for a DC motor from an exercise treadmill w/ controller, or........ buy a bench top gear drive mill/drill.

 

[zkling]

I would use a motor with a base 1725 rpm instead of the higher speed motor you suggested. You can always run the VFD up to 120 hz and get more speed out of it, but if you start with the faster motor and always run it slower you are losing power.

This, go with a 1hp 1725 motor, pretty common.

Or

I vote for a DC motor from an exercise treadmill w/ controller, or........ buy a bench top gear drive mill/drill.

This, although unless you come across a real nice treadmill, it can be a pain to convert the odd sized treadmill motor both shaft size and mounting plate. DC controllers are typically cheaper than VFD's, but are usually dumb and are offset by the typically higher cost of DC over 3ph AC motors.

Nice shop BTW!!!

 

[454ragtop]

As suggested, go with a 1 HP 1725 RPM motor, with the same frame as you have now, and use your current pulley. Done a few of these, they work out well. I usually make a switch box with a pull on push off mushroom switch, a speed pot, and a fwd-rev switch. Much easier than using the keypad.
HTH, Jim

 

[RAMBIN]

I just run my press in its slowest speed, I do a lot of 3/4 and 1" holes in up to 1"plate... I think its around 240 which is even then a bit too fast... when im doing smaller holes or pilots to reach my larger sizes I just run them at that same speed... sure the smaller bits can run faster but how much time are you really saving for a few holes? jmo your going to a lot of work and expense there... another idea would be an adapter for the press to run annular bits... if you really want a better drilling experience!

 

[JunkYardDawg]

I'm subscribed. I want to see where this thread goes. I'm looking at getting a bridgeport, and I want to put a VFD on it. I've been studying up on it, but have made no concrete plans yet.

As suggested, go with a 1 HP 1725 RPM motor, with the same frame as you have now, and use your current pulley. Done a few of these, they work out well. I usually make a switch box with a pull on push off mushroom switch, a speed pot, and a fwd-rev switch. Much easier than using the keypad.
HTH, Jim

Jim, I also want to make a switch box with said fwd/rev/stop/speed controls. My question is: Do all VFDs have the ability for adding remote controls? What should I be looking for when I buy one?

 

[Daveo]

Might be some help here

http://bbs.homeshopmachinist.net/threads/68982-Show-me-your-VFD-remotes!

 

[manwithtools]

All FVD's have remote inputs for start / stop / fwd / rev and speed control.

I will confirm using the slower speed motor (1725) as it can be problematic running an AC motor at the lower end of it's RPM range, not just from a torque prospective but also from a cooling prospective. AC motors rely on a fan (external or internal) to help cool the motor. Prolonged operation at low speeds can lead to over heating. Large HP VFD rated motors sometimes have an auxiliary fan that is run by it's own motor to prevent this problem.

 

[JunkYardDawg]

All FVD's have remote inputs for start / stop / fwd / rev and speed control.

Thanks, Man... with tools.

My next question is: Are the cheapass chinese VFDs any good?

 

[454ragtop]

Thanks, Man... with tools.

My next question is: Are the cheapass chinese VFDs any good?

Have no experience with those Chinese drives, I was thinking of something like this http://dealerselectric.com/JNEV-101-H1.asp
Note the 115 volt input, 230 volt input is available if you'd rather.
HTH, Jim

 

[JunkYardDawg]

Have no experience with those Chinese drives, I was thinking of something like this http://dealerselectric.com/JNEV-101-H1.asp
Note the 115 volt input, 230 volt input is available if you'd rather.
HTH, Jim

That is a decent price. I'd go with 230V if it were me.

 

[454ragtop]

That is a decent price. I'd go with 230V if it were me.

Why? Seems most shops have more 115 volt outlets than 230 volt outlets, so the 115 volt would seem more convenient. These things aren't welders, the 115 volt ones work just as well as the 230 volt.

 

[mtechgunman]

This thread is relevant to me.

I just bought a VFD for my LeBlond 15" lathe yesterday. I've never messed around with them so it should be interesting.

 

[manwithtools]

Thanks, Man... with tools.

My next question is: Are the cheapass chinese VFDs any good?

I'd have no problem with most any that are on the market today. It's likely no matter what you buy it's made in some part of Asia.

If you have 230 volts available I'd use that version as it will be more efficient in the fact that it's not stepping up the voltage, resulting in lower current draw vs the 120 volt units.

Input current on 120 VAC version is 17.9 amps, the 230 VAC version is 10.4 amps.

 

[JunkYardDawg]

^^^This, Jim. ^^^

 

[aosborne]

I converted an older Delta-Rockwell Vari-speed to 3 Phase using a VFD from Automation direct. I replaced the pulleys with the largest and smallest that would fit to give me the maximum torque multiplication, about 3:1, can't recall the exact numbers. I built a small swingarm to hold the entire VFD just to the left of the head. It's at least as ergonomic as the factory system of speed adjustment.
Overall I am very pleased with it, the 6" stroke of an old well built drill press will spoil you. I hate moving the table to drill a center hole, back down to drill, then up again to chamfer. I would do a few things differently if doing it again:

1. When you buy your VFD, read the manual and write in big bold letters "IN" and "OUT" or something similar to make sure you don't hook it up wrong. This will ruin the VFD immediately and my EE friend couldn't fix it.

2. Really think about what speeds you need. I do almost exclusively metalworking, and I'm the right combination of lazy and competent that I will drill a small hole with a cordless drill so the drill press only gets used for large holes. While the speed is adjustable over a large range, the torque drops linearly. I never spin anything at 1000 RPM in the drill press, I'd rather have useable torque down to 20-30 RPM to use holesaws in steel. I've worked as a machinist for a few years and prefer to spin drills a little slower and have them last longer. The speeds you see in handbooks and published by manufacturers are under ideal conditions with rigid machines, consistent materials, held perfectly and published by the folks who want to sell you more tools. The opposite conditions that happen in my shop, in other words. Given the chance to do it again, I'd shoot for about 8:1 or 10:1 reduction with the 1725 RPM motor I have. As you noted, you can use a VFD to go above the speed rated at 60Hz.

3. Start with good iron. You are replacing a substancial number of parts on the machine such that you can consider buying surplus industrial machinery that may not work when you bring it home. This will get you a much better table lifting mechanism, heavier castings which dampen vibration, a longer spindle stroke, possibly a larger spindle than you could buy for similar money and industry standard bearings and other hardware. What do you do when big box store X has a new supplier for this year's drill presses and you need a part from 3 models ago? I wish I had bought a bigger Powermatic, and keep an eye out at HGR Surplus for a deal on a repairable press. There's something special about a well used machine that has a good story to tell.
Good luck, I think you will be happier with the results than with what you have now.

 

[DougWil]

If you are worried about torque and you should be, you need a bigger motor!

You will not have 1hp unless you are running your vfd at 60hz. Anything more or less hz and the hp and torque decline and you are back to moving belts.

I have a Logan 14" lathe that originally came with a Reeves drive (variable V belt sheave diameter) that was missing when I bought the lathe.... cheaply.
Originally a 2hp 220 single phase motor was on it.

I put a 3 phase 5hp 1725rpm motor and a 5hp vfd and 2 step pulleys on both the motor and spindle.
Now anything from 20hz to 120hz has plenty of hogging power.
I have never had to switch to the other belt groove.
When I need more, I use the existing backgear.
Which I do anyways to slow down the speed for up to 1.25" dia drilling in steel.

Anytime I run the motor at lower than 40hz for any length of time, I turn on a auxiliary fan to help cool it.

I am guessing you want a 3hp, but you might get away with a 2hp.
2hp vfds are usually much lower in cost than a 3hp or more.

 

[manwithtools]

If you are worried about torque and you should be, you need a bigger motor!

You will not have 1hp unless you are running your vfd at 60hz. Anything more or less hz and the hp and torque decline and you are back to moving belts.

Not exactly true. Modern motors and drives have constant torque ratings that allow the motor to develop full torque at less than 60hz.

For instance the motor suggested by the OP has a 4:1 constant torque ratio meaning that it will deliver full torque at 25% of base speed, in his case that would be 15hz and 900 rpm - if he uses a 3250 RPM motor. If he was to choose a 1725 motor it would be 450 RPM for full torque. As I mentioned before it's not a great idea to run a motor for extended periods of time at that low speed without auxiliary cooling, but it can be done for short intervals. If the motor is getting hot, adding a fan could help.

I'm not saying it's a bad idea to have more HP, but only within the capability of the equipment to handle it. Having bigger iron is always a good thing if you can find and afford it

 

[DougWil]

Not exactly true. Modern motors and drives have constant torque ratings that allow the motor to develop full torque at less than 60hz.

Well I did my conversion 20 years ago, so I don't know if my set up is considered modern or not.

But with his original motor at 1hp and say 1725 rpm he had X torque at the motor and because of the belt reduction to 450 rpm at the spindle he had about 4 times more torque than at the motor.

So using a 1hp motor and vfd will get him down to the rpm he wants, but with so little torque that it would barely will be able to drill through butter, much less steel.