View Full Version : Swapping out motors

11-07-2013, 10:51 AM
First off what a great looking site. Thanks for having me. I'm looking forward to reading past posts and adding whatever info my pee brain can contribute.
Now to the meat of the post. I have a Delta 17-600 and want to swap out the 3 ph 1140 rpm motor with a LN203 frame itch something more friendly in a home shop. Can use 220v would like a variable 1725 rpm motor. I have considered using a VFD but have concerns as to wether or not this is the best viable and efficient way to adapt the motor or if there are other motors ,pulley adapters and other frames that can be used on the press. I hope I have asked enough questions to provide an adequate answer.
Thank Jim

11-07-2013, 11:00 AM
- what's a Delta 17-600?
- where are you located (please fill in your profile)?

11-07-2013, 11:13 AM
I have a few of those 3 phase Deltal motors off their 17" drill presses.
I run them from a VFD. They run so sweet and smooth, with good
balance at all speeds. I would not swap them out for single phase
garbage. Single phase motors will vibrate (not from physical imbalance,
but from the drone harmonics for the 90deg phase shift that malkes single
phase motors run). And the quality of newer motors is not as good in general.
The switch from 1200 rpm to 1800 rpm means you loose troque (bad) and
gain speed (on a drill press, also bad). The choice is yours, but it seems to
me like a downgrade to me.


Forrest Addy
11-07-2013, 11:31 AM
Keep your 1140 RPM motor unless you need greater speed. The original 3 phase motor will work fine from a VFD. I can hardly think of a better application for a VFD than on a drill press. A VFD controlled by a foot switch is a power tapping fool.

A VFD once set up is easy to use and trouble-free. Single phase input VFD's are universally available in 3HP and below. Scrounged three phase input VFD's are usable if you understand a few limitations.

One limitation is induction motors are constant torque devices so the HP halves with the RPM. You will still need the stepped mechanical reduction for capacity operation at lower speeds. For light loads you can dial the speed down. If you wish to hole saw or run large Forstner style bits shift the mechanical drive to lower speeds THEN dial down the VFD if necessary.

I used to have 7 machine tool powered from VFD's. They ran trouble free and many were run to capacity. Now I have 4 machine tools on VFD's and one is nearly 20 years old, still going strong.

11-07-2013, 12:14 PM
Thanks for the reply. Which VFD would you recommend ?

11-07-2013, 12:26 PM
Thanks for the reply. Which VFD would you recommend ?

Ok more details about the motor. It's a Robbins & Meyers 3/4 hp 3 ph 220/440v 1140 rpm motor on a LN 203 frame. Which VFD are recommend model #'s and manufacturers would be appreciated. Thanks Jim

11-07-2013, 01:21 PM
A good source for VFD's is automationdirect.com. They are a full fledged industrial electrical supplier with their own house brand VFD. Tech support is excellent if you need it. My first choice would be a GS3-21P0. Second choice would be GS2-11P0. The advantage of the GS3 is it's sensorless vector mode which give increased torque at low speeds versus the standard V/F mode of the GS2. Either one will work on a drill press. Belt position changes will rarely be needed unless you are running a big hole saw of some such.


11-07-2013, 01:22 PM
Ok more details about the motor. It's a Robbins & Meyers 3/4 hp 3 ph 220/440v 1140 rpm motor on a LN 203 frame. Which VFD are recommend model #'s and manufacturers would be appreciated. Thanks Jim

Heck I thought you were talking about a Delta brand motor.
Robbins n Meyers? Do you post from England??


11-07-2013, 01:30 PM
Electrical help is meaningless unless we all know where you are from.

11-07-2013, 01:50 PM
I agree with those that say keep the motor and use either a VFD or a rotary phase converter. I made the mistake of swapping pout a 1 1/2 hp 440/220 three phase 2 speed motor with a 1 1/2 hp 220/110 single phase single speed motor. I still have all the higher range speeds on the (Jet) drilling/tapping machine, but it no longer can be run at the lower speeds (down to 60 rpm) I need for drilling or tapping large holes.

The original motor is long gone, but If I ever run across another one I'll swap it back in a minute. All the features that made the machine unique are gone for now. It used to drill to a mechanically preset depth at a preselected faster motor speed, slow to a preselected tapping speed and continue to tap to a mechanically preset depth. Then reverse itself at the low speed and back out to the start of the tapping speed and shut itself off.

All the fancy electronics and mechanical stops are now useless. It's just another drill press with a speed range of 300 to 1800 rpm

11-07-2013, 02:25 PM
Not 100% related but...
At work we had a Bridgeport type mill with
a 2 speed motor. It was very handy to use
high and low, and direct and back gear, and
you rarely had to shift the belt. It was super
If you have a VFD, well cat's ass for sure, just
touting how nice more speeds are.


11-07-2013, 02:26 PM
Thanks just what I needed to make up my mind . I hate changing things out. In many instances you find yourself changing and spending more money then if you had in just going out and buying a new press . Thanks everyone cudo's to the group. btw I'm in NW Ohio will update profile soon.

Mike Nash
11-07-2013, 08:30 PM
Electrical help is meaningless unless we all know where you are from.

You keep harping about this :), but then you hide behind a handle. Those of us using real names are quite a bit at risk exposing our locations and then posting pictures of all our great tools. But the real name usage helps some of us keep our posts on a more polite and even keel :) (Yeah, yeah, "crazydog" is unlikely to be his/her given name, but you never know anymore!)

I'm not saying you aren't on an even keel, BTW, but I really do like to have that reminder for myself before posting. I am on another forum that I felt obligated to post my location, so I keep mum about my stuff there for fear of enticing anyone to come shop for their HF goodies at my house ;)

Sentences with italicized words are intended to be tongue in cheek humorous in this post!

11-07-2013, 08:42 PM
A state or even a county all we need. What's the point of asking or trying to give any electrical help (but I said that already) when you don't even know which continent the poster is from? If you don't want to give a "location", say where the heck you are from in the post, particularly if you are a newbie.

I use my "real name" as email, so only partly "hidden".

J Tiers
11-07-2013, 09:36 PM
Further to that..... to make it very very clear.....

If you are US, or Canada, we know you probably have 60Hz, 120/240V service.

If you are elsewhere, you might have anything, but probably 230V/50Hz. Could be anything from 100 to 240V, and either 50 OR 60 Hz outside the US.

Inside the US you will have the US NEC..............Outside, you will have "something else" as your standard for electrical installations.

These things make a difference.

11-08-2013, 06:58 AM
yep you make a good point about stateside 50/60 hz duty cycle . Some you obsessing about location ( I do have other things to do then just filling in profiles , give people a chance to get use to the site PLEASE . just saying) should have noticed that I had updated my location around 3:00 P.M yesterday . all some of you had to say was what cycle .