VFD conversion and Glad I did

Gentlemen,
I recently got my EE lathe converted to a VFD drive. I changed to a 5hp motor and yaskawa vfd. WOW I am so glad I made the change. I ended up changing out the motor from the original reliance to a 5hp tefc inverter duty baldor, made and adaptor plate and used the original gearbox. The original controls had been removed some time ago and replaced with two ac drives, one for the field and one for the armature, it worked ok but this setup is awesome. If anyone would like model numbers or pictures let me know and I will try to post them. In closing, I would just like to say that if there are any out there that are on the fence about this change, I would say without a doubt, Go for it, you will be happy you did.

Thanks
FredT

Hi Fred,

I did the same with my 10EE some years ago, but with a different brand of VFD.

I agree... It's the only way to go.

- Leigh

I for one would encourage picture posting. Eventually the next generation of machinists will likely need the VFD as the control to keep these fine machines running.

I've got a Hitachi SJ700 (15HP) VFD sitting around so while my 10EE works fine, who knows what the future may bring. Tell me more, please. In fact, show-and-tell, e.g. photos and part numbers would be nice. Drawings, welcome too.

Specifics Please!

jbeech said:

I've got a Hitachi SJ700 (15HP) VFD sitting around so while my 10EE works fine, who knows what the future may bring. Tell me more, please. In fact, show-and-tell, e.g. photos and part numbers would be nice. Drawings, welcome too.

Click to expand...

+1 on these sentiments.

I am currently knee deep in my restore. I want to know how you dealt with the spindle lock solenoid, and the backgear gearshift solenoid. Powered through the VFD...............

Fred T said:

Gentlemen,
I recently got my EE lathe converted to a VFD drive. I changed to a 5hp motor and yaskawa vfd. WOW I am so glad I made the change.

Click to expand...

Fred,
What is the benefit of AC and a VFD vs. DC and tubes or SSD controller?
I'm currently replacing my "mickey mouse" controller that is limited to 1000rpm back to the original tubes and never really considered AC.
Forgive my ignorance, but with a good DC motor in the belly of the lathe, torque and speed are controllable independently and over the entire range from zero to maximum ratings (torque proportional to current supplied, speed proportional to voltage). Why go AC?
Mark

The attached link is a "sticky" at the top of the Monarch forum.
http://www.practicalmachinist.com/vb/monarch-lathes/vfd-conversion-99166/
Since that topic was written, I have had the opportunity with 2 10EE's side by side, one with original Module drive and one with a VFD, to compare the machines. The differences in performance between the 2 drives is so minute, that I have a hard time believing all these superior performance claims of the DC drive. In fact I found that the VFD is the better performer.
Harry

beckley23 said:

The attached link is a "sticky" at the top of the Monarch forum.
http://www.practicalmachinist.com/vb/monarch-lathes/vfd-conversion-99166/
Since that topic was written, I have had the opportunity with 2 10EE's side by side, one with original Module drive and one with a VFD, to compare the machines. The differences in performance between the 2 drives is so minute, that I have a hard time believing all these superior performance claims of the DC drive. In fact I found that the VFD is the better performer.
Harry

Click to expand...

Given that they are very similar. What would be the benefit to converting to AC drive unless the DC motor was bad.

Also, although a DC motor has a continuous horsepower rating, it can deliver and sustain multiples of that horsepower, subject to heat dissipation and mechanical limits. A 3/4 HP DC motor can easily replace a stock AC motor rated 1 to 2 HP and replacing the 5 HP DC motor would likely require a 7.5 to 10 HP AC motor for equivalency.

What size AC motor did you use?

Mark

In response to Aerodark question. The spindle lock has a micro switch, not solenoid, so you can just wire it in series with the control wiring. The backgear does have a solenoid, that blocks shifting while the motor is running, I choose to leave it out of the modification, if I recall it was set to block when no current was applied, and released when current was applied, sort of backwards of the controls with a vfd,so it was not used. In this case no one uses the machine but me, so it is an easy choice.

Toms Wheels said:

In response to Aerodark question. The spindle lock has a micro switch, not solenoid, so you can just wire it in series with the control wiring. The backgear does have a solenoid, that blocks shifting while the motor is running, I choose to leave it out of the modification, if I recall it was set to block when no current was applied, and released when current was applied, sort of backwards of the controls with a vfd,so it was not used. In this case no one uses the machine but me, so it is an easy choice.

Click to expand...

Thanks Tom.

"Given that they are very similar. What would be the benefit to converting to AC drive unless the DC motor was bad."

Given what you are missing from the drive, how much is it going to cost to replace all that stuff? It's not only the motor, there's a whole lot of stuff missing, and you still don't know all that is wrong. My 1st EE was just as bad as yours. I screwed around with it for a year or so, and finally got disgusted and VFD'ed for about a 1000.00 and a bit of machine work. I had already spent close to 2000.00 messing with the DC drive and got no where near acceptable results, that was my tuition.
All this talk about low end torque, is just that, unless you're going to spend all your time in the basement. The only time I had problems with the VFD was in 150 RPM , or less, in direct drive,; then I would switch to backgear and problem solved. Needless to say most of my turning was over 1000 RPM. Even with the gearhead machines I hardly ever got under 300 RPM.

I used a 5HP inverter duty rated motor on the EE.
Think very carefully about the components you're going to use. Somehow, I think there is a lot knee jerk reactions to copy what Monarch is doing. Monarch uses a 7-1/2HP VFD motor, that's what I'm going to use; that is nonsense.

BTW, I'm don't care what drive you use, just study your options, and not just the short term, the long term is more important. Make a considered choice, you may be surprised at what you pick.
Harry