[Noteworthy] VFD & BP Series 1 speed adjustment

There are various iterations on how to use a VFD depending on the system and how it is installed. Most smaller factory installed VFD mills and lathes have 2 mechanical speeds and the motor is used over a 10 fold speed range, usually something like 20-200Hz. The motors are usually oversized, so that the Hp which decreases in a linear fashion below the base speed is sufficient at the lower speeds. They also have an electric blower or are TENV. When you over speed a motor beyond its base speed, the Hp stays flat (up to a point) and you are delivering more Hp to the spindle (when factoring in the mechanical ratio change) then with a fixed frequency motor with a mechanical speed adjustment.

In your situation with a varispeed type of head, your are probably better off using the mechanical adjustment for most of the speed range, also using a fixed mechanical speed would cause uneven wear in one point. What is often done in a mill VFD conversion would be to use a larger (2 or 3Hp) inverter motor and do some form of direct belt drive. With the stock 1 Hp motor you would loose too much Hp using the VFD as your primary adjustment. I also had seen some postings that the Bridgeport pancake motors were a bit more difficult to drive from a VFD stand point, so you may want to go with a 1.5 or 2 Hp VFD, and dial it down to the settings on your motor. The VFD can also provide something on the order of 120-150% overload capacity for up to 1 minute, but this can be a problem for non-inverter motors. There have also been some posting on this site of people using the Lenze or Leeson SMV VFD with good results on this machine. I would set the maximum frequency to something like 75Hz, and use a VFD range of something like 45-75Hz, or use it in a fixed 60 Hz frequency and just use the start/stop and reverse controls.
http://www.globalindustrial.com/p/m...or-series-drive-vfd-nema-1-3ph-1-5hp-200-240v
https://www.wolfautomation.com/esv112n02yxb-ac-drive-1-5hp-208-240vac
 
There are various iterations on how to use a VFD depending on the system and how it is installed. Most smaller factory installed VFD mills and lathes have 2 mechanical speeds and the motor is used over a 10 fold speed range, usually something like 20-200Hz. The motors are usually oversized, so that the Hp which decreases in a linear fashion below the base speed is sufficient at the lower speeds. They also have an electric blower or are TENV. When you over speed a motor beyond its base speed, the Hp stays flat (up to a point) and you are delivering more Hp to the spindle (when factoring in the mechanical ratio change) then with a fixed frequency motor with a mechanical speed adjustment.

In your situation with a varispeed type of head, your are probably better off using the mechanical adjustment for most of the speed range, also using a fixed mechanical speed would cause uneven wear in one point. What is often done in a mill VFD conversion would be to use a larger (2 or 3Hp) inverter motor and do some form of direct belt drive. With the stock 1 Hp motor you would loose too much Hp using the VFD as your primary adjustment. I also had seen some postings that the Bridgeport pancake motors were a bit more difficult to drive from a VFD stand point, so you may want to go with a 1.5 or 2 Hp VFD, and dial it down to the settings on your motor. The VFD can also provide something on the order of 120-150% overload capacity for up to 1 minute, but this can be a problem for non-inverter motors. There have also been some posting on this site of people using the Lenze or Leeson SMV VFD with good results on this machine. I would set the maximum frequency to something like 75Hz, and use a VFD range of something like 45-75Hz, or use it in a fixed 60 Hz frequency and just use the start/stop and reverse controls.
http://www.globalindustrial.com/p/m...or-series-drive-vfd-nema-1-3ph-1-5hp-200-240v
https://www.wolfautomation.com/esv112n02yxb-ac-drive-1-5hp-208-240vac

My VFD is a Lenze 3HP. The motor on my BP is 2HP. I went ahead and bought a VFD that was rated higher than what I had.

I cannot remember who gave me the info, but I drove over to Automation Direct and picked up the start, e-stop, fwd/rev, buttons or switches and have them mounted into a small box. I am now wondering if that wasn't a waste of money ( at least some of it) because if I just use the VFD for "power" for the most part, I don't think I will need everything I bought.

With so many to-do's in the garage getting everything setup, moved around, getting power run etc... I just have not had much time to get out there and really dig in and play with it. Which brings me back to the reason for my post... I want to make sure of what I "need to do" given the type of milling machine I have.
 
It seems to me that a review of the use of VFD's in industry for the intended purpose would tend to shed a lot of light on whats proper and frankly what's not.
The two uses I have seen are fan controls and material handling IE conveyors.

Fans are straight forward. But they are only varied to 30 to 50% on the bottom side and are never setup with the idea of going over 100% speed.

Conveyors and material handling are all configured the same. The VFD runs a gear reduction motor that drives the conveyor or other material handling device like a spin table, auger, or a take up real for cloth.
Again with this you are gear reduced so torque isn't as much a factor. And the speeds are more a product of the gear reduction than the motors ability to vary RPM a great deal.
A lot of this stuff is using 90 to 1 or 128 to 1 reduction. So if you look at the math, 3450 divided by 128 is 27 RPM. Then take the motor to 1000 RPM and you get 3.45 RPM. So the speed change is going to be linear, but if you think cutting tool, it's 25 RPM. It don't matter much in milling and turning.

Thats why it's typically better to use a RPC or run a VFD at a fixed setting and vary the machine through its mechanical means.
 
It seems to me that a review of the use of VFD's in industry for the intended purpose would tend to shed a lot of light on whats proper and frankly what's not.
The two uses I have seen are fan controls and material handling IE conveyors.

Fans are straight forward. But they are only varied to 30 to 50% on the bottom side and are never setup with the idea of going over 100% speed.

Conveyors and material handling are all configured the same. The VFD runs a gear reduction motor that drives the conveyor or other material handling device like a spin table, auger, or a take up real for cloth.
Again with this you are gear reduced so torque isn't as much a factor. And the speeds are more a product of the gear reduction than the motors ability to vary RPM a great deal.
A lot of this stuff is using 90 to 1 or 128 to 1 reduction. So if you look at the math, 3450 divided by 128 is 27 RPM. Then take the motor to 1000 RPM and you get 3.45 RPM. So the speed change is going to be linear, but if you think cutting tool, it's 25 RPM. It don't matter much in milling and turning.

Thats why it's typically better to use a RPC or run a VFD at a fixed setting and vary the machine through its mechanical means.

Great explanation ! The only thing I was stumped on is the abbreviation RPC. What is that? (of course as soon as you type it I will say to myself "oh yeah I knew that") LOL
 
I cannot remember who gave me the info, but I drove over to Automation Direct and picked up the start, e-stop, fwd/rev, buttons or switches and have them mounted into a small box. I am now wondering if that wasn't a waste of money ( at least some of it) because if I just use the VFD for "power" for the most part, I don't think I will need everything I bought.

That would be me :) And yes, you will need those parts unless you are mounting the VFD on the head and operating from the VFD keypad.

As far as speed adjustment, just limit the the Hz range from about 30 to 60. Sometimes it easier to just turn down the VFD for light work like reaming or sometimes tapping. Saves having to adjust the speed on the head when working back and forth between drilling and other operations.

The parts will also be needed when you convert your machine to direct drive.:grin:
 
Great explanation ! The only thing I was stumped on is the abbreviation RPC. What is that? (of course as soon as you type it I will say to myself "oh yeah I knew that") LOL

Rotary Phase Converter
 
That would be me :) And yes, you will need those parts unless you are mounting the VFD on the head and operating from the VFD keypad.

As far as speed adjustment, just limit the the Hz range from about 30 to 60. Sometimes it easier to just turn down the VFD for light work like reaming or sometimes tapping. Saves having to adjust the speed on the head when working back and forth between drilling and other operations.

The parts will also be needed when you convert your machine to direct drive.:grin:

Okay Jim the old noggin is starting to remember now... Thanks for the input!
When you say "direct drive" do you mean leave the VFD for the most part static and just use the BP speed controls?

I don't know why having to use the switches/buttons didn't click in this thread. I was just in the garage with an electrician friend of mine to get a quote to run a 40AMP 220v outlet for my welder, add three new 220v outlets with 3 2-gang 120v outlets next to each of the 220v outlets. I stood right in front of my mill and explained how I have the VFD set up with the switch box.

All I can say is that if it isn't tough enough getting old, the pain meds I have to take are compounding the senility.:idea:
 
Rotary Phase Converter

As I said... Yes I have read very briefly about them... DOH! They are usually kind of expensive compared to a VFD aren't they? Also, don't you lose about 25% of your rated HP using them?
 
All I can say is that if it isn't tough enough getting old, the pain meds I have to take are compounding the senility.
Yup, I hear what you're saying;)

Direct drive means removing the mechanical variable speed hardware, and replace it with fixed pulleys.
http://www.hobby-machinist.com/threads/mill-spindle-direct-drive-conversion.49130/

Also, don't you lose about 25% of your rated HP using them?

No, that's a static phase converter
 
A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.
Img_1921.jpg


I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.
Img_7597_zpscb8b5dd7.jpg


Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

SMV_VectorDrive_1.jpg
 
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