Static converter or VFD

[wvlongshot]

Unloaded my new to me Supermax mill yesterday. This unit is the vari speed model, so no belt changes in regards to speed needs. I'm thinking a 3ph static conversation will work just fine for my needs. Never been around any of the digital VFDs. Thoughts?

 

[jimcasey01]

I do not have experience with any except the Teco L510. It works flawlessly, but takes a few minutes to program when originally installing. Nothing too difficult.

 

[liljoe]

I have the same vfd as Jim. Took a little bit of time to get the settings to my liking but very happy with it.
There are lots of things that a vfd can do besides just turning it off and on.
I would buy another one tomorrow.
Joe Hynes

 

[butchlambert]

Remember, static convertors deliver about 75% of power. I have a couple VFDs and a couple rotary phase convertors.
I personally wouldn't consider a static.

 

[Westhunder]

Tagging in. Picking up mill this weeks and been doing lots of research. Vfd is great for something thats not already infinitely variable speed from what I can gather. You also usually have to hook it directly to the motor instead of the plug on the machine. Great for a lathe. Ok for a mill in certain circumstances. Rotator phase converter, while initially cost a little more, it extremely simple, and it acts a generator. So if you have a 5hp rotary phase converter, you can start up a 5hp motor and then another machine with let’s say 3hp motor, because both are making power. The only other thing the vfd has that would be a huge plus and one minus is, slowly starting up, building of power bc it’s electronically controlled. Same with cutting off. And the negative is, emergency cut off. Things to consider.


I’ll be watching closely for other thoughts as well

Wes

 

[butchlambert]

Tagging in. Picking up mill this weeks and been doing lots of research. Vfd is great for something thats not already infinitely variable speed from what I can gather. You also usually have to hook it directly to the motor instead of the plug on the machine. Great for a lathe. Ok for a mill in certain circumstances. Rotator phase converter, while initially cost a little more, it extremely simple, and it acts a generator. So if you have a 5hp rotary phase converter, you can start up a 5hp motor and then another machine with let’s say 3hp motor, because both are making power. The only other thing the vfd has that would be a huge plus and one minus is, slowly starting up, building of power bc it’s electronically controlled. Same with cutting off. And the negative is, emergency cut off. Things to consider.


I’ll be watching closely for other thoughts as well

Wes

Wes, I believe in my estimation is the rotary will allow you to run more machines at once on a single convertor. I'm not good enough to operate more than one at a time. The VFDs can be programed and I added braking resistors to allow instant stop without any delay. A great advantage "sometime". Say that you are tapping a blind hole with the tap in the spindle, it is nice to watch the DRO and instantly reverse the motor or just turn the spindle off.

 

[akajun]

Vfd or rotary
Static does not deliver full hp as stated. Vfd is probably your cheapest option
2-3 hp 1ph in to 3ph out can be had from good manufacturers like teco, hitachi, etc for around $200. Wiring on a mill is easier than a lathe.
There’s other advantages like programming speed up and slow down time, remote functions like jog, e stop ,
They are also quiet in that you don’t have a rotary phc making noise or the annoying hum static converters make the motor do.

 

[ronsatspokane]

VFD is the only way to go. They basically rectify and dump the voltage from both legs of single phase input on to a DC bus. The bus feeds an inverter that pulse-width modulates the AC output to the motor. They provide true and very accurate 3 phase output. The output frequency is variable through a broad range which provides speed control. Breaking resisters can be added to most. They also insulate the machine from fluctuations in the input power source and their capacitors provide power for graceful shutdown in the event of an outage. And they are cheap. I'm using an LS brand rated for 3hp to drive a 1960's vintage Kondia mill. Works like a champ. Think I paid $250 bucks for it. The feature set on these VFD's has to be read to be believed. Basic setup is pretty straight forward. Leveraging the more advanced features is... well... advanced. If you want to leverage those features then it may be worth bringing in someone who does machine setup and pay an extra couple hundred bucks to have them do it. Depending on the complexity of the machine you are driving and the electronics already present, you may need to wire it into those electronics. The guy I bought my mill from was replacing it with a Bridgeport clone CNC. Lot of electronics already driving his machine and he had to bring in someone who knew what they were doing to integrate it in.

 

[Westhunder]

Wes, I believe in my estimation is the rotary will allow you to run more machines at once on a single convertor. I'm not good enough to operate more than one at a time. The VFDs can be programed and I added braking resistors to allow instant stop without any delay. A great advantage "sometime". Say that you are tapping a blind hole with the tap in the spindle, it is nice to watch the DRO and instantly reverse the motor or just turn the spindle off.

can you tell me which vfd you used on your milling machine? Are you using the controls on the mill itself for start stop? Or did you order low voltage push buttons that were wired into the vfd. What about spindle wear? Seen some issues raised with this. I would like to keep the adjustment of speed on the head in the typical location. The machine I have promised to buy has a CBC attached to it, but it can be used in dro or feed mode as well. Doesn’t have to be programmed, however it would be nice to make my own programs for some things.

Pic of mill attached

 

[hoz53]

can you tell me which vfd you used on your milling machine? Are you using the controls on the mill itself for start stop? Or did you order low voltage push buttons that were wired into the vfd. What about spindle wear? Seen some issues raised with this. I would like to keep the adjustment of speed on the head in the typical location. The machine I have promised to buy has a CBC attached to it, but it can be used in dro or feed mode as well. Doesn’t have to be programmed, however it would be nice to make my own programs for some things.

Pic of mill attached

isnt the variable speed on a bridgeport like that mechanical-- i think so. i would leave the machine speed on one setting and get a vfd for use as a phase converter, speed contol, and other things u may want like braking.
the vfd can be wired into your existing controls if you want. (unhooking old) a vfd does need to be hooked directly to the motor. anything else you need power for on the mill would need to be wired seperate.

 

[Westhunder]

isnt the variable speed on a bridgeport like that mechanical-- i think so. i would leave the machine speed on one setting and get a vfd for use as a phase converter, speed contol, and other things u may want like braking.
the vfd can be wired into your existing controls if you want. (unhooking old) a vfd does need to be hooked directly to the motor. anything else you need power for on the mill would need to be wired seperate.

I’m a complete greenhorn to electronic controllers and converters..... but what I have read says that leaving the mill in a single speed and using vfd for the control of the spindle is what causes wear in one spot on the spindle. Now this may be after extreme use, like hundreds or thousands of hours, on a sub 100 dollar part. And if that is true, then great, but I have no idea. Which is why I tagged in. Rotary is idiot proof, and I know nothing about this. But I do like the idea of instant stop, cleaner power, slow spin up ( especially since I am converting the power) and slow draw down ( power has to go somewhere)

 

[ronsatspokane]

I’m a complete greenhorn to electronic controllers and converters..... but what I have read says that leaving the mill in a single speed and using vfd for the control of the spindle is what causes wear in one spot on the spindle. Now this may be after extreme use, like hundreds or thousands of hours, on a sub 100 dollar part. And if that is true, then great, but I have no idea. Which is why I tagged in. Rotary is idiot proof, and I know nothing about this. But I do like the idea of instant stop, cleaner power, slow spin up ( especially since I am converting the power) and slow draw down ( power has to go somewhere)

You can still use your mechanical speed control in conjunction with the vfd frequency output. I currently have mine set to 60 Hz but I'm building a control box that the vfd will fit inside. That control box has an external POT to control the frequency (as well as start, E stop, jog, reverse start). I'll wire those in when I get time. When I do that, I'll use both the frequency control and the mechanical. My thought is that I could run the motor at about 80 Hz and use the mechanical to drop the speed when I need some torque to hog out deep pockets. In looking at your mill, I'd be pulling in a pro to wire in the vfd so you maintain all the functionality in the control circuits already present. Your mill is more like the one the guy I bought from replaced it with.

 

[Westhunder]

You can still use your mechanical speed control in conjunction with the vfd frequency output. I currently have mine set to 60 Hz but I'm building a control box that the vfd will fit inside. That control box has an external POT to control the frequency (as well as start, E stop, jog, reverse start). I'll wire those in when I get time. When I do that, I'll use both the frequency control and the mechanical. My thought is that I could run the motor at about 80 Hz and use the mechanical to drop the speed when I need some torque to hog out deep pockets. In looking at your mill, I'd be pulling in a pro to wire in the vfd so you maintain all the functionality in the control circuits already present. Your mill is more like the one the guy I bought from replaced it with.

I think that the prototrax is a separate circuit, single phase 110v. but I am considering getting someone to come and set up the vid. a 10hp rotary phase from a local manufacture in Anderson, SC is only 800 bucks. so I have to way that option too. the clean, true 3 phase power is very convincing on the vid as well as any other little pros with the slow start and immediate stop for tapping and such.

 

[sdean]

I think that the prototrax is a separate circuit, single phase 110v. but I am considering getting someone to come and set up the vid. a 10hp rotary phase from a local manufacture in Anderson, SC is only 800 bucks. so I have to way that option too. the clean, true 3 phase power is very convincing on the vid as well as any other little pros with the slow start and immediate stop for tapping and such.

Not sure about true 3 phase. Put a voltage meter on the output on one and see what it reads. I have one on my S/B lathe and on my Bridgeport. Love them.

 

[Scotty Crawford]

Not saying the static converters are as good as the vfd’s but I’ve been running a shop for almost thirty years. I have run static converter and rotary converters the whole time , I’ve only replaced one static converter in that time period. I did have the bright idea to put the whole shop on one large rotary converter and it worked just fine until that rotary went down and then the whole shop was down, that’s when I went with a static or rotary for each individual machine. Good luck!!

 

[hoz53]

I think that the prototrax is a separate circuit, single phase 110v. but I am considering getting someone to come and set up the vid. a 10hp rotary phase from a local manufacture in Anderson, SC is only 800 bucks. so I have to way that option too. the clean, true 3 phase power is very convincing on the vid as well as any other little pros with the slow start and immediate stop for tapping and such.

yes the DRO would probably need powered seperately and probably the table and knee travel motors and that power draw bar.

 

[Walt Krafft]

A VFD will work for a single motor. If your machine has multiple motors (spindle, coolant, feed) or you have more than one machine, you will still need a source of 3 phase power. I use a rotary converter to create 3 phase for my lathes, mill, and grinder. My lathe has a VFD built in to control the spindle. I have had bad experiences with static converters. I built a box to cover my converter and its hum is barely noticeable.

 

[butchlambert]

I have 2 rotaries and 2 VFDs in my shop. The rotaries are both outside with a little roof over them and beside my compressor. I use a Hitachi and a Mototronics VFD on my 2 step pulley Bridgeports. You need to wire from the VFD directly to the motor and then wire the factory on off reverse switch to the proper terminals on your VFD. I just used bell wire for that. I have breaking resistors on one mill. My DRO and power feed motors are still on their existing voltage.

 

[wvlongshot]

Thanks guys for the info. I just ordered a teco and will give the vfd a try. May be back for further instruction.

 

[akajun]

A VFD will work for a single motor. If your machine has multiple motors (spindle, coolant, feed) or you have more than one machine, you will still need a source of 3 phase power. I use a rotary converter to create 3 phase for my lathes, mill, and grinder. My lathe has a VFD built in to control the spindle. I have had bad experiences with static converters. I built a box to cover my converter and its hum is barely noticeable.

If your machine has two motors your vfd must simply be rated for the sum of the hp. Ie my surface grinder has a 1hp spindle motor and a 1 hp hydraulic motor, ie I needed a 2hp vfd. FYI I ran it on a 1hp vfd for a while and it would randomly trip the overload before I discovered that it was not like a rpc where every motor you run on one actually increases your rpc capacity.