My milling machine is bigger than yours

[nsracing]

Yeap - on the Criterion. Has the silver ring above the body.

[TXHCBeetle]

Those of you who have Burke Millrite's, do you have this tag on your motor? The PO appears to have used a chemical which removed the etched text so I have no idea what any of this means..I mainly want to confirm HP and phase. I'm assuming the 1 and the 3 in the upper right may be 1 hp and 3-phase..

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In Progress:
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[RickS]

[nsracing]

A small mill like that be in the 1hp range - nice if 3phase. Get you a rotary converter and be golden.

I built all mine - rotary converters. They are not hard to build. Enjoy.

[TXHCBeetle]

[Vanapplebomb]

I run my 3phase tools off individual VFDs wired directly to the motor with shielded cable. Then I just control the VFD with the factory switch rewired to the 5 volt inputs. Nice thing is I can use the VFD on my lathe as a brake when I turn it off. Many modern VFDs also can keep the spindle speeds more consistent with varying loads since they can sense current draw. Cheap too. The price of good drives has gone down a ton in the last 10 years.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[jpaull]

[Brian_e]

Here is the tag off our older Miirite. It has a stubby motor like yours. Our slightly newer Millrite has a taller Bridgeport style motor.

New VFD is the way to go for sure. Variable speed, braking, and phase converting in a small box for less than $200.
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www.type-emotorsports.com

[nsracing]

Rotary converters can power higher HP requirements and can support several machines at once. You cannot do that w/ VFDs. For iddy biddy 1 hp -yes VFDs.

I like the rotary coz they are like plows-sturdy. Other than the noise of rotary, I have no preference for VFDs. I like to build the converters in very low RPM motors in the 15-20 HP range. Just a little hum - is fine w/ me.

I run a giant 100gal. 10hp 3 phase compressors and I gotta have the power. Same time running, I use the lathe or mill while the compressor is running.

Rotaries are more expensive but well worth to me.

[oprn]

Rotaries were used to convert single phase to three phase long before VFDs were invented. That was our only option back then.
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[Vanapplebomb]

We have a current project on our shop floor with a 75hp motor driven by a VFD… and even that isn’t a big drive. I have seen them for applications approaching 1000 hp… so, yeah, you can drive just about anything you want with the VFD.

One thing I will say, is be careful with sizing if you want to use it as a motor break. Quickly stoping a motor and rotating mass takes a lot of current. For example, I had to use a 2hp VFD on my 1hp lathe to use it as a brake.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[nsracing]

Rotary converters will power 3-ph machines and act just as intended. If i throw that lathe in reverse at full forward speed, it will reverse. Can a VFD do that?

[Vanapplebomb]

Yes, you have to size it properly though so that it can drive the current required to brake the motor and start it quickly. It’s all about current capacity and acceleration times. Also moving mass is important. Accelerating a larger mass places higher current demands on the drive, so size accordingly.

We stop, start, and reverse motors on a dime with VFDs all the time. In fact, I can’t remember the last machine we built that used 3 phase from the main panel to drive a motor. Even though we have 3 phase in the panel, we drive them with a VFD. 480v 3 phase into the VFD where it is rectified and inverted back to 480 3phase. It sounds redundant, but we get a lot better motor control that way.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[modok]

[Vanapplebomb]

I guess my perspective is a little different because my work is designing/building automation machinery. On the equipment, we frequently use VFDs for safe stoping distance of hazards to the operator. Operator breaks the safety circuit, and that machine has to arrest all movement in a certain number of milliseconds so the machine can’t injure and operator. And these machines can run millions of cycles. No harm to the VFD if you get the right size for the job. In you are undersized, it will let you know, typically by faulting out an over current error.

No VFD is set up ready to go out of the box. It’s a control unit. Treat it as such. You need to program it to have it do what you want. Unless you tell it otherwise, the only thing it will do is on off and forward reverse at an arbitrary acceleration rate.

The VFD on my lathe can brake and start the motor way harder than the belt grips the pulley. If I set the acceleration rate of the VFD too quick, the headstock continues spinning after the motor stops or changes direction. Right now I have the acceleration rate set so that I start/stop/reverse as fast as I can without ever slipping the belt. Works pretty nice.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[jpaull]

[nsracing]

I like powering up my 15HP rotary converter. She hums at about 950 RPM -all day long. I am building an even better rotary - 20HP Westinghouse in 1150 RPM. I have several dozens of unused capacitors still in their packagings..all surplus. Be a shame of nobody finds any use for them in the shop.

Saves me time to just to the machine and turn it on. The VFDs may seem cheaper to start out but if you gotta work w/ several machines I would think they will add up. And can you do repairs on VFDs?

The rotary converters are easy to fix and easy to build. Since the motor is not even loaded by any means -just hums and induce the 3rd coil windings- is all it does. The capacitors do the rest to keep the juice up.

I started out w/ the static converter and quickly did not like it. I went rotary immediately. Never looked back.

[Vanapplebomb]

Yeah, I will agree, static converters are garbage. Never used one that was worth a darn.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[heimlich]

When I bought my machines I bought a rotary converter. It just seemed the better choice. The static modules are tempting because of the price.
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[nsracing]

Also - the static ones will spill all sorts of ruckus in the neighborhood for electrical interference.

Everyone will probably hear all the humming on the radios when you are running your machines.