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Leblond Spindle Brake with VFD

Maverick302

Aluminum
Joined
Dec 24, 2018
I am fixing to hook up a 15" Regal to a VFD. I know I can ramp down decel, and/or add a braking resistor, but I would like to know how difficult it would be to hook up the factory spindle brake to work like originally controlled. My thinking is with the varying loads the lathe spindle will see, an electro-mechanical brake has some advantages. It is a DC input, and if my understanding is correct, the power is applied to release the brake, and cut to apply it (like air brakes on commercial vehicles). Is it a simple matter of adding a DC power supply, or using the factory transformer somehow? Would I be best served by just forgetting about it and using the VFD?
 
I am fixing to hook up a 15" Regal to a VFD. I know I can ramp down decel, and/or add a braking resistor, but I would like to know how difficult it would be to hook up the factory spindle brake to work like originally controlled. My thinking is with the varying loads the lathe spindle will see, an electro-mechanical brake has some advantages. It is a DC input, and if my understanding is correct, the power is applied to release the brake, and cut to apply it (like air brakes on commercial vehicles). Is it a simple matter of adding a DC power supply, or using the factory transformer somehow? Would I be best served by just forgetting about it and using the VFD?

Send me an email or dm. Can’t respond at this very moment with specifics but I wired my regal to use the factory Eaton brake via emergency stop button. Works perfectly


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more than one way to do this...

You got three phse input? if so, just place the VFD after the forward reverse contactor and before the spindle. See red box in my leblond servo shift print.

program VFD to start automatically when powered, and coast to stop.

Now you have changed nothing on how the lathe runs except variable speed.
 

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more than one way to do this...

You got three phse input? if so, just place the VFD after the forward reverse contactor and before the spindle. See red box in my leblond servo shift print.

program VFD to start automatically when powered, and coast to stop.

Now you have changed nothing on how the lathe runs except variable speed.


Unfortunately no 3-phase, hence the need for the VFD.

An RPC is an option too but I'd much rather have the VFD and no mechanical brake, than an RPC and factory control.
 
Is your machine still factory wired? Is it a servo shift or manual shift?


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Still factory wired, minus a disconnected coolant pump (no intentions of reconnecting).

Manual shift.
 
Still factory wired, minus a disconnected coolant pump (no intentions of reconnecting).

Manual shift.

Is it a 7.5 hp motor? Is the VFD wired direct to the motor or is it operating as a phase converter for the entire machine?


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It's a 3hp. My intention is to use a VFD to run the motor. It's currently in it's factory state, ready to be moved into place and wired up.
 
We'd best see a print of your wiring.

This will take a bit of re-wiring, assuming you want to use the same forward, off, reverse, brake control lever.

The concept, in general, put Forwad,reverse, and brake on low voltage inputs to VFD. BE CAREFUL not to give the VFD inputs hi voltage or you'll let all the smoke out. Remove the old forward reverse contactor set. Put single phase input on L1 and L2 of VFD, three output wires direct to spindle.

the forward and reverse inputs can easlily be programmed to run the lathe F and R.

The brake input can be programmed to fire the output relay on the VFD - be sure your VFD selection has this option. Use this relay to energize the brake.

there are other ways to do this, i'm sure.
 
Yep, wiring diagram would be helpful.

If no wiring diagram, what year is the machine?


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Unfortunately I haven’t been able to locate a wiring diagram. It’s a 50-60’s era machine. I’ll do my best to get more info.

Power switch to vfd, and relay output makes sense. But what then? DC power source?
 
Unfortunately I haven’t been able to locate a wiring diagram. It’s a 50-60’s era machine. I’ll do my best to get more info.

Power switch to vfd, and relay output makes sense. But what then? DC power source?

Call Leblond with the serial number in hand, they will be able to tell you what year the machine is, may be able to email you a manual. I can't remember if I paid for a hard copy on mine or not, but Leblond supplied me with one.

Can you post a pic of the machine, front & then one of the rear with electrical box opened up?
 
Unfortunately I haven’t been able to locate a wiring diagram. It’s a 50-60’s era machine. I’ll do my best to get more info.

Power switch to vfd, and relay output makes sense. But what then? DC power source?

That needs a print or an electrician to test what you got.
 
The brake is not a fail safe or normal on,it needs to be energised to brake unless someone changed it to a spring or magnet applied brake.
Ours is a Warner 90v dc and has a small rectifier for supply.
 
The Drive you are using should have a programmable relay output. Just wire a properly sized relay through those contacts that will energize the brake when you stop. Program the relay output of the drive to energize when running. Connect the brake Power probably 90vdc through the normally closed contacts of the relay and the relay contacts will open when the drive is running and close when the drive is stopped.
 
If you HAVE the Warner brake, you'll want to retain it, even service it. Not hard.

VFD's don't stop as fast, even with braking resistors.

Most especially if the "emergency" is associated with a mains power outage leaving them brain-dead as well as - literally - "powerless to act"!

:(

Follow the advice you are getting from those who have done it and nothing especially clever needs to be done with the VFD.
 
If we haven't scared maverick off, thermite brings up a good point. that brake should work even if the VFD dies.

Two ASSUMPTIONS here.
1. the "brake on" is one of four positions on your Forward/off/Brake/reverse lever.
2. brake is a warner style as discussed a couple posts up.

If correct, just set up brake so it always runs when in "brake" position. Don't run it to VFD.


Now your VFD set up is simple. I would suggest a brake resistor so it will stop reasonably fast if shifted to neutral.

I know this can seem overwhelming to somebody that has never done this sort of work before.
 
Ok it's starting to make a little more sense - I have the VFD and braking resistor, and intend to do as described and have it stop at a reasonable rate in neutral. So ultimately I just need a DC power supply, and hook it up to use the drum switch middle position to power/activate the brake?

Thanks to everyone for the help so far. I haven't had a chance to touch the lathe yet this week but I hope there is a tag on the brake with electrical specs.
 
Ok it's starting to make a little more sense - I have the VFD and braking resistor, and intend to do as described and have it stop at a reasonable rate in neutral. So ultimately I just need a DC power supply, and hook it up to use the drum switch middle position to power/activate the brake?

Thanks to everyone for the help so far. I haven't had a chance to touch the lathe yet this week but I hope there is a tag on the brake with electrical specs.

The brake actuator is just an electromagnet that moves a plate. Springs apply the brake. The electromagnet releases it. Which sound bass-ackwards but is the reason it is "fail safe".

As happens, 90 VDC is what results when 120 VAC line power is rectified. You need no transformer, regulator, or anything else "special" to produce it.

Store-bought packaged PSU are plentiful. Money may be less-so.

Lots of info is published, if DIY is on your dance-card. Here's but one example of many:

Suppression circuits for clutches and brakes | Machine Design

In the most bare-bones form, a packaged full-wave bridge rectifier at mebbe $3.00 to $6.00 is all the "power supply" you need. Spikes off coil inductance with a 90 VDC supply can hit close to 500 V, so I use 1000 PIV ones.

DC likes to make arcs always, not just once in a while when the sine wave dice-roll hits it at the highest current. Supressor add-ons will extend life of rectifier and brake as well.

Protecting the switch is easier. Put the ON/OFF switch on the 120 VAC input side. It will last much longer than if on the 90 DC output side.

Also only an example for DIY as just about EVERYBODY has these:

Skycraft - BRIDGE RECTIFIER 50A 1000V

Heat-sink it to available metal or provide some metal for it.

It will hum at 120 Hz when RUNNING the machine, be silent when stopped. Considering where it is, that probably won't bother you, if even it is to be heard much at all over all-else as is going on when running.

The store-bought PSU?

This may not be the correct one - you can look that up - just used as an example:

Warner Electric Power Supply MCS-805-1 / MCS-805-2 - Warner Electric Parts

Good as such things go, but more capability ("soft" braking, etc.) than you really need.

Do some research before spending coin. Helluva range between five bucks and $300!
 
The brake actuator is just an electromagnet that moves a plate. Springs apply the brake. The electromagnet releases it. Which sound bass-ackwards but is the reason it is "fail safe".

As happens, 90 VDC is what results when 120 VAC line power is rectified. You need no transformer, regulator, or anything else "special" to produce it.

A packaged full-wave bridge rectifier at mebbe $3.00 to $6.00 is all the "power supply" you need.

Put the ON/OFF switch on the 120 VAC input side. It will last much longer than if on the 90 DC output side.

DC likes to make arcs always, not just once and a while when the sine wave dice-roll hits it at the highest current.

Just about EVERYBODY has these:

Skycraft - BRIDGE RECTIFIER 50A 1000V

Heat-sink it to available metal or provide some metal for it.

It will hum at 120 Hz when RUNNING the machine, be silent when stopped. Considering where it is, that probably won't bother you, if even it is to be heard much at all over all-else as is going on when running.

Ok, let me see if I got this straight...

Ignoring any VFD wiring, I would wire 120VAC to the drum switch input, and the output (closed circuit when in middle position) would go to the brake, with the rectifier in line? So when the switch is in any other position, no power would be applied, and the brake would be free? Or do I have that backward, and the circuit would be open when the brake is applied, therefore powered while running, and dead when the switch is in the brake position?
 








 
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