VFD Confusion for my Bridgeport
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  1. #1
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    Default VFD Confusion for my Bridgeport

    I've been reading on here for a long time, but have had my Bridgeport sitting without power since I got it in July. I'm no closer to knowing what VFD I should get than I was when shopping for the mill. Lately, I'm reading about sensorless vector, flux vectors, open vs closed loop (but all are closed...or something). I'm not an electrician, just a gunsmith. I'm trying to avoid blindly ordering something and seeing if my electrician can hook it up while hoping not to damage the machine. I could really use a Barney-style, simplified suggestion as to what to focus on. I thought I was going to order a Mitsubishi 2HP, 230V single phase input, 3 phase output, until all these other things came up. Gunsmithing is the purpose, so the workload is pretty light. Thanks.



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    I gather you're going this route, since you don't have a 3-phase supply. If this is the case, there is no reason to get a 2 hp drive with a 1 hp motor, unless you plan on upgrading your motor in the future, you will just be paying more without any benefit. i.e. you will have to limit the output current so you don't burn out your motor. Y

    You can ignore most, if not all, the advanced features. You need a single phase input 120 or 240, whatever you have available in your shop and a 3 phase output, rated to your motor... 1 hp @ 3.5 amps. That's the basic part. The control wiring is the only advanced part you need the electrician to deal with.

    I have a Leeson on my bridgeport and a TECO Westinghouse on my lathe. The contol wiring was a little weird on the TECO, but I emailed them and they told.me how to configure it to the existing machine controls. The Leeson was way more straightforward for the Bridgeport wiring. It was pretty much plug and chug.

    Hope that helps...


    J.

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    That is a great help! Thank you!

    I was only looking at a 2hp for the potential to run a surface grinder at some point, too. No reason I couldn't get a second VFD when/if I get the surface grinder.

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    Quote Originally Posted by MRC2014 View Post
    That is a great help! Thank you!

    I was only looking at a 2hp for the potential to run a surface grinder at some point, too. No reason I couldn't get a second VFD when/if I get the surface grinder.
    You'll want each machine to be on its own VFD.

    You don't need to get into closed loop unless you really want to monitor the motor RPM, but then you'd need an encoder and other stuff.

    A basic VFD with phase conversion would do it. Call a local motor shop and tell them what you need to do, they should be able to quote you something. Internet prices will be cheaper if you know what you want.

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    Quote Originally Posted by bloomautomatic View Post
    You'll want each machine to be on its own VFD.
    Damn skippy! You will run into current overload or underload by sharing a single drive between machines, unless they are all the same horsepower/currnt rating and even then it's not advisable.

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    Quote Originally Posted by Jarrod View Post
    Damn skippy! You will run into current overload or underload by sharing a single drive between machines, unless they are all the same horsepower/currnt rating and even then it's not advisable.
    As has been pointed out recently in another thread,
    If you plan to do power tapping you might want a VFD
    That has enough braking resistance to stop the spindle
    And reverse quickly. Not sure how to calculate that but
    Shortening the deceleration time on mine is on the
    List of things to do.

    Otherwise nothing special required.

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    There are several VFD experts that frequent the VFD forum: https://www.practicalmachinist.com/v...rters-and-vfd/

    They often recommend Hitachi WJ200 as well as Teco E510 (not L510) and Yaskawa V1000 drives. There are several other good drives but those seem to be mentioned the most.

    I have 2 of these: WJ200-007SF | Hitachi Drives | AC Drives

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    Quote Originally Posted by Brandenberger View Post
    As has been pointed out recently in another thread,
    If you plan to do power tapping you might want a VFD
    That has enough braking resistance to stop the spindle
    And reverse quickly. Not sure how to calculate that but
    Shortening the deceleration time on mine is on the
    List of things to do.

    Otherwise nothing special required.
    I've seen youtube videos about power tapping where they didn't even have a VFD. They just slowed the speed way down and hit reverse when needed:

    YouTube

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    Quote Originally Posted by ptsmith View Post
    I've seen youtube videos about power tapping .....
    SOP on a B-port running off of line power. This is how you tap on a B-port. Hit that switch at the right time in a blind hole..

    A VFD on the electric making side won't like the standard B-port FWD/REV switch being flipped.
    You have to do the control though the VFD's inputs and switches/buttons. And then, acc/dec settings and then somewhere for the power to dump. All that gets messy.

    I think one could "share" a VFD among a few machines as long as only one is running/connected at a time. Stored settings would have to sort of be a compromise.

    The process of just reading though a VFD manual and setting it up can be a long slog if you want to do instant reverse under load or drive more than one machine.
    I know that for some here it's easy, for mere mortals all kinds of what the heck does all this mean.

    Before I scare the OP which is not the intention...... straight forward VFD power to your machine for your use is not hard at all and in most drives you can get away with bloody murder.
    It's not plug and play but it is close.

    If you buy a new drive they come set normal and robust. If you buy a used drive you have to sort out what settings are in it and you have to go through them all.
    Bob

    (2 cents worth from a semi-rookie, others here know this like the back of their hand and can likely quote parameter numbers and settings off the top of their head.)

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    Quote Originally Posted by CarbideBob View Post
    SOP on a B-port running off of line power. This is how you tap on a B-port. Hit that switch at the right time in a blind hole..

    A VFD on the electric making side won't like the standard B-port FWD/REV switch being flipped.
    You have to do the control though the VFD's inputs and switches/buttons. And then, acc/dec settings and then somewhere for the power to dump. All that gets messy.
    This dawned on me on the way to get something to eat (which I'm eating as I type). I assume a VFD can't instantly switch two legs of the 3 phase like a Bridgeport switch. It has to go through the normal dec/acc times that it's programmed for. So Brandenberger is correct. One would need an external brake resistor to allow acc/dec settings fast enough to power tap.

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    Just a couple of comments (I think we have touched already most everything essential, otherwise)

    1) Sharing a VFD between machines: I second the general feeling that it is better to have dedicated VFDs and, if sharing, not only the motors should be equivalent, but the "mechanics" of the two or more machines should be very similar. As pointed out, it would be extremely handy to have instant braking on a mill for power-tapping. If you plug a surface grinder (or even a lathe with threaded spindle) on the same VFD, life could become very exciting, with grinding wheels and chucks unscrewing themselves when you stop or, even worse, you do an accidental instant reverse.

    2) Instant reversing is fairly demanding on the VFD. An external power resistor is a must. Given that you need that kind of braking only with emergency stop and power-tapping, and given that most VFD allow you to set different braking values for regular stop, emergency stop and jog function, I'd suggest to use the jog function for power tapping: you put in forward, push the jog button and release it when the tap is at the depth you want, flip the selector to reverse, and push your jog button again (or start the motor with the regular start button, since you don't care if the spindle keeps spinning when the tap is out).

    3) I find VFDs extremely useful on lathes and grinders, a bit less useful on milling machines. Especially if you have/plan to have more 3 phase machines, you might consider investing in a decent rotary phase converter (RPC) instead. Or, if your second 3 PH machine is/will be a surface grinder with a motor larger than your BP, you might spec out the VFD for the spindle of the grinder. For now you can use it on the mill and, when it comes the time to power up your grinder, you can evaluate how many times you have adjusted the frequency on the mill and decide if to buy a second VFD (for the mill) or a RPC.

    4) As mentioned, VFD do not like any switch downstream and, except for special conditions (e.g. conveyor belts of similar load run by identical motors), they cannot run multiple motors at once.
    For instance, in the case of a surface grinder, it's common to have a second motor for the feeds and a third one for the coolant pump. You would therefore need a VFD for each motor. The spindle motor is the one that would profit best to be driven by a VFD (e.g. slow ramp-up curve, limited braking, speed control, etc.) whereas the other two could run at constant speed (perhaps, depending on the design of your grinder, also the feeds motor could profit of a speed control). Therefore, having a combination of RPC and VFDs would be the best (and RPCs, contrary to VFDs, work better the more motors they run at a given time-within their load capacity, of course!).

    Paolo

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    Quote Originally Posted by Paolo_MD View Post
    4) As mentioned, VFD do not like any switch downstream and, except for special conditions (e.g. conveyor belts of similar load run by identical motors), they cannot run multiple motors at once.
    For instance, in the case of a surface grinder, it's common to have a second motor for the feeds and a third one for the coolant pump. You would therefore need a VFD for each motor. The spindle motor is the one that would profit best to be driven by a VFD (e.g. slow ramp-up curve, limited braking, speed control, etc.) whereas the other two could run at constant speed (perhaps, depending on the design of your grinder, also the feeds motor could profit of a speed control). Therefore, having a combination of RPC and VFDs would be the best (and RPCs, contrary to VFDs, work better the more motors they run at a given time-within their load capacity, of course!).

    Paolo
    I've run 3 motors off 1 VFD simultaneously for about 9 years now with no ill effect. Blade, coolant, and hydraulics on a large-ish h-band, and the combined HP ratings exceeds the capacity of the drive. But I don't push the saw very hard, so it works. It does have its downsides, like not being able to raise the arm without the blade moving.

    As far as power tapping- IMO, instant reverse is nice but not required and neither are braking resistors. One can set the VFD to coast to stop and use the hand brake, or set the VFD to ramp to a stop and turn it off a little sooner knowing it will take 1.5s for it to stop.

    Lots of ways to skin this cat.

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    I have a Jet 20" Drill press that came with a Delta VFD. It has a tapping feature that works fairly well but not as quick as my 3 phase powered Bridgeport. It's not instantaneous but does get the job done. I really like the drill press but it came with a large mortgage.

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    I don't recall ever modifying the factory setting of my Leeson drive, except maybe the accel, because I'm impatient, but I can tell you I haven't had any issue power tapping on my BP. The Leeson's control uses the BP's drum switch. This was one of about four or five wiring options, for the control block.

    I let the tap rotaion nearly stop before switching to reverse it out... did 48 holes without issue.

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    If your plan is to run multiple machines on a single power source consider a RPC. If you have access to an electric motor you can put together RPC reasonably cheap. On my BP I have been running it using a VFD for several years, and it works good. There are several benefits to the VFD, being able to control the speed though the touch panel. It allows you to drop the spindle rpm to warm it up. Using the touch panel for fwd - rev is a simple sequence. Mine is WJ200, it power off 110v 20a circuit. I even tap using the touch panel just holding the tap with my drill chuck.

    RPC is run off 220v 40a circuit, that runs HLV-V and surface grinder.

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    Yup, get a rotary and some ear plugs, good ones are bulletproof, no settings to worry about.

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    Quote Originally Posted by Jarrod View Post
    ,...
    I let the tap rotation nearly stop before switching to reverse it out... did 48 holes without issue.
    How many revs and are these blind holes?
    Though tap holes do not count.
    Bob


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