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Thread: VFD for Old Northfield Jointer Question

  1. #31
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    I am using a hitachi both on the Bridgeport mill and recently on
    a Japanese drill press.

    They are great and with some guidance (thanks, Malcolm!) I wired in push button controls and an e-stop that shuts the machine down ASAP.
    Bumbling forward into the unknown.

  2. #32
    Quote Originally Posted by Terry Therneau View Post
    To answer your question about programming. You follow the manual. I have 3 TECO VFDs and one cheap Ebay one, and for the latter they definitely skimped on hiring someone who could write an understandable English sentence. I never did get the setup completely right on that one: the edge sander starts/stops but quirky speed control. Did the best guessing I could. The TECO manuals are worlds better.
    From the manual you need to do 3 things: a) enter the motor characteristics into the VFD (full load amps mostly), it uses that to protect the motor should you overload it. b. Tell it what you want for final speed (likely 60 HZ), how fast to ramp up at the start and how fast to brake it at the end. A slower start (4-8 sec) is easier wrt current draw, but for a jointer you don't need to worry too much. Too slow and you may be annoyed by waiting for it. Braking at the end is a function of mass, but again no need to get carried away. It is safer for the machine to stop quickly, but if you stop it too fast the VFD will complain about it (or add a braking resistor). My 26" Moak bandsaw has a foot brake, and I set the VFD to freewheel when I stop, those big wheels are just too much mass for the VFD.
    c. Set the VFD up for 2 wire or 3 wire, making sure of course that what you tell it is the way that you wired it. My dust collector is set up for 2 wire. That means that the +12V terminal on the VFD is connected to the FWD terminal via an ordinary light switch. In fact, I have mine on 2, exactly like the two switches at the top & bottom of the stairs for a light bulb. The problem with that is that if power goes out when you are running it, trip a breaker for instance, it will start up again when power returns. Okay for a dust collector, not safe for a saw. Those are set up with 3 wire + two buttons: start and stop. If power goes out, the machine does not restart. (I'm skipping over forward/reverse, which you don't need).
    Wiring has to be controls to VFD, VFD directly to motor. You can't run the VFD as power that then passes through the on/off buttons of your saw. On my bandsaw I did what many do, which is to repurpose the buttons on the saw so that they go to the VFD control terminals. They are, after all, in a handy spot. A bit overly beefy for a tiny 12V control current, but so what.
    Last, be prepared to skip over 9/10s of the instruction manual. There are a dozen parameters about motor waveforms, the shape of the startup curve, etc. etc. There are 2 or 3 more sophisticated ways to wire the start/stop/revers process into digital control circuits. If you don't recognize it, you probably don't need it.

    Terry T
    This may be a stupid question, but after looking around a little at different models, I had a question about AMPs. At 220 volts, the name plate says the AMPs are 10.4. When selecting a VFD, should I match that as closely as possible, or do I just want to make sure The VFD will exceed those AMPs. I have seen some VFDs that say 10 AMPs, some 10.5, and some 12. I assume I wouldn't want to 10 AMP VFD since it is lower than the name plate, but would there be a preference between 10.5 and 12?

  3. #33
    Quote Originally Posted by Larry Feltner View Post
    This may be a stupid question, but after looking around a little at different models, I had a question about AMPs. At 220 volts, the name plate says the AMPs are 10.4. When selecting a VFD, should I match that as closely as possible, or do I just want to make sure The VFD will exceed those AMPs. I have seen some VFDs that say 10 AMPs, some 10.5, and some 12. I assume I wouldn't want to 10 AMP VFD since it is lower than the name plate, but would there be a preference between 10.5 and 12?
    Exceeds. Although, even then, it won't hurt to use a smaller one, because it simply won't produce more than it's supposed to. So if you pick one with a 10.0 amp output, it'll never exceed 10.0 amps, and your motor will get 2.9HP instead of 3.0 (which is certainly not noticeable).

  4. #34
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    Quote Originally Posted by Larry Feltner View Post
    This may be a stupid question, but after looking around a little at different models, I had a question about AMPs. At 220 volts, the name plate says the AMPs are 10.4. When selecting a VFD, should I match that as closely as possible, or do I just want to make sure The VFD will exceed those AMPs. I have seen some VFDs that say 10 AMPs, some 10.5, and some 12. I assume I wouldn't want to 10 AMP VFD since it is lower than the name plate, but would there be a preference between 10.5 and 12?
    You can program the vfd to the amperage rating on the name plate so as long as you meet or exceed the nameplate amperage you will be good. The programing is pretty easy to do especially if you buy a name brand with decent English instructions.

  5. #35
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    I have no idea how Asia does it but Europe reverses the USA usage of decimal point and commas for math.
    What a USA vfd calls 10.5 amps a euro one will say 10,5 amps.

    As far as amps the bigger the better. But as the put out more amps they physically get bigger and may not fit. If you put one inside a enclosure you need extra space for wiring and cooling air flow inside the enclosure as well as some vents to the outside world. Just because you can squeeze it inside. a small box does not mean it will last long if it overheats.
    Bill D
    Last edited by Bill Dufour; 01-12-2022 at 3:38 PM.

  6. #36
    This has been very helpful. I have one other question. Do you typically buy a new on/off switch? If so, what do you look for in a switch and where is a good place to find them?

  7. #37
    Quote Originally Posted by Bill Dufour View Post
    ... Just because you can squeeze it inside. a small box does not mean it will last long if it overheats.
    Bill D
    +1 - The VFD manual should specify the recommended minimum top/side/bottom clearances when installed inside an enclosure. If you vent the enclosure in a dusty environment, it improves the cooling in the short term, but eventual dust buildup will obviate any gains. I'd recommend following the minimum clearances with a 'sealed' enclosure. NEMA 4 should be adequate inside the average pro or home shop (NEMA 1 only protects against 'falling' dirt, not 'blown' ... so you should locate a '1' in a closet, etc.). MY DC VFD is mounted to simple panel in the open, no enclosure, but inside a storage area with the DC.

    Quote Originally Posted by Larry Feltner View Post
    This has been very helpful. I have one other question. Do you typically buy a new on/off switch? If so, what do you look for in a switch and where is a good place to find them?
    You can repurpose your existing operators (pushbuttons/switches) in current locations using the control voltage (typ. 12 or 24V DC) and inputs on the VFD; look in the manual for discussion of "2-wire" & "3-wire" control. You'll have to decide which operators* you have and want to keep, program the VFD to accept this 'scheme', remove the existing DOL starter wiring from the operators, and run new to/from the VFD. The good news is that this new wiring can be very light gauge (20-26 ga?).

    To reiterate something Mr. Friedrichs alluded to earlier (maybe in other thread??), for the sake of this discussion you should never have any interruption or disconnect in the wiring between a VFD and the motor.

    You can run more than 1 motor on a properly sized VFD (all at the same time and all at the same 'Hz'), and you can muti-plex motors' operation off of a single VFD, but the control scheme, programming, and understanding required is well beyond the scope of this discussion (and my typing).

    *- you need to know if the existing operators have normally open and/or normally closed contacts, and are they momentary or maintained.

    Oh, and how many aircraft takeoffs per hour are you expecting on that thing?
    Last edited by Malcolm McLeod; 01-14-2022 at 11:29 AM.

  8. #38
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    Quote Originally Posted by Larry Feltner View Post
    This has been very helpful. I have one other question. Do you typically buy a new on/off switch? If so, what do you look for in a switch and where is a good place to find them?
    All vfds can be controlled with the buttons on the vfd itself. Most brands also offer a option for a external control which just plug in. Usually the external controls for a particular vfd are very easy to install and require little to no programing. If you chose to use the existing buttons or purchase new ones and hook them up to the vfd you will need to do some programming. When hooking up external button it is typically easier to choose ones that are maintained rather the momentary. Maintained simply means a button or switch that latches on. On a older machine I generally like to buy a simple start stop switch with a large stop paddle in case of a emergency. The basic start stop switch can be bought form a woodworking or machinery dealer or website. Other buttons, contacts, switches, and wire I usually buy from automation direct. It is with noting that yout switches or buttons do not need to be rated for 240v or any certain amperage as the vfd handles the actual switching of the line voltage.

  9. #39
    Quote Originally Posted by Malcolm McLeod View Post
    +1 - The VFD manual should specify the recommended minimum top/side/bottom clearances when installed inside an enclosure. If you vent the enclosure in a dusty environment, it improves the cooling in the short term, but eventual dust buildup will obviate any gains. I'd recommend following the minimum clearances with a 'sealed' enclosure. NEMA 4 should be adequate inside the average pro or home shop (NEMA 1 only protects against 'falling' dirt, not 'blown' ... so you should locate a '1' in a closet, etc.). MY DC VFD is mounted to simple panel in the open, no enclosure, but inside a storage area with the DC.



    You can repurpose your existing operators (pushbuttons/switches) in current locations using the control voltage (typ. 12 or 24V DC) and inputs on the VFD; look in the manual for discussion of "2-wire" & "3-wire" control. You'll have to decide which operators* you have and want to keep, program the VFD to accept this 'scheme', remove the existing DOL starter wiring from the operators, and run new to/from the VFD. The good news is that this new wiring can be very light gauge (20-26 ga?).

    To reiterate something Mr. Friedrichs alluded to earlier (maybe in other thread??), for the sake of this discussion you should never have any interruption or disconnect in the wiring between a VFD and the motor.

    You can run more than 1 motor on a properly sized VFD (all at the same time and all at the same 'Hz'), and you can muti-plex motors' operation off of a single VFD, but the control scheme, programming, and understanding required is well beyond the scope of this discussion (and my typing).

    *- you need to know if the existing operators have normally open and/or normally closed contacts, and are they momentary or maintained.

    Oh, and how many aircraft takeoffs per hour are you expecting on that thing?
    It does kind of resemble an air craft carrier, lol.

    How can you determine whether the existing operators have normally open or closed contacts and are momentary or maintained? Will the switch say that somewhere? Are the switches that are on these older machines magnetic or are they simply on/off switches. I'm trying to learn as much as I can by reading a few things here and there, but I'm a fish out of water when it comes to three phase machines.

  10. #40
    If the future brings more 3ph equipment (tablesaw, bandsaw, planer, dust collector) then a rotary phase converter might be a less expensive option. I found a used 10hp rotary phase convertor for $350.

  11. #41
    Quote Originally Posted by Larry Feltner View Post
    ... three phase machines.
    Once you run the 3ph power from supply (1ph?) to VFD to motor, there is virtually no difference in 3ph vs 1ph 'control', or even AC vs DC 'control' - - excepting maybe where & how you source the control power. A direct-on-line (DOL) contactor was probably OEM to your machine, and the contactor used either '2-phase' line supplied 220VAC control power (=no transformer) to the coil, or a transformer to drop it to 120VAC (I suspect it did not use 24VDC controls, but anything is possible in my ignorance).

    If you are switching to a VFD, then the control power will come from the VFD. There is typically a terminal labeled as '24V', 'DC+', 'cntl, or maybe even '5V+'(?) - - depends on the VFD. This terminal provides power out to the switches, and they return what is now a signal to the VFD's inputs. The VFD parameters are set so that a particular input performs a given function - start, stop, etc.. As others have pointed out, you can generally leave 99.5% of the parameters alone. You'll not need them. I'd bet the default parameter for 1 or 2 inputs is already set for start/stop.

    To determine the function of the existing switches:
    Momentary or maintained is easy; just push or twist. Does it stay where you moved it? (=maintained) Does it 'spring' back? (=momentary) Usually a magnetic starter will use momentary for both start & stop functions. E-Stops are always maintained.

    I believe someone (sry - not memorized all) advised the VFD will use maintained (and NO contacts), they are likely correct, but this depends on what VFD is used and how you program it. Be aware this may allow a unit to re-start unattended when you come out of a power failure - - but there is USUALLY a parameter in the program to detect this and prevent re-starts. In my experience this parameter is set to ALLOW restarts as the default.

    Normally Open & Normally Closed - needs a meter, or a good set of eyes. Some contact blocks are clear and you can see if the conductor bar inside is open or closed; the 'normal' part is usually determined by the condition it's in sitting in your hand, not installed. You can also use a meter to measure continuity across the contact block's terminals. And if fairly new (aka readable), you can look up the part number and see NO/NC state.

    As Mr Shiffer points out, many of the better VFDs have a operator module (or HIM::Human interface module) that can be moved, or supplemented with a remote HIM. Some old ones used a simple phone cord (RJ-6?? ...-4?), but most today will use a standard CAT5 Ethernet cable. You can put the HIM convenient to the machine, with the VFD itself squirrelled away in the basement-attic-closet. I might still be tempted to install a E-Stop button - - the HIM's typically tiny membrane 'stop' button might require motor skills to be a bit too finely honed when a lumber launch dictates an abandon ship event.

  12. #42
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    Momentary switch 3 wire control is only one more parameter to program. Keep your existing machine control and just wire the vfd to them.

  13. #43
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    Feel free to ad an extra stop switch near the output end of any machine. This is dead easy to do once you have a stop button wired in. Just add more in series with the first one.
    My lathe has a total of three stop buttons and one master stop button ahead of the VFD.
    Bill D

  14. #44
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    On the two older machines that I reworked recently I went to a modern format with disconnect, push button on/off and E-stop. The hitachi VFD has an emergency stop cycle which rapidly slows the motor and requires resetting before it will start running again.

    If something is going wrong it’s easy to have the ‘punch big red button’ command still functional in your thought process.
    Bumbling forward into the unknown.

  15. #45
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    Quote Originally Posted by Bill Dufour View Post
    Feel free to ad an extra stop switch near the output end of any machine. This is dead easy to do once you have a stop button wired in. Just add more in series with the first one.
    My lathe has a total of three stop buttons and one master stop button ahead of the VFD.
    Bill D

    This is why my table saw has a foot switch. No need to let go in a tricky situation, such as when stopping while the blade is still engaged with the wood

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