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Need a new motor for South Bend

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  • YukonHam
    replied
    Maybe I've been away from motors / controllers too long - I was thinking someone might consider recommending a permanent magnet DC motor and drive as a (slightly) less complicated way for the the OP to get continuously variable speed control and dead simple reversing.

    Before passing them to me, my father converted an SB 9, a Logan 9, a small vertical mill and 2 sizes of bench-top drill press all to DC motor/drive. For a not too capable/experienced hobbyist like myself, the continuous variability saves all kinds of crashes and disasters.

    A cursory search suggests places like Nebraska Surplus (and others) have fractional hp DC motors and drives for prices not too different from 3 phase. Still have to do a bit of moving belts from pulley to pulley if the required RPMs are significantly spaced - such moving from a 3" hole saw in the drill press to a 1/32 drill - but the middle ranges do most things for me, most of the time.

    Is DC out of favour for some reason I am overlooking?

    Leave a comment:


  • PStechPaul
    replied
    The closer I looked at that home-made circuit, the worse it looked.

    Once a single phase induction motor gets up to speed, it might be able to run without the auxiliary winding, although probably at much reduced torque. And it would need a spin to get started.

    Capacitor start and capacitor run (PSC) motors depend on having a specific frequency and voltage to operate properly, although a range of perhaps 45-65 Hz might work. With a proper V/Hz VFD, a wider range should be possible, but the fixed capacitor size is a problem. It should be possible to program a custom designed VFD to provide the appropriate voltage and phase shift for the third winding over a range of frequencies.

    Leave a comment:


  • Tincamp01
    replied
    Those wiring diagrams are way over my head right now.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Doozer View Post

    Mind blown.
    But everyone makes the (their) world go round.

    -D
    No reason to have your mind blown.... I knew I wanted more 3 phase machines, and it was an easy cheap way to do it. Arco RPC, for maybe a hundred bucks from a guy who replaced it with a bigger one, motor from Surplus Center $50, and all done.

    If I ever decide I really need variable speed, I will put a VFD on that machine. So far it is not worth the work, so I have not.

    Leave a comment:


  • Wirecutter
    replied
    Originally posted by J Tiers View Post

    What evidence of stress and wear did you observe?
    Bent motor brackets. My 10K has the motor under the lathe headstock in the cabinet. Perhaps I should have taken some photos, but I didn't. It was just obvious that the sudden start of the relay-controlled motor arrangement was hard on the mechanism. Anyway, the soft start/stop imposed by the VFD is obvious on the lathe and on the Bridgeport. Ah, and the speed control using the VFD means that I don't have to change the step pullies as much on either the 10K or the Bridgeport. (Both are step-pully machines.) Anyway, IMHO the usefulness of the VFD and 3-phase motor is well worth the extra $$. Does anyone run a Bridgeport on a single phase motor? My South Bend 9C had a single phase motor, but the Bridgeport and the 10K both have 3-phase)
    -Mark

    Leave a comment:


  • Doozer
    replied
    Originally posted by J Tiers View Post
    ... I converted a single phase machine to 3 phase, and put in an RPC.... because it was a lot better as 3 phase. .
    Mind blown.
    But everyone makes the (their) world go round.

    -D

    Leave a comment:


  • Bob Engelhardt
    replied
    Originally posted by PStechPaul View Post
    Here is a project for building a single phase VFD, although I think it would be much better to use a PIC:

    https://www.homemade-circuits.com/si...equency-drive/
    Use at your own risk: "I have not tested it yet, but everything looks correct to me in the design…" (the designer)

    Here is a company that sells single phase input and output VFDs from 1/2 HP to 10 HP:

    https://www.ato.com/single-phase-vfd
    What!?! There goes a central tenet of my understanding of single phase motors: they cannot be operated very far outside their native frequency. I always believed that there was something inherent in their design that made them unsuitable for VFD use. That they overheated and/or lost power and/or something or other. What's the real story?

    Does this mean that all those conversions that I made to 3-phase motors were unnecessary & I could have just used single-phase output VFD's?

    BTW - those VFD's are 220v output.

    Leave a comment:


  • PStechPaul
    replied
    Here is a project for building a single phase VFD, although I think it would be much better to use a PIC:

    https://www.homemade-circuits.com/si...equency-drive/

    Here is a company that sells single phase input and output VFDs from 1/2 HP to 10 HP:

    https://www.ato.com/single-phase-vfd

    Leave a comment:


  • CalM
    replied
    Originally posted by RB211 View Post

    The speed control on those if you want to interface to them, sends line voltage on the wires to the pot. You need to isolate it for CNC control. Maybe not an issue for this. Buy then from Amazon, they sometimes come with a bad speed control.
    There is no speed control with a single phase induction motor. That is what the step pulley in the head stock is for.

    A 3ph clutch motor driven by a VFD would be cat's meow.

    Myself, I would take the clutch motor over the variable Frequency drive in a South Bend application.

    Leave a comment:


  • RB211
    replied
    Originally posted by CalM View Post
    The speed control on those if you want to interface to them, sends line voltage on the wires to the pot. You need to isolate it for CNC control. Maybe not an issue for this. Buy then from Amazon, they sometimes come with a bad speed control.

    Leave a comment:


  • CalM
    replied
    Originally posted by JRouche View Post

    Hahaa. I have no doubt you know what you are doing.. Sewing machine motor? I wouldnt. I think they are ac/dc motors also, no torque really.. That big gallon sized motor you have is probably a legit US motor with legit HP rate. Id stay in that lane. Let us know. Id like to hear if you go VFD. I would like to on mine but my single phase works still. JR
    Jees'em Get with it

    https://www.consew.com/View/Consew-Clutch-Motors

    Leave a comment:


  • RB211
    replied
    Only reason I have an RPC was for the 10EE. Going to gut the old system and put a big servo spindle drive in it. Only my surface grinder uses the RPC. That should have a VFD on it as well

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Doozer View Post

    The discussion is replacing a SB lathe motor.
    It was submitted that a 3ph motor and a VFD
    offered numerous advantages over 1ph.
    No one is considering converting the SB lathe
    to 3ph and then running an RPC. That's crazy.
    Just another opportunity for you to talk about
    how great you think RPCs are ? ? ? ? ? ? ? ?

    -D

    Well, Doozie-boy, so far, 17 of the 40 the posts (including yours) have mentioned and generally recommended using VFD and 3 phase. Posts 2, 4, 6, 7, 9, 10, 11, 15, 16, 19, 20, 22, 23, 36, 40, 47, and 49.

    Now, perhaps you disagree, but an idea that has come up, with enthusiastic recommendations, in almost half the posts in the thread, seems pretty damn relevant. It needed some clarification as to what ways it can be done.

    BTW, 3 phase is 200% better, whether done with a VFD or an RPC. I converted a single phase machine to 3 phase, and put in an RPC.... because it was a lot better as 3 phase. I did not do it for variable speed, which is pretty good for some things, but did not seem needed for the lathe. Still doesn't, there isn't anything I have run into that having it would do better.

    Yes, I chose an RPC because I figure to install some more 3 phase machines.

    Go back under the bridge, stop being a troll.
    Last edited by J Tiers; 05-01-2022, 10:06 PM.

    Leave a comment:


  • Doozer
    replied
    Originally posted by J Tiers View Post

    The major advantages of a VFD are well known...... well balanced 3 phase, and variable speed.
    .......
    I have never seen a pressing need for that in my shop, so I do not have any VFDs, just one RPC. You may be different.
    The discussion is replacing a SB lathe motor.
    It was submitted that a 3ph motor and a VFD
    offered numerous advantages over 1ph.
    No one is considering converting the SB lathe
    to 3ph and then running an RPC. That's crazy.
    Just another opportunity for you to talk about
    how great you think RPCs are ? ? ? ? ? ? ? ?

    -D

    Leave a comment:


  • RB211
    replied
    Originally posted by J Tiers View Post

    The major advantages of a VFD are well known...... well balanced 3 phase, and variable speed.

    The major advantages of an RPC are different. What it does is simply provide 3 phase, in very much the same way as the power company. What that does, is make any 3 phase machine a "plug and play" installation. If the voltage is right, the machine will run. And one RPC can run any machine in the shop, by simply turning on the machine. Depending on the power capability, it can run 2 or 3 or more machines.

    Yes, I know, and can intelligently discuss, the differences between powerco 3 phase and RPC 3 phase. Those differences are not huge, and need not be a problem.

    The other side of the issue is "what are the disadvantages?".

    For a VFD, the first disadvantage is that one VFD can run one machine only. You cannot use one VFD with more than one machine, unless you simply use it as a converter, and ignore the variable speed feature. And if you do that you need a MUCH larger VFD. Buying a lot of VFDs can run to some serious cash, even though they are each reasonably low cost.

    The second issue with a VFD, is that essentially, you have to tear out the controls in the machine, they cannot be used with a VFD. You may be able to salvage a few switches, but the rest is of no use. You are on your own to re-wire the machine to operate with the VFD.

    The third issue is for machines that have more than one motor. One VFD cannot run all the motors, unless, as before, it is considerably larger, AND you do not want to use variable speed. If there is a coolant pump, or an axis feed, you are on your own to figure out what to do about those, as the VFD can only run the spindle. You need another VFD for the next motor, etc, etc. (Or you can make some sort of static converter, etc to run each other motor.)

    For the RPC, the disadvantage is basically that you do not get variable speed.

    All the controls work fine, and any feed or pump motors will work fine. If the machine has a mechanical speed variation, that will work fine. It is "plug and play". All you need to do is provide an RPC that handles the total power you want at one time, meaning the ratings of the motors or machines you want to run at one time.

    So, to decide what you are going to do, ignore ALL the people who tell you what THEY would do. THEY are not YOU. It's easy for them to tell you what to do, and how to spend YOUR money.

    Look at what you want to do.

    If you just want to run the machine, or machines, then an RPC is probably the least trouble, as it is plug and play, with no modifications, re-wiring, etc. And the RPC can power any other 3 phase machines you have, or get, if it has sufficient power capability to handle those that will be run at once.

    If you just gotta have variable speed, then you need a VFD for each machine you want to run. And you need to make all the modifications and re-wiring necessary, on each machine that you want to run

    I have never seen a pressing need for that in my shop, so I do not have any VFDs, just one RPC. You may be different.
    Yep, I have both an RPC and many VFD's.

    Leave a comment:

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