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Thread: VFD Conversion

  1. #1

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    In mid March I posted about the splined motor shaft and that I was going to switch to a VFD. The conversion has been completed with the exception of the braking resistor(s) for the drive.
    I made a new 32 tooth 16 DP 14-1/2 deg PA gear to slide on the motor shaft with a 1-1/8" bore and 1/4" keyway to fit the motor shaft. I did not attempt to duplicate the splined set up that Monarch used due to the fact that I could not fully identify the type of spline employed with confidence. The gear was made from 4140 pre-hard and the teeth have been flame hardened to further increase the hardness. The tooth form does not match exactly with the form that exists on the originals, and it does introduce a bit of a noise problem in backgear, that seems to be getting less noisy as it wears in.
    I also purchased a new 5 HP inverter duty rated motor with 184TC frame with feet. The motor/gearbox adaptor plate was made from 1" thick HRS, that the supplier supplied from Blanchard ground stock, that must have been excess from a previous job. I also extended the shaft of the motor, by drilling and tapping the end, and fitting a 3/4" long extension, the threaded portion of which was made much like a threaded lathe spindle with a register section. The shaft keyway was aligned in the mill and the keyway was cut in the extension. The key and extension have been pinned to the motor shaft. As could be expected there were some minor fitting problems to be addressed; the extension was a few thou too long, the bore of the gear had a tight spot, but it was basically a straight forward machining job.
    The motor and gearbox combination were mounted to the original mounting plate and reinstalled in the lathe.
    The VFD installed is a Hitachi SJ100-037LFU Sensorless Vector Drive. The unit is set to top out at 115 Hertz for a top end of 3900 RPM approx.
    Several cutting tests have been conducted which have demonstrated the capability of the drive. Cuts were taken at rpm's from 100 to 2500 at feeds of .0074"/rev with .150 DOC. The only time I stalled the drive was at 100-200 RPM, .180" DOC, .0148" feed(this was the only time this cut was tried). Stock was 1-1/4" 1018. All cutting tests were in direct drive.
    I don't know how this compares to the original DC drive, as mine was never fully functional in delivering the full 5 HP, but I'm very satisfied.





    Harry


    [This message has been edited by [email protected] (edited 04-14-2004).]

    [This message has been edited by [email protected] (edited 04-14-2004).]

  2. #2
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    I have the Teco/Westinghouse "Fluxmaster 100" 3 hp from Dealer's Electic and a new Marathon 3hp 3phase motor. When I initially hooked everything up, my low end was weak. I noticed that I could lower the hz down to about 10. Anything lower and the motor would start "cogging". After reading the book from cover to cover I decided to fiddle around with Function 05 which is the V/hz curves. Factory setting was preprogrammed at 09. I tried 10 first and got a lot more low end torque. My test was to install the 5c collet adapter because of its smooth outside and try to stall the spindle with my hands. It setting 09 (factory setting) I could disappointingly stall the spindle) At 10 it took all the strength I had to stall it. At 11, forget it, there was no way I could stall it. The options go all the way up to 17 so I was thrilled at this point. I went up to 12 and the motor cogged badly. Ok, keep going...up to 17 would not even turn the spindle. So I went back to 11 and its great!! Plenty of low end torque and did not affect the high speeds. So it pays to play around with different settings. I couldn't be happier with the system.

    Jeff

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    Miss Cellaneous ramblings ...

    3 HP + VFD seems to be pushing the envelope.

    5 HP + VFD still is only 2/3 of Monarch's first conversion (7.5 HP/backgear) and 1/2 of Monarch's second conversion (10 HP/open belt).

    I would be reluctant to go less than 5 HP unless that was the only way I could obtain single-phase operation.

    But, the "sweet-spot" of C-face inverter duty motors and single-phase VFDs is at 3 HP right now, and its good to know that a 10EE can indeed be made functional at that level.

    Of course, with its tube dc drive (WiaD or Modular), 3 HP or even 5 HP is single-phase, and either gives the machine all the power it needs or can use.

  4. #4

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    I've added some pictures. In the 3rd picture the gear on the right is the original.
    Harry

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    I am doing the same swap but i think I got lucky as the original motor/gearbox are joined by an 1 1/4 shaft and a 1/4 keyway. (no splines)

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    Harry - is this the post you were looking for?

  7. Likes sbh10 liked this post
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    Thanks for the repost, Harry.

    Peter

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    Russ, thanks for finding it, thought it was lost.

    Harry

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    Shortly after the initial post was made a bank of braking resistors was added to the VFD. The resistors were purchased from Surplus Sales of Nebraska, IIRC cost of about 50.00. The stopping time was set at 1.5-2 seconds with the spindle spinning at 1500RPM, with a 5-C collet mounted, which is the spindle set-up that is used most on the lathe. I've had a chuck mounted less than 10 times. The braking time with chuck mounted is a little longer due to the increased mass from the chuck, but not objectionable.
    Some other changes have been made to the lathe also, most notably the way the spindle is controlled with an apron controlled on-off switch. The drum switch is still on the headstock serving as direction control. The pictures are in the middle of the link.
    http://www.practicalmachinist.com/vb...ad.php?t=99246
    In the 4 years the lathe has been in use, the VFD has performed without problems. I do run a considerable amount of production through the machine, so it does get cycled a lot.
    If there is a difference between the VFD and DC drives, it will be the VFD's torque available under 100 RPM in direct drive, and only if I'm chasing a particularily coarse thread. I don't use the machine as a "hog", I've got the CK and CY for that.

    Harry

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    Toms Wheels posted a very helpful thread on a similar adaptation.

    He explains that the splined gear is hardened, but the (internal) splines are not, so the gear may be bored quite easily to the standard (for a 5 HP motor) 1-1/8" dia., and thereafter a standard keyway may be broached.

    http://www.practicalmachinist.com/vb...d.php?t=100284

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    For those on the cheap I stripped ALL the guts out of the DC motor and mounted a 3 hp three phase motor on the side of it with all thread to tension the belt. Then cut a hole in the side of the DC motor case and drove it with a cog belt. I used a cheap VFD drive, but still have back gear. Haven't done much with the lathe yet but I think it will be ok.

    K.

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    Here is another thread with a couple more conversions.

    http://www.practicalmachinist.com/vb...ad.php?t=99982

    Jeff Major

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    Default AC Tech drive

    I have a 1946 10EE and I am collecting information on doing a retrofit of my own. I was looking at a AC Tech 5 hp 208/240V one phase scm ac drive and they say on industrial live it can be used as a phase converter to operate a 3 phase motor on single phase power. They also have a 7.5 hp model.
    I have read in earlier posts that say 3 hp is the limit for doing this. If some one could shed a little light on this it would be appreciated.

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    Peter has, at my request unlocked this thread so that I can post some more information. Thank you Peter.

    I have had this wiring diagram since shortly after the VFD was installed 5 years ago, and after I remembered I had it, felt it was time to post it. As this is specific to my machine, it should serve as a guide for others currently doing this. All of the wiring instructions are in the Hitachi manual, but I do remember getting the size of the braking resistors from the supplier, Drives Warehouse, and a lot of help from Russ Kepler. I did not do the wiring, or the diagram, my friends Bob G and Bob B manage to keep me out of electrical troubles.


    The following pictures are the mechanicals for the apron control switch. The same set-up will be added to the "Wreck". All my other lathes have apron mounted clutches that I find quite convenient and they seem a bit safer than reaching over a spinning chuck.






    Harry

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    Default I need help doing this for my 10ee

    My '48 10ee DC motor has given up the ghost and I too am faced with this conversion.

    If someone would not mind the trouble of providing a little information it would be greatly appreciated.
    It appears that I need to be in the 5HP range.
    What are some of the better manufactures, models and styles of motors I need to consider for this task?

    Also, what are the brand names and models of a dependable VFD?
    I only have 220 single phase at my shop.

    I desire the better quality components, but don't know enough about it to make an intelligent decision.

    If there are any machinist in the Dallas area that would be interested in making pieces for this I will be back from Afghanistan in late February and commencing on this project ASAP.
    Thanks for any help in advance.

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    Here's a couple of pics of the third 10ee vfd conversion I have done on machines missing drives. The first image shows the motor compartment. I like tucking the vfd against the back side of the original start button's opening. That way it is accessible enough to program and reset if needed.

    I used a motor that has both c-face and feet mounts, that made grafting/mounting the motor pretty easy, but still takes a whole day to do. The second pic is the way I like to mount the potentiometer (hidden under electrical tape) in line with the factory knob using a simple spring to connect the two.

    I turn the end of the stock shaft down to 1/4" to match diameter of the Pot, then "screw" the spring onto both (lined up) shafts. I slip a piece of hose around the center part of the spring that is in free-air to prevent bulging of the spring. This creates a crisp action, and also provides a means for slipping so as to not destroy the pot if maxed out either direction.
    Brett



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    Quote Originally Posted by Brett by Portland View Post
    The second pic is the way I like to mount the potentiometer (hidden under electrical tape) in line with the factory knob using a simple spring to connect the two.
    Nice work. How'd you join the motor shaft with the gearbox?

    The trick I've seen on the speed control pot (on the later models, not round dial) is to simply replace the double pot with the odd control taper with a standard pot in the same range. That way you still get the same 3x turn range and have the hard stops at the ends.

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    rkepler,

    I turned the end of the motor shaft to 5/8", cut the splined shaft off of the old motor, bored it out to .06233 inches heated and shrink-fitted to motor shaft.

    I did what you mentioned on my last conversion, but this lathe was really gutted, no pot, no hardware. Just an echo chamber in the motor/control compartment. i kind of like the faster slope speed control, it seems very easy to fine-tune to any speed, but, if I had my preference i would still go with the reduction........

    On the last lathe I used the exact spring "clutch" arrangement, but connected to the original pot's shaft, so as to preserve the 3 to 1 reduction but not the hard stops; the clutch action of the spring allows slippage upon hitting the pot's stops.

    Brett

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    Does anyone make a 5hp VFD that will accept single phase input and output 3 phase?

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