# I think my Rong Fu mill's original motor is about to die?



## stioc (Oct 5, 2019)

During the milling the motor came to a stop (with the click/relay noise) and started buzzing (like electricity energizing a transformer) as if there's load on it but there was none. I flipped the switch to off and then back on (even tried reverse) and it just made the same buzzing noise. Pressed the reset button on the motor, same thing. Pressed it a few times again and flipped the switch to on and it started working again. Then same exact senario 20 mins later. So a couple of questions:

1. Is it the brushes? the run capacitor? or something else. I don't know much about motors...but sounds like I'm about to learn lol

2. If the motor is toast I would love to convert it to a VFD because changing two belts at the top is such a pain I mostly don't and run at incorrect RPMs. What style motor will bolt up to this guy?


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## stioc (Oct 5, 2019)

Actually, upon closer look using the infrared temp gauge it seems the motor's just getting too hot. Makes sense because I mounted a boring head and had it running at low RPM for a long time.

However, still interested in guidance on getting a bolt-on motor to convert to VFD.


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## mksj (Oct 5, 2019)

Sounds like a capacitor failure, I would replace both the run and start. capacitor first. Frequent switching single phase motors on and off can result in over heating of the start capacitor and the motor will not turn and just sit there and buzz.








						Enco Mill - motor takes a few tries to get to full speed
					

Hello experts, I have my Enco mill (RF30) up and running and have an annoying problem.  When I turn the switch (forward or reverse, doesn't matter), the motor immediately kicks on and comes up to about 1/3 speed, then stalls or "pulses" at about that speed. It must pull a ton of current, as I...




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You would need to see the motor frame and shaft size (diameter and length), as well as the mount to the machine. My read from other posts is it is a metric motor, if so I would look at the Leeson Metric motor specs and see what compares to the dimensions of your motor. The site below list these motors with specs and drawings. Ideally if you plan to use the mill as a single speed with a VFD you may want to opt. for a larger Hp motor in particular for low speed work. Below the motor's base speed of 60Hz the Hp drops off in a linear fashion. Alternative is to over speed the motor to say 120Hz and belt it down, but usable power range is still probably in the 30-120Hz range in particular with heavier loads. There is no down side to running a 1750 RPM motor to 2X its base speed in this application,





						Electric Motor Whole sale
					






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Lots of information already posted on converting the RF30 to VFD, just an example of an old post. These days the Teco L510 seems to be a popular VFD for use on mills. If you plan on having the VFD controlled by the CNC/use the mill in this application then I would invest in a better motor (inverter/vector) and a better VFD like the Hitachi WJ200, Teco E510 or similar VFD. You have provided us with very little information as to the mill, setup and type of work/needs.


			https://rick.sparber.org/VFD.pdf


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## Superburban (Oct 5, 2019)

Agree, I have had to replace the caps in mine a few years back.


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## stioc (Oct 5, 2019)

Thanks for the info and the links Mark. I pointed a fan at the bottom of the motor and it has been fine so far. 

I'll research the VFD/motor option more and see what I find out. I don't intend to control the motor through CNC. In fact, for quick projects lately I've just been running the machine manually using the arrow keys etc 

@Superburban, how long did it take to replace the caps do you recall? a couple of hours or an entire day/weekend?


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## Superburban (Oct 5, 2019)

stioc said:


> @Superburban, how long did it take to replace the caps do you recall? a couple of hours or an entire day/weekend?


Probably 1/2 max. While I did it, a went ahead and replaced all the seals in the head unit. The whole thing was the better part of a day. I have the HF version of the RF 40, with the geared head. so it was like 3 or 4 seals.


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## stioc (Oct 6, 2019)

Cool, thanks. Not quite sure where the seals go and the part# etc. but I'll look around.


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## Superburban (Oct 6, 2019)

stioc said:


> Cool, thanks. Not quite sure where the seals go and the part# etc. but I'll look around.


If I remember, yours has belt drive so no seals. Mine has gears, an oil box, and shift levers, and seals to keep the oil in.


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## stioc (Oct 6, 2019)

Yes, mine's a dual belt system...aka. the pain in the neck system that needs to go away


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## Tim9 (Oct 7, 2019)

I’d change the capacitors first.... AND THEN check your voltage at the motor when running to make sure you aren’t suffering from a voltage drop issue. Wouldn’t be the first time low voltage was overtaxing the motor.
   I find it’s always best practices to wire dual voltage machinery  motors to run at 230 volts.  Running them at 110v is almost a recipe for early failure IMO.


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## stioc (Oct 7, 2019)

Haven't had the issue since then. Good idea on checking the amp draw...I have it on a dedicated line I ran into a 20 AMP breaker and wire sized accordingly. However, I do run the CNC computer, motors and controls off the same line. I'll plug in the Kill-A-Watt and see what it says.

The date on the motor says 1993 so may be after 26yrs (only 2yrs in my ownership lol) it's ready to retire.


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## Cadillac STS (Oct 7, 2019)

Could consider getting a large treadmill motor.  That way it is 120 volts and just turn the knob for speed. Put on a tachometer.


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## WCraig (Oct 8, 2019)

stioc said:


> The date on the motor says 1993 so may be after 26yrs (only 2yrs in my ownership lol) it's ready to retire.


I am not an electrician, but...

electric motors just run.  Until the magic smoke gets out.  Or maybe a bearing goes bad which often ends with the same magic smoke problem.

I would carefully check the wiring.  A connection may be loose due to years of vibration.  A wire may be abraded and is just starting to short, etc.  With the belts off, make sure the motor spins freely and doesn't feel crunchy.

Craig


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## pontiac428 (Oct 8, 2019)

stioc said:


> The date on the motor says 1993 so may be after 26yrs (only 2yrs in my ownership lol) it's ready to retire.



Uh-oh, my identical motor was made in 1997... I am going to go put a reminder in my calendar to order caps in August 2023.


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## Joeman77 (Oct 8, 2019)

I've never worked on this mill but a motor is a motor and I agree with the capacitors idea, they're cheap & easy.
 If you have to pull it off & go much deeper I'd at least replace the motor bearings, not as cheap as the caps but, it'll buy time while you round up all the parts you need for the conversion to VFD.
 And if it's down you'll be absolutely amazed how much you take it for granted and how much you just go do something quick, I was lost when my lathe was down. You'll have to work quick to avoid withdrawal!


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## pontiac428 (Oct 8, 2019)

By the time you tear into that Asian motor for an overhaul, you may as well get a new 3-phase motor with the same NEMA mount (it's a common one) and run it from a VFD.  The mill really needs it, those RF belt changes are a pain in the tailstock.  I was going to do that with mine, but with that Lagun on my shop floor I don't think I'll be putting any more effort into my (highly polished) little Rong Fu.


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## stioc (Oct 8, 2019)

Agreed, can't afford the machines to be down but I'm swimming in too many half done garage projects already...I need to clone myself or set everything on fire and start over


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## pontiac428 (Oct 8, 2019)

While waiting to start on finishing my building, I've been going through my work benches and closing out unfinished projects.  I've been at it for weeks and still have little odds and ends to finish.  It's fun to rediscover things, but I can't seem to remember all of the details of what I was doing...  At least all of my mills and drills are sharp.


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## Joeman77 (Oct 8, 2019)

pontiac428 said:


> Uh-oh, my identical motor was made in 1997... I am going to go put a reminder in my calendar to order caps in August 2023.


There's little or no warning before they die and you know they're going to die right in the middle of a project on Saturday afternoon on a holiday weekend when you can't get parts!
 You can probably get a set for under $10 & swap them out before you actually need them.


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## stioc (Oct 8, 2019)

So do I have to open the motor up to find the part no info on these caps or are they well known for these motors that someone can point me to?


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## pontiac428 (Oct 8, 2019)

Just remove the cap cover (looks like 2x C battery cover, 2 screws) and order matching capacitors from your supplier of choice.


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## stioc (Oct 8, 2019)

Will do!


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## Tim9 (Oct 8, 2019)

Stoic.... here’s a good video on motor capacitors... and induction motors.

  Jeremy Fieding has very good videos on electricity and motors. He does a good job of explaining theory and design.
Induction motors and capacitors


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## matthewsx (Oct 8, 2019)

+1 on replacement with 3 phase and VFD. You'll be glad you did.


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## stioc (Oct 9, 2019)

Tim9 said:


> Stoic.... here’s a good video on motor capacitors... and induction motors.
> 
> Jeremy Fieding has very good videos on electricity and motors. He does a good job of explaining theory and design.
> Induction motors and capacitors


Thanks so much Tim. I recall seeing Jeremy's videos before but that was a few years ago but thanks to your link I just subscribed to his channel. Easy to follow guy with a very down to earth tone. 



matthewsx said:


> +1 on replacement with 3 phase and VFD. You'll be glad you did.



Yes, that will be the ultimate setup. However, I also keep thinking that it's my first mill I bought used 2yrs ago (it's about 25yo but well taken care of). I converted it to CNC as cheaply as possible and so far it's been a decent mill for me. However, before I put more money into it may be I should instead save up for a 'better' mill. If I had the room I'd get a CNC mill and convert this one back to manual mill (with DRO) and keep it. Or maybe save the better mill idea for when I retire and have a bigger shop etc and for now just do the VFD conversion. OK I'm just rambling now.


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## matthewsx (Oct 9, 2019)

stioc said:


> Thanks so much Tim. I recall seeing Jeremy's videos before but that was a few years ago but thanks to your link I just subscribed to his channel. Easy to follow guy with a very down to earth tone.
> 
> 
> 
> Yes, that will be the ultimate setup. However, I also keep thinking that it's my first mill I bought used 2yrs ago (it's about 25yo but well taken care of). I converted it to CNC as cheaply as possible and so far it's been a decent mill for me. However, before I put more money into it may be I should instead save up for a 'better' mill. If I had the room I'd get a CNC mill and convert this one back to manual mill (with DRO) and keep it. Or maybe save the better mill idea for when I retire and have a bigger shop etc and for now just do the VFD conversion. OK I'm just rambling now.



I'm building a CNC from parts I bought so I can appreciate converting it "as cheap as possible". Either way you will be miles ahead with the VFD setup. Cheap Chinese VFD's can be had for $60 and used three phase motors in that size are pretty common. I converted my lathe with a good Teco VFD and Baldor motor for less than $300 and it made a world of difference. The ability to dial in the right speed is great and if you're into CNC you could even add spindle control.

Unless you already have a replacement motor you're almost all the way there just buying a decent single phase motor alone. If you sell the machine it should add value (variable speed), and if you keep it you'll be grateful for not having to mess with belts nearly as much.

John


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## stioc (Oct 9, 2019)

matthewsx said:


> I'm building a CNC from parts I bought so I can appreciate converting it "as cheap as possible". Either way you will be miles ahead with the VFD setup. Cheap Chinese VFD's can be had for $60 and used three phase motors in that size are pretty common. I converted my lathe with a good Teco VFD and Baldor motor for less than $300 and it made a world of difference. The ability to dial in the right speed is great and if you're into CNC you could even add spindle control.
> 
> Unless you already have a replacement motor you're almost all the way there just buying a decent single phase motor alone. If you sell the machine it should add value (variable speed), and if you keep it you'll be grateful for not having to mess with belts nearly as much.
> 
> John


Agreed 100% - what mill are you converting btw?

The VFDs are so cheap these days it's silly...I'll check the NEMA frame no and see how much the bolt-on 3 phase motors are. Then it'll also be moving the single 220V dryer outlet to where the mill is...more projects!


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## matthewsx (Oct 9, 2019)

Here's my machine, built from parts & pieces not a conversion.









						Homemade vertical mill/drill CNC project
					

I'm sure some of you have seen my posts in the general section about this project.  https://www.hobby-machinist.com/threads/homemade-vertical-mill-drill.77611/page-3#post-664686  But now that I'm ready to start on the controls I figured it would fit better here (mods please let me know if...




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## stioc (Oct 10, 2019)

So there is no NEMA frame size listed on the motor anywhere but here are the rough dimensions. I won't know the length of the shaft without removing the pulley but it's definitely longer than 1". I found an article about someone converting a RF30 and he said he replaced his with a NEMA 145T but the article also said he replaced the motor mount.

Regardless comparing the rough dimensions I took and the specs for 145T, they're very close so a 145T motor should bolt right up. I found this one for not a bad price https://www.surpluscenter.com/Elect...P-3500-RPM-230-460-3Ph-TEFC-Motor-10-2899.axd

Thoughts?


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