Electric Motors

T

Texasbowhunter

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Jan 24, 2019
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I was doing a search on the WWW and stumbled upon a topic on which electric motor was needed to compliment the members 2 x 72 belt sander...Older topic of conversation...
I am new to your forum and hope this is posted in the correct area...If not I apologize...
I'm in the process of fabricating a 2 x 72 belt sander and was doing some research on motors and its over whelming to the guy who is electrical illiterate...I'm at a loss here and am seeking some guideness...
I have read and am under the impression that the Baldor is a quality motor or at least used to be...Then there's the Leeson motor who used to be competitive until they started out sourcing...
So I'm at a loss here as to who is making a reasonable priced motor whos quality is good and prices will not break the bank...
Also any help here on which model you would recommend...Model numbers would be very helpful so when I do a search it would help to narrow down which specific model I can compare prices to...
I'm planning on an additional cost for the VFD...From what I read the KBAC-27D with a on/off switch is the most sought after...seemingly...
I understand I should seek out 2hp, 110/220v, 3 ph, 1750 rpm, 56 frame C face TEFC or TENV...Now with this said I'm open to a different sized motor if suggested...Shaft size is not a factor at this time since I have not obtained the wheels yet...What would the most sought after size be? 5/8"?
Inverter rated ??? I'm not sure what this identifies...
4 pole??? not sure what this means and is it needed...
Right now I'm working out of the garage and have 110v available along with 220v for my welder, plasma cutter and air compressor so either will be available...220v would probably be preferable for me but feel like it would be advantageous to cover both my bases and get the 110/220v motor...
I'm sure more questions will come about during our conversation assuming there will be a conversation...
Thanks in advance...Look forward to your guideness...
 
Also I recall something about soft start motors...Any thoughts???
Are they worth the seeking or are they necessary since I am planning on a VFD???
 
2Hp, 220V, 3Ph, TEFC, 56C, 4 pole is more powerful.

Inverter rated is nice, but not worth the extra price unless you find a great deal on one used. Regular duty will work fine.
Standard shaft is 5/8" slotted for that size motor.
 
Thank You for your reply
However I'm at a bit lost here as far as meaning…
Inverter rated is nice, but not worth the extra price unless you find a great deal on one used. Regular duty will work fine.
"Inverter rated" is this something built into the motor or you speaking of the vfd? and If I was to go VFD would I need a VFD rated motor? Is this where the term Inverter rated is meaning? Inverter rated cost? about how much more are we speaking? $$ or several $$$
regular duty can you elaborate?
Sorry for the ignorance but just trying to grasp the entire embarkment I'm fixing to embark on...
I'm just trying to get the most bang for my dollars and last a long time...

One more thing the sander will be serving dual duty...Metal and wood since I enjoy wood projects as well...
 
Inverters are often referred to as Variable Frequency Drives, VFDs. They use Pulse Width Modulation to synthesise a 3-phase waveform from sub-millisecond “slices” of full Voltage. The Voltage rise time is extremely fast and this can cause problems with older motors.
Back when VFDs were cutting edge technology, Inverter-Rated motors were designed to tolerate this (mainly with better insulation materials). Since about the 1990s, VFDs have become very common and it is not worth the manufacturers making a separate line of non-inverter-rated motors. Pretty much all 3-phase industrial motors currently available will work fine with VFDs.
Assuming you only have single-phase power available, you cannot run a single-phase motor now and add a VFD to it later. You will need to get a VFD and 3-phase motor together. There are still some motors made specifically for use with VFDs in those applications where the ultimate in performance is needed: usually extremely precise speed/motion control. You do not need to worry about this.
Baldor are certainly very good motors (I think they are now part of ABB). Typically a top-of-the line industrial motor will last perhaps twice as long as a "meh" motor. Say 15 years (130,000 hours) of 24/7 operation at full load for a premium motor vs 8 years (70,000 hours) for the cheaper one. This matters in industry where downtime is expensive: It's not good stopping a $5000/hour production line for several hours to change a $200 motor.
For "us", it is not really a consideration. Even at 40 hours/week, 50 weeks of the year, 70,000 hours is 35 years of motor life.
The drive is where you should spend your big (-ish) bucks. You need an IP65/NEMA4 sealed drive for a grinder to keep conductive metal dust from getting in and shorting out the power electronics. Either a KBAC or a KBDA would probably be ideal, along with a reasonably good industrial motor (Iron Horse motors seem to hit a price/performance sweetspot in the US, as far as I can tell).
The VFD will let you run down to 10 Hz smoothly if you use a V/Hz drive (like the KBAC), mayby 7 Hz on a good day. A Sensorless Vector drive (like the KBDA) will let you run to even lower speeds. Top speed is usually set by the motor design and you can generally run safely to 3600 RPM, which is 60 Hz on a 2-pole motor (plated speed about 3500 RPM) or 120 Hz on a 4-pole (plated speed about 1750 RPM)
 
Inverter rated is a grade of motor with heavier windings and more insulation. As Tim said, it matters in industry with big time equipment, but doesn't matter at all for knifemakers. I would venture a guess that less than 1% of knifemaking equipment has an inverter motor on it. It will be marked on the data plate on the motor if it is inverter rated.

I agree with Tim that the VFD you pick is far more important than the motor.
 
Spot on Tim - you've covered the motor part nicely. One note, the idea of getting a 120/240 volt 3ph motor is an EXPENSIVE option. The standard 3 ph motor will be 240/460 volt. Your question of 2 pole vs 4 pole is about the rpm of the motor. A 2 pole is 3600 rpm and a 4 pole is 1800 rpm. Either one works, several folks on here prefer the 1800 rpm, while I and several others tend to prefer the 3600 rpm motor.

Even the cheap IronHorse motors linked above are inverter capable (I also have 3 of them & 1 Lesson motor):https://goo.gl/n5g4Bh
*****************
Highlights
  • Reversible motors
  • Inverter capable
  • Removable bolt-on / bolt-off base
  • Industrial gauge steel motor, frame and base
 
I'm basing this off of memory, but Inverter Duty is usually somewhere around an "F" class of insulation, which most industrial grade motors already are. As far as shaft size, shaft size and frame size are interrelated. A 56 frame will always have a 5/8" shaft, 143 will be 7/8", etc... You can find NEMA frame size charts. Base size and shaft distance from the base are 2 other constants (among a few others), and that helps ensure that if you ever have to swap out a motor, a motor with the same frame size SHOULD fit, in the majority of instances.

As for brands, Baldor, Leeson, Dayton, etc... are all still good brands, though for the average hobbyist knife maker who might be running their grinder maybe 10 hours per week (or less) on average, you can probably go with just about anything and it will likely last you for years, if not decades. The IronHorse motors are a great option.
 
Well Guys I have read the above and re-read them, thank you for replying the way you guys have, I have a bit more ammo to go with however I am still confused...
So I believe I would at least at this time like to use a VFD to adjust my speed for the various materials and projects I will be working on...If I don't use the afore mentioned VFD unit is there another alternative to being able to control my speed while still keeping the power and torq.?
I'm going to go out on a limb here and assume that the above mentioned Linked motors are VFD rated in which If I choose to I could use a VFD... Right?
If so would the 3600 be to fast if the max RPM I would probably seek would be 3600 range...
Now this is where I may be losing this...
I had read on here on one of the earlier topics from years ago that a 1750 RPM with a VFD was the ticket...That since the motor was attached to a direct drive 4" wheel this would be the 3600 range it would produce...Is my understanding wrong?

(drive wheel diameter x 3.14) x rpm
gives you inches per minute

divide that by 12 to get sfpm
so using the above formula it seems that
(4" x 3.14) x 3600= 45216 divided by 12 = 3768 SFPM

Thxs again
 
To give you the short answer, a VFD and 3 phase motor is the generally the cheapest (and easiest) way to get truly variable speed while still maintaining torque.
As for speed/RPMs, many VFDs have a 2x speed jumper, or a way to program up to 120hz (or higher). 1800rpm at 2x will technically give you more torque on the lower speeds, though it's probably pretty negligible, compared to the 3600. Some guys like to double a 3600 RPM motor to get better efficiency out of the more expensive ceramic belts. Other guys buy the 3600 RPM because they're a little cheaper, and maybe they keep the VFD at 1x speed.
At the end of the day, either will work just fine for you. Personally, I have an 1800 rpm with a 5" drive wheel. (Some guys like 6" drive wheels.)
I don't do a lot of high speed hogging, so it works well for me.

Obviously not all grinders (or attachments) can handle 7200 RPM. As long as everything is balanced well and right and tight, you'll probably be fine, but God help you if it's not! ;)
 
Drew, I'd like to comment that most electric motors are designed with a "not to exceed" 5,000 rpm. This has to do with motor balance if I remember. Of course I may have these all wrong, but it seems I've read 5,000 was a good ROT to follow?

The 7200 might be the belt speed which is obtained with the 6" (or larger) drive wheel. With a 6" drive wheel 3600 RPM gives a calculated 5600 SFPM and with an 8" drive wheel gives 7500 SFPM belt speed.

I max my 3600 rpm motor at 4,000 RPM with a 4" drive wheel to give about 4100 SFPM belt speed. if you use a 3.82" diameter drive wheel the belt SFPM speed matches the motor RPM.

The 1800 or 3600 is the theoretical motor RPM based on the number of poles and freq of power source. Due to motor slip this is usually more like 1750 (or 1725) for a 4 pole motor and 3450 for a 2 pole motor.
 
Thank You guys
I have now more understanding of what I'm needing...Or at least enough to make me dangerous...
So in a nut shell the above mentioned MFG of the motor, the iron horse will be a very good choice for the average user...
Whether it is a 1750 or 3600 is my choice.. either will work...
Using the VFD will allow the 1750 to be ran at 3600 by using the x2 feature of doubling my RPM
or I can use the 3600 buy using the x1 and keeping my speed using the MFG rating...
However if I so desired I could use the 3600 and use the x2 feature in the VFD and get @7K out of the motor speed...
Thank You All... I may have a greater understanding of what to order...
 
Well, If using a 3600 rpm motor I wouldn't double the speed to 7200 rpm, that's pretty fast and well in excess of manuf recommendations. Remember the difference between belt speed in "Surface Feed Per Minute" (SFPM) and motor RPM.

Yes, While I never spec'd an Ironhorse motor in the chemical plants, my "opinion" is the IronHorse motor is just fine for our use.

Yes, either the 1800 or 3600 rpm motor will work just fine and you'll never know the different between use of the two motors, except for the extra weight of the 1800 rpm 4 pole motor and when paying the extra cost of the 4 pole motor.

Also, withe VFD you've got a choice of a $72 shipped Chinese VFD, or the expensive KBAC-27D VFD. While the KBAC-27D is a good VFD, for my use I tend to prefer the $72 Chinese VFD because it's got a display that will show belt speed in SFPM. I don't think the KBAC-27D has a display?

The $72 VFD is an open frame and must either be mounted in a dust proof box or as I do put filters over the air inlets to prevent metal dust from getting inside. "IF" this grinder is something to be powered on running 8 hr/day 5 days/wk as a full time grinder, I might go for the KBAC-27D, but for my hobby use where it's ran only a few hrs per week, the $72 option works for me. If you go with the $72 option and after a yr or so you decide you prefer the KBAC-27D, no problem, just lift wires from one and put other in place. All you've lost is the $72 for how ever long you decide to use it.

Ken H>
 
Ken H> said:
Drew, I'd like to comment that most electric motors are designed with a "not to exceed" 5,000 rpm. This has to do with motor balance if I remember. Of course I may have these all wrong, but it seems I've read 5,000 was a good ROT to follow?
Click to expand...

That's part of the reason I added the little disclaimer about "not all grinders can", though I should have probably clarified that can be as much to do with the motor, as the wheels and attachments. Regardless of if a motor can hit 7200 RPM without walking off the bench, the higher speeds will certainly decrease bearing life, among other things. That said, I'm sure very few makers run their grinders full speed for very long, and only utilize the capability a small percentage of the time. I doubt even those who have the 3600RPM at 2x speed are hitting 100% on the speed pot very often, if at all. I was under the impression it was more for "head room". Personally, I'd rather take up the slack with a larger drive wheel than a faster motor anyway.
 
Ken H> said:
Well, If using a 3600 rpm motor I wouldn't double the speed to 7200 rpm, that's pretty fast and well in excess of manuf recommendations. Remember the difference between belt speed in "Surface Feed Per Minute" (SFPM) and motor RPM.

Yes, While I never spec'd an Ironhorse motor in the chemical plants, my "opinion" is the IronHorse motor is just fine for our use.

Yes, either the 1800 or 3600 rpm motor will work just fine and you'll never know the different between use of the two motors, except for the extra weight of the 1800 rpm 4 pole motor and when paying the extra cost of the 4 pole motor.

Also, withe VFD you've got a choice of a $72 shipped Chinese VFD, or the expensive KBAC-27D VFD. While the KBAC-27D is a good VFD, for my use I tend to prefer the $72 Chinese VFD because it's got a display that will show belt speed in SFPM. I don't think the KBAC-27D has a display?

The $72 VFD is an open frame and must either be mounted in a dust proof box or as I do put filters over the air inlets to prevent metal dust from getting inside. "IF" this grinder is something to be powered on running 8 hr/day 5 days/wk as a full time grinder, I might go for the KBAC-27D, but for my hobby use where it's ran only a few hrs per week, the $72 option works for me. If you go with the $72 option and after a yr or so you decide you prefer the KBAC-27D, no problem, just lift wires from one and put other in place. All you've lost is the $72 for how ever long you decide to use it.

Ken H>
Click to expand...

The last job I worked at started using a vendor that liked to spec "import" motors. I forget the specific manufacturer name at the moment, but the font on the nameplates reminded me very much of the IronHorse motors. They were significantly cheaper than the Baldor equivalents, and for the most part, they did just fine, running 12 to 16 hours per day on smaller pumps, conveyors, and other little odds and ends. We'd burn one out occasionally, but I think it was more from extenuating circumstances than the quality of the motor.

As for digital displays, I believe the KBDA series of KB drives (vs the KBAC series) do have digital displays, and if I'm not mistaken, they can be set to display SFPM, as well as RPM.
 
Drew Riley said:
I doubt even those who have the 3600RPM at 2x speed are hitting 100% on the speed pot very often, if at all. I was under the impression it was more for "head room". Personally, I'd rather take up the slack with a larger drive wheel than a faster motor anyway.
Click to expand...
I'd forgot about the KBAC series of drives, seems like they provide on the 60 hz or 2X jumper for 120 hz speeds. The Chinese VFDs I've used don't have the 2X jumper, but you set a parameter to max hz desired. I set my VFDs for a max speed of 4,000 rpm, and with the 4" drive wheel that gives me all the belt speed I need of around 4100 SFPM. I do use 3800 to 4,000 SFM a good bit when profiling and am starting to use with beveling. Sure removes metal in a hurry with ceramic belts. I think I'd be scared to grind on a grinder at 7,000 SFPM - that's too fast for my old age {g}

I've really slowed things down in my old age, heck, I've even stopped popping wheelies on my GoldWing, since about 2 yrs ago I popped one and due to arthritis in my left wrist my hand slipped off the left handlebar. This allows the front wheel to twist a bit while up in air and I had to get it start FAST before it hit the ground. Scared me a bit thinking how that could have skinned up my bike.... and me! {g}. Decided I was too arthritic to be doing fun stuff like that {g}

Old Man Ken H>
 
Ken
You bring up a valid point with the VFD's... I thought the KBAC-27D was the standard that all you guys were using...I never gave it much thought as to that there were alternatives in the Chinese field of VFD's...And the suggestion you made that since I am a novice and the unit will not be running all day, every day is certainly a point well taken...
So I did a search on Chinese VFD's and not sure what I would be looking for/at...
If its not to much trouble would you send a link of what to be considered...

FWIW...I don't see any reason where 7000srpm would be needed either...Its just a way for me to wrap my feeble mind around the explanation to kinda get a grasp understanding of what I took from it...
Thxs
 
Somebody can please correct me if I'm wrong, but I wanna say that the Norton ceramic belts are recommended to run between 5,000 and 7,000 SFPM, in order to properly shear grit and not glaze over prematurely. My set up maxes out around 4700 SFPM for so, which may technically be close enough I suppose.
Again, 90% of your grinding is likely going to be much lower than that anyway.

The KBAC drives are somewhat of the "knife maker's standard" for VFDs, only because they're NEMA 4x (knife making can be very dusty, and if wet grinding, this is especially nice to have), and they're dead simple to set up and use. Another major draw to these drives is that they can be set up to run on 110VAC (up to 1.5HP anyway), where most import VFDs have to run on 220VAC, at least for anything over 1HP.

That said, the China VFD's are actually a bit more versatile as far as parameter sets (although most of the "extras" have little to no application to something as simple as a belt grinder), and as long as you can protect them from dust and whatever else might be floating through the air in your shop, they're normally pretty decent drives. You do have to "program" them, and if I recall, there's about a dozen or so parameters that you'll have to set specifically to your motor, as well as how you want your display and controls to work. The manuals can be a bit hard to read, though I think most of the newer ones are better than what used to be out there.

As for which brand, there seems to be about a million of them now days. I have an old Huanyang that I use for my knee mill and surface grinder.

You might also try something like this:
https://www.ebay.com/itm/220V-1-5KW...h=item41e3d8c260:g:ugoAAOSwl0VbFgYE:rk:9:pf:0

This one is a little smaller, but more expensive:
https://www.ebay.com/itm/1-5KW-2hp-...2:g:O00AAOSwfWxba~G2:rk:2:pf:1&frcectupt=true
 
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