Motor advice on belt grinder (gathering materials)

[Chris165]

I am going to build the Polar Bear Forge 2x72 belt grinder. Having trouble deciding on the motor. I can't run a 1.5hp motor on the 15a outlets. (Have tried with a 12" disc sander)
The closest outlets to the garage door: 1x 220v 20amp outlet 25' away that runs a 3hp lathe
1x 115v 15amp 15' away
1x 115v 20amp 25' away
The motor I was looking at was a 1hp 3450 run by a TECO VFD 115v. I have a feeling that this motor will be too small. Next option, 1.5hp 1725 single speed with 115v magnetic switch no vfd. This would need to be run on the 20a circuit. Final option, 2hp 3450 run by a TECO VFD 220v. Would there be a problem running the 2hp on the 220 outlet 25' away?

[alanganes]

I am far from any sort of expert but will toss this out:

I have a Wilton "square wheel" 2x72 belt grinder that came equipped with a 1 HP single phase motor. It has NO shortage of power for anything I have ever tried doing with that machine. In fact that machine is rather startling in its ability to remove whatever sort material that you feed into that belt.

Personally I'm not sure I'd worry too much about the 1hp motor being too small.

As to running a larger motor on a 25 foot cord, that is simply a matter of making the cord of sufficiently heavy gauge wire. 25 feet isn't that far away. After all, if you wired a new outlet 25 feet closer...

Just my thoughts, worth just a bit less than you paid for them...

[lakeside53]

If you going to use a vfd upsize the motor. Your 1hp motor will be 0.25 hp at 1/4 speed.

Use the 2hp motor. Distance of 25 feet is no issue. 12awg will handle it easily.

[darryl]

That was my first thought also- the 1 hp motor is plenty. Look at it another way- with a 2 inch wide belt you don't want to be applying so much pressure (drag) that you're stressing the belt. It will do a better job for longer if you don't push on it too hard.

[oldwing]

I had problems with a true 1.5 hp Baldor motor on a tablesaw that kept tripping the breaker. Turns out the 15 ft cord was undersized, so I switched it to a #12 multi-stranded wire and have not ever had a problem since.

[sasquatch]

Agreed #12 wire is good, i like to use #12 to almost everything because i had it, and i like to know i,m not getting a voltage drop.

[mf205i]

I just looked at the grinder you are considering and, from the pictures; it appears to have a serious design issue. If you want a true belt GRINDER, not a sander, you are typically talking a belt speed of 5000 to 6000 surface feet per minute and with enough HP to keep it there. A direct drive design using a 3450 RPM motor needs a 6 inch drive wheel to achieve 5420 SFM. So, if you can fit a 6 inch drive wheel, then all is well, but it sure looks tight in the Pics. 1 real HP is enough for a fixed speed design and more HP is necessary for a variable. I use a 2HP, two speed, 240v motor and find it a delight to use. Your 220 option is definitely your best bet.
Have fun with it, Mike

[flylo]

I bought a batch of new120V 1HP tile saw motors & they're the best I've ever found. So smooth you can set your coffee on one & not get a ripple. They have a outlet built in that comes on when the built in child proof switch is turned on. Also have a built in reset,3450RPM 5/8 keyed shaft & long heavy cord. I originlly bought 3 & liked them so much I bought a dozen donuts and two coffees no sugar

[metalmagpie]

IMO variable speed is an absolute must have on a 2x72" grinder. Have to have high speed (~6000 fpm) to hog metal; have to have low speed (~600 fpm) to run Scotchbrite belts or e.g. 2000 grit micron belts. And everywhere in between. A 3-1/2 digit readout which directly reads surface feet per minute is useful too.

[Chris165]

IMO variable speed is an absolute must have on a 2x72" grinder. Have to have high speed (~6000 fpm) to hog metal; have to have low speed (~600 fpm) to run Scotchbrite belts or e.g. 2000 grit micron belts. And everywhere in between. A 3-1/2 digit readout which directly reads surface feet per minute is useful too.

Where might I find one of those readouts?

I think the 1hp should do fine so I'm not bound to the 220 plug, but I'm going to the motor shop tomorrow so ill see what he has. Might just come home with a 2hp if the $$$ is right.

[aboard_epsilon]

i have one running on a 3/4 hp motor ..and you need to press on it quite hard to stall it ......and the belt is 150mm x 1100

so im thinking your two inch grinder can easily run on a 3/4 hp one .

dont waste extra money on a more powerful motor, if a cheaper 3/4 will do .

all the best..markj

[metalmagpie]

Where might I find one of those readouts?

We used 4 digit displays that we bought off ebay. They were cheap, about $18 IIRC. I don't see the 0-10V ones on there at the moment, however. The model number was ME-SP037 and a current seller who seems he might carry it is lcdsmartie. The ones we used are programmable via a USB cord and a primitive interface. We programmed them to scale the input voltage by 0.60 because the VFD puts out 0-10VDC as it goes from 0 to max Hz, and we'd designed our top speed as 6000 sfm. We further programmed it so that e.g. instead of reading 4.635 it read 4635. The programming was easy, only took a few minutes and only had to be done once. I'm pretty sure ours came shipped from China. They work fine. You can see them (not lit up, sorry) in the following pic: http://www.tinyisland.com/images/temp/twoGrindersDone.jpg

These grinders are a derivative of the "Unigrinder" design, and as you can see we built two of them. Way too much work, but they work really well.

metalmagpie

[Tait]

I have a 3HP motor with VFD and LOVE it. I can only bog the motor down by REALLY leaning into it, so I basically never have to think about the motor. I would think that 2HP would have been plenty for use with a VFD.

There are various wire size calculators and references online, such as this one (http://www.gorhamschaffler.com/wire_size_calculator.html), which can be used to determine gauge needed. From my quick check, it looks like #14 would be OK, (and #12 would be even better) for a 25 foot run at 220v to carry 10 amps (you'll need to check it yourself).

P.S. A NEMA 4 or better VFD is really nice and most can be configured to show RPM. As mentioend below, some can show an arbitrary conversion from RPM (such as SFPM based on your pulley sizes).

[Tait]

P.P.S. Not sure of your experience level with grinding belts. Different belts are amazingly different, ranging from inexpensive old aluminum oxide that wear out quickly even cutting wood to ceramic belts that can do a decent job cutting hardened steel to polishing belts that don't cut a lot but last a long time. So, it's worth experimenting and asking around!

[RWO]

Most quality VFD's have the ability to display ft/min directly on the digital display by programming the appropriate scale factor.

RWO

[lakeside53]

But many don't... Teco have a 3 digit display and the models I've used won't accept a display scale factor; the Hitachi do.

Adding the 4 digit voltmeter display module the 0-10v output is easy, and allows the display to be away from the vfd.

The Hitachi SJ and WJ series allow the remote mounting of the VFD display in a Nema 4 housing (about $35).

[dvo]

[QUOTE=Chris165]Where might I find one of those readouts?

I'm currently building 10 of these. Very useful for just about everything for me.

http://www.machtach.com

[Chris165]

[QUOTE=Chris165]Where might I find one of those readouts?

I'm currently building 10 of these. Very useful for just about everything for me.

http://www.machtach.com

That looks very useful. If you purchase the complete kit, box and transformer is that all you need? How complicated is it to build one and what is the quality of the parts.

[metalmagpie]

[QUOTE=Chris165]Where might I find one of those readouts?

I'm currently building 10 of these. Very useful for just about everything for me.

http://www.machtach.com

Wow. Big $$$! All you need is the 0-10VDC output from your VFD and a small inexpensive panel meter. If the meter can't scale the voltage then probably the VFD can. Even my bare-bones TECO has this capability. And if neither the panel meter or VFD can then a simple resistor divider (resistor, trim pot, done) will work.

Sure, spend the money if you like. PT Barnum says there's one born every minute. But if you have to build it yourself anyway, why not just use the VFD you have?

On our unigrinders, the things you would mount sensor tapes on sometimes get dismounted and other tooling installed. Plus to install sensors on the machine requires wiring to be run often in areas very hostile to such.

[metalmagpie]

[QUOTE=Chris165]Where might I find one of those readouts?

I'm currently building 10 of these. Very useful for just about everything for me.

http://www.machtach.com

Wow. Big $$$! All you need is the 0-10VDC output from your VFD and a small inexpensive panel meter. If the meter can't scale the voltage then probably the VFD can. Even my bare-bones TECO has this capability. And if neither the panel meter or VFD can then a simple resistor divider (resistor, trim pot, done) will work.

On our unigrinders, the things you would mount sensor tapes on sometimes get dismounted and other tooling installed. Plus to install sensors on the machine requires wiring to be run often in areas very hostile to such.

[lakeside53]

The DVM panel meter approach is good for +/- a few % - certainly good enough for a grinder. There is a simple switch/ resistor network for rpm/sfm, and can be expanded to 10 different settings (sfm will be constant by drive wheel, but rpm varies depending on output wheel size).

Also... we run the DVM module from the VFD 24 volt power out. Takes very little current.

Good luck with optical sensors on a grinder -nothing layers more filth around ;)


Here's the operator console with panel meter working.

http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN2362Medium.jpg

[RWO]

The cheapest Automation Direct VFD , the GS1 series can accept frequency scale factors from 1-160 and the display is 4 digits. A 1 hp drive is $133. They have excellent tech support and warranty.

RWO

[Tait]

The cheapest Automation Direct VFD , the GS1 series can accept frequency scale factors from 1-160 and the display is 4 digits. A 1 hp drive is $133. They have excellent tech support and warranty.

The cheapest might not be your best option.

The GS1, for example, appears to have open ventilation slots. For conductive dust, such as generated when grinding metal, this invites a destructive and potentially dangerous short.

A NEMA 4 enclosure, such as on the more expensive KBDA-24D (here (http://www.electricmotorwholesale.com/9536-KBDA-24D/) and elsewhere) are waterproof and, hence, basically dustproof.

[edit] p.s. A speed control knob, such as on the GS1 or KBDA-24D is much nicer for grinding than using buttons to control the speed.

[Chris165]

Just got back from the motor shop. He had a new leeson 3/4hp dc motor and dart speed control for a very good price (less than 1hp 3ph and vfd). Will most likely go with that. I like that it can be run off the standard outlets. The dart speed control is a model 125d open unit. Can this be mounted in a small ventilated box?

[mf205i]

Not enough HP and if it’s a permanent magnet motor it will attract grind dust-crap.
Mike

[Chris165]

Not enough HP and if it’s a permanent magnet motor it will attract grind dust-crap.
Mike

When the motor is operating the outside of it becomes magnetized? Guess i'm back to the drawing board.

[mf205i]

Pool and spa pump motors are a cheap and plentiful source of 3450 RPM, 1 to 2 HP, single and two speed motors.
Again, 5 to 6K SFM and at least 1 HP for a single speed. Anything less will still make a nice sander, but one that you will soon regret not building to its full potential. If you can’t swing the variable speed, a two speed grinder is a good choice. A 2HP, 2 speed motor with a 6 inch drive wheel will give you 5420SFM for grinding and 2710 SFM for sanding and finishing, an outstanding combination.
Mike

[Chris165]

Pool and spa pump motors are a cheap and plentiful source of 3450 RPM, 1 to 2 HP, single and two speed motors.
Again, 5 to 6K SFM and at least 1 HP for a single speed. Anything less will still make a nice sander, but one that you will soon regret not building to its full potential. If you can’t swing the variable speed, a two speed grinder is a good choice. A 2HP 2 speed motor with a 6 inch drive wheel will give you 5420SFM for grinding and 2710 SFM for sanding and finishing, an outstanding combination.
Mike

You are right about building it to its full potential. I want to do this right the first time. The motor shop had a nice 2HP Leeson 56c motor sitting there which he looked at but thought it would be way overkill for what I want to do. Maby 2hp isnt so bad, just have to run off my 220 plug. As for the NEMA 4X drives, has anyone used the KBDC drives? I have never heard of them before.
http://www.electricmotorwholesale.com/9520-KBAC-27D/
Also, has anyone ordered from this company?

[metalmagpie]

You are right about building it to its full potential. I want to do this right the first time. The motor shop had a nice 2HP Leeson 56c motor sitting there which he looked at but thought it would be way overkill for what I want to do. Maby 2hp isnt so bad, just have to run off my 220 plug. As for the NEMA 4X drives, has anyone used the KBDC drives? I have never heard of them before.
http://www.electricmotorwholesale.com/9520-KBAC-27D/
Also, has anyone ordered from this company?

That's a big price tag. Especially for a drive with no display. Compare:
http://dealerselectric.com/item.asp?cID=28&scID=165&PID=394

Nothing against electricmotorwholesale.com but lots of guys recommend dealerselectric.com for price & service.

metalmagpie

[dvo]

[QUOTE=dvo]

That looks very useful. If you purchase the complete kit, box and transformer is that all you need? How complicated is it to build one and what is the quality of the parts.

Yes, that is all you need. It is very easy to build, nothing to it at all. You of course would need to solve the mounting and environment issues that comes with any installation.

I just buy the chip for $10 and diy the rest as I have most of the stuff already and can customize my own pcb to suit my needs.

[flylo]

fleabay #220772028703 $126/delivered,2 yr warranty. We've had the import discussion. These seem to work fine. I've talked to folks that have used them for several years. I bought several because the price is going up soon. I talked to the guys at Dealers & they said those are imports too. Just what I chose.

[alanganes]

The cheapest might not be your best option.

The GS1, for example, appears to have open ventilation slots. For conductive dust, such as generated when grinding metal, this invites a destructive and potentially dangerous short.

A NEMA 4 enclosure, such as on the more expensive KBDA-24D (here (http://www.electricmotorwholesale.com/9536-KBDA-24D/) and elsewhere) are waterproof and, hence, basically dustproof.

[edit] p.s. A speed control knob, such as on the GS1 or KBDA-24D is much nicer for grinding than using buttons to control the speed.

I've had a GS1 on my mill for years now. I put it in a $20.00 electrical enclosure I got from a local supply place to keep the dust & swarf out, and wired remote speed, start and stop switches. Works great. Just another option...

[Tait]

Good to hear about the GS1 in an enclosure.

I was worried about enclosing the whole thing for possible heat buildup. I live in SoCal and have worked in the shop in excess of 100 degrees (admittedly that's Fahrenheit, so it's not THAT impressive).

Has heat been an issue for you?

[Chris165]

Thanks for all of the replies. I will call the motor shop Monday and see what kind of 2hp motors he has. I was talking to a friend who has the same grinder kit and was supprised at how much power theese things eat up. I have a TECO FM50 3hp for my lathe so might as well get the FM50 for 2hp to keep everything the same. I don't really need the controls on the face of the vfd because it i'll be using a remote on/off/speed controls to keep the drive as far away from grinding dust as possible. Mount it in an enclosure on the back of the base for the grinder and possibly add some fans with filters on them. The price of the drives really go up for the NEMA 4 boxes even without the face mounted controls. What is different about the manufacturer supplied ones vs. purchasing an aftermarket NEMA 4 box?

[lakeside53]

It's pretty easy to mount the VFD in a box if you plan for ventilation and dust. Mine is below - a 3hp Teco in a stock NEMA 3R 12x12x6 box - about $20. The 2 bottom knockouts fit the 3 inch fans perfectly. I put another hole with louver on the upper left side. The fans in the bottom ONLY turn on if the box temperature exceeds 105F (simple thermostat in the top of the box. The VFD fan runs whenever the motor is on. For most short term use, the main fans never turn on keeping the box a lot cleaner. The old laptop power supply in the box is 24 volt for the fans and to drive the sealed relay that switches all power to the vfd - I didn't want a 220v switch with the low voltage controls up in the operator console. YMMV.

If the vfd gets too hot, it will simply shut down and display the heat sink over-temp error.

The filter is just a stock furnace filter cut down. A thin finer filter is put on top of the main filter (not in the picture).

The fans "push" into the box; if not, the box pressure will be lower and it will act like a vacuum bag!


http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN2351Medium.jpg

[Chris165]

I purchased a 2hp 4-pole 220/440 3ph 1750rpm motor. Running it on a vfd drive with 6" drive wheel I figure 2826 sfpm@60hz to 3768 sfpm@80hz which I think is probabably the fastest that motor should run. Now the fun part of selecting contact wheels, attachments and abrasives. For some reason 3450 c-face motors are almost impossible to find used or rebuilt down here.