Yet another NWGS Motor question

C

cbeatti2

Member
Hi. I bought the plans for the NWGS and figured I would see if I could find a decently priced motor first. Unfortunately I wasn't able to find a 1.5HP 1750 RPM motor but did find a new 2.0 HP 2350 RPM (115/230) one. The NWGS plans do mention a 3450 RPM motor will work but doesn't go into much more details. I suspect it is simple a matter of finding a larger pulley for the drive wheel side or should I have other concerns about this motor? What do you think...am I in business or did I make a bad purchase?

Here are the specs:

2 HP
115/230
15 / 7.5 Amps
3450 RPM
Ph 1
Class E (just read that Class E motors are a higher efficiency version of class B)

Model # LR63420 Model D (It appears to be a motor for a fairly nice table saw)

Thanks!
 
I don't have that type of grinder, nor am I an expert on the mechanical side of it, but I am a Master Electrician by trade so I do know the electrical side of it. Usually the 3450 rpm motors would be great with a VFD or variable frequency drive that way you have a larger range of rpms to run. I think you will be fine with it on your set up, you will just have to size your drive pulley accordingly. Say you want so many belt feet per minute using a 2" pulley with the 1725 rpm motor, you would have to change it to a 4" pulley on the 3450 rpm motor to get the same speed. Also use 230 volt to supply the motor instead of 115. Motors love voltage. It will run quieter, stronger and more efficient. Motors pull quite a bit more to start than they do while running. Take your FLC or full load current which is the nameplate rating you stated. At 230 it is 7.5 , take that times 1.25% and that's the amount of amperage it will pull when starting. You end up with 9.3 amps. The breaker will need to be sized accordingly also. Take your FLC times 250% or 2.50, you end up with 18.75 amps. So now we know you need a 20 amp double pole breaker, cause we want to round up our breaker size because it's a branch circuit. The wire can be sized to the FLC, again times 125% . Giving us the 9.3 amps. So we know that we can use 14 gauge wire to hook up the circuit, cause it's good for 15 amps. I hope this helps with the electrical side of it. Be sure and have a licensed electrician do all your electrical work. Very dangerous stuff if you don't know what your doing. I accept no responsibility for your actions, just pointing you in the right direction. :)

Sent from my SPH-L710 using Tapatalk
 
Thanks. I guess I need to sit down and decide if I should wire 230 out to my workshop or not...I thought I could use 115 and move my breaker up to 20 Amp but that doesn't sound like a good idea. I just put a heater in my garage (230 V, and it was wired up by a cert electrician) so perhaps I should leverage that and then I could grind year round. Or maybe I need to go grab a 1 HP motor and be happy with the lower power and the portability of that. Thanks for the well explained reply...I just have some decisions to make now.
 
First of all, do you plan for a direct drive motor? OR, do you plan for a stepped pulley to allow different speeds? With a stepped pulley setup, I'll bet a 1hp motor would provide plenty of power for grinding. About the only place power might be lacking would be above 3,000 FPM which is used for "hogging" a profile. For bevel grinding and finish grinding you'll find working at speeds less than 3,000 FPM the 1hp will provide all the power required.

As Mr Taylor said, you do have to be concerned about the FLA (I think the motor nameplate will use "FLA" rather than "FLC") to provide plenty of starting voltage/current.
 
Hi. Originally I was planning on going with a stepped pulley system, but this motor with the higher RPM threw a wrench into that unless I source out a larger stepped pulley. I am just starting out so I don't think I need anything too aggressive or will be hogging blades (hey, I learned a knifing term). The motor tag doesn't say anything about FLA or FLC but yeah, I think the surge might be a problem at start-up unless I wire in a 230 outlet into my garage. I might have too much power here for what I need from a realistic standpoint. Thanks.
 
If you have a chance to get the 1 hp motor, I suspect it will work just fine. Using a 4 step pulley setup I have the following belt speeds with a 3450 RPM motor. To get this low belt speeds, I had to use a 2.7" diameter drive pulley.

Motor RPMMotor Pulley Shaft Diameter Drive Wheel Diameter Belt SFM
3450242.71218
34502.53.52.71742
34503.52.52.73414
3450422.74877

Have fun, Ken H>
 
Last edited:
Good to know Ken, I might still see if I can get this 3450 to work. I tried out this 2HP at 115V in my garage first and then my shed and it didn't blow the GFI or breaker that my shed is running off of, but it wasn't under any load. It was more of quick experiment to be sure the motor works. Do you recall when you sourced your stepping pulleys Ken? When you say 2.7" diameter drive pulley, you mean drive wheel I think, right? It's Sunday and I know my brain is taking a bit of a vacation today, but am wondering about the chart above. Wouldn't the larger motor pulley size result in higher SFM and the smaller motor pulley drive result in a lower SFM...the chart seems reversed to me as far as SFM <---> pulley ratios. And perhaps I am reading it all wrong. :question:
 
Yes sir - you are correct. When I was building the table I got the motor/shaft in wrong columns. I have now corrected it.

Yes, drive wheel, not pulley.

Here is the 4-step pulley I used: http://tinyurl.com/p65deaj ($19 each, and with both pulley's ordered I think that includes shipping.)

They are not perfect, but still run "ok". I trued them up on lathe and it seemed to help a tad.

As long as the cord connecting the motor to plug is sufficient to prevent excessive voltage drop, you "can" run the motor on a 15 amp duplex outlet. The grinder will always be starting with no-load. If you have a 20 amp rated 120vac duplex outlet (with correct breaker & wire) you should be just fine for the 2hp motor. You mean that motor tag doesn't show FLA anywhere? Is this a new motor? If so, do you have a link to where you ordered it?

Ken H>
 
SAM_0592 (528 x 396).jpg It seems like a new unused motor (very clean all around), although it is dated 2006, so not new as in recently built. Definitely doesn't say FLA, but there is a large capacitor under on of the shrouds, and another smaller one in the wire connection box. I might try something like putting the step pulley on the drive shaft and have the motor mounted to move laterally (then locked in) to support the different pulleys, with the motor on a hinge supplying the tension to the belt through all of the pulley configurations. I would keep the motor pulley the same size (2" I suppose).
 
Personally, I think you'll find the 3450 a little fast.

I use a 1725 (or somewhere thereabouts) RPM motor with a 3 step pulley setup, and I RARELY go to the third (fastest) step. Sometimes I wish the slowest setting was slower yet.

As for using a 1HP motor, I think you might get by with that on a direct drive or a 2 wheel set up, but for a belt/shaft/pulley system on a 3 to 4 wheel grinder, I think you'll be bogging it down quite a bit if you lean into it or grind very wide material. 1.5 HP is the minimum I would go, given the option, and 2 HP is even better.
 
My 2 cents is to use whatever motor you have in front of you until it blows up!
I have used many old motors over the years and while a TEFC 1 1/2 hp or bigger 1750 rpm motor is optimal you can use what you have. I have a pre WWll 2 hp motor with the oil ports thats open and I have been waiting for it to burn from metal grit for years.

I do recommend a 4 step pulley for the 3400 rpm motor and I have found them at Heating and air repair & Hardware stores. Put a smaller pulley on the motor to reduce speed.
Because if you run it to fast, you can separate the rubber off of your contact wheels. Ask me how I know this?:biggrin:
 
cbeatti2 said:
View attachment 47448 It seems like a new unused motor (very clean all around), although it is dated 2006, so not new as in recently built. Definitely doesn't say FLA, but there is a large capacitor under on of the shrouds, and another smaller one in the wire connection box. I might try something like putting the step pulley on the drive shaft and have the motor mounted to move laterally (then locked in) to support the different pulleys, with the motor on a hinge supplying the tension to the belt through all of the pulley configurations. I would keep the motor pulley the same size (2" I suppose).
Click to expand...

I do stand corrected on the FLA - I've got a couple of motors that also only have "amp" on the name plate. Industrial motors "tend" to have FLA. Your idea of using a hinged plate for the motor works great. Makes changing speeds very quick 'n easy. Since you're sorta limited to size on the stepped pulleys, the place to change belt speed is the motor drive wheel. Note the table that shows slowest speed as 1219 FPM with 3450 RPM:

3" drive wheel gives 1355 FPM,
4" drive wheel gives 1806 FPM
5" drive wheel gives 2258 FPM

The 4" and 5" are a bit fast for the lowest speeds for fine grit belts.

Actually, a 1hp motor works better with a stepped pulley setup rather than direct drive. Using the same size drive wheel, the 1 hp motor with a 2"/4" pulley setup for low speed gives about the same torque as the 2hp motor with drive drive.

Ken H>
 
How about the step pulley on the motor and a 5 inch (or 6 maybe even) pulley on the drive shaft? I haven't done the math yet, just imagining how to properly gear down the motor speed. I got a good deal on this motor yet it would hurt to not put it to use and need to buy another.
 
Well, it depends on the drive wheel diameter (3450 rpm).

With a 4" drive wheel, 5" shaft pulley = 1445 SPM; 6" Shaft pulley = 1204 SPM

With a 5" drive wheel, 5" shaft pulley = 1806 SPM; 6" Shaft pulley = 1505 SPM
 
Thanks for doing the math Ken. :happy: I think we are in the ballpark of acceptability...those speeds will vary up and down with the stepping pulley. Probably go with the 4" drive wheel and save a little money too.
 
You must log in or register to reply here.
Back
Top