NWGS completed! Now questions...

D

Dagr

Joined
Jan 25, 2006
Messages
76
I finally finished building my NWGS following the plans provided by Mr Mickley. I spent all day today with my respirator and safety glasses on grinding away at some steel (and my fingers, but skin grows back...)

Question after photos :
Grinding
Grinder
Grinder 2

Using the three step pulleys, how fast am I going? My motor is 1750rpm, so far I've only used the slowest speed, as I get used to it. But I haven't made any sparks yet. I'm moving plenty of metal - does the lack of sparks mean that I'm grinding too slow, or just that the belt and metal are staying cool?

Thanks for any help!

~ Dagr

ps. It took me *way* too long to figure out that I can't post photos...
 
Sparks kind of depend on the steel you're using and your belts.

I'm not sure about your pulleys, but if your three settings equate to 1:2, 1:1 and 2:1, then I think you're running at around 900sfpm at the lowest speed, which is a bit on the slow side and you might not see sparks. That's assuming you're running a 4" drive wheel from beaumont (what it looked like to me). Anyways, it's not "too slow", I don't know that there is such a thing, but on your highest setting, your grinder should fly. I run about 1600sfpm on my current setup and it's a tad slow for me at times, I think 2000ish is probably the happiest medium - yours should run near that on the middle setting.
 
Good looking grinder, wish I had time and tallent build my own.

I run a Coote with step pullies, I don't know the belt speed, but I can speed it up to hog with or slow it down for finish work. I'd love to have varible speed, but I don't know if I ever will get it as the step pullies work good.
 
To determine your speed, first divide the diameter of the motor pulley by the diameter of the drive shaft pulley, then multiply this by 1750, the rpm of your motor, this will give you the speed in RPM of your drive shaft. Next take that and multiply it by the circumference of the wheel it's driving to drive the belt to get your fpm

example, what i've been using, 1725 rpm motor, 2" step of a 4-3-2 pulley on the motor, 6" step of a 6-5-4 pulley on the 10" coote

1725x2/6 = 575 RPM
575 RPM * 2.6 Feet per revolution ~= 1500 fpm belt speed.
 
If you are griding stainless you won't get any sparks,just dust.
 
Got a little work done on my NWGS this weekend. Not much and I still have quite a way to go, but it is shaping up. No problems with the construction, the plans are great. I just gotta order the rest of the parts and get it completed.

Bob
 
Very nice looking grinder. I have my steel cut and squared up, now I just need to build the thing. Every time I see pictures it gets me excited. Thanks for the pictures and congrats on the nice grinder.

-Mike
 
I just got my copy of the plans today and have started to look over all the parts. The plans are very well laids out, and I have already begun to assemble the parts, though I am maing a slight adjustment by using a wider base Tubing that the plans call for. I have a wider square tubing stock available to me, and it will allow me to set the pillow bearings further apart for stability. I am also planning on welding up the majority of the connections, but the plans are still extremely helpful. I will post pics of the completed grinder once I have it running.

My only quuestions so far are regarding step pulleys and pillow blocks. All of the ones I've found locally specifiy for fractional horsepower only. the plans specify a minimum 1HP, and I have a junkyard motor that is 3HP that I'd like tto use on this. Are the "fractional Horsepower only" warnings something I should concern myself with or will these pulleys and pillow blocks work for me?

Kindyr
 
Dagr, great looking grinder build. I'm going to post a few of those pics on my website if you don't mind. I really gotta paint my next build. It really looks good.

Kindyr, generally the pillow blocks called for will be fine. I'm not sure what step pulleys you are looking at. I know chicago casting makes some that are for less than 1hp. There are better step sheaves out there that can handle up to 5 hp.
 
I am in the process of building a machine however the motor I have is 3450 rpm. So if I use a 2" motor pulley to a 6" driven pulley that should give me a 2987 fpm speed. Is my math correct and is that too fast? Should I keep looking for a 1750 rpm motor?

MW
 
mwinans said:
I am in the process of building a machine however the motor I have is 3450 rpm. So if I use a 2" motor pulley to a 6" driven pulley that should give me a 2987 fpm speed. Is my math correct and is that too fast? Should I keep looking for a 1750 rpm motor?

MW
Click to expand...

I didn't check your math but that SFPM isn't too fast to begin with. It's kinda fast to finish with as the slightest twitch will really have you chasing grind lines trying to get them matched.
 
With all the money you saved by building DYI grinder, consider VFD setup :)

You should be able to score 2HP motor + 2HP VFD for around $600 if you shop around.

On sparks - although I can crank up my grinder to high SFPM and lean in with a bar
of O1 to throw 15 foot long trail of sparks, most of the time I want more controlled
grinding and don't mind having to spend few extra minutes to grind that blade :)
 
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