Variable Speed vs. Step Pulley (KMG)

silver_pilate

silver_pilate

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Oct 30, 2002
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Well, with a year end bonus and Christmas rolling around, I just may be able to afford a KMG!! Right now I'm grinding on a one speed Grizzly that runs WAY too fast for detail work, so I'm eagerly looking forward to the day when I can use a better grinder.

My understanding is that with a basic setup, top speeds will be roughly the same regardless of variable speed or step pulleys, so here's where I'd like to get some feedback.

With my bonus and some gift money, I can probably just barely manage the 2hp step pulley KMG 10" wheel and platen package. If I opt for a 2hp VS motor/driver, I'll have to wait a while longer before I purchase the motor, so I'll just have the KMG sitting idle.

For all of you running KMG's with variable speed or step pulleys, what do you think? Wait for the VS motor? Or get up and running with the step pulley setup? Is a three speed step pulley enough, or do I need that infinite control of the VS?

Interested in hearing your opinions. Thanks!

--nathan
 
I have used both, I LOVE the variable speed setup. But I use the step pully set up that I had gotten with the motor from the person that is teaching me to make knives when he upgraded to DC drive.
The 1.5 hp AC motor I use will bogg down if you put a good bit into it and his with a 2hp DC drive will not bogg down no mater what.
 
You just cannot beat variable speed. I had to first use step pulleys until I could afford VS. My recommendation would be to do what you need to do but have your end game plan to have VS.
 
A big advantage of the KMG is no spec motor. Maybe you can dig up a free or dirt cheap used motor while you save up for the vs. Who knows, you might find a vs bargain while your saving up for the brand new version.

Good luck, Craig
 
When I got my KMG I set it up with step pulleys and had the motor hanging so it was easy to change speeds and it was ok. I then made a kmg clone and put a variable speed on the kmg and use the clone with the step pulleys. I love the variable speed. It helps a lot. But, if I was you I would get the KMG and steps. Then keep my eye open on craigs list/Ebay for a 2hp 3phase or DC motor cheap. Then get a controller. You can grind away and always find a use for the original motor.
 
I agonized over the same question this summer Nathan. In the end I opted for the step pulley/2hp setup and spent the extra money on a MAP arm. For now with my limited experience, it proved to be the right decision. When I'm ready and the money is there, I would like to upgrade to the VS, but for now the step setup is more than enough. Best of luck ~Cliff.
 
I use a four step pulley and a 2 HP motor I had laying around. 1,000 SFM to 5,000 SFM. I could upgrade to VS with little trouble, but I haven't done it because I really haven't felt the need.
 
Nathan, my VS KMGs runs at 3450RPM (drive wheel speed) @100%. I find that, when I actually look to see what the setting is, I tend to use 100 at the profile and initial grinding, around 60 & 30 the most for bevel grinding, and around a 10% crawl for some occasional delicate tasks in the plunge. Mostly I just crank it to where it "feels good" and go with that, with little regard for the numbers.
I'd check the ratios of the pulley sets and see where they could put you in the spectrum of final speeds and what kind of inexpensive 2HP motor you can acquire to get going. A good grinder with pulleys is more important now than waiting for the VS.
 
My KMG is set up with a 2 hp AC wired 220, with the pullies.
my only problem with the step system is keeping the drive belt tensioned. I had it set up where the weight of the motor was keeping it tight, but start up torque would really kick the motor, and laying into the platen would slow the speed down. So now I have a slightly loose drive belt with a solidly mounted motor.
Other than that I find the pulleys a useful solution until I can get a VFD.
I almost never use the fastest speed, because it slows down too much. The middle step removes material the fastest for me.
 
I'm too poor to buy cheap! Buy it once and buy it right! Get the VS, in the long run it will pay for itself.

In this economy your lucky to be getting a bonus!
 
Nathan

I have traveled the exact path that you are on. I started with a Griz. I then converted the Griz to a step pulley setup. I then got a KMG with step pulleys and have since gone to VFD.

The VFD is the only way to go. I am sure that you have more discipline than I do, but I found myself only needing to touch up something up a little bit and rather than switching the belt, I just left it where it was and ended up taking off more than I should.

If you do a little shopping around, you might be suprised how little a VFD will cost you. My entire setup for the drive and motor was around $250. This was with a new drive and new 2 HP motor. The motor was a lucky ebay find.

Brian
 
I put the pulleys on my KMG. Since I left the race yrs ago, taking 60 seconds to change the v-belt was no big deal .
 
Nathn
If all you can afford at the time is step pulley get them. Just the upgrade of switching to a KMG will make a huge improvement in your work. I have been running the pulley's for a couple of years and been happy with them,but will upgrade to VS when able.
Stan
 
My top belt speed with a steep pulley is over 5000 SFPM, My low speed is around 900 SFPM I can usually find a good working speed with the other 2 choices. My motor is on a hinged plate and I could change the belt one handed if I wanted to.
Just my $00.

Mike
 
My vote is for variable speed. It is SOOO fast and easy, and like Brian mentioned... you won't get lazy and not change the speed when it just requires turning a dial.
 
I don't even hinge the motor, it is just screwed down. I put this together in about 15 minutes and got back to something else and have never revisited it.

Anyway, the belt is an appropriate tension. To change speeds I roll it onto the smaller pulley first, then up onto the bigger pulley. It takes no more than 5-10 seconds to change speeds.

That said, I wish it was a VS, but it just hasn't been worth the PITA to change it over. Get the VS if you can swing it, but don't sweat it if you can't.
 
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