KMG grinder

I've had one for a couple years now... It's been a machine that I've had to tinker with in order for it to work in an acceptable manner. My biggest complaints about it are the belt wobble--solved by squaring up the drive wheels and installing a better tension spring or gas piston--and the fact that it's about as smooth as a forklift driving down a washboard road. The pulley system produced quite a bit of vibration and only gets worse as you ramp the speed up. The cheap quality bearings they use don't help at all either; I've had to replace almost every single one on the machine and I'd consider that unacceptable considering that I only use it a couple times a week at best.

Overall it's a decent machine and I've turned out a bunch of really nice knives on it, but there is MUCH better out there for comparable money. For a few bucks more, I'd seriously look at Esteem grinders. They run MUCH smoother and quieter--direct drive is the way to go in my opinion and I'm currently saving up my pennies to do a direct drive conversion on my KMG.
 
Many moons ago, there were basically three choices available to knifemakers: the Wilton Square Wheel, which worked but lacked flexibility, the Bader BII/BIII, which was the right answer but spendy, and the Burr King, which was smooth as hell but kludgy to make tooling changes to. The KMG was designed by Rob Frink to compete with all of them, and do so really inexpensively, while also being a platform which could be added to. He was active in the community, and a string of really innovative products sprang up (the rotary platen, for example). You could use your own motor and have a cheap three speed grinder with his pulley sheaves, or you could run variable speed with a vfd. Replacement parts were cheap, and readily available at most hardware stores, should something fail.

I can't speak for quality control at that point, but I can tell you that there are plenty of examples like JBC69's. Seems as though, if you manage to get a good machine, it's great, but if you don't...

I've had to go to great lengths to get my KMG working the way it should have from the beginning. The driveshaft for the pulley/drive wheel was bent, causing tremendous vibration and belt wobble, the tracking wheel adjustment was skewed, and almost every idler wheel was threaded into its attachment cock-eyed, so tracking was horrific. I've since made my machine direct drive, eliminating the pulley garbage, and my friend Joe is making a kit to replicate what we did to mine to fix this for others. They sell briskly, which leads me to believe I'm not the only chap to have these issues.

Long story short, since the advent of the KMG, the market has become rife with exceptional products designed to compete with it, and in many cases handily surpassing it - all for the same, or less money, and with genuine customer support behind them. It really is a buyer's market. Esteem, Pheer, Weurtz, Outlaw, Northridge, AMK, Oregon, Wilmont. Any one of these are great machines, and I don't remember hearing a single complaint about any of them - really just comes down to preference as a result of features, or grinding style. Product reliability or customer service don't ever seem to come up as concerns with them.

Even the briefest of searches will turn up lots of info on this. I still contend the best way to choose a grinder is to go somewhere and use someone else's - see for yourself what works and what doesn't.
 
JBC69 said:
I've had one for a couple years now... It's been a machine that I've had to tinker with in order for it to work in an acceptable manner. My biggest complaints about it are the belt wobble--solved by squaring up the drive wheels and installing a better tension spring or gas piston--and the fact that it's about as smooth as a forklift driving down a washboard road. The pulley system produced quite a bit of vibration and only gets worse as you ramp the speed up. The cheap quality bearings they use don't help at all either; I've had to replace almost every single one on the machine and I'd consider that unacceptable considering that I only use it a couple times a week at best.

Overall it's a decent machine and I've turned out a bunch of really nice knives on it, but there is MUCH better out there for comparable money. For a few bucks more, I'd seriously look at Esteem grinders. They run MUCH smoother and quieter--direct drive is the way to go in my opinion and I'm currently saving up my pennies to do a direct drive conversion on my KMG.
Click to expand...

JBC69, do you have any resources to point to for getting a KMG less wobbly. I'm a complete newbie when it comes modifications, but i'd like to give it a whirl.
 
Like Mathew I remember when we had about two choice the square wheel and the bader. I didn't even know about the burr king back then..Even at that the bader cost more than my trucks did at the time.
We have a Coote with the disc and small wheel attachment. Its the best of that two wheel style grinders I think. We bought an esteem with 2hp VFD about two years ago and its as smooth as silk. Got it with the platen, 8" wheel and small wheel attachment. Its as smooth as any grinder Ive ever used and smoother than most..
I don't want to sound like Im dogging the KMG because im not. Its a tank and built to last, thousands of good knives have been made on them..Now to the "honest part"..All of the KMG's Ive used were not by any means smooth. Like riding a tater wagon compared to baders, esteems and other nice grinders.
Using a LINK BELT helps smooth the motor out and truing a few other things helps belt wobble. They are a good grinder but keep in mind to get it really smooth you might have to tinker with it a bit.
 
shamu said:
JBC69, do you have any resources to point to for getting a KMG less wobbly. I'm a complete newbie when it comes modifications, but i'd like to give it a whirl.
Click to expand...

direct drive is the way to go in my opinion and I'm currently saving up my pennies to do a direct drive conversion on my KMG.
Click to expand...

JBC69 said it all right there - direct drive. "IF" I were considering a purchase of a new KMG I'd push very hard to get them to drop the pulley/shaft setup and drop the price some. The price drop should just about cover the cost of a Chinese VFD drive, and the 3 ph 2 hp motor required would be about same cost as a 1 ph 2 hp motor. Simple to just bolt motor base plate direct to mounting plate for grinder.

Later
 
Ken H> said:
JBC69 said it all right there - direct drive. "IF" I were considering a purchase of a new KMG I'd push very hard to get them to drop the pulley/shaft setup and drop the price some. The price drop should just about cover the cost of a Chinese VFD drive, and the 3 ph 2 hp motor required would be about same cost as a 1 ph 2 hp motor. Simple to just bolt motor base plate direct to mounting plate for grinder.

Later
Click to expand...

I guess i was also interested in...

"solved by squaring up the drive wheels and installing a better tension spring or gas piston"

in addition to exactly how a direct drive conversion would work.

thanks
 
I have used a KMG for a couple of years now. I haven't had any issues with mine but having said that I have not tried or seen any other machines so maybe I'm just tolerating it's limitations because I don't know any different or better. This and other threads make me want to try some of the other grinders out there. I would love to try an Esteem and Wuertz first. I'll definitely be getting another grinder in the next year or two.
 
Customerservice is horrible. I need a couple of new small wheels for mine but I need to place a minimum $1000 order for international orders.....
I was lucky to get an answer though. First time in years.

I am getting a Northridge.
 
Pertinent posts from Brian Fellhoelter from this thread:

http://www.bladeforums.com/forums/showthread.php/831688-KMG-Grinder-Tweaks-Thread?highlight=KMG



Fellhoelter said:
It's hard to explain it all, since it was actually a pretty big procedure.

Since there are no dowels or anything in the build, and the screw holes are oversized to allow the screws to fit, the whole machine wasn't square.

I started by making sure the receiver for the arm was actually square to the drive wheel.
It wasn't, so that took some creative adjusting and measuring.
This is an important step, because otherwise the drive and driven wheels end up with axis that are not parallel with each other. something like this \ |
They need to be parallel, more like this ||
Hope that's clear, because it's the key.

Once that was done, and I was sure the axles weren't cocked in relation to each other, I put the tracking wheel in a neutral position, and took a measurement off of it.
Again, no easy task, I had to get creative.

I then made sure the centerline of the drive wheel was on the same plane as the tracking, and did the same for the wheels on all the tooling arms.

All was better after that.

Maybe a drawing will help a little.

Screwy_Tracking.jpg


This is looking straight down on the grinder, it's just the wheels.

You can see on the right, what I started with.

The wheels were crooked in relation to each other, and the centerlines didn't all line up.

The left, is what you want.
Click to expand...

Fellhoelter said:
By the way, I discovered all of this, when I built my own grinder.

I made a 3 wheel grinder that tracked like a dream, and when I moved the belt to the KMG, it wobbled all over the place.
Same belt, 2 machines, 2 different results.

I investigated, and fixed it.

It seems like when the wheels are crooked to each other, the drive wheel is trying to drive the belt off of the contact wheel/platen/slack belt.
It only gets so far before the tracking wheel overcomes it, and brings it back.

Diving off and coming back = Wobble

At least that's today's theory.
Click to expand...


The direct drive kit my buddy makes is my version of David Sharp's direct drive conversion. I saw what he did, and my buddy Joe and I figured out how to make something that didn't require it to be welded in place. I knew the pulleys, even after squaring everything up, would be a possible source of power loss and vibration, so rather than continue to troubleshoot them, they were yanked. Absolutely no regrets for ditching them.

Erik, I hate hearing that, man. Not that it will make you feel any better, but I just heard from another maker yesterday that wants a direct drive kit. He's on the other side of the world, and flew his KMG home after breaking it down and putting it in his suitcases, only to put I back together and have all the same problems we have. It's never worked right, the idler wheels are all crooked, etc, etc. No customer service support. He's on his own, despite buying the machine NEW from Rob.
 
I've been having problems with mine recently where the belt drifts after about 5 or 6 minutes grinding. I don't know if any other grinders have this issue. For example, if I'm letting the belt roll over the side of the platen in order to round a plunge, it will drift back the opposite way. I don't remember ever having this problem until recently. Like a couple of others have said, there's just a lot of really nice features on other grinders in the same price range. You're limiting yourself in my opinion if you don't shop around.
There's no doubt you can make great knives on the kmg, but you may have to tweak or alter some things in order to get more features that come standard on it's competitors.
 
I'm a little surprised that Rob hasn't updated the design of the KMG at all in these years, or AT LEAST offered a direct drive adapter.

It seems that the majority of complaints (vibration, misalignment/out of square or parallel) are very simple fixes, especially using 'state of the art cnc machines' as his website states.
I imagine that despite the arguably better options that are available now days, Rob must still be keeping up with sales enough to not feel the need to update or improve anything.
Perhaps the problems are as prolific as perceived?

Who knows...
 
josh i think more tension on the belt might be the answer. if i do not put enough on mine, it tracks fine but when i apply pressure the belt shifts to one side. ( but it still runs with no wobble). i guess i got a "good" kmg just by chance. i had heard in the past some are good, some are not. i think an important feature is for the grinder to tip on its side or horizontal, which the kmg does not. if i get another one it would have to have this feature.
 
I think about getting a second grinder sometimes, but space...
I got Brett's Esteem grinder, and I am so glad I did. Two years and I haven't had any trouble with it. If my belt is jumpy, I know it's a bad splice or something else wrong with the belt.
I worry about the base a little sometimes because I grind wet quite often. But the powder coating seems to be holding up well.
I do a lot of thin tip work on both flat platen and rotary platen and the grinder just works. No vibration. His customer service is quite amazing too. He WANTS to make things right if there are any issues.
I've called him once or twice for what I thought was a grinder problem, turns out it wasn't the grinder. But he helped me figure it out.

I can't speak for the KMG, but I am not looking back either. No regrets at all.
 
You must log in or register to reply here.
Back
Top