Converting a KMG to direct drive...?

As per the provided link:

I removed the original KMG pulleys, bearing blocks, and shaft and TIG welded in a plate configured for 56C motor. I know have the only direct drive KMG I have ever seen. This modification fixes the absurd drive arrangement of the factory KMG. The factory drive arrangement takes up space, seems to rob significant power, and adds to the vibration I mentioned above.


12345678910 said:
http://sharpwerks.blogspot.ca/2013_03_01_archive.html
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This is PRECISELY what I'm talking about doing. Thanks, Count!
 
Matthew, I had just bought out a man's whole powder supply when I finished this grinder and didn't move the powder before taking the picture and trying the grinder. I moved the powder to storage a short time after. I think you could check the spacing on your idler wheel and drive wheel to make sure they line up with the belt in the exact center and then space the contact wheel to match using machine bushings. Also, lubricate and tighten the idler arm pivot. This can stop a lot of vibration. Good luck . Larry
 
butcher_block said:
maybe right abut the bearings tho i am on my 3rd driveshaft
maybe im jsut hard on things
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I think it has something to do with the amount of grinding you do :) :thumbup:

Having problems uploading the pictures from my phone, should have them up tomorrow.

correction on the base plate, I used was 3/8" aluminum plate, 1/2" plate would be plenty thick.

I am running a 3450 rpm 2 hp motor with 5" drive wheel and it seems a little slow, but it sure runs smooth.
 
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this latest sheet im keepig al the grindign off to the side to see the waste that i trash ever sheet i get in the shop (im sure its disgusting) i have half a 5 gal bucket filled so far from a 2x3 foot sheet .100 thick
 
grinder in normal position

mounted on car seat rails to bump out to clear the VFD when on its side and to go over the trough


motor bike jacking base to adjust the height (not the most stable, a work in progress)


with removable trough I'm setting up for wet grinding
 
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MeatRobot said:
...1/2" aluminum plate...when you tension the belt it flex's the plate like a bow.
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Nice mod! However, it is worth pointing out that your base plate does not appear to be 1/2" thick, which may explain why you're getting the bow. The KMG receiver top and sides are 1/2" thick, and look thicker than your base plate.
 
Also, that appears to be a 4" drive wheel, too. Would explain your speed concerns...
 
P.Brewster said:
Nice mod! However, it is worth pointing out that your base plate does not appear to be 1/2" thick, which may explain why you're getting the bow. The KMG receiver top and sides are 1/2" thick, and look thicker than your base plate.
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your right I measured it last night its 3/8"s if I had to do it again I think that 1/2" would work fine.
 
Matthew Gregory said:
Also, that appears to be a 4" drive wheel, too. Would explain your speed concerns...
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I did get a second drive wheel that is bigger because I was concerned with torque loss at low speeds with a 3450rpm motor I have the smaller wheel on right now, I haven't tried the bigger wheel yet. I still haven't done any real grinding with it yet
 
Ill have to agree..I used a pulley drive grinder for a long time and when I got a direct drive it was like night and day..Not a knock on KMG, I like them and have used them plenty..i even built a really nice sliding system for our grinder that got 4 true speeds and used link belts..It is very nice for a pulley set(also the quitest pulley set up Ive used period) up abut our direct drive grinder is so quite and smooth you will literally forget it is on..No vibration and no noise other than a sound of air coming off the belt as it moves..
 
Resurrecting this one, because the conversion to direct drive has JUST been completed. Took a bit of doing, and there are a handful of considerations...

My machinist friend Joe made this one, and it's obviously a protoype. The idea was to make this an EASY conversion, should anyone else want to do this. It assumes you have a 56C face mount motor. Mine is 1725RPM, 2hp, with a KBAC-27 vfd which I run in 2x mode (speed doubled). The adapter plate and motor bracket use the existing pillow block mount holes to bolt to the KMG body.

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Other than being easy to do, it also means you aren't permanently modifying the grinder, so should you choose to return it to stock, it's just as simple.

One of the issues had to do with the length of the factory pulley shaft - it's quite a bit longer than a 56C face motor's output shaft. We could have just had the drive wheel sticking off the shaft a bit, but that's icky. Joe elected to make a custom drive wheel. This one is 5.5" in diameter, with an offset to compensate for the difference in shaft length:

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With everything mounted and ready to roll, you end up with this:

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As you can tell, I've also added an additional tool slot. That sucks up a lot of real estate, so along with moving the drive pulley back AND increasing the drive wheel diameter, you can quickly run out of belt length. My 12" wheel just barely fits. Nonetheless, every one of my attachments works, including my Bader double billy roll, which eats up belt length like there's no tomorrow. The flat platen and contact wheels are a custom rig I made, with a 2" wheel on top and a 3" on bottom. That's one thing my Wilton got right. Should be a pinch smaller up top (1-1/2" would be dandy), but I had the wheel, so there it is.

While I'm at it, here's a couple shots of the gas strut tensioner and the monster custom ape-hanger tensioning arm:

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Tomorrow will be cleanup and re-locating the spark shields, and preparation for other additions, but this is enough for right now, I'd say. Quick vid of the grinder running wide open with the 12" wheel - previous to this modification, that belt would shift as much as 1/8", and it could NEVER have been run at this speed. The vibration was unbearable. Even the noise is reduced dramatically!

 
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Dang... I wish my KMG ran that smooth!! :eek: Is your buddy planning on making more of those conversion plates\drive wheels??
 
JBC69 said:
Dang... I wish my KMG ran that smooth!! :eek: Is your buddy planning on making more of those conversion plates\drive wheels??
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He's looking into it. When I find out what he comes up with, I'll let you know!
 
Matthew, Your KMG is beautiful and runs perfectly. I also added a second tool arm slot this week to my KMG. I had to lower my tool bench 2 inches to compensate for the extra arm. I have built four or five tool rests for my other direct drive grinder and this is the best one I have used. It will be used most of the time on my KMG. Thanks for the photos of your project. Larry

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Do you sit when you grind, Larry? I stand, and I'm tall and skinny - I keep my grinder up pretty high so I can lock my elbows into my sides and really push.

I still have to make a rest like that. I almost never use them, though, and I think that's foolish. I should be taking advantage of the increase in stability. I've just never done it that way - always just done it freehand.
 
Matthew, I was a "self taught" knife maker for my first 3 years and then I started buying dvds of Bob Loveless and Stephen R Johnson and then found Blade Forums where I asked a lot of questions. I had already started grinding sitting down with a fixed height chair and a welded rest I designed for myself and now I only feel comfortable grinding from a sitting position. Last March I had a knee replacement and tripped and fell afterwards and broke my hip...another replacement. I was 64 years old and I am still walking with a cane and going to physical therapy. Long story but I am glad that I can grind sitting down because as I get older I will always be able to grind sitting down.

If you feel comfortable grinding freehand then by all means do what works for you. I use a 2 inch wide rest so that I can rock my blade to follow any curve. You might want a rest adjustable for angle for grinding swedges. I like a setting of about 65 degrees for a false edge and a 10 inch or larger wheel. Your new modifications to your grinder are great and I want to see some photos of your new knives. Thanks, Larry
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