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Author Topic: Coote belt grinders?  (Read 18040 times)
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Daniel Rohde (D-Vision)
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« on: July 03, 2013, 07:48:01 PM »

What do you guys think of this coote belt grinder? do you think it could be a good grinder for convex grinding? http://www.cootebeltgrinder.com/    

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billy brewton
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« Reply #1 on: July 04, 2013, 06:24:27 AM »

Hey D, imo the coote grinder is a bit to expensive for what it is considering it has no motor and u can't change the contact wheel. Check out polar bear forge he has a grinder in a box that has more versatility at a excellent price. If you know a good machine shop u can get free plans from wilmont grinders.  A good source of motors an vfd's is surplus center. Just my 2cents
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Joe Calton
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« Reply #2 on: July 04, 2013, 09:57:02 AM »

I think you would be better off building a grinder! get wayne goddards $50 knife shop, start looking in junk piles and salvage yards to see what you can find. and start making it!

my first 2x72" grinder that I built is still going, and if I remember right, I had less than $100 into it. the nice thing about building one, besides the cost savings is that you can build it exactly how you want it, and if it ever breaks, you know how to fix it.
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mreich
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« Reply #3 on: July 04, 2013, 10:20:41 AM »

But you have to have equipment to build a decent grinder. Or a machinist friend, or a machine shop you frequent.

I got a Coote with a 10" contact wheel. They are pretty easy to use. I actually use mine quite a bit, in conjunction with my other grinders. It doesn't make a super good main grinder, but I think they are worth the money. If you get one, I can help you make it as good as it can be.

I got a 3hp 3phase motor for free, and that's not unusual. 3 phase motors are cheap. For VFDs, you can't beat Southland Electric. I got a 5hp Allen Bradley VFD, which is as industrial as it gets, for an unbelievably low price. They have incredible customer relations, and they service everything they sell.

I'm not saying you can't make a grinder for less, or make a better grinder, but the Coote has an excellent track record, and I use mine a lot.
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Daniel Rohde (D-Vision)
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« Reply #4 on: July 04, 2013, 12:59:23 PM »

Thanks for the input guys!
so a few Q's  do you guys know the what the differences in motors that are  1 phase 2 phase or 3 phase?
Joe I think that mite be an option but one question how or where to get good wheels?
Thanks guys
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Joe Calton
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« Reply #5 on: July 04, 2013, 01:27:08 PM »

when I built my first grinder, I didn't use anything special to build it.

handheld drill, drill press, tap and die kit, lots of c-clamps to position things before drilling, chisel and old knife for truing up the wheels.

I did not use a welder or a lathe or mill or anything.

ive since built 4 other grinders, and learned a lot on all of them.

for the wheels, on my first one I used cart castors found at the salvage yard, they are some kind of plastic, I used automotive water pump bearings for the bearings and the shaft on the tracking wheel, and the drive wheel was a castor also, and I just drilled a piece of wood for the motor shaft and then turned it in place on the motor till it was a tight fit inside the wheel for a bushing.

even if you were to buy the wheels from usaknifemaker like I did on the last one I built, I think the tracking wheel was $50, and the drive wheel was $50 also.

A grinder is a very simple machine, a drive wheel to turn the belt, a tracking wheel to keep it running straight, and a tension device. everything else is just to hold those parts in alignment and to support your work piece.

after you build one, then if you want another grinder for a different application you can build another real easy.
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mreich
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« Reply #6 on: July 04, 2013, 04:37:47 PM »

IMHO, Joe must have great mechanical sensibility. Knowing that he builds all his own equipment leaves me with little doubt, but I've never really heard of anyone or anything like Joe.

On the other hand, I'm pretty sure my Bader 14" contact wheel, with the bearing cost about $400 alone. The 10" Bader contact wheel that came on my Coote, costs $309 from Texas Knifemakers Supply. I just looked it up. Everyone that I have ever heard of uses Bader wheels, so I don't know how Joe can do so much for so little. I'm kind of in awe.  Smiley

On electrical "phases", it doesn't make total sense, and it's hard for me to explain. There is no "double phase", although there should be. Single phase covers 110 and 220 volts. 3 phase simply adds another "hot" wire, so it runs on 330 volts. It's pretty strictly industrial use only.

For our purposes, single phase motors that draw 1500 watts (or about 15 amps) can usually be wired to run on 110 or 220 volts. What happens, is that a motor that draws 20 amps on 110 volts, draws 10 amps on 220. You get the same amount of power, but instead of the power being delivered through 1 wire, you simply use two. Drawing fewer amps is a big plus, not only on your wiring, but on your electrical bill.

The reason that 3 phase motors are typical on grinders, is that they use the "third leg" to make variable speed, through the use of a Variable Frequency Drive, which is the only way to get variable speed without robbing power and burning out motors. 

I know this isn't an explanation, it's just the minimum required information.
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Joe Calton
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« Reply #7 on: July 04, 2013, 06:25:25 PM »

Thanks Mreich, but im just an average Joe that likes to make stuff. I remember as a kid I liked to work on cars, guess how many carburators I rebuilt before I had one that worked better after I was done with it than before?? I would guess at least half a dozen  Smiley

I hear that everyone likes bader wheels for hollow grinding, but about the only time I hollow grind anything is when im doing a tapered tang, and the recycled cart wheel works well enough for that. If I was going to hollow grind the blade, I would build a 3 wheel machine and run it with the wheel out front, and might buy one of those wheels. but for flat and convex grinding, you just need something to run the belt fairly straight, a platen and a slack area, and those don't need to be anything fancy.

Here are some pics of the 2 grinders I use every day.



both grinders on the same stand, made from 2x4's, with a 1/4" steel plate bolted to the top of the stand



my first grinder I ever built. has a 1 hp 110 volt hard grinder with the wheels taken off, and bolted to the plate, the frame is also bolted to the plate, the drive wheel is a 5" and the motor is 3450rpm, so it runs around 5000 sfpm I think. I use this one for rough grinding, and profiling.



my old tracking setup, the tracking wheel is crowned. I turned it in place by cutting a 2" belt down to 1" and using that to turn the wheel while I held an old knife to it to true it up. I have plans to change the tracking arm to my new style when I get a chance.



my newest grinder. runs on a 2hp 3500rpm motor with step puleys to change speeds, and the motor sits on a hinged/sliding plate that uses the motor weight for tension on the belt, I built the hinge out of 5/8" roundstock, and a 1/2" black pipe nipple about 6" long.



new tracking setup. it is way nicer than the old setup.

on the new grinder, I will end up changing the top wheel to a larger diameter wheel so the bearings run slower and are quieter sooner or later. I also need to make a platen extension for the bottom as it runs with way too much slack to really grind a convex grind, but I use this machine for mostly finish grinding anyways, so its more of a finish grinder and has worked pretty good the way it is so far.

now that Mreich has me sold on wet grinding, Ill set the new grinder up for that, I would do the old one also, but it is an open frame motor, and has some slots in the case under the shaft and Id rather not get water in it. I already have to blow it out with compressed air once a week or so.

I suppose I could clean then both up and paint them, but all I care about is how they grind, and that they work for what I need them for.
« Last Edit: July 04, 2013, 06:32:21 PM by Joe Calton » Logged

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mreich
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« Reply #8 on: July 05, 2013, 12:04:01 PM »

I like the license plate guard, Joe!

That's close to something you'll need on top and bottom to keep the water on the belt.
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Daniel Rohde (D-Vision)
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« Reply #9 on: July 06, 2013, 01:43:57 PM »

one thing I really want to be able to do with a belt grinder whether I build one just for it or not is I want a small (1/2" to 5/8" diameter) wheel for roughing out guards and onther thing but not sure how to do it? is there some thing I could use for a wheel that is the small?
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Joe Calton
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« Reply #10 on: July 06, 2013, 06:21:43 PM »

I usually just rough the guard out with the corner of the belt, and then use a round file, and half round file or dremel tool with 60 grit wheels, and then sandpaper wrapped around a dowel or piece of rubber hose for guards.

If I were to set up a grinder with a small wheel attachment, I think I would either buy the small wheels and build a attachment, or maybe use drill rod of whatever diameter with stationary bearings. seems to me like the smaller the diameter wheel, the harder it is on the bearings and with a drill rod setup, you could run larger bearings.
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mreich
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« Reply #11 on: July 07, 2013, 02:35:34 PM »

one thing I really want to be able to do with a belt grinder whether I build one just for it or not is I want a small (1/2" to 5/8" diameter) wheel for roughing out guards and onther thing but not sure how to do it? is there some thing I could use for a wheel that is the small?

Bader makes all sizes of contact wheels, from 1/2" to 14". I don't even know of anyone else that makes them. They are ubiquitous throughout the industry. I'm not sure, but I think even Burr King uses them. I use a 5/8", 3/4", and 2" on every knife. Then if I'm hollow grinding, I use big wheels too.

If you use or make a grinder with interchangeable tool arms, like a KMG, B-III or TW90, you will be very happy. Actually, the KMG is probably the best normal duty grinder for the money on the market. The TW90 is just one step beyond everything else.
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wnelson aka. dedox
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« Reply #12 on: July 12, 2013, 09:39:42 AM »

if you put a really good, variable speed, high power motor and a really solid base for the coote could it be as a good as a burr king?
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mreich
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« Reply #13 on: July 12, 2013, 11:07:56 AM »

Nope. Not even very close. I made mine as you describe- Heavy steel base, 3hp motor, and an excellent industrial VFD.

Belt changing, tension and tracking are primary differences that separate Cootes from machines that cost so much more.

IMHO, trying to find a used grinder would probably be better, but I didn't realize that when I got my Coote.

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wnelson aka. dedox
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« Reply #14 on: July 12, 2013, 07:04:36 PM »

their still very good for a beginner, right?
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