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Author Topic: Knife Grinder?  (Read 5341 times)

keweenaw

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Knife Grinder?
« on: September 28, 2012, 08:17:37 PM »
Picked this up from a neighbor yesterday. 
The wheel is 27" in diameter and 3 3/4" wide.  Has an attached wheel dresser (stone is in really good shape, nice and flat with only a few minor edge chips) and a cast iron can to attach to drip water on the wheel. I put a littel oil in the oil cups on the bearings an it a few turns had it spinning nicely.   When I mentioned getting this to another friend this morning and said I was going to look for a gear reduced motor to drive it, he gave me a reduced variable speed motor/gear unit that is continuously variable from 15.4 to 154 rpm.  Anyone have any thought about what an appropriate speed might be for a unit like this?  There is a 14 1/2" pulley on the other side where it was probably driven by a belt from a line shaft.  It should be wonderful for doing nice cool grinds of knife blades, but definitely not very portable!

Tom
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Offline heinz

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Re: Knife Grinder?
« Reply #1 on: September 28, 2012, 09:29:52 PM »
I would try starting from 15 to 30 rpm.  With the size of that old wheel and the mounting, shake may be considerable as you go beyond 6o rpm
« Last Edit: September 28, 2012, 09:31:49 PM by heinz »
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Offline T*O*F

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Re: Knife Grinder?
« Reply #2 on: September 28, 2012, 10:00:59 PM »
Regardless of the variability of the motor, you will have to do some math to figure out what diameter drive pulley to put on the motor.  RPMs will be variable depending on it.
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Offline Chris Treichel

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Re: Knife Grinder?
« Reply #3 on: September 28, 2012, 10:28:13 PM »
You probably want it spinning real slow as any high rpm could cause it to come appart and that would launch some pretty big pieces of rock... maybe a foot treadle would be better.
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Offline LRB

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Re: Knife Grinder?
« Reply #4 on: September 29, 2012, 12:48:03 AM »
  I would second that, or at least keep the RPMs slow. That stone is a mere pebble compared to those used in cutlery factorys in the 18th c. and earlier, but still could do a lot of damage if it came apart.
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Offline Habu

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Re: Knife Grinder?
« Reply #5 on: September 29, 2012, 04:16:59 AM »
Check your bearings for play.  If they are babbitt and in good condition, you should be OK at 30 RPMs.  A friend had a similar setup w/24" wheel.  After I re-poured the bearings it ran fine at 30-35 RPMs.  It worked great for sharpening axes. 

BOLT IT TO THE FLOOR.  It doesn't seem like it, given the weight, but they can be a bit top-heavy.
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Offline The Original Griz

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Re: Knife Grinder?
« Reply #6 on: September 29, 2012, 02:45:00 PM »
The one I have has a bicycle frame mounted to it and you pedal it for the wheel to turn, so that should tell you how fast it turns. Keep water on the wheel and if you work it slow and wet you will get scary sharp tools and knifes. Them old timers knew what they were doing.
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Horner75

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Re: Knife Grinder?
« Reply #7 on: September 29, 2012, 06:46:33 PM »
Another vote here for very slow rotation! .... Better than possible injury to you or damaging a fine old machine!

Rick
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Offline Collector

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Re: Knife Grinder?
« Reply #8 on: September 29, 2012, 08:33:16 PM »
You probably already know this, but always drain the water when not in use.

Nice addition to your collection!
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keweenaw

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Re: Knife Grinder?
« Reply #9 on: October 01, 2012, 04:58:18 PM »
There is a hole at the edge of the 14" driving pulley that I put a 3/8" rod in so I could crank this old baby.  It's actually pretty easy to crank it to 120 rpm by hand.  Runs very smoothly with no noticeable vibration.   But since that's moving the perimeter of the stone at something about 850 lineal feet per minute, clearly faster than one would want to run this.  I think if I can do a 1 to 1 drive off of the variable seed motor I have which maxes out at 150 rpm I should be good to go in the 30 to 60 rpm range. There seems to be no play in the bearings.  Sharpened my scythe before I cut the corn off the garden on Saturday.... 

Tom
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Offline cmac

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Re: Knife Grinder?
« Reply #10 on: October 02, 2012, 03:10:17 AM »
My brother has a wheel like this, but it sits on a wooden frame and has a rod that goes down to a foot pedal. It also has a bent rod that holds a metal can over the top of the wheel. The can has a hole in the bottom and slowly drips water on the wheel
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Offline Clark Badgett

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Re: Knife Grinder?
« Reply #11 on: October 02, 2012, 03:14:26 AM »
It looks like an old machine shop grinder from the early 20th century.
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Offline Dr. Tim-Boone

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Re: Knife Grinder?
« Reply #12 on: October 03, 2012, 12:42:00 AM »
My dad had one of these on the ranch made in the 1920's. I used it to sharpen axes and scythes as well was butcher knives...had a foot peddle. Nice work for a trusted little kid.  Kee p the water on it when it is being used.at 30-35 rpm as others have said.
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keweenaw

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Re: Knife Grinder?
« Reply #13 on: October 03, 2012, 04:16:13 PM »
Athol Machine Co. that made this grinder went out of business in 1905 so that rather dates this.  They made many treadle grinders mostly in smaller sizes but this one was apparently always designed to be driven from a line shaft.  I'm looking forward to getting my motor on it to give it a try.  It should be great for striking round barrels to remove ripples as well as general clean up work on forged parts.
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