# power sharpening



## Karda (Nov 19, 2016)

Hi, I made strop wheels for my grinder, the motor is slow, I think a washer motor. My problem is that when I srop with the leather wheel it dulls the blade rather than sharpen it. the leather wheel is the rough back of a leather belt, I also use one made of cereal box same results. However when I hand strop with the same leather it works well. What am I doing wrong


----------



## BillWhite (Jul 23, 2007)

You're "dubbing" the edge. Strops are for the final refining of the edge, not sharpening. Very light touch on the wheeled strop.
Bill


----------



## Lazyman (Aug 8, 2014)

I'm still honing my sharpening skills (pun intended) but from what I have read, you should match the bevel exactly on the strop to avoid rounding over the edge. When you do this with a few strokes on a stationary strop it may be less of a problem than when you do a few hundred feet against a moving strop wheel.


----------



## Karda (Nov 19, 2016)

ok, sharpening was the wrong term. But when I touch the sharp knife to the wheel it dulls it rather than strop it


----------



## Lazyman (Aug 8, 2014)

If you have the strop wheel mounted on your grinder, which direction are you stropping. This might be obvious, but the strop should run backwards from the way you normally grind the bevel on a grinding wheel.


----------



## Karda (Nov 19, 2016)

the the wheel rotates forward soit rotstes away from the cutting edge


----------



## hairy (Sep 23, 2008)

I think speed might also be a factor. What is the rpm of the motor?

I use a Tomz sharpener that runs at 33 rpm. http://lumberjocks.com/reviews/3198


----------



## Lazyman (Aug 8, 2014)

> the the wheel rotates forward soit rotstes away from the cutting edge
> 
> - Karda


Then the only thing that makes sense to me is that you are not keeping the bevel perfectly aligned with the wheel and must be rolling over (dubbing) the edge. Try looking at your edge under magnification before and after stropping. That might give your more insight into what is going wrong.


----------



## Karda (Nov 19, 2016)

the plate is not clear but the highest number is 1140 so I am assuming that is RPMs


----------



## mpounders (Jun 22, 2010)

"Slow" is a relative term. 1725 rpm is slow compared to a grinder that may run at 3000 rpm, but both are a little fast for stropping. I used a pulley on my motor shaft and a larger one on a shaft holding my stropping wheel to step the speed down to about 600 rpm. I also place my finger on the blade, back behind the edge, to help hold it flat and to judge when the temperature is getting too hot. Faster can mess up faster as well as sharpen faster, but I bet with a little practice you will get the hang of it. Just hold the bevel flat against the wheel. Many people will use a Sharpie marker to blacken the edge on both sides. Then when you hold it to the wheel, you can see if you are not holding it flat enough by how it wears the marker off. When you take the blade off the wheel, make sure that the compound is smeared on the blade all the way to the cutting edge. When you are holding it to the wheel and you see compound curling up over the edge, you may be holding it a little too stepp and need to flatten the angle a bit.


----------



## mpounders (Jun 22, 2010)

Here is a good video by Allen Goodman. He starts with hand stropping, but about halfway through he uses a reversible drill and shows the process for power stropping.


----------



## Karda (Nov 19, 2016)

ok, my motor wheel is 3" and the arbor is 2". I don't know if I can i ncrease the arbor size, it is shrouded. do you have any ideea what size wheel or wheels I would need thanks Mike


----------



## ClaudeF (Sep 22, 2013)

To slow down the honing wheels, the pulley on the motor needs to be smaller than the pulley on the honing wheel arbor. Your measurements indicate you are making the honing wheel go faster than if it was mounted directly on the motor. If the motor is at 1140 RPM, your honing wheel is rotating at 1710 RPM.

As to the size of pulleys you need, it depends on the speed you want to end up with. The ratio of drive wheel diameter to driven wheel diameter is your speed multiplier: 2 inch drive pulley and 4 inch driven pulley will be 1/2 of the motor speed. 2 inch drive pulley and 6 inch driven pulley will be 1/3 of the motor speed and so forth.

Claude


----------



## Karda (Nov 19, 2016)

I I would want stropping speed, you are a better judge of that than I am. I can't change the driven wheel size because of the shroud over the wheel, I might be able to go 3" but I won't know until I take it appart


----------



## mpounders (Jun 22, 2010)

The slower, the better! If your rpm is correct and you do have a 3 inch pulley on the motor, then a 6 inch pulley on the arbor shaft would cut it down to around 550 rpm, which is fine. My factory made Burke has a 1 inch pulley on the 1725 rpm motor shaft and a 3 inch pulley on the arbor, which means it runs about 575 rpm.


----------



## Karda (Nov 19, 2016)

what would happen if I put the 3" 0n the arbor and a 1 or 2 inch on the motor


----------



## ClaudeF (Sep 22, 2013)

3 inch on the arbor and 1 inch on the motor would drop you down to around 375RPM; 3 inch on the arbor and 2 inch on the motor would drop it down to about 760 RPM. Is there any way to remove the shroud?

Claude


----------



## Karda (Nov 19, 2016)

no the shroud and stand are one molded piece of pot metal


----------

