Paper vs Felt wheel

T

timbit

Joined
Jul 21, 2011
Messages
1,011
I recently picked up a small scrap fan motor that was no longer needed on a job. It is a 110v 1/4 horse 3 speed motor with a rotor that protrudes out of each end. I thought that it would be PERFECT to spin a pair of paper or felt wheels for sharpening. Mount it on a piece of 1/2 inch ply with a switch in a gang-box and I am good to go. I can run it at 3600 rpm, 1800rpm or 900 rpm.

My question is, which is better for general purpose sharpening? Paper or felt. I would very much appreciate some pro's and cons for each one. Also, are the abrasives used for paper sharpening the same that would be used on felt? Is there an optimal rpm to run the felt/water disc at?

Thanks!
 
Forget sharpening on either, Paper and felt are still uncooled high speed abrasion that will ruin the critical several microns at the extreme edge of your cutting edge (the part that does the work) and instead get yourself a good set of diamond stones and keep them wet to take the heat away from that extreme edge.

-Page
 
I am just a newbie, but I have been using paper wheels forever. I use the grit wheel to put the first edge on and then benchstones to finish it off. however, I have always had good results with the edges off of the polishing wheels. YMMV
 
Thanks for the info guys. I do have a couple of bench stones that do the trick :) I just wanted to give the paper/felt wheel a go.
 
They are amazing for putting the main secondary bevel on. benchstones are nice, but slow. the paper wheels are anything but slow.
 
Good Ole Phill Hartsfield would do a chisel grind and then take it to a buffer for a razor sharp edge. I have used a buffing wheel, paper wheel, stones, leather belt, spyderco Sharpmaker, Lansky System etc.

They all will produce a fine edge once you master the technique. But the safest is the slowest and that would be stones. Murray Carter has some good videos on how to sharpen with stones on YouTube if you are interested.
 
I would be very much interested in those videos. I can consistenly get a nice keen edge on my scandi knives, but have some trouble with other types of edges.
 
I was using a 9micron 3M belt followed by a loaded leather belt but found my edges weren't holdig up as well as my hand honed(waterstones) blades. I don't know too much about the science behind it but I do know that I get better performance on stones. I am going to give those DMT plates a go, soon.
 
a 1/3 hp motor is not enough to run a wheel on. there is just not enough torque to keep from bogging the motor down. you need at least a 1/2 hp motor minimum.
 
richard j said:
a 1/3 hp motor is not enough to run a wheel on. there is just not enough torque to keep from bogging the motor down. you need at least a 1/2 hp motor minimum.
Click to expand...
Good catch Richard.1/4 hp is for sure too small.I like having the paper wheels in my sharpening arsenal.Although typically i use a belt and then polish on the wheel.Check your local pawn shops.A grinder can be had for very little and make excellent paper wheel spinners.
 
The thing with any system where the edge is being abraded without any fluid coolant/lubricant is the frictional heating brings the extreme edge, the steel that does the work, up to temperatures that well exceed the tempering range of the steel, (Roman Landes said that he measured it going over 800 C) essentially softening the edge. When people talk about raising a burr on their abrasives then polishing that burr, what they are doing is softening the steel so that they get plastic deformation of the extreme edge which bends in a thin sheet away from the abrasive rather than standing firm and getting ground off while maintaining its basic shape. Basically raising a burr and polishing it to an edge is softening your edge, pulling a small bit up, and thinning that small soft bit, not a big deal on a thick convex edge with big chunky carbides acting like teeth, but on a thin acute edge like a sashimi knife that softening will render it useless quickly

-Page
 
Thanks for the heads up on the lack of power :) It was turning a smallish blower. If I wait, i'm sure I will come across a 1/2 to 1 HP motor before too long. I see atleast 2-3 a year up for grabs. Those youtube videos were just the ticket. I will definitely subscribe to his website. Thank you for all of the advice.

Page,
That is very good information to have. Thank you. I was mostly planning on using it to put a nice edge QUICK on some chisels I have kicken around. I'll not be using the buffing wheel on anything dainty.
 
I use a fairly new 320-400 belt on a fairly slow speed to raise the burr and take it off on a leather barber strop. A dull belt will indeed overheat a thin fine edge.
 
I was also going to suggest the wet wheel grinder, they have attachments for knife sharpening too. They're moderately inexpensive compared to most of their other tools, as well. I'm curious as to your results, I've been thinking of buying one myself.
 
Last edited:
sunshadow said:
The thing with any system where the edge is being abraded without any fluid coolant/lubricant is the frictional heating brings the extreme edge, the steel that does the work, up to temperatures that well exceed the tempering range of the steel, (Roman Landes said that he measured it going over 800 C) essentially softening the edge. When people talk about raising a burr on their abrasives then polishing that burr, what they are doing is softening the steel so that they get plastic deformation of the extreme edge which bends in a thin sheet away from the abrasive rather than standing firm and getting ground off while maintaining its basic shape. Basically raising a burr and polishing it to an edge is softening your edge, pulling a small bit up, and thinning that small soft bit, not a big deal on a thick convex edge with big chunky carbides acting like teeth, but on a thin acute edge like a sashimi knife that softening will render it useless quickly

-Page
Click to expand...

Page, I've read bits and pieces of the info from Roman re: loss of temper when using non-lubricated or powered abrasives. I'm curious if there's been any discussion of, for example, setting the bevel initially with a belt @ low speed and refining/finishing the edge on waterstones. Theoretically it would allow for fast removal of material to establish the bevel, then slowly abrade the material that was overheated by the belt in a fashion consistent with Roman's research; the exposed material on the finished edge would have been removed slowly with a water cooled abrasive and shouldn't be overly soft like an edge finished with a non-lubricated or power tool, right? Naturally, with all this I'm assuming that with the initial bevel grind the heat was kept down to a level where there would be no color change or obvious loss of temper, as is recommended for all post-HT grinding.
 
Pete84 said:
Page, I've read bits and pieces of the info from Roman re: loss of temper when using non-lubricated or powered abrasives. I'm curious if there's been any discussion of, for example, setting the bevel initially with a belt @ low speed and refining/finishing the edge on waterstones. Theoretically it would allow for fast removal of material to establish the bevel, then slowly abrade the material that was overheated by the belt in a fashion consistent with Roman's research; the exposed material on the finished edge would have been removed slowly with a water cooled abrasive and shouldn't be overly soft like an edge finished with a non-lubricated or power tool, right? Naturally, with all this I'm assuming that with the initial bevel grind the heat was kept down to a level where there would be no color change or obvious loss of temper, as is recommended for all post-HT grinding.
Click to expand...

I now do a very light finishing grind, just to get the decarb/scale layer off of the flats (I flatgrind all of my blades) on the belt,dipping and wetting the belt, and no longer set my edge bevels on the grinder, rather I do all of my edge bevel by hand on a series of DMT Diamond stones from Extra Coarse right down to the green Extra fine (5 abrasive steps in all) using water with a drop of liquid dish soap as a wetting agent, and have noticed a difference in my edge performance. I no longer have lab access to be able to measure the difference, but the edge feels harder on the stones, and I am getting no burr (wire edge) at all, just straight to scary sharp. I am going to be building a low speed rotary lapping machine with a wetted diamond plate for doing faster edge bevel grinding (doing it by hand takes a while) when I can afford the parts, similar to the wet grinding equipment used to facet stones, but right now it is all hand work, and I am happy enough with the results to consider the time and effort worth it

-Page
 
You must log in or register to reply here.
Back
Top