Magnetic disc hub and discs

M

mike-E

Joined
Mar 2, 2013
Messages
400
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figured id post this up for anyone interested and able to make their own. the major o.d. of the hub is 7 3/4''x 3/4 thick. the step on the backside is 3'' dia., 1'' long. it's bored at 1.5005 and keyed 1/4''. the 1045 steel insert is 2'' long reamed 5/8 and internal keyed for motor shaft and has an external pocketed key at 180 degrees. the magnets are 3/4'' diameter 1/4'' thick and are countersunk for a 6-32 flat head screw. the pockets in the hub are countersunk to .290 deep. the discs started out as 10x10 1/8'' thick. they were stacked six at once and bored to 1.5015. after the plates were sawed close to 9 1/4 in diameter i chucked the hub back in the lathe stuck the discs on and using light cuts machined them with nothing but the magnets holding them(crazy huh). the discs were the easiest part to make. obviously i got inspiration from the nielsen system, but i couldnt see myself spending the cash on his knowing i could make my own improved version. i did not like the idea of constantly trying to put steel discs precisely onto an aluminum pilot. eventually that aluminum will get burred up and throw the disc out of round. also i wanted to be able to replace the magnets and add/remove as needed. and at about 2 bucks a piece they cost $25 total. i know things can look familiar at first glance guys, but from a block away an f-150 and a super duty could be confused too, so please dont bash me hard on this one.
 
That's very nice. I have the Neilson grinder and love it. I think you will be very happy with this. And you saved alot of money by making your own.
 
thanks tony, how many discs do you have, and are you running any of them with rubber sheet on the face? i plan on making some 1/4'' thick ones with a 1 1/2 degree bevel. do you think 6 is enough?
 
I have 2 flat discs and one tapered. I usually keep 120 grit paper on one and 400 grit on another. I think 6 discs is definitely enough, but will need the taper disc for sure if you make blades longer than 3 or 4 inches. Any time the tip of the blade crosses the centerline of a flat disc it will get very wobbly in your hand. The taper completely eliminates that problem.
 
Your's looks great mike-e. good you could make it. Mine is super because I got it all ready to run with 6 or 7 discs. Yes, it's also a Nielsen I am totally impressed with it! I use a thin cork gasket on them.
Frank
 
mike-e, Your disk setup looks like a real quality well built tool. Very impressive work. You must share some photos of knife projects. Larry
 
Looks great! How did you countersink the magnets? Isn't neodymium iron boron really hard/brittle?
 
Wouldn't your knife bump into that middle projection? Or do you just try to use the areas above and below?
 
Speed control is almost a necessity to be able to fully use one of these. I do most of my grinding at around 35% - 40%.
Frank
 
lazlo, the magnets come countersunk, check out magnets 4 less. maelstrom 78, i can position the central pilot at any distance i want from the face.
 
here are some pics on the grinder. i researched a lot before i built it. i decided i wanted a beaumont style rest, but i didn't want to weld on it, and i wanted a mitre slot. i also wanted the ability to go horizontal, so it tilts 90 degrees with an 80 lb. gas spring assist. i also included a pic of a sharpening jig i built a couple years ago. enjoy.
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count, i could try, but flash never really works out. it's one reason i dont post knife pics, my camera makes them look worse than they do, if that's possible. ill try though
 
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