Aluminum Discs?

DaveMartell

DaveMartell

Joined
Apr 22, 2010
Messages
235
I'm wondering on how the aluminum discs hold up to grinding hardened steel? It seems a bit odd to me to use hardened steel platens on belt grinders but then to use aluminum plates on disc grinders.

I'm thinking about buying a VFD disc grinder set up that I'll use on post heat treat blades and I'm wondering about how the aluminum plate will hold up. I'm guessing that even though it seems odd to me that it's probably OK since so many of you use them for there to be a problem.
 
The aluminum discs hold up fine.

I imagine that they are not used as platens on belt grinders because they conduct heat more readily than steel.
 
I did use an aluminum platen until very recently. It actually stayed much cooler than the steel platen I am using now. I believe it was because the heat would spread out quicker and cool down better than the steel. The problem was that the belt moving over the aluminum was slowly deforming and gouging the aluminum. The back side of a belt still has some abrasive function on a platen. On a disc, the sandpaper is attached to the platen so there is to abrasive action.
 
i used aluminum to make the 2 discs that i use. one has a 1 degree taper and the other i put a slight convex on it. the steel i grind is already hard at 56rc and i dont have a bit of trouble. both of mine are 9" and i use 24 grit on both for roughing out a blade and then finishing the blade up on my flat platen. one disc i made is much less than 1/4" thick and it does just fine. i have some vids of chuckinohio learning how to grind on one. if anyone wants to see the vids send me an email. rje196021@gmail.com
 
If you have a choice between the steel and aluminum I'd get the steel. When you cut the paper off the disc the steel is less likely to get little notches in it from the knife. I use the edge of the disc and run it up into my plunges and little dings in the edge would mar up the face of the plunge. The aluminum being softer than steel that's hardened might not have any effect though. I don't have the aluminum disc so maybe someone who has one will chime in.
 
i dont have any problems with my aluminum discs. the paper comes off easy if you take it off after grinding on it. the glue is soft and will come off easier with less pull.

i use spray glue to hold the discs on that i use and sometimes i have to scrape them off but the little marks do not bother anything if you smooth out any proud nicks.
 
A platen wears because of belt friction, the sandpaper on a disc is not moving relative to the disc.
 
All good, but I would like to try to get Rob Frink or someone else to make a run of steel discs.

I would pay up front. They are tougher, as mentioned above, and the weight keeps them moving nicely with momentum.

Dave,

Would you be using them to reestablish flats, or to sharpen, or both?
 
I know many use them and I have never seen one complaint. I plan on getting one soon myself.
 
Timely thread! I just got mine today and got it setup just a bit ago. Should last a lifetime with basic care, there is no friction between paper and wheel.
I dont know how i got by without this thing! i thought i was getting a good flat on my first batch of knives but after just testing/messing around using this disc with a blank im working on I can see a world of improvement in flatness and finish. Cant wait to get my heat treated blades back to use this thing on and improve my fit and finish by roughly 100%.

Here is a gratuitous picture:
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John Frankl said:
All good, but I would like to try to get Rob Frink or someone else to make a run of steel discs.

I would pay up front. They are tougher, as mentioned above, and the weight keeps them moving nicely with momentum.

Dave,

Would you be using them to reestablish flats, or to sharpen, or both?
Click to expand...

inertia also works in your favor with steel
 
Inertia is only an advantage if the motor you're using will have a braking system. I don't have variable speed on my disc grinder, and no braking, so waiting longer to change grits doesn't sound like a plus to me. Also, it's very easy to touch up an aluminum disc's edge with a lathe file if it gets dinged.
If I could do it over again, though - it would be steel, and have a 1 degree bevel. AND VARIABLE SPEED!!!!

Next one, I swear!
 
i have 2 stainless steel 9" x 3/8" discs that i thought about putting hubs on so i can use them for disc sanders but i'm not too wild about the weight and inertia. it cant do a motor any good over time getting something heavy spinning. i think i'll stick with my aluminum discs. you can always go with thicker aluminum.
 
I've had aluminum discs in my shop for 15 years and have always been happy with them.

But for some of the things I've been trying to use my disc for lately, I think a steel one would be nice. I've been kicking over the idea of whether I want to make one or buy one.

John, I agree about Rob making a run of steel discs. I know he did some years back.

But according to their web-site, K&G sells them everyday. :)
 
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