Grinding wheel arbor question

[rleete]

As shown elsewhere, I bought a cup grinding wheel.  It needs an arbor.

I have a length of 12L14 that I will be using to make said arbor.  It goes into a 20mm (.787") hole in the wheel.  As the stock is only 1" diameter, this doesn't leave much in the way of a flange to support the wheel.  I plan on adding large (~2") washers either side of the wheel to help support it and distribute the forces more evenly.  My problem stems from the fact that I don't seem to have any suitable steel available.  

My question is, will aluminum (.13" thick) be strong enough to support the wheel, of do I need to get some steel?  Note that this wheel is to be used on the mini mill, so maximum speeds will be well under 1100rpm.

[EdK]

Can you get some 3/4" fender washers from the hardware store and bore them out to 20mm?
Maybe stack a couple together to get a thicker washer.

Ed

[rleete]

I can. I was trying to avoid a trip to the store. I'll buy them on my way home from work tomorrow.

[rleete]

Follow up question:  How tight should the bolt be holding the cup wheel?  I have steel washers on either side, backed up by cardboard (cereal box) on the wheel.  Do I crank it down, or only just tight enough to hold it?  Somewhere in the middle?

[EdK]

(Yesterday, 04:49 PM)rleete Wrote: Follow up question:  How tight should the bolt be holding the cup wheel?  I have steel washers on either side, backed up by cardboard (cereal box) on the wheel.  Do I crank it down, or only just tight enough to hold it?  Somewhere in the middle?

That's a good question. I think I'd do "somewhere in the middle".  

Ed

[Highpower]

(Yesterday, 09:58 PM)EdK Wrote: That's a good question. I think I'd do "somewhere in the middle".  

Ed

I describe it as "snug". In use it will have a tendency to tighten itself.

[rleete]

My gut tells me this is right, but I have an ingrained fear of fast spinning things, and I am afraid of either having it too lose or cracking the cup.