Mounting options on sand cast flywheel?

[DeltaCharlie]

Hi all, before I remove the sand cast model steam flywheel I'm working on I wanted to ponder what the best next way to proceed might be.

What I have is a aluminum sand cast flywheel that I center drilled using the mini mill then tapped for a 1/4 by 20 bolt. The bold is threaded into the flywheel and a pad chucked into a 4 jaw. I need to remove the bolt and re-center the hole and enlarge it to 5/16

My original idea was to flip it around to use the machined face and mount it to the face plate but how do I dial that in? The clamps would be in the way and how to make slight adjustments?

Did not really want to machine the back as I like the rough look but I could machine at least some of the back then re-mount in the 4 jaw. I did leave the draft angle on the outer rim as I thought it looked interesting but if I machine it parallel I could flip it around and use the machined face in the 4 jaw.

what to do? Thanks, Dale

 

[markba633csi]

Machine the inner major diameter to match the outside major diameter, then you can indicate it in when held by the 4-jaw
You'd want to bore (not drill) the 1/4" hole to 5/16" otherwise it won't be concentric with the major outside diameter of the flywheel
You may have to use a small boring bar or improvise grinding an old drill bit into a boring bar (I sometimes use one flute of an endmill)

 

[DeltaCharlie]

Machine the inner major diameter to match the outside major diameter, then you can indicate it in when held by the 4-jaw
You'd want to bore (not drill) the 1/4" hole to 5/16" otherwise it won't be concentric with the major outside diameter of the flywheel
You may have to use a small boring bar or improvise grinding an old drill bit into a boring bar (I sometimes use one flute of an endmill)

I was thinking of running a die over a short section of 1/4 aluminum rod (will turn down to the correct dia for the die) then jam it into the 1/4 x 20 threaded hole so I can start a center drill fresh. I have a hard time getting boring bars to work and so far a starter hole of 1/2 inch is my minimum.

After thinking about it for a bit I think I'm going to face the back of the flywheel and make a rim about 1/2 inch wide. Think it will look nice and I believe after I do this I will be able to mount the flywheel in the 4 jaw with just enough room left on the front of the rim to use the dial indicator. We will see. Thanks, Dale