How to hold this?

After going through building the stock for this part I'm going to make with the mill the other day I tried to work out how I am going to hold it in the mill.

As you can see there is a groove all the way around which I had planned to use to hold on to with some clamps and T nuts.

These ones in fact. However what I discovered is that all of the shorter screws that I have are a much coarser thread than what the nuts have so I'd need to pack underneath the longer ones quite substantially. Not impossible but I'd rather avoid that if I can.

So I figured I'd use the little vice that came with the mill. Some comprimises there also, but better than having to space it out by a mile. However do you think I could find it? Option C it is then.

Here we have some longer bolts that we faced the head down a little so that they will fit in the T slots. It isn't ideal as they have a hex head rather than a square head but they do lock in the slots nicely enough. The only problem is that the cutter is sitting on the block and the spindle is pretty close to the ideal height now so it would probably crash into the hold down bolts. Less then ideal.

But there is a solution. I have chucked the first bolt up in the lathe and I will part it off as short as possible which will give me plenty of length to hold this down.

Here we are, all set up and ready to go. I probably won't do this before the weekend as I don't want to be making too much noise at night and upsetting the neighbors. That can come later.

So keep an eye out and I will try to get some video of the parting off so anyone that knows a bit more than me can point out where I am going wrong.

Cheers,
Rex