No reason why not at all. I often bolt a wooden angle plate to the bed of the drill behind the lathe with a hole bored in to support long lengths.

No need to over think the idea.

No mention of lathe bed size? I might just use a fixed steady, with tailstock at the end of the bed, and that would mean not a lot hanging out the back end For a 'one off'. I might tap in some aluminium strip at the rear of the spindle for extra security, proceed steadily and see how it goes. How long is your lathe?

I would worry about it working against the chuck jaws as nearly 4' of bar unsupported behind the chuck has a lot of leverage. Perhaps a bush turned to fit at the back of the spindle would help as well? This could be a close fit on the bar, or more universal using radial screws to clamp the bar.

Brian

An extended steady is needed to stop the end of the workpiece whipping about and causing vibrations or disasters.

The two I have used are a bored out piece of wood which is okay… but later I found an old taxi propshaft bearing and jammed it over the end of the workpiece, then mounted the bearing end into the piece of wood, it was much more stable and meant there were no more "wear" or heat issues.

Once you have the far end of the workpiece shoved securely into a bearing you can mount it in anything stable you can cobble together

I have done something similar to this in a bedless lathe (really a cymbal-making lathe with a temporary 3-jaw chuck fitted it) with a 3.2m length of heavy aluminium tubing hanging out of the chuck. 300rpm or so. I was actually only abrading the tube, not cutting it.

Get hold of a little laser pointer – I found a cheap one on Amazon or Ebay, fitted inside a dummy bullet for lining up rifles, etc. – and mount it in your chuck (in your case with the laster pointing into the headstock, through the spindle bore and out the back). This will greatly help you line up your steady. You can also see how well aligned your chuck is while you are at it – does it project a spot or draw a circle on the wall when the lathe is turning? Though, with a cheap laser pointer, that error may be in the pointer itself.

I made a very simple steady from a couple of casters, some dexion and a lump of wood. I clamped this in a Black and Decker Workmate which allowed easy adjustment of height and left-right position and was also suprisingly stable. Hold a 1" diameter stump of whatever on your casters and align the steady it so the laser dot (or circle!) is central on the 1" diameter face. Ideally have the casters contacting the bar at 90 degrees to each other, 45 degrees either side of the underside of the bar. You may have to stagger them to fit on such a small diameter. Though it sounds like other people's ideas for a steady with more friction would work just as well.

You might want to run your cutting speed a little slower than usual just to be on the safe side, but I don't think you'll have too much trouble with 4.5' of 1" steel whipping around too much especially if you make a steady.

I would put the steady about 1/3 of the exposed length of the bar in from the free end.

Cheers, Matt.