3D printed bushings. I’ll give it a try and report back. (That’s just 5/8" cold rolled steel)
What material did you use?
PLA. Any thoughts on lubrication?
The best PLA to PLA lube I have found is Teflon spray for your snow blower so the snow dont stick. Might work with dissimilar materials also. They had cans of the stuff for 25 cents in the Walmart discount isle.
I’ve used this on my tools for construction for years, it in my opinion, attracts less foreign debris and this is a high particle environment of construction. I’ve used it on my 3D printers as well.
Awesome. Thanks guys. I’ll give it a shot.
These bushings won’t work on a rough rod like that. You need a smooth chromed rod for this to work.
Cold rolled steel is pretty smooth.
@Michael_Boquist bright chrome should be smoother though. Plus chrome also offers excellent corrosion protection too. Even a hard chrome job would be nice. I worked at a place that heat treated and hard chrome plated printing press dies for a while. We had huge barrels of chrome flakes. They’re a very pretty iridescent purple. Pretty deadly poisonous stuff though. I should have swiped a bucket while I was working there. I did hard chrome one of my combination square rulers though.
Yeah. I’m worried about rust acting as sand paper.
@Dale_Royer Both. It’ll probably move a bit but as soon as the friction starts to heat up the plastic, you’re in trouble. It will cease and ruin your motor (or more).
On my 3d printer i also have chromed rods and even they have to be lubed every now and then.
@Michael_Boquist that’s drawn steel - you can clearly see the machining marks as it’s been twisted and pulled through the die. The original steel it came from may have been rolled, but I would be keen to see how you roll a
millimeter-accurate small rod/cylinder from cold steel.
The machining marks will abrade the pla in a matter of hours, to the extent it’s no longer accurate to anything like is needed for CNC machining.
Polished, then chromed, rods are smooth enough. That, from an engineering perspective, is as rough as a badgers arse. 
@Paul_Frederick “We had huge barrels of chrome flakes. They’re a very pretty iridescent purple. Pretty deadly poisonous stuff though.”
You would have to make them into a solution and drink it for it to be ‘deadly poisonous stuff’. You could get dermatitis, though, if you handle it a lot. O.o
@Mike_Thornbury That is pretty much what we did with the stuff. We had to put it into a solution in order to chrome plate.