Aluminium rods

Has anyone used Aluminium rods instead of steel smooth rods? If so what was the outcome? Theres a stupidly large price difference and there is going to be a reason for it but worth asking!

Aluminium rods are going to be too soft, and won't last very long against lm8uu bearings,

you can use stainless steel rod which is pretty cheap and seems to work well, however the hardened balls in the lm8uu will make little grooves in that over time,

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thejollygrimreaper Wrote:
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> Aluminium rods are going to be too soft, and won't
> last very long against lm8uu bearings,
>
> you can use stainless steel rod which is pretty
> cheap and seems to work well, however the hardened
> balls in the lm8uu will make little grooves in
> that over time,


Heck, they'll do that on some softer steel rods as well. I had to toss some O1 drill rod I was using after I found nice little grooves in them that the LM8UUs had gouged out. It really helps to have precision ground and hardened rods.

In the US stainless is usually much more expensive than either plain steel or tool steel. Hardening goes a long way to eliminating the grooves (as do good bearings) though hardened rods are around the same price as stainless. Much of the time the grooves aren't so much from the travel on the surface of the rods but from the binding and digging into the rod or the tolerances in the less expensive bearings. The import linear bearings that are a buck or two aren't nearly as consistent as an IGUS or Thomson but they can be US$20-30 ea. To help reduce the potential to groove on softer steel take a piece of rod and some light machine oil and run the bearing up and down the shaft. For most in a good batch this will help though some just aren't that good and even if used on hardened rod they'll bind or seize in short time.

Fair points raised! Best not to cheapen out on those then. cheers!

I've seen people use plastic bushings on aluminum rods... Seemed to work just as well as plastic bushings on steel rods!

Igus bushings run on anodised aluminium rails...

Good point on the IGUS bushings. In fact I can't recall seeing them used on machinery with anything but AL rod.

Just make sure that the aluminium rods are anodized or else...

I see aluminium rods being especially useful in Ultimaker style bowden setups where 2 of the rods have to move with the carriage. Steel rods add significant moving mass so switching them out for aluminium ones with plastic bushings seems like the way to go.

I wonder how good PLA bearings would be on ally' rod?

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Waitaki 3D Printer

@RP Iron Man: Unfortunately, aluminium is a lot more flexible than steel, so you would have to use much thicker rods (or tubes) to compensate for that. Instead, I am considering to use thinner steel rods. 6mm is about the lower limit for an Ultimaker-style gantry with up to 150mm of travel.

@Waitaki: AFAIK, the Foldarap 2 uses PLA bushings on aluminium extrusions with good results. You can find a short write-up by the developer in the link I posted above. As long as you apply a little bit of oil, they glide really well, but are supposed to wear faster than other higher end materials like PET, taulman 618 etc.
If you have an all-metal hot end, PET might come closest to the mechanical properties of PLA (in fact, PLA seems to be designed to replace PET in some applications like packaging) with the added benefit of extremely low wear and higher temperature resistance.
To give a perspective about the low wear of PET: it is performing very slightly worse than UHMWPE on ground steel. I have used UHMWPE bushings on Cf53 almost daily for several months without lubrication and there are only faint hints that there might be wear in some places.