But plastic does not keep dimensional accuracy and it gets scuffed up over time. ? So, you end up with just any kind of. Metal, ?even the lowest grade of junk-metal will be over kill. ? ? ?Again, as said before. ?Amazon Prime delivers overnight for “free” I’d think that I lived an hour from any place I’d be dependent on Amazon for most everything.

I while back I converted my Harbor Freight Mini Mill ti full CNC. ?I simply added three motors and wired them to an older PC. ? I had to design and make some motor mounts. ?If the motor had a maximum torque of (say) 4 Newton meter my mount only had to withstand a reaction force of 4 Nm, plus a safty factor of about 2.5. ?As it turns out 3D printed plastic motor mounts will do that. ? On a large machine these parted would be made of CNC steel because the motors are very powerfull but I’m using only NEMA23 size stepper motors to run the lead screws on the mill. ?Plastic works for this. ? ?

Back to metals. ?Salvage is a good source of materials. ? Junk disk brake rotors are very good. ?Barbell weights are made from cast iron. They can be cheap if bough used. ?Then I can buy steel bolts over 1" diameter at Home Depot (or Amazon) ?2-foot log kind that are made to set into concrete are a good value.

There are also eBay sellers who sell a US Postal Service fltat rate box filled with metal. ?THese ship for $23 and you get something like 40 pounds, whatever the max weight of a domestic flate rate box is.

Look at Aliexpress too. ? Being a Chinese site they mostly ship from China but Chinese shipping rates are incredibly low. ? I see I can get a 1/2 meter long 100x25mm chunk of aluminum alloy for $40 and they charge $3.40 shipping.

That said most of what I make now is ABS plastic. ? I can print it for 2-cents per gram. ? Some parts must be metal, bearings and bushing, shafts and gears but much of the parts I make don’t need the strength and certainly don’t need the weight of steel.