If I’m doing a 24"x24" MPCNC will I need 20’ of conduit?
Assuming you are using 4" of vertical Z travel, NO.
According to the conduit calculator the total amount of conduit you will need is 244 inches which is 4 inches more than 20 ft.
I just recently built my MPCNC, so I am no expert, but I ended up buying 6 five ft lengths of conduit. I cut the 6 long X and Y axes from each stick and used the scap to cut the Z and legs.
I used the short pieces of conduit because when shopping at Lowes, every 10’ length of conduit had a descent bow already, but the 5ft pieces seemed pretty straight. There was a price difference but it was worth it to remove a possible source of precision errors.
Thanks! Heading to buy them now.