Do imperial machines even exist? I kind of want to make a black and white one, storm trooper style, to bring people to the dark side. And hate me forever for it heh.
I checked back when I built my machine, other than a few wiki pages I had a hard time finding anything. I knew eventually I would have to start working in Metric so i just started switching everything over. Hard to do when you have been measuring in thousandths of an inch for so long.
The meter is the international standard since 1875. Good to hear America is finally starting to use the standard. 
By the way:
0.001km = 0.01hm = 0.1dam = 1m = 10dm = 100cm = 1000mm = 10000µm
the American way:
0.0001646 nautical miles = 0.0001894 miles = 0.3333yard = 1feet =12 inches
I hope i never have to learn imperial because it does not make any sense to me. 
@Frank_Opmeer Its a serious pain, as someone who grew up with both. Imperial makes no sense.
The trouble is that in america you cannot buy metric hardware in very many places at all. Get out of the big cities and ask for a 3mm drill bit and they scratch their heads and say “They make those?” no lie. just finding small metric bolts and screws is almost impossible. When I built my 3DR I could only find anything at 1 hardware store (out of 6 in the near vicinity) so ended up ordering from amazon, or using english sizes that were close. Very frustrating, not to mention expensive and time consuming. Even the supply on amazon is not so great. At least they have stuff - if not a lot of choices.
Yea in america you have to rely on the mom n pop shops as big retailers like home depot have near to no metric stock. I do have one metric retailer who does big orders but I usually go with McMaster and MCS online. MCS is better pricing but less metric from what I’ve found.
So we have two choices: either we make an abomination that is an imperial 3d printer or we start a kick starter for a “let’s ditch imperial” Superbowl ad.
I vote for the latter. It’d be easier.
Regardless of any other screws you use, the screws for use on the stepper motor will probably have to be metric.
Mom and pop shops are not just more likely to have the screws you want, they are less likely to have the massive markup that a big chain store has ( most likely due to a combination of greed and property tax).
Heck I live in Canada, we are supposed to be all metric but it’s more half and half. I was taught Metric in school but have used inches my hole working life. None of the hardware stores around here have anything metric, if you want a metric drill bit you have to go to places like KBC and order it. It’s a mess to say the least.
As for the lead screws being imperial, the stepper motors don’t care, they will move however many steps you tell them to. Metric or Imperial they don’t know the difference. Finding a couple metric ones might make life easier though.
Oh. To be more specific, the stepper motors will most likely have metric screw holes.
Oh my bad I thought you meant the leadscrews. The stepper motor mounting screws will most likely be metric, I don’t know of any that are not.
I get most of my metric hardware and tools at Ace. I don’t know if this is standard for them, but several around me have a good metric selection.
My Ace has nothing. Home Depot is a joke. The store I can get metric stuff at is a mom and pop that specializes in stainless and “odd” stuff.
I seriously want to make a vending machine for stuff like this some day…
Heck - this is an internet startup if I ever saw one - sell 10 packs of metric bolts /nuts /washers /screws at a reasonable cost - use the flat rate shipping envelopes - if I had found this I would have bought everything there