Only ordered 1605 for the z-axis (should be fine I think) I may consider 1610 for x and y then
@Paul_Frederick I have not ordered any electronics like motors, PSU or drivers yet so I’m open for suggestions/recommendations
Actually that was the second thing I picked up from research, get it all worked out before you order any parts, I read it, though what ever, now I have a box of parts for the next build 
I’m running at 30 volts at the moment as that’s all tinyg supports, I’m going to external drives and I’ll run them at there Max around 50 volts I think it was.
@Paul_Shaw is right. You’re not going to be able to practically use the resolution of 5mm pitch lead screws. Even in quarter step mode that means every step your machine will only move 0.00625mm. It takes a lot of those small increments to move an appreciable distance.
There is a practical upper limit to the frequency you can run your step signal too. Which is something you’re going to learn very shortly.
That is one of the harder lessons to take in this DIY CNC stuff. One that tends to haunt us regularly.
Yeah your accuracy isn’t your step size. It is manly to do with how rigid your machine is.
@Paul_Shaw
hmm with the drives you have now it is package dissipation that is killing you. An A4983 is 32 W/C So you can’t get many Watts out of the chip before it is sending smoke signals. Less than 4.5W according to the data sheet.
I really don’t like surface mount parts for power applications. I like a part with a beefy tab that I can attach a honking heatsink to. That to me symbolizes power.
My cheesy TB6560AHQs have a theoretical maximum power output of 43 Watts. If you can find a magical infinite heatsink for it. Realistically I’d say you can get slightly north of 20 Watts out of one.
Because they’re big, bad through hole components. I just got some TB6600s to upgrade my machine with. There’s some secret sauce inside those chips. They’re a huge improvement over the earlier drives.
But the boards I got say max 32V input on them? I guess I’m just going to have to get chips and make my own. I don’t know though, I’ll probably be happy with these imported drives. Bench testing them I have to say I am impressed with their performance. Nine bucks, and no fuss, no muss.
@Paul_Shaw
that, spindle run out, temperature variations. Once you’re down into the ten thousandths of an inch everything starts to matter. It is impractical resolution for a home gamer. I’m happy my machine seems repeatable to the thousandth of an inch. But it could rapid faster.
Yeah I’m the same, accuracy is good enough speed could be more. Hence the drive upgrade I’m going with the cheap eBay drive I found an pdf where a uni student went through it and picked all the faults, mostly bypass capacitors and other little things they left off to save a few cents. So I’ve added them in. If the chips good for more voltage I can’t see why you can’t run it at that as long as all the other bits in there are good for it, and there’s not that much in there. Only thing I’d look at would be the electrolytic caps.
@Paul_Shaw
I am thinking there is an on board regulator for the logic circuitry on the drives I have that cannot handle higher voltage. Or the chips are counterfeit, and they can’t handle the maximum voltage of the genuine devices. The filter caps on the boards look like garbage to me. But they’re working, so I’m going to run them as they are. Replacing them with decent caps would cost more than replacing the whole drives.
Maximum voltage on stepper drives includes inductive kickback, or back EMF. Which can be higher than input voltage is.
One of the stepper motors I consider (3mH) http://www.cncrouterparts.com/420-oz-in-30-mh-nema-23-stepper-motor-38-shaft-p-188.html
http://www.cncrouterparts.com/420-oz-in-30-mh-nema-23-stepper-motor-38-shaft-p-188.html
@Oyvind_Amundsen
You like that motor? Here’s some name brand hardware to compare it to http://catalog.orientalmotor.com/item/stepping-motors--1068/pk-series-stepping-motors/pk296-f4-5a?&plpver=11&origin=keyword&by=prod&filter=0 It is a shame the real thing costs so much.
Thank you for all help - My plan for now:
z - Use the 450mm 1605 ballscrew I have ordered + a 425 Oz motor (this can have a higher inductance value so I get more “friction” in the motor and the z-axis does not go down when I turn off the power.
X and Y - use 1610 ballscrews + 300-425 Oz motors with low inductance.
Couplings - I may use belt, but 1:1
Hope this sounds ok
@Oyvind_Amundsen
ah steppers don’t hold when you remove power. Well, they do a little. But nothing like when they’re powered up. They hold pretty good if you short all of the leads together though. One thing you can do is use a gas shock on your Z to make it neutral buoyant. Some folks do that to offset their Z axis weight.