Help choosing steppers and drivers

[Aaronem]

Hi
I need help to figure out the size of steppers and drivers I need to run a 1.5m x 1.5m gantry style w/w router. Gantry weighs about 70kg, lead screws are 16mm dia. with 4mm pitch. Money is tight and I need to know what to look out for on ebay UK.
Please help
Thanks
Aaron

[DistortedDesign]

Thats a very beefy machine. You are going to want something pretty big. Probly nema 34 800 Oz + if not 1000 Oz. It depends on what you are wanting to cut with it and what speeds you are wanting to cut at. You could get away with less but it would be at lower speeds 60 ipm or less depending on what you are cutting. I am building Joes 2006 and I am putting 500 Oz motors so that I can get the speeds that I want. 120 ipm with jogs of 200 ipm. I am not an expert though. Hopefully this helps.

[ger21]

Generally with steppers, the larger the motor, the slower it'll spin. I'd gear it 1:2 or 1:3 to change the effective pitch to 8 or 12mm per motor rev. You can probably get away with 600 oz motors, but there are a lot of factors involved.

[Eurisko]

Aaron,

Here's a thread that will answer many of your questions:

Calculating What kind of power i need ?

Read post #10 by Mariss Freimanis. Although Mariss made a slight mistake in running the numbers, it is a great post.

[Eurisko]

Aaron,

Here's another thread, some of it applies to steppers.
Read post #7 by ... guess who?... Mariss Freimanis.

Very interesting facts about acceleration.

Servo set-up help

Maybe I should just read ALL of Mariss' posts.