[Nitrografix]

I went to school for mechanical engineering some time ago and never finished. New to the board here and I am pretty fluent on autocad and inventor. Just bought solidworks 2012 and it seems pretty comparable to inventor only a lot more user friendly than the one I used to use. That being said. I'm anxious to build my machine, I'm gonna be using it to cut a lot of guitar bodies. I seen an eBay kit from longs company for 3 nema 23 425oz and their stepper driver and card, any thoughts?

[Trotline]

Some of the best advice I can give is to spend a good bit of time researching on these forums before buying anything. These machines are simple in concept, but complex in execution. There are a lot of folks building and using them for just what you plan to do, and reading about their progress and problems will greatly benefit you. Start by posting a basic drawing and getting some feedback on that, then as you evolve your design, you'll make decisions about things like what sort of drive system is best for your needs.

Matching motors, drives, and power supply to the machine and it's mechanical drive system is important. There are few "one size fits all" solutions in this game. It really bites to buy components and then feel stuck with them, even though you later find something else that would have been a better choice. You'll eventually have to pull the trigger and commit to the design, but that initial period of exploration and learning is really helpful, in the long run.

Luke

[ger21]

I seen an eBay kit from longs company for 3 nema 23 425oz and their stepper driver and card, any thoughts?

Most Chinese kits on Ebay feature poorly matched components, which don't perform well at medium to higher speeds.

[aarggh]

The problem with a lot of the Chinese kits I've seen, are the steppers are quite often fairly high inductance, usually with good quality individual drivers, but are supplied with a power supply around half the recommended voltage. Use the generic Gecko PSU sizing equation of 32 x the square root of the inductance, to tell you how much voltage the steppers you see advertised really need. If they need 90v but are supplied with a 24/48v supply, you can see the obvious performance deficit.

On the other hand if you connect that same motor in parallel mode, the PSU would be fine, but you'd be doubling the current requirements.

cheers, Ian