Re: [CAD_CAM_EDM_DRO] Re: CNC power supply question

On Saturday 06 March 2004 02:47 pm, caudlet wrote:

> Sit down and decide what kind of machine you are building or retro-
> fitting.

I guess for retrofitting this isn't that hard, but for building something
from scratch?

> Determine the type of machine and work envelope.

By "work envelope" do you mean the largest bit of material that the machine
could handle? This is just one example of a lot of terms I see being tossed
around in these groups that I'm not familiar with, so mostly I'm guessing...

> Is it to be moving table or moving gantry.

What are the tradeoffs? Seems to me that moving table would be more
complicated to build, but again I'm guessing.

Taking a look at a web site with a bunch of different kinds of machines (take
the crankorgan site for one example), there's not much there that would tell
me which of these would be more suitable for what kind of task. Or which
would be that much harder or easier to get going with.

> What kind of drive approach will you take: rack and pinion, toothed belt,
> ballscrew, acme screw, etc)

For me I'm guessing (again) that the first thing I build is probably going to
use threaded rod from the hardware store or home center. :-) I don't see
where I can justify spending the money on some of the alternatives, or at
least not yet.

> Decide how fast you want it to go

How do you decide this? I was surprised to see in one of these groups a while
back that routinnng-type tools need to move at a certain minimum speed
(depending on the tool and the material?) or you end up burning the material
instead of cutting it. Where do you guys learn this stuff?

> and roughly how much you think the moving parts will weigh. In other words
> design the machine first. If you already have some components run your
> numbers using those items and see if you can get there. Once you have a
> pretty good grip on what you want to move and how fast, you can shop for
> motors. IF you want to use servo's and hobby level motor controllers (not
> to infer that hobby grade controllers are any less capable than commercial
> units but they will not drive certain motor types) then you need to shop for
> DC brushed motors with either encoders or a way to mount an encoder.

Hmm.

> Once you have your design and motors THEN it's time to start thinking
> about a power supply.

Makes sense. Know what the load needs first...

Me, I don't have too much trouble with the electrical/electronic side of
stuff, it's all of this machine-shop stuff I'm needing to learn.

Any suggestions on that?