Re: [CAD_CAM_EDM_DRO] Noob needs advice on retrofit

andy_paul_2000 wrote:

>I would like to get started on my CNC retrofit. I had a servo cnc
>system in the past that was by flashcut on a small Sherline mill.
>Overall it worked great but was a little small for what I was doing.
>I now have a chinese mini mill that I would like to do a conversion
>on.
>

What size? I have done a servo conversion on the 150 Lb minimill, and other
that the light construction of the machine ways, it works quite well.

> I do have a good idea how CNC works, difference between servo and
>stepper, etc etc, but the flashcut system was "plug and play" if you
>will. Can someone push me in the right direction as far as choosing a
>setup as far as motors, drivers etc, and how to interface all of this
>together. From what I understand you can use software alone to drive
>the motors directly from a windows PC. Is this the way I need to go?
>

Software step pulses and no position feedback to the computer are a drawback
to these systems, but you can't beat the price. For a little bit more
money,
you can have encoder feedback to the computer, and that gives several
advantages. One, you can't ever "lose steps" without knowing about it.
Two, you can evaluate following error and make decisions on what feedrates
give acceptable accuracy. Three, you can optimize the control loop to
obtain the minimum error. Four, you can switch between manual and CNC,
and use the CNC program like a DRO when in manual mode.

>I do have BobCad software that I would like to utilize as well. All
>in all I would prefer to keep this project under $1000 if at all
>possible. I need 3 possibly 4 axis of control, most G-code functions,
>interpolation etc.
>
>Is "EMC" a decent way to go?
>

If Linux doesn't scare you, then definitely. If you have a total phobia
about
anything that doesn't work under Windows, then it might be better for you
to go with Mach2. If you want to get into the guts and change stuff, then
EMC is about as good as it gets (open source).

>I have seen "gecko drives" mentioned, are these good products? they
>are very cheap
>
>

Gecko makes a good product, and the price is right. They are not
"bulletproof",
but work well in most systems. But, the standard Gecko setup is not closed
loop, by that I mean, no position feedback to the computer.

Jon