Re: CNC retro fit - Gray aera , need help.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "pastypies <pastypies@y...>"
<pastypies@y...> wrote:

> Hi all,
>
> I am looking for the missing link between a Solidworks part and the
> actual part being machined. I have a JFC-500C mill/drill (quite a
> size as mill/drills go), I would like to make it a CNC mill/drill

by

> fitting NEMA 34 size stepper motors to the X and Y axis and perhaps
> something smaller to the Z axis. I have researched the Internet for
> about a month now and have found many informative sites, CNC Retro-
> Fit website at http://www.mendonet.com/cnclinks/index.html is
> especially good. From what I have read I conclude the following.
>
> 1.My mill/drill must have stepper motors fitted to the X/Y and Z
> axis.
>
> 2.If possible I should change the standard Acme lead screws with
> ball screws for greater accuracy.
>
> 3.The motors must connect to some kind of driver or amplifier.
>
> 4.The driver(s) then connect to some kind of controller card fitted
> inside my PC, or connect to an external controller that connects to
> the parallel port etc.
>
> 5.Software on my PC needs to convert G and M codes into signals

that

> my controller card can understand (i.e. to be compatible with) to
> drive the motors.
>
> 6.The software (be it the above or other) needs to convert my
> Solidworks 3D model into G and M codes so the part can be machined.
>
> I understand that within reason a stepper motor is pretty generic

be

> it 4, 6 or 8 wire. In the same way so is a ball screw, its just a
> ball screw, what you see is what you get. Presumably I can go out
> and get any brand of stepper motor or ball screw and it will make

no

> difference what so ever?
>
> The trouble for me comes when choosing drivers, controller cards

and

> the software to make the whole thing work. A lot of companies offer
> motors and drivers but no controllers or software, or you can get
> software but it can't translate g-codes. Or you get companies
> that
> just offer software and that's all, like Mach1 from Artsoft
> (www.artofcnc.ca).
>
> There appears to be a grey area when it comes to this compatibility
> issue. Perhaps I'm just being dim or something, or it is just
> assumed that everyone knows what the score is here. Here is an
> example. Suppose I buy three stepper motors from Pacific Scientific
> (but it could be anyone) I also buy 6410 micro-stepping drivers

from

> the same suppler to drive my motors. I now need to find a

controller

> from a third party that will work with my drivers, and hopefully
> they will also write software that I can use to control my mill g-
> codes etc.
>
> I suppose what I am saying is `Is this whole thing generic'
> by that I mean do all these controllers use a standard command
> language?. If so I could then use any vendor's software to
> control them. As another example could I use the motors and drivers
> above and say a controller card from someone else and software like
> Mach1. This whole CNC retro business seems to be a bit of a black
> art so any help or advice would be more than welcome.
>
> Steve B...

Hi Steve, don't feel bad this is something that has gotten very
complex and confusing to anyone.

The basic roadmap is

CAD--CAM--Signalgenerator--MotorsMove.

where

CAD - A Software Program that is about you Parts geometry.
It defines geometry from partial to complete Parts in
every detail.

CAM - A Software Program that is about Toolpaths.
It defines the Tool geometrys to uses and where this
Tool is suppost to go or what it is suppost to cut
and when and how.
It uses a Post Processor that allows this info to be
converted to generate a G-code file that will work for
your machine.

Signalgenerator - A Software Program that is about generating
Motionsignals your Drivers can use to make your motors
move.
This usually means reading a G-code file translating the
instructions into the proper sequence of driving signals.
There are some that don't use G-code or only a limited
subset of them, this would make it more difficult to find
a proper Post Processor for.
The most compatible Output type is called "Step+Direction",
wich is supported by a lot of generic driver electronics
that use the Parallel Port of the PC to receive the signal.
There are also a lot of proprietery types out there that
often use additional Hardware to be installed.
This may not be a bad solution because due to the hardware
wich often speeds up processing significantly, however you
will be tied to one vendor and often have to pay a high price
for his Hard/Software.

MotorMove - this is the Hardware - Driver electronics that convert
the Signals received into a current that will move your motor.
There are a large veriety of drivers that have to match the
requirements of your motor.
There are drivers for stepper or servo motors of variable size.
The more powerful the Motor the bigger the Drivers have to be.
The Price for Power will raise exponentaly on these items.
A trade off can be made by sacrefising torque for speed when
gearing the motors to the leadscrews.

Hope this helps
Good Luck.