Re: re:Re: programming by hand

> Date: Thu, 11 Jan 2001 23:08:05 -0700
> From: "Smoke" <Smoke@...>
>Subject: Re: re:Re: programming by hand
>
>If you don't already have "canned" cycles, it's easy enough to "write your
>own". Every time you do any kind of "simple" project, save the useful steps
>as "sub-routines" for possible incorporation into your next project. In
>fact, if you put all your "sub-routines" at the beginning of your main
>program, it would be easy to number each differnt one and add new ones as
>you "discover" them. You could then start EVERY program with your own
>personal basic "canned routines".
>

I have found this to be a very useful practice in the past when working in a production
CNC environment. I don't use it too much in my hobby activities, but whenever I am
Trying to earn a living from in front of a CNC machine it becomes important. I do not however,
agree that subroutines should be placed at the beginning of a program. The most elegant
that I have seen is to place the individual routines in sub-programs. It is much more
intuitive also to have them at the end "out of the way", and to call them from a main
program that is much better to have at the beginning. That way it is easier to see the
order of processing and what tools are required, etc.

>You could also include your personal canned package as you edit the gcode
>produced by your CAM package as well.
>
>CAD is NOT a must...unless your doing really complicated parts. I ran an
>experiment the other night to generate some gcode using the BobCAD demo.
>The code it generated was extremely long for the part to be machined. Also,
>it generated the part with only one tool size.

If you knew what you were doing with even Bobcad, you can run circles around
anyone doing manual programming at the machine. You may not be able to do
this 5 minutes after installing your cam system, but the time to setup the macros,
subroutines etc, will be shorter with the CAM system than doing it directly at the control.
The reason, is that it is easy to set up prepared series of instructions that can be
customized on the fly to cut a particular item. You can also include instructions
to yourself to, for example set the value of Va=-.5 to the actual depth required for your
part. Since you are working in Windows, the editor in most any cam system is more
productive than most machine controllers, especially the DOS based controllers, and
the older dedicated controllers such as Fanuc, Allen-Bradley, etc..

>With a good isometric
>drawing of the part I can write a MUCH simpler program. I'd also save time
>by inserting a tool change and bigger Z moves. Having canned cycyes
>mentioned above would make the whole process that much simpler.....and
>probagbly faster since I wouldn't have to wade thru the generated code to
>make changes that didn't need to be there in the first place.
>

If you spent a little time with a good Cad-Cam system, you would realize that
when you know what you are doing, you can exercise MUCH more control over
the toolpath than you can manually. Also most drawings being generated today
are in electronic CAD format, so the issue of having to draw the part to machine it,
is becoming obsolete.

>Incidently, I've got another part to cut that can be done using three tools
>rather than one. In fact, I'd get a better cut using three tools rather
>than one strait cutting (or a bull nose) end mill. I'd use two ball end
>mills to cut the required radii using only ONE "move" with each tool. Rather
>than cutting the radii via a complex program using step cutting ...which
>leaves a rough surface.
>
>So there IS a place for generating your own gcode programs by hand.
>

Again if you know what you are doing, it is no problem to produce this cut,
even with Bobcad. The benefit is that you won't make a typographical error
when you try to type in a coordinate value like X10.0 instead of X1.0. The
CAM programs won't make this kind of mistake, but operators/programmers DO!

>Smoke
>
>>Nice post! It's good to remember that it all boils down to lines and
>>arcs! For those who HAVE the 'canned cycles' at the level you
>>mention ; i.e.,bolt circles, pockets,macros, etc.(many will just have
>>drill cycles) it is good advice. Single line programs and cutter
>>comp 'tricks'.
>>
>>>But, I think their(CAM) need is overrated. On the other hand a CAD
>>>system is a must.

Last point, lest some think I am biased in favor of CAM systems, and this
is a point that many who squeezed in to the CNC discussion last year at Names
have already heard:

Often times it is more efficient to produce the part with a manual machine rather than a CNC.

This is not a particularly popular thesis, but I can guarantee you that for a single hole I can walk
over to my Bridgeport and poke it into a part faster than you can warm up and boot the controller
on most CNC machines. You want it tapped and a chamfer at the top? 3 tools? I will have it done
before you poke the macro program on your conversational machine OR program it on your Cad-Cam system.

I am concerned that those getting advice don't always understand the background of the advisor & maybe
it would help in some cases if people would describe a little about the kinds of parts that given kinds of
approaches are suggested for.

As an example sometimes Rhino is suggested as a great Cad system. It is , provided
that you want to make swoopy, nurbs surfaces. It is however not that great if you want
to make simple 2 axis CAD drawings of parts with edges. The free Intellicad may do a
better job in this case.

For another instance, if I make parts that consist solely of shapes cut from solid
rectangular bar stock, with drilled and tapped holes, my techniques will be very different
than if I make 3D sculpted artwork, with no straight lines anywhere. I often times see
people arguing over the best technique to do these two things, but they don't say that
the techniques are for making different kinds parts.


Best Regards, Fred Smith- IMService
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