Help with workflow for a total newb? Mach3

[Sandiapaul]

Guys,(and gals!)

I have some cnc experience, mainly with a Prototrak BP that I use all the time in my shop(work and personal) I also have some exp with a big VMC, but that was mostly just to find my 0,0, load parts and hit run! I learned the E stop button pretty good too

I have a small Dyna 2400 I converted with a kit to run Mach3.
I also have Onecnc software and Autodesk Inventor.

After YEARS, I am finally about ready to make a real part with my little setup and am running into a plethora of problems!

OK so I have my part I made in 3D in Inventor.
I make a DXF
I import the DXF into Onecnc
I select the various features and end up with the g code
This is just a 2D part(I'd like to get to 3D, but I need to get this down first)

Now here is where I have a problem...

Do I need to tell the software in my CAM where 0,0 is? Like the center of a hole, or a corner, etc..? IF that is so, I need to figure out how to do that.

Or can I somehow in Mach select a feature and make it the 0,0?

I can make a part, but its just guesswork where the part is truly located so far.

I know VERY little g code...

Thanks for any help!

Paul

[GlennW]

I'm not familiar with your software, but the CAM software usually picks up 0,0 from the .dxf by default, but you can re-orient the part to reflect a different 0,0 if needed..

[Harold_V]

What Glenn said.
I'm poorly schooled on CNC, but you must consider that your drawing has datum points. All features on your part originate from these points, which, for me, would be the left hand side and far side of the part, as if I was making the part on a manual machine (CNC operators use the near edge instead of the far edge). In a nut shell, the upper left hand corner would be my reference point.

In any case, you must identify as a starting reference point on your machine, those same two datum points, where ever they may be. If you hold your work in a vise, that would be the fixed jaw and the stop set (for me, to the left). Once you've inserted that information, the machine defaults to that location to begin making your part.

Take all of this with a grain of salt, as I have precious little experience with CNC, but what I've posted works for me.

Harold

[Rick]

I'm not familiar with your software, but the CAM software usually picks up 0,0 from the .dxf by default, but you can re-orient the part to reflect a different 0,0 if needed..

In general this is true, but some software will ask where you would like 0,0,0 and then you pick the point with the cursor. I always reorient the part as the model comes to me from the designer without regard to what is needed for programming/machining plus the first software I used required the 0,0,0 to be the system (software) 0,0,0 and I am to old to change my ways
Never used the software you are using so these are just general comments.

[Sandiapaul]

Thanks all...I'm still in the steep part of the learning curve, but making headway!

[RET]

Hi,

I'm a long way from claiming to be an expert in CNC, but I try to make 0,0,0 on the axis of a part feature that I can reorient on easily if a disaster occurs, like a hole center or something else that is easily referenced.

For example, when I did a coupling rod for Dart, it was the center of the fixture bolting for one of the rod ends. As I said above, I do this because it allows me to recover the start position easily and accurately after a crash or some other mishap.

You always hope things will go well, but then reality has a nasty habit of stepping in at the most inconvenient time.

Just my experience.

Richard Trounce.

[Jim_Nolan]

I have the feeling I may be talking well outside my comfort zone as I am only fair to middlin’ at CNC work.

But once you bring the geometry into the CAM software I would have thought it needs to know where 0,0,0, is and that will also be governed by what the size of stock is you’re machining the part from.

I bring 3D models into my CAM software and the first thing you do is press a button to locate zero then, the stock box then adjust to allow for the stock size.

Have you had a look on YouTube to see if there is a tutorial on importing geometry? I use Sprutcam and there is a good one for doing this which might give you some clues?

Jim

[JimGlass]

Knowing where you are and where you want to go is the most difficult concept to grasp in CNC machining. Over time and experience it is learned.

There should be a menu in your CAM software that will ask you if the origin for X0, Y0 is an edge or the center
of the workpiece. The software should then move the drawing to where you want X0 and Y0 to be.

Below is a link to an old post of mine on this topic. On the workpiece shown in the link, I indicated a bored hole
in the piece. I then made X0 a known distance from the hole and the same for Y0. There was extra material to machined off at X0 and Y0.

http://www.chaski.org/homemachinist/vie ... ht=deskcnc

Hope this helps,
Jim

[woodguy]

"Do I need to tell the software in my CAM where 0,0 is? Like the center of a hole, or a corner, etc..? If that is so, I need to figure out how to do that."

Yes you do. All cam programs have a way to define the stock, to align the stock, and to align the part in the stock. I took a look at the OneCNC web page, but there isn't a downloadable demo so I can't tell you how these things are done in your software. Once you have defined the stock, imported/aligned the part, defined machine operations using appropriate tools, and settled on suitable spindle speeds and feed rates, you can generate the code. At that point you could load it into Mach3, set up the machine with the appropriate tool, locate 0,0 and set the machine's axes to 0,0 at that point, locate the surface of the stock and set Z to zero there and run it - BUT - it would be a better idea to simulate the code first to make sure you'll get what you want. OneCNC seems to be a fairly high end product, and probably has a simulator built in.

If you are using Mach3, you need to tell OneCNC that it needs to use a Mach3 postprocessor - that's all you need to make your Gcode compatible with Mach3.

When I first ran my own gcode, I set 0,0 to the centre of the stock ( I used an oversized piece of material) and just guessed at the centre of the stock when setting up the machine. Z is another matter - you need to get that right. That way I was sure I'd get my test part because any small error didn't matter.

When you want to use fixtures and the like, you'll need to indicate to a specific point, but that's for later.

CNC is bags of fun - good luck.