[crashwg]

Ok, so I'm quite intrigued by the whole concept of CNC routers and I'm hoping to build one in the next year or two.

When I do get arround to building one I want to be a seasoned profesional when it comes to G-Code though which is pretty much the purpose of this post.

I have autocad 2000 installed on my computer currently and I have 2004 & 2005 I believe somewhere arround my house, I would just have to find them.

I downloaded MicroTech CncSimulator the other day also so I should be able to test anything I can actually get converted into G-Code once I figgure out how that program works!

So that's pretty much where I'm at now. I'd like to start of small, maybe just simulating 2D designs and working from there.

Now what? Are there any tutorials out there that would be helpful to someone with no experience like myself? Maybe some examples that the author has documented start to finish so I can see what goes into the whole deal?

Thanks in advance!

[Bubba]

Crashwg,
Personally, I think you are jumping ahead of the cart! If you want to LEARN g-code, I think you need to HAND CODE simple shapes first. Cad is fine, and you can plot out the shapes and then figure out how to do the code by hand.
Then, when you finally enter into the world of using a Cam program (converts the drawing file into G-code), you will be able to look at the coding to see where problems are if they occur.
Its kind of like learning to drive. If you learn on a standard shift, the move to an automatic is easy; however, I have seen cases of people who have learned to drive on an automatic that no matter how hard they tried could not master a standard transmission!

[Al_The_Man]

I agree, if you hand code some shapes and run them in the simulator, you can see the results. There are plenty of turorials on the web as in http://www.jjjtrain.com/vms/cnc_intro_code.html
I would suggest starting with simple linear and circular interpolated moves first and then include M codes such as spindle etc. Then progress from centreline programming to tool dia and length offset, followed by fixture offsets where the part zero is re-positioned.
Next canned routines such as peck drilling or threading.
For maximum flexibility, study macro and parametric programming which makes G code programming very powerfull.
I have two references I use which I find excellent, first is 'Computer Numerical Control Programming' by Michael Sava and Joseph Pusztai, try and get it if it is still in print.
The second which complements the first is 'Computer Numerical Control' by Warren S. Seames, published by SME.
Al.

[corrie]

Hello all I,ve got a ?Lets say I,m cutting out a square for example and my initial Z plunge is .25 into my material,after completing the four sides and coming back to the initial place where I first did my .25 plunge,do I have to add another .25 onto the initial .25 in order to plunge down .25 extra?Or do I write a new line of code with the addition.Cheers.

[ger21]

Hello all I,ve got a ?Lets say I,m cutting out a square for example and my initial Z plunge is .25 into my material,after completing the four sides and coming back to the initial place where I first did my .25 plunge,do I have to add another .25 onto the initial .25 in order to plunge down .25 extra?Or do I write a new line of code with the addition.Cheers.

It depends what you want to do. Are you asking how to mill the part? Tell us what you want the tool to do, or give us some sample code.

It's a good idea to start a new thread for a new question, rather than posting in a thread with a different (although similar) topic .

[corrie]

Hey ger21 sorry about that,what I want to do, is to have the router keep going along at different Z levels but from the start point each time.Somewhat spiral cuting along the same path.Was just wondering if a new z level was to be given from the start plunge or would that # take over from the other,thanks.

[ger21]

Ideally, with a router, I try to never plunge straight down. It will burn up bits quicker and put a load on the router it wasn't designed for. (Assuming a standard handheld router). Try this:

G1 X0 Y2 Z0 (lower tool to top of workpiece)
G1 X0 Y0 Z-.25 (move to bootom left corner while ramping down)
G1 X2 Y0
G1 X2 Y2
G1 X0 Y2
G1 X0 Y0 Z-.5 (ramp down for the next pass)
G1 X2 Y0
G1 X2 Y2
G1 X0 Y2
G1 X0 Y0 (clean up the ramp)
Lift the tool.

This is just 1 way to do it. I think this is what you're asking, but I'm not completely clear. The above example uses absolute coordinates. You can also program in incremental coordinates, which would be relative from the previous positions.

[corrie]

Thanks Ger21 I,m going to give that a go.By what you stated you should give the Z a little more -Z to get the required depth that one is after.Cheers.

[ger21]

Whatever depth you want, is the depth you set in the code.? The example I posted was making 2 passes to get to a depth of .5. That's what I thought you wanted to do.

[corrie]

g92 x0 y0 z0
g00 z0.1
g00 x.25 y6
g01 x14 y1 z-.125 f10
g01 x16.50 y2.50
g01 x14.25 y6.25
go1 y8.25
g01 x16.50 y12
g01 x14.50 y13.50
g01 x.25 y8.50
g01 y6 z-.125 f10
g01 x14.50 y1
g01 x16.50 y2.50
g01 x14.25 y6.25
g01 y8.25
g01 x16.50 y12
g01 x14.50 y13.50
g01 x.25 y8.50
g01 y6 z-.125 f10........g00 z0.1 Call me thick .So in a g1 lineal move you can include a -Z move?And if the line feed rate is lets say 10 does the Z feed become the same?Or does it not matter due to the fact that X and Y are in motion.does this code make sence.

[ger21]

How deep do you want to cut? I think all your X14.xx should be the same.

A g1 move is a straight line from the current location to the position specified on the line. If the Z is a different depth, then the cut will ramp up or down. The tool will move at the specified feed rate along that path.

g00 z0.1
g00 x.25 y6
g01 x14 y1 z-.125 f10 (This should be X 14.25, or 14.5, not sure)

From this point on, everything will be at F10

g01 x16.50 y2.50
g01 x14.25 y6.25
go1 y8.25 (this line won't work, should be G zero. You have G (letter "O"))
g01 x16.50 y12
g01 x14.50 y13.50
g01 x.25 y8.50
g01 y6 z-.125 f10
g01 x14.50 y1
From this point on, you are repeating what you already did.
g01 x16.50 y2.50
g01 x14.25 y6.25
g01 y8.25
g01 x16.50 y12
g01 x14.50 y13.50
g01 x.25 y8.50
g01 y6 z-.125 f10

[corrie]

Thanks,the material is 3/4 inch thick and I only want to cut down to about 7/8 of that.According to my drawing and the points that are plotted out there are two different X14,s one being x14.25 and x14.50.I,ll have to run it and see what becomes,thanks for your help.

[MIKE JEFFERS]

crashwg
back to basics
build something just do it gantry router is good but a converted mill drill /mini mill
is easier for the first one forget ball screws just cnc a mini mill it will give you an
over all feel for what is possible.
"the next year or two " you can do this in a few weeks ,and for little cash.
after that the realisation that the "investment" is worthwhile will kick in
do it now ...life's too short( and this cnc nonesense is fun)

[crashwg]

crashwg
back to basics
build something just do it gantry router is good but a converted mill drill /mini mill
is easier for the first one forget ball screws just cnc a mini mill it will give you an
over all feel for what is possible.
"the next year or two " you can do this in a few weeks ,and for little cash.
after that the realisation that the "investment" is worthwhile will kick in
do it now ...life's too short( and this cnc nonesense is fun)

The "next year or two" plan is pretty much based on the fact that I live in an apartment at the moment so pretty much the only way I'll be able to build anything would be when my GF's parents build their garage or we move into someplace else.

Another thing that I'm taking into account is that I want to at least be able to do 18x36 on my first machine and hopefully eventually 49x97, a sheet of MDF! That I'm sure can wait a while though... Now I'm not sure if you could get 18x36 out of a mini mill which is why I haven't looked into that route yet, also looking at examples of cnc routers, they don't look all that hard to me.

Don't get me wrong though, I don't think I'm smarter than anyone else or anything, it's just I pick things up pretty quickly when it comes to building things and math too so I'm not too concerned with the build itself but when it comes to g-code I can't say that I've ever seen reference material before, but I haven't been looking either.

I guess I'll be looking for simplistic g-code examples that I can study and experiment with. But if anyone has any that they'd like to share feel free! Start em off easy though, squares, circles and I'll go from there!

[ger21]

A pretty good source of gcode info is the EMC documentation. http://emc.sourceforge.net/Handbook/node45.html

I wrote an AutoCAD macro to write gcode from inside AutoCAD. It may not work in 2000, but will in 2004 and 2005. You can get it here:
http://www.cnczone.com/forums/showth...6&page=1&pp=25