How do you do it? -- CNC Programming

      Programmers share their methods. August 17, 2004

I've programmed CNC routers a long time. I have little to no errors and do it pretty efficiently. After reading and replying to the "BobCAD" thread, many questions surfaced. How do *you* do it? In simple 2-d programming I would make a drawing, pick a starting point, drop my cutter to the proper height, pick a direction and machine that chain of entities. Lift my cutter and continue cutting or end. (My cutting strategies are figured in advance). After the code is generated, I go back over the program to enter increase, decrease of feed speeds or stop checks for square corners and things like that. After reading other replies to some of the threads here, it seems as though many people are using some creative processing software. Is it then a matter of making your drawing and letting the software take over? I'm really curious about this.

Forum Responses
(CNC Forum)
First I would like to acknowledge your "G" code ability - as with any CAM software, this is valuable. I am new to CNC and I'm self taught or phone tech trained. The use of AlphaCam has made my learning curve easier, I'm sure. To answer your question, yes, it's that simple! Create a geometry, pick a tool, tool directions, set elevations, feeds, spindle speed, tool lead in-out, move rapids to where you want, etc. This takes about a minute. I could not imagine having to write the G-code for that. The new CAM packages are definitely a time saver. I say invest!

From Brian Personett, forum technical advisor:
One note before I start: I program a P2P, not a router, so if some of you are only familiar with routers, this may seem off the wall.

If it's a simple part, no odd radii, just routing and maybe a few holes, I would program it with my machine's software, Winner90. I do have some parametric programs set up that do standard run of the mill stuff, where I just plug in variables. Using this method would typically take me a couple minutes. If it requires more than that, I opt for option two.

Option two, draw the part in ACAD and run it through CADCode. Again I have an ACAD template set up, just draw the part using PLines, put holes wherever they need to be, send the DXF to CADCode, make code and go machine it. This process is also pretty simple and straightforward. Feed speeds, RPMS, layernames - I have all that set up in my ACAD template.

Standard cabinet parts, like I produce every day, cabinet info is entered into an Excel spreadsheet that generates all the sizes and geometry, and a CSV file is kicked out to CADCode, which then produces saw patterns, labels, and G-code.

As far as checking G-code or looking at the programs, I never mess with it.

I use Enroute3 and AutoCAD. I just draw my parts in AutoCAD and import the .dxf in Enrout3.

It takes less than a minute to enter tool, direction, feed speed, etc. if I don't already have a template for that tool and material thickness. If I do have a template, then it takes literally a few seconds.

I use a program called MillWrite 2000 - very easy to use for drawing and setting up for tool paths. I run a self-built machine with up to 4 spindles. I have had people show me many high end Cad/Cam packages and none of them beat MillWrite for cost vs. ease and versatility.

It depends a little on whether you need as much control as you have now. For example, most of the newer software can adjust the acceleration/deceleration in the post (if you request it) or the control may do it with a G-code, if it is of the newer variety. If you still need all the manual controls over the toolpath, make sure you get a "CAM" system and not a "batch processing" system, as most of them do not allow robust control over the toolpath.

Since I am dealing with other people's designs, and we are surfacing complex entities, I begin by converting their Pro-engineer models to IGES files. These are read into Mastercam and then a series of toolpaths are generated. Probably not typical of most users of this forum, but an honest answer to the question posed.

I write programs for both 2 Komo vr508 and a Busellato Jet 400 using acad 200i, Router-sim and autolink. I receive the drawings directly from our network and make any changes necessary for ease in manufacturing. I sometimes find that it is easer to edit the nc code right at the Komo. We work mainly in hardwoods such as oak and maple, so finding a good feed rate is sometimes a hit or miss. I average around 20 programs a day 6 days a week.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
I program our CMS router using CMS's Wintools software. For 2D stuff, I just have to draw in the paths, holes, etc., assign them to a layer for each process, and then import them. The software automatically applies the right machining data to objects on each layer. Then I go in and check the start points, directions, feeds, etc. and make any changes. After generating the g code, I check it and make changes to the feed and rapid speeds to make the programs faster. For 3D stuff, like guitar necks, I draw the paths as a 3d polyline in Autocad 2000i and manually apply the machining data.

For our Weeke PTP, it's about the same process, but there is more manual data to enter. For simple parts, I just program them at the machine.

Comment from contributor B:
Alphacam lets you slow down at corners. You enter your percent of speed to slow down and how far away from the corner you want to start slowing down as well as in how many steps to do the slow down. Then you can accelerate back out of the corner again. It has worked great for me in the past.

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