Chunky's Strategy

[Chunky]

Link a dink

[ynneb]

I think you might be going about it the wrong way.
Most people do not write thier own Gcode. They use programs to do it for them.
These programs are called CAM programs.
You insert the drawing you have into a CAM program and it will automatically concert it into Gcode.

The only reason I introduced you to CNC simulator was because you were asking questions about how to write your own gcode by looking at a picture.

I recomend you download a program called Sheetcam www.sheetcam.com
This program is shareware and will make little gcode file for you without needing to buy it. It costs $150 if you did want to buy it.

Mach2 although it is primarily a program for driving your machine, it also can create basic gcode too. Again it is trial ware and cost 150 bucks.

I feel for you, and wish I could sit beside you for just 1 hour so as to make it all clear for you. When I entered into this all, I was exactly like you. So much to learn and tons of new terms etc. It was a painfull few months. You will get there.

I recommend you just start by making your machine even if you dont know how to use it. When I had finished my first machine I did not know how to use it either. But if you break the whole thing down into small "Chunks" you will get there. Promise.

[Chunky]

I think you might be going about it the wrong way.
Most people do not write thier own Gcode.

I know. I wasn't thinking it was something that I would forever be doing. I just figured it would make it easier for me to learn CAM if I knew precisely what it was doing (making g-code-- right?)

The only reason I introduced you to CNC simulator was because you were asking questions about how to write your own gcode by looking at a picture. I recomend you download a program called Sheetcam

Well- It's not like I'm hell-bent on learning G-code. I just thought it was a bitter pill that I had to take and figured I'd get it over with. Nothing would please me more than hearing that I can forego that part. Is that what you're suggesting? (Putting a halt on CNCSimulator learning till I hear from you or someone in the know).

I feel for you, and .....

Don't give me too much sympathy. I'm just a whiner. I'm loving this stuff. It challenges me. There are people out there wondering where they're going to get their next meal. I'll get this thing done.

I recommend you just start by making your machine even if you dont know how to use it. When I had finished my first machine I did not know how to use it either. But if you break the whole thing down into small "Chunks" you will get there. Promise.

I respect your advice. It's all seemed good. On this I must disagree though. Nothing about the physical machine will help me. When you get right down to it there's nothing there but some rails and motors. Won't help me a bit to look at those. I want to draw a part, CAM it (I guess), send the file to you or someone willing to take it, let them run it. I wouldn't want them to even know what the final object is supposed to look like. (Maybe that's impossible since they'd have to check the tool path.) But, when it works, I'll order. Money's burning a hole in my pocket. Like your new avatar. Doesn't make me near as dizzy.

[buscht]

Chunky, very interesting discussion. Obviously, everyone who's doing this has had a learning curve and depending upon our background, various things have stumped us.

I don't understand your last statement here.

I respect your advice. It's all seemed good. On this I must disagree though. Nothing about the physical machine will help me. When you get right down to it there's nothing there but some rails and motors. Won't help me a bit to look at those. I want to draw a part, CAM it (I guess), send the file to you or someone willing to take it, let them run it. I wouldn't want them to even know what the final object is supposed to look like. (Maybe that's impossible since they'd have to check the tool path.) But, when it works, I'll order. Money's burning a hole in my pocket. Like your new avatar. Doesn't make me near as dizzy.

If you want other people to run your parts, you don't need your own machine nor do you need CAM software. All you have to do is draw the part in CAD. If you are just making a point about having someone check your G code for correctness, then you can do that yourself by using a G code simulator program.

Anyway, let me chime in with my 2 cents.

I see learning G code is like when you learn how to drive a car, women just learn how to drive, guys feel like they need to know how to fix and tweak the engine, change the oil, etc, etc. Sure, women can drive. but if they have a problem they have to call for help.

If you learn G code you know what to do if something goes wrong. There are thousands of people who program without knowing G code. That is what a CAM program is for. I am of the opinion that knowing G code is important and will make you more successful, but if you are overwhelmed with the whole process, put this lower down on your list of things to do.

Chunky, I understand your intention of being able to run a part within a couple of hours after tightening the last bolt. That's a good plan, but don't get too caught up in that.

There are alot of things to know about running a CNC and its impossible to anticipate all the problems.

Benny has good advice about breaking things down into "chunks". That will help you meet your goal.

1. Software
A. CAD
B. CAM
C. Machine controller
2. Electronics
A. Computer
B. Motors
C. Motor drivers
D. switches and relays
3.Physical Machine
A. lead screw or timing belt drive
b. linear bearing
C. Structure
D. router spindle
E. Router bits
F. Style of machine
G Work Envelope
4. Set up
A. Motor tuneup
B. Binding
C. lead screw/motor step setting
D. current settings
5. Operation
A. part holddown
B. Router RPM's
C. proper router bit
d. Proper feed speed

This list is not complete. You should make your own and use it as a check off list.

I've been pretty impressed with your thoroughness, but if you waited until every stop light was green before you left home, you'd never go anywhere.

Good luck.
Trent

[mxtras]

Learning can be frustrating - I commend you for trying this new adventure and I urge you not to let it get the best of you!!!

Sounds to me like choosing a direction presents the biggest challenge - once you gain enough insight into make decisions, the journey is fun!

I like Buscht's list - break the huge project into smaller buckets - all at once is overwhelming.

Hang in there, Mr. Chunky!!

Scott

[Chunky]

In response to Buscht:

I don't understand your last statement here.

I respect your advice. It's all seemed good. On this I must disagree though. Nothing about the physical machine will help me. When you get right down to it there's nothing there but some rails and motors. Won't help me a bit to look at those. I want to draw a part, CAM it (I guess), send the file to you or someone willing to take it, let them run it. I wouldn't want them to even know what the final object is supposed to look like. (Maybe that's impossible since they'd have to check the tool path.)

I know. I don't communicate worth a damn. Especially in text where you cannot hear tone. What I was saying was that I wanted someone to take my ready-to-run file, or at least what I think is my ready-to-run file, tell me if it would work or they can even run it to see if it makes a pine door stop or whatever I've drawn. That would prove to me that I'm capable of going from idea to software to CNC machine to doorstop in my hot little hand. And... I don't want to diminish the marvel that is the homebuilt CNC. I know there's a lot to it in terms of evolution of the components, the electronics and so forth. But in day to day usage I don't need to know how to make a linear bearing and I don't need to know whether that signal went from a capacitor to a diode or vice versa (proably neither). But I do need to know how to communicate with my router and I'm assuming ones and zeros is all it will understand. I don't speak a word of it.

women can drive. but if they have a problem they have to call for help. Honey, the green text is what someone else said. I didn't say that. Honest honey!

If you learn G code you know what to do if something goes wrong. Well.... say no more. I'll have to know it. Something goes wrong with everything I do. Looks like g-code will be an absolute necessity for me-- based on what you just said.

There are thousands of people who program without knowing G code. Are you among them? I mean no sarcasm. I just want to know if you're able to CNC without ever having learned it. As I said before I'd love to forego that part. If you have I probably can to.

if you are overwhelmed with the whole process, put this lower down on your list of things to do. Nothing I'd rather do than take it off the list all together. Somehow I felt starting at that phase of the works and working backward to CAD would be easier for me. That way- if I couldn't catch on to CAD I'd still be able to write simple g and get by. Yes? No?

if you waited until every stop light was green before you left home, you'd never go anywhere. I know what you mean by that and I appreciate your kind words. I just don't want to start ordering from a position of ignorance. AFter I get the software figured out, then I'll start driving you guys crazy with component questions. Maybe I'll be less obsessive about that, just order what most folks order and let it go.

[buscht]

Chunky, that last post was very clear.

Yes, I can program manually with G code very well. I have been in this field for almost 30 years. Before CNC was NC, we typed G code manually into a teletype machine and out came a paper tape full of holes that the NC machine read to make the parts.

Keep in mind that my statement is like saying I can read and write English. I still don't know every word in the dictionary, nor do I know everything about G code, but I can still write a program.

You can post your G code here as a Zip file or .TXT and lots of people will look at it for you. Its pretty simple. I would just run it through my G code simulator and see what it is. You would have to tell us the size of tools and blank though.

When learning G code. I recommend just learning the simple stuff to start.
1. What are G code versus M codes
2. Absolute versus incremental
3. Rapid travel versus feedrate controlled travel
4. Linear moves
5. Circular move, clockwise and counterclockwise.
6. Program start and stop.
7. Modal versus Non Modal commands

With that, you can write just about any program. There are lots more commands
Cutter comp, right, left, on, off may or may not be useful
sub programs and sub routines are more advanced and you don't need to worry about them right away.
Tool and fixture offsets and tool and fixture tables are important.
Drill cycles, helical interpolation, etc. are probably not worth your time unless you have a specific need.

Think of writing a program just like witing a story. You need a opening, body, and conclusion.

The opening consists of commands that guarantee you have the software in the condition you want it. For example, you want to make sure that the machine is always in Absolute mode, spindles turned off, etc. you would put the appropriate commands at the beginnig of the program.

Then you would write the body. This consists of the machine motions to produce your part.

The conclusion is just like program stop, move to home, etc.

That's plenty to start with.
Trent

[Chunky]

Responding to Buscht:
You can post your G code here as a Zip file or .TXT and lots of people will look at it for you. Its pretty simple. I would just run it through my G code simulator and see what it is. You would have to tell us the size of tools and blank though. Ah Hah! Well, that's exactly what I want to do. I'm not sure how well I can execute my plan. I'll just give it a go. I will attach two pictures. It's the same "part", just two views. And... I'll post a file. Here's where it gets complicated: I have drawn the part in SketchUp. That program allows you to export in four different formats that MIGHT be compatible with CAM software (so I'm told). But... it offers both 2d and 3d and if offers two versions of each. Bottom line-- there will be four files. I have no way of knowing which one would work for any particular person interested in participating in this exercise. If I can get some good feedback more people than just me can benefit. I will now try to attach the pics and files. (The start point is 1/4" hole, end point is 1/2" hole). The blank is 6" x 6" x 3/4" MDF.

[buscht]

Chunky, The files show up on Autocad Ok, The 2D files are worthless for going to a CAM program because they came across as a weird perspective projection.

If you could output 2D in a top down (plan) view it would work fine.

I'm not sure what else you want done with these.

PS, I'm going on a business trip for 2 weeks, so I won't be able to reply for awhile.
Trent

[Chunky]

Chunky, The files show up on Autocad Ok, The 2D files are worthless for going to a CAM program because they came across as a weird perspective projection. Okay.That tells me that. That narrows it down from four files to two files. I guess the only other consideration would be DXF versus DWG (I think that's right). Do you recall if one of those was preferable to the other?

If you could output 2D in a top down (plan) view it would work fine. Good.

I'm not sure what else you want done with these. I would like for someone to see if they can be processed (for lack of a better word) as if they were files that you, yourself had generated. I'd like to know if you can put them into a CAM program and generate toolpaths and g-code. The ultimate test (as I see it) would be for someone to machine the MDF with a CNC router and see if it produces the part I have drawn. It may well be-- with your level of experience-- that you know very well that the part would machine without actually having to do it. If that's the case- let me know. Then I'd know that my SketchUp would suffice for a CAD. From there I'd select and master a suitable CAM. Then I'd order parts. Or... Have I overlooked something?

PS, I'm going on a business trip for 2 weeks, so I won't be able to reply for awhile. Trent Bummer. Maybe someone else will pick it up. You've been a huge help getting me this far. I really appreciate it. Chunk

[Chunky]

I better ask you this before quitting for the night: You said the files opened okay in AutoCAD.

(1)Would I be correct in assuming that pretty much any CAM program would take the files and use them to make paths and gcode?

(2)For that matter am I even correct in believing that that's what I need (tool paths and gcode)?

(3)Would a simulator actually take the place of a CAM program for my purposes?

[chuckknigh]

Most CAM programs take the files, and convert them based on the way (and the order) in which they were drawn. This involves 2 things...gcode and toolpaths.

Gcode is a description of the movements a machine is supposed to make. It says things like move the X axis +1.00 inches. Move the Z axis -3.05 inches. That sort of thing.

The toolpath is the path your tool is going to take. I know it seems silly, but it's am important distinction. If you've ever seen a graphics program render a graphic, you'll understand why this is important. Often it draws a line on the left side, then a circle on the right side, then a few other things in the middle, then zooms across the screen to put a single dot in the corner. If that was your toolpath, it would take forever to cut your part! It matters, to take time and make sure your toolpath makes some sense.

SOME CAM programs can optimize your toolpaths...simpler ones can't.

A simulator is just that...it's a "pretend" CNC machine that works in software. It lets you view the results of your gcode, and see your toolpath and machine movements, virtually, before you cut a giant swath through that irreplacable piece of walnut, or that expensive piece of aircraft aluminum alloy.

-- Chuck Knight