Need Help - Trying to learn Gcode & NC

[jdebott1]

I built a ShopNotes Router Milling Machine (a hand-crank woodworking milling machine) and now I am turning it (slowly) into a CNC router lathe with the help of many teachers on the internet.

I would like some assistance in how I go about converting a simple drawing into Gcode. And, I would like someone to show me how to work with the attached computer scan of a centerpost so that I can cut it on the CNC router lathe using just the two axis (wood piece will be turned separately using an old garage door motor that I've wired up and use a belt to turn).

Thanks for any help you can offer me.

Joe DeBottis
The Canterbury Workshop
USTV America

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[txcncman]

Have you purchased and read any of the several CNC programming books that are available?

[jdebott1]

TX,

I am currently reading several CNC books which detail Gcode, as well as numerous internet posts regarding turning scanned drawings into DXF files and converting them into Gcode. But, all of these seem to deal with "flat" cnc and not CNC lathes.

Right now, my budget is very limited. Plus, I'm working 10 hours a day and volunteering at a local food bank to help feed the poor and elderly. So, I'm finding little time to learn all this cnc stuff quickly to help keep my small business end going.

I'm trying to use an Arduino Uno with serial port to control the stepper motors. This will allow me to use GRBL interpreter without having to spend a lot of time and money learning other CNC controls. My needs are simple right now, so I want to do whatever I can to quickly get up and running.

The centerpost pic I posted will allow me a basis to learn the Gcode required to turn my basic items -- table legs and centerposts. And, I'm using CNC Sim to learn how to control CNC in two axis only.

Any help you can provide would be appreciated.

Joe D.

PS - Thank you for the link to your website. The general info you have posted there is very helpful.

[ger21]

I'm trying to use an Arduino Uno with serial port to control the stepper motors. This will allow me to use GRBL interpreter without having to spend a lot of time and money learning other CNC controls. My needs are simple right now, so I want to do whatever I can to quickly get up and running.

If you spend some time reading here, you'll see literally hundreds of home built machines.
And you'll have a very hard time finding even ONE that uses an Arduino to control it with Grbl. Imo, that combination is not really a viable option for anything more than small, simple "toy" type machines.

Having said that. You can probably use that combination to get it working, but you'll quickly want to upgrade to something a bit more robust.

I would like some assistance in how I go about converting a simple drawing into Gcode. And, I would like someone to show me how to work with the attached computer scan of a centerpost so that I can cut it on the CNC router lathe using just the two axis

A 2 axis wood lathe type machine like you have is not very common, and I'm not really aware of any CAM programs that can create the g-code for you. Regular Lathe software (for metalworking lathes) may work, but I'm not familiar with any. So you may have to improvise a bit.

The first thing you'd want to do is draw your part in a CAD program. A 2D drawing should be all that you need. A lot of people like Draftsight, which is free.
I've attached an image from the CAD file, as well as a .dxf drawing.
You only need to draw half the profile, from the centerline out. I have the centerline drawn in red.

Once you have the profile drawn, it gets a bit trickier. Depending on the CAM program you're using, or if using another method, you need to account for the tool diameter, so the actual toolpath will be offset.
You also probably need to make some roughing passes, as you won't want to remove all the material in one pass. This may require you to actually draw the roughing passes in, unless you have lathe software that can calculate them automatically.

You're really attempting a process that very few people are doing, so you may have to figure out a lot of this on your own, unfortunately.

[jdebott1]

Gerry,

Thank you for all your guidance. Yep, I'm starting off small, but using the example of CNC lathe developed by someone else using the Arduino. The reason why I want to use the Arduino is because it has WIFI and Bluetooth capabilities which will allow me to eventually control the CNC lathe from a different location. That way, I can do several multi-tasks all at one. LOL - As a small business owner, I wear many, many hats.

Example I am learning from:
Chris's project notes...: May 2012

I'll follow your suggestions, and yes I will definitely be upgrading once I get up to speed on this initial build. I will also take the DXF you converted for me and work with it to create Gcode that I can learn from. I'll buy the steppers shortly and give it all a test run.

Thanks for your help.

Joe DeBottis

[Al_The_Man]

You can also step through it in a simulator CncSimulator.com
Al.

[txcncman]

Remote machine control without robotics and production runs is not practical, and even those functions can be programmed and automated with the right control. So, in either case, there is no need for real time remote machine control.

I still have yet to see a "press one button" machining system. The amount of user input can be reduced with higher end software.

[jdebott1]

Al,

Yes, I have downloaded the CNC simulator and am learning how to use it now. Once I convert the DXF that Gerry provided to Gcode, I'll pull it into CNC simulator and see what other code I have to put in roughing passes.

Yes, Gerry is correct in that my project is unusual and I'm not finding too much that focuses only on 2 axis. But, my needs are simple right now, and I'll upgrade as a go along.

Right now, I rough out about 50 - 2"x2"x21" blanks a week on the ShopNotes router milling machine. All that cranking and measuring is wearing me out. So, anything I can do to develop CNC capability will be much better. I already have wifi video capability in the shop, and I hope to be able to set up the machine and let it run while watching it from my iPad. That way I can be in my finish room while the lathe is running - 2 things at one. And, there's always the phone calls . . . .

Thanks for all your help. I'll keep the forum posted on my progress.

Joe D.

[ger21]

I can tell you how I would program it.
This is all done in CAD.
Assuming you'll use a ballnose tool, first offset the profile line by the tool radius. I'd use this offset line as my final toolpath, but you have to make sure you set the Tool Tip zero position to the center of the tool radius. This makes it very easy to follow the profile.

For the roughing, I'd first offset a line from the centerline by the radius of your stock. Offset up on the screen. This line would be the start of your roughing.

Next, offset the toolpath profile by the depth of cut. COntinue to offset up, until the entire offset line is above your roughing line. Then trim away anything above that line.

Now, all the offset lines will become your roughing toolpaths. Start with the highest, and work down towards the profile.


Once you get used to doing this, and learn your CAD program, well, this shouldn't take long at all.

[jdebott1]

Al,

I converted the post.dxf that Gerry provided bia ACE converter to Gcode. I then loaded it into CNC Simulator, but it shows the wood blank being loaded vertically and give a -0.018 out of limit (0 to 11.2) Parameter Z error.

I'll have to read more on the simulator to see if I need to reorient the dxf vertically before converting to NC .

Can you offer any direction on this?

Joe D.

[jdebott1]

Gerry,

Okay, all that makes sense. You say to do this all in CAD, which I'm reading and learning about now. Are you saying that the roughing paths that you've shown can be laid out in CAD so that when the DXF is created and converted to NC the code will already include the roughing paths? This makes sense to me if that is what you and your drawing is telling me.

The table legs and candlestand center posts that I do are really very simple. I do them now by hand crank milling, so CNC 2-axis with the roughing paths you've indicated should be quite simple to program. I'm not familiar with the ballnose too, but I'm googling it now to see what it is and how it is used.

I'll also move the post.dxf you provided into Adobe Illustrator CS and quickly draw the roughing paths you've shown me. Then I will experiment with the resultant DXF to NC in CNC Simulator.

Thanks again for all your help.

Joe D.

[ger21]

Are you saying that the roughing paths that you've shown can be laid out in CAD so that when the DXF is created and converted to NC the code will already include the roughing paths? This makes sense to me if that is what you and your drawing is telling me.

Yes. But your going to need something more sophisticated than Ace, or possibly break it into multiple drawings.

You're g-code seems to be incorrect. The I and J values seems to be wrong, and give errors in Mach3.

See if this works better.
Personally, I've never had good results with CNC simulator. I'd download and install Mach3, and use that as a simulator.

G20 G40 G90
G0 Z0.25
G0 X0.0000 Y0.9688 Z0.25
G1 X0.0000 Y0.9688 Z-0.01 F50
G1 X2.0000 Y0.9688 Z-0.01 F110
G1 X2.0000 Y1.0000 Z-0.01
G3 X16.8402 Y0.5624 Z-0.01 I14.4906 J239.5875
G3 X16.8788 Y0.5923 Z-0.01 I-0.0001 J0.0400
G2 X16.9384 Y0.6666 Z-0.01 I0.1134 J-0.0298
G2 X17.3876 Y0.8277 Z-0.01 I0.8258 J-1.5962
G2 X17.9035 Y0.9055 Z-0.01 I0.8926 J-4.1654
G2 X18.6250 Y0.9375 Z-0.01 I0.7215 J-8.1285
G1 X18.6250 Y0.5625 Z-0.01
G3 X18.6875 Y0.5000 Z-0.01 I0.0625 J0.0000
G1 X19.3750 Y0.5000 Z-0.01
G1 X19.3750 Y0.0000 Z-0.01
G0 X19.3750 Y0.0000 Z0.25
G0 Z0.5
M30

[jdebott1]

Gerry,

Okay, I'll download Mach3 and use that as a simulator for the Gcode.

I did a Google search on open source DFX conversion to Gcode and found the Ace converter. I'll look for another.

Yes, I see now that I can use multiple drawings to create the roughing paths. Adobe Illustrator CS will allow me to do that and export a DXF.

In the meantime, I'll run the Gcode you posted.

Thanks again,

Joe D.

[txcncman]

Remote machine control without robotics and production runs is not practical, and even those functions can be programmed and automated with the right control. So, in either case, there is no need for real time remote machine control.

I still have yet to see a "press one button" machining system. The amount of user input can be reduced with higher end software.

Al,

Yes, I have downloaded the CNC simulator and am learning how to use it now. Once I convert the DXF that Gerry provided to Gcode, I'll pull it into CNC simulator and see what other code I have to put in roughing passes.

Yes, Gerry is correct in that my project is unusual and I'm not finding too much that focuses only on 2 axis. But, my needs are simple right now, and I'll upgrade as a go along.

Right now, I rough out about 50 - 2"x2"x21" blanks a week on the ShopNotes router milling machine. All that cranking and measuring is wearing me out. So, anything I can do to develop CNC capability will be much better. I already have wifi video capability in the shop, and I hope to be able to set up the machine and let it run while watching it from my iPad. That way I can be in my finish room while the lathe is running - 2 things at one. And, there's always the phone calls . . . .

Thanks for all your help. I'll keep the forum posted on my progress.

Joe D.

Remote operation and remote monitoring are two different things to me. Walking away from a reliable CNC machine while it is in operation with a proven program for minutes or even hours should not be an issue. I can monitor a CNC machine while in operation by the sounds that it makes.

[jdebott1]

Just wanted to post this link that I am following to set up my 2-axis (third axis run by old reversible garage motor) router lathe mod to my ShopNotes milling machine.

Chris's project notes...: Router lathe build

Mine will be a bit different, but will use the Arduino Uno and geared stepper on the Acme 1"-5 Rod.

Thanks again for all the help that I've received. Gerry, Al, and everyone else on the CNCzone forum have put me on the right track and I'm learning Gcode quickly.

Joe D.

[jdebott1]

Gerry and all,

I just wanted to thank you and everyone else on CNC Zone for your kind help, and to let you know that I have finally developed a quick process to go from 2D DXF to full working Gcode using OpenSource CAD, GMAX, and the CNC ToolKit.

I'll post more about this later for anyone else who wishes to do the same.

Joe D.