Help/direction for a newbie

[Yves514]

Hello Everyone,

I've been lurking on this site for a while now. I'm not sure if this is the correct forum for my questions.

I've got a small home machine shop with lathe, mill, welding and some metal fab. equip. So I'm comfortable with manual machining. By day, I work in IT and software development. So I'm very comfortable with programing. I've also work with AutoCAD, electronics and microcontrollers as a hobbyist. Although, I'm not entirely interested in building a controller, etc. from scratch.

With all that said, I've been very interested in building a CNC router/dremel table and converting my existing mill into CNC. Not sure which one I want to tackle first yet. I'm thinking of doing the router table first as a learning curve before spending on much larger motors for my mill. Heck, I've even got some little old stepper motors from dot matrix printers lying around that I could mess with for testing. Right now, I'd really like to just get a system going where I can feed some G-code and have that move some motors. After that, I would feel more comfortable working on the final solution.

So my first questions are. Is there an FAQ or a good site/thread on a quick overview of a CNC solution? I still don't have a grasp on all the components yet. So I'm having a hard time figuring out what I need to buy and what I need to make. Am I understanding the following correctly?

Overview
---------
1. drawing software (AutoCAD or something similar)
2. Convert drawing to G-code (Is this manually done or are there software packages to help you get the G-code started?)
3. CNC software
4. A CNC Controller
5. Stepper motor drivers
6. Stepper motors
7. Machine/table being controlled

Is that it? Am I missing or misunderstanding anything? BTW, I'm still unclear as to what the drivers do vs the controller. I'm guessing the controller translates the G-code to digital signals for the drivers which feed a higher voltage to the stepper motors? Is that how it works?

Anyways, I hate posting these kinds of newbie posts but I'm not sure where else to start.

Thanks in advance,
Yves

[Yves514]

Hum... Guess no one wants to help the new guy?

[danreetz]

A controller generates the steps and the driver boards "amplify" them to levels that actually drive a motor. You can often get boards that are a driver and a controller all in one.

Everything else you've said sounds pretty accurate, and if you need more guidance, you might consider doing a kit build like a Joe's 2006 or something to get learning out of the way. After that, you'll see that it's as simple as you describe and you'll be able to retrofit your own machines.

[Yves514]

Ok, thanks. At least now I know I'm looking/researching the right things.

Cheers,
Yves

[epineh]

If you are familiar with and have done a little machining, work in IT, and have electronics/microcontroller background, you are well on your way.

It might sound a little ambitious but I would suggest CNC'ing your mill, you didn't mention what type of mill it is, but there is a good chance someone has already done this on your type of machine and posted the conversion log here on the 'zone.

The reason I would suggest this is mainly that most of the mechanical's are already done, you will have to make some motor plates and possibly pulley's and couplings but that is about it for starters, you may also want to install ballscrews to improve accuracy.

You can then use it to make cool parts for a router type machine

I'm not too sure if there is a "how to" type of manual, but all the info you need is on this site somewhere, you just need to find it

A quick overview on the CNC process (once the machine is going) :

Draw your part - Cad of some sort, AutoCad etc (I like Autosketch for most simple stuff)

Import the finished drawing to a CAM package, and create your toolpath(s) - I use DeskCNC, there is a free trial version that is limited to 1000 lines of code and 30 day trial. Here you setup things like cutter size, feedrates, depth of material to be cut with each pass etc.

Load the finished code onto the machine controller - a PC with software loaded to directly control the electronic drivers that in turn drive the steppers (or servo's). There are a few options here, TurboCNC is a free program and runs entirely on DOS, yes that's right...DOS.

Mach3 is another option that runs on XP, and there is a free trial version of this, again 1000 lines of code.

DeskCNC has a machine controller function as well that is nice but you need to purchase the controller card to do this.

EMC is another controller that runs on a real-time kernel of Linux Ubuntu, it is very nice and I am in the process of trying this out myself.

Most of the above controller programs use a parallel port to get the step/direction signals to the machine and also get things like limit switches, emergency stops from the machine. DeskCNC uses a serial link to it's controller card.

Once the G-code is loaded into the controller PC, you setup the machine, put the job to be machined where you want, usually jog the cutter to a set position and zero all axis's, then run the code. If all goes well it then sends the info to the electronic drivers that move the steppers(servo's) as required and voila!!! your part is made.

Now I have not mentioned ALL ways to get from A to B but just some of the more popular. You will have to try things for yourself to work out what suits your needs the best.

Good Luck but be careful, this stuff gets REAL addictive, and you will have a seriously silly grin when you first make the machine move under control, and even sillier grin when you start cutting stuff with it.

Russell.

[Yves514]

Thanks for all the tips Russell. I did find a company who does a conversion for my mill. It's this one: http://www.cncmasters.com/CNC%20Jr%20Mill.htm

Guess I'll have to search this site a bit more to find an end-user who's done a conversion. Just sooo many forums on this site!

The reason I figured I wouldn't start with the mill is cost. Learning curve could be more costly if I get it wrong.

But thanks for all the tips. Glad to hear there are a lot of opportunities to use trial versions before deciding/buying a specific one.

Ciao!
Yves

[epineh]

There is a lot of info here and it can be overwhelming, best thing is to read the DIY router logs, plenty of people doing exactly what you have in mind, much easier to learn from other's mistakes first before you start...I know I made heaps of mistakes on my router

Only other tip is to read read read

Russell.