Hello all, new to CNC
 

I would like to say hello to all and introduce myself. My name is Paul and I live in Toronto Canada.
One of my loves is metal working, and as such love to spend time building projects. My latest project I want to build is a CNC router for mainy making PCB's. Some of the people on one of the machining forums was kind enough to provide my the link for this site and told me if the people here dont know, then there isnt an answer :)

Looking forward to learning as much as I can here.

Welcome to the MM forum and enjoy the reading.
Ideally, the place to start is the forum main page and read the sticky notes for an understanding of the MM CNC machine.

Welcome Paul, best of luck.
Mark

Welcome.
I might add, the MM is a pretty big machine for PCBs....

MM can probly mount a few hundred PCD at one go. & its the size of a car.

Or one massive industrial PCB :) !!!

Welcome aboard !!!

Thank you all for the nice welcome :) My goal is to learn as much as I can about CNC machines as my goal is to build one. It sure wont be a large unit like the MM one, more along the lines of 2' x 3', but I want to be able to not only do PCB work (main reason for making it .... plus I like the project challenge) but also strong enough to mill steel and aluminum (talking tiny steel parts, not truck tires lol, just want it to be build like a small tank).

I am really enjoying reading the stickies and other posts, as it surely helps with the research and design phase.

You will find the MM design doesn't really easily build that small.
I personally built a 5' x 5' MM for plasma, which was about right.

Gerald and other explored a small form factor set up....(like the shopbot buddy) and found the best use of parts and money would be to build a FULL SIZE gantry for 4' wide cutting and the rails to be short, like a table top. That way, when you wanted to upgrade to the larger machine, all that was needed was a larger base table...the affordable part of the machine. 75% of the big dollars are spent on the gantry, controller and spindle.

Good luck with your choices.

Thanks very much for the info, as I have debated making it bigger but I have to be careful with the limited space I have in the shop. After seeing the big expense is the motor/controller/PS and spindle, it sure makes a lot fo sense to go big. My main concern I guess is the slides for the x-y-z. I would love linear slides, but the expense is BIG, and I have opted for either TGP rod and bearings (multi axis roller bearing set up, or maybe linear bearings like th LM type), but the bearings seem to be limited to about 40mm max, and the longer the rod the thicker I need it before requiring support. I figure with the 36" square one a 1.5" TGP rod should be fin unsupported, but longer than that Im not sure.
Glad I found this site as I may indeed scale up the size a bit. For the first rev I wanted to use a "dremel" as the spindle ($200.00 - $800.00 for a spindle is a LOT) and if it turned out OK I could just replace it later on. Hoping the smaller NEMA motors (Nema 23) will be ok for a larger unit, then I can buy a package (motors/controller/PS) and use Mach3 to run it.

Have to do some more thinking about this, as maybe larger may be better.

unsupported round linear guides and bearings? on a 4' cnc machine?

For engraving PCB-s you really want a small precise machine using ballscrews probably with fixed bridge, explore the cnczone for this one.

For anything else except steel use MechMate :)

Steel, aluminum, limited space, pcd, small....
Get a bench top milling machine & convert it. that will suit your needs best. interms of performance, cost & foot print.
other bench top toys won't survive cutting real metal.

Well, while its going to be used mainly for PCB's, The main goal is a build project (already built a vertical mill). Since I have a mill, I want to get into CNC and figured a small unit would be a nice project (plus I need to justify the build, so since I need PCB's from time to time its a good justification).
Want to make it on a shoe string budget, as aside from the stuff I HAVE to buy (motors/controller/PS/Software), I want to keep the cost as closet to $0 as possible (meaning making the bits myself).

If I have a good budget, I would simply buy a CNC machine, but this is more about the "build" than the product

MechMate is not intended mainly for PCB's where traces are in range of 0.2mm or 10mils

And if you plan to buy spend couple of 1000's on motors, drives and software , what is a couple more for a nice steel construction :)

if you have a cnc vertical mill what is the problem in milling PCB on it? its just perfect for the job?

No, have a mill that I built, but its not CNC. I want to get into CNC, but want to keep the project small (have limited space) but want it a lot "beefier" than a bench-top unit that can only cut plastic and wood. While I wont be machining steel truck wheels, I would like to be able to do some small steel work, or at least have it hefty enough to do it if I need to.
Since its a build project, and I dont have any real "free cash" I try to make what I can over buying something. Some stuff I will have to buy (NEM23's, controller, PS and probably Mach3 license) which will run about $500.00, but the rest of the stuff I would prefer to make using available stuff I have.
If the project turns out to be a resounding success, then I can always at a later date rip off the guts and transfer it to something bigger.

Maybe this site isnt really geared to what Im planning, but being new to CNC I was pointed here by some members of a machine forum.

Most people will tell you that any router type design will NOT be usable for cutting steel. And everyone will tell you that a machine with unsupported rails is not stiff enough for cutting steel. At any forum with really knowledgeable people on it, most people will tell you that unsupported rails have no place on a CNC machine of any type.

If you don't already have the rails, do some careful Ebay watching and you should be able to pick up good quality used profile linear rails and bearings for no more than the unsupported shaft will cost.
If you already have 1-1/2" shafts, then I'd recommend building no bigger than 24x24 for maximum rigidity.

Take a look at www.cnczone.com. There's a lot more variety there, and machines of all types and sizes. Just not many with unsupported rails. Anyone who's used them typically builds another machine without them. :)

Thank you for the info, and while i will probably keep steel work to my mill, the info Im gaining is really helpful.

This will suits your resources.
http://www.instructables.com/id/DIY-...IS-CNC-Router/