[Boomer8404]

Hello all, I am looking to build a 3-Axis CNC machine. My friend and I have our own small computer company, and our new focus is to start building our own branded machines. Along with building custom computers, I am a long time hobbyist welder/metal worker.

I want to build the CNC frame out of metal, 1"x1" square tubing and angle iron for the frame. The CNC machine would need to be capable of cutting materials like plexiglass, Lexan, computer case plastic, thin aluminum and thin sheet metal (such as the type found in the side panels of computer cases, which is no thicker than 20-22ga).

I have done a little research into building the machine, but Im really looking for some advice. I know that I would need a computer to run a CAD/CAM & CNC software, motor controller, x/y/z & tool motors, ball screw rods and the other various materials (bearings, frame materials, hardware, wheels for the carriage). Would preferably like to have 16"-20" of x & y axis travel & 8"-10" of z axis travel.

As far as what brand/spec type of motors, controller, software I would need, I'm pretty much in the dark on that. Any help would be really appreciated, thanks for you time and sorry for the long read.

Don

[awerby]

That 1" x 1" tube is tricky to keep straight in a welded assembly, but you probably knew that already. Steel angle iron is not usually very flat to start with; aluminum angle is straighter.

If you build your own computers anyway, build two: one for doing your CAD/CAM and another one for running your CNC machine (that has a parallel port). The CAD/CAM computer wants to be fast, with a good graphics card and lots of RAM. The router computer doesn't have to be that great, but it wants to be stripped of anything that might interfere with spitting out pulses continuously (Internet, networking, Windows Update, power management, etc.)

Wheels? Is that to move the router around or what?

More Z axis travel is great, but it means that everything has to be more rigidly built than if it was shorter. All the things you're talking about cutting seem pretty thin; why do you need so much Z?

The consensus controller choice around here for small stepper machines is the Geckodrive G540. It has the breakout board and 4 drives built in, all you need to provide is an enclosure. They'll also sell you suitable 23-frame motors for it. Get Mach3 for the control software. Design and CAM software depends on what you're trying to make.

Andrew Werby
www.computersculpture.com

[wizard]

Hello all, I am looking to build a 3-Axis CNC machine. My friend and I have our own small computer company, and our new focus is to start building our own branded machines. Along with building custom computers, I am a long time hobbyist welder/metal worker.

You need to become familiar with some of the engineering involved. Building a successful CNC machine is nothing like building up a computer. Believe me I've built more than a few computers and as such feel it is important to warn you that the task of building up a unique CNC machine is very time consuming.

I want to build the CNC frame out of metal, 1"x1" square tubing and angle iron for the frame.

Stop right there!!! 1x1 tubing wouldn't even be suitable for a router for use on wood only. At least not for a machine of any size.

The CNC machine would need to be capable of cutting materials like plexiglass, Lexan, computer case plastic, thin aluminum and thin sheet metal (such as the type found in the side panels of computer cases, which is no thicker than 20-22ga).

It sounds like you need a router type machine to machine sheet goods. Nothing wrong with that except that trying to machine thin gage sheet metal may be a problem.

I have done a little research into building the machine, but Im really looking for some advice. I know that I would need a computer to run a CAD/CAM & CNC software, motor controller, x/y/z & tool motors, ball screw rods and the other various materials (bearings, frame materials, hardware, wheels for the carriage). Would preferably like to have 16"-20" of x & y axis travel & 8"-10" of z axis travel.

Interesting, that is a lot of Z travel for the material you describe. If you think you will be machining sheetmetal and plastic boxes you may want to think carefully about that. Really thing gage unsupported metal and plastics can be difficult to to well with milling type cutters. I've done some work on industrial type enclosures on a mill, that is enclosure made with heavy gage steel like ten gage or similar, even these sorts of material are a pain to deal with on a mill.

As far as what brand/spec type of motors, controller, software I would need, I'm pretty much in the dark on that. Any help would be really appreciated, thanks for you time and sorry for the long read.

Don

The long thread isn't a problem but I'm not sure if you are looking at the right machine. If your intentions are to machine already formed sheet metal or plastic boxes you may find that it takes a bit of extra effort to get passable results. Depending upon how unsupported the materials are it may be next to impossible to get good results without making up support fixturing for the box in question.

On top of that, generally when working with sheet goods like lexan or other plastic sheet goods you want a router type machine with fairly long X & Y travels so that you can work on fairly large sections of the sheet goods. I guess I'm a bit confused as to how you expect to use this machine. You describe for the most part sheet goods yet you seem to want traditional vertical mill capacities.

In any event I think you need to look at machine tools to see how they are built and get a grasp on rigidity requirements. Obviously most routers don't need the rigidity of a Hass vertical mill but on the other hand I see very little chance of a successful machine built from 1 x 1 tubing. The fact is machines built from wood products would be stiffer (given a solid design).

[Boomer8404]

Thanks for the replies, after reading them I'm starting to think that maybe I was shooting a little high. Basically just sheet goods are what I am looking to machine. The reason for the tall z axis is because some of the computer cases that we use don't have removable pannels on either side and I was only thinking of so much z axis movement for the purposes of if I need to lay a whole computer case on its side to mill a panel that couldnt be removed from the case. After some more thought on the idea I would rather move away from that.

The wheels I was referring to were castors for easy morement of the machine, I was going to add in leveling screw jacks.

I have become all to aware of keeping 1"x1" steel tubing straight but, I can keep it straight enought for what I'm needing, but I have been thinking of moving up to 2"x2" and brace it really well and use a tortion box built from 3/4" mdf. I was also considering building the frame out of wood instead fo the steel tubing or maybe extruded aluminum.

[awerby]

If you want to work on taller items you can do that without having to increase your Z travel. See if you can design it so the table can be repositioned at various heights as needed. That way, you can accommodate taller parts, since you're just working on the top surfaces of them. But you'll need to figure out a way to support the thin sheet metal somehow - it doesn't cut well if it's floating.

If you're putting the machine on casters, then use the kind with brakes.

2"x 2" sounds a lot better than 1" x 1". Torsion boxes might work to brace it without having to weld in cross-members, which usually warps things.

Andrew Werby
www.computersculpture.com