[sabastion]

Hi everyone, nice place you have here.

Just joining in on the CNC craze. I've looked around with google to try to find some good CNC gantry plans but everything i've seen didn't meet my high standards and was really trashy. I don't have a lot of money so or any knowledge so I'm going to have to start and build from ground up.

I will be milling copper block up to 4" thick by 5" square and copper, aluminum, billet aluminum up to 3" thick by 8" square, acetal, plexi or lexan plate up to 1 1/2" thick by 12" square, some aluminum sheet panel and steel panel (computer case panels) up to 1/16 - 1/8 thick by 3 feet square.

I need a small foot print and because of 3 feet square sheet panel I will be incorporating a gantry on linear guide rails. I realize this requirement means that I will have to go with a foot print of 4 feet square (because of sheet size)...np. Sheet size and small foot print is why I,m going gantry.

I will also be automated using servo motors, steppers, stepper controllers, computer and some version of CNC software.

If you guys have any suggestions and or advice I'd appreciate it...tyvm

[rowbare]

Clearly you are early in your process, since you say you have little money to play with and yet you are talking about cutting up $70 blocks of plastic, $150 blocks of aluminum and $500 blocks of copper.

I think you need to start with getting some knowledge. That is cheapest of all. There are a lot of good build logs here so do some searching and you will find most of the information you need to make a choice. Once you have read through 50 or 100 build threads (it isn't as onerous as it sounds) you will start to get a good idea of what you are in for in terms of effort, cost and results. I will tell you this, not a lot of money, high standards and a large work envelope means you are going to have to be really really creative.

You will also want to look up threads that talk about machining techniques for the various materials you want to work with. That will help inform your decisions. For instance you will likely find that some aluminum alloys and most copper alloys are sticky gummy messes to machine and that you will likely need coolant to machine them successfully. The question this brings up then is what type of machine is best suited to coolant use. Also are any people using gantry routers to successfully cut steel?

My first thought is that you would be better served with two machines. A mill for the copper and aluminum etc... and a router for the sheet goods. Or start with the mill, and farm out the sheet goods till you can build a bigger machine to deal with them.

good luck
bob

[sabastion]

When I say I have little money, what I mean is that I don't have 5,000 - 30,000 dollars just sitting around to buy A CNC or buy everything needed to build one at one time. Going to have to do it in stages.

TY for your reply and suggestions

[Al_The_Man]

Up front, I am a MTB first and a machinist or sorts second.
IMO, The need you are going to run into to in machine square blocks of aluminum and copper is Rigidity, as well as cooling already mentioned.
Many of the gantry's you will find here have high RPM spindles and are built for wood and thin sheet metal material that require no cooling.
Any machine where the lateral forces on the tool are high requires a great deal of rigidity in the construction of the gantry.
I would have though a small Knee mill such as BP or XLO would have been a good choice for the blocks.
The thin panel material could be done on a solid quality router gantry?
I think one machine to do all will be a compromise.
Al.

[stevespo]

Yes, ditto. I've spent a fair amount of time researching this type of machine.

There aren't a lot of gantry designs out there doing what you are describing, with many reasons why. One that comes close is the Datron line (see youTube), but they are very expensive, very specialized. To try and duplicate that type of performance and functionality with your first build, on a limited? budget, is really asking a lot.

Having built a fairly robust (aluminum, 8020, BLDC servos, etc) gantry that can cut aluminum and other soft metals, it is possible to get there. I'm talking light cuts in 1/2" plate stock. Big blocks and coolant are another consideration, especially if speed is important. When you add in the 3' work envelope and the need to cut steel, it kind of throws a spanner in the works.

You might consider buying a mid-sized bench top mill and doing the CNC upgrade on it. Get your feet wet. That takes care of your soft metal needs and possibly your acrylic, etc. Use the mill to build a really robust gantry and that would expand your work envelope in the softer materials. The steel panels, I just don't know. Sub that stuff out, or maybe you can work out a way to do it with your gantry once it's built. I've seen people cutting steel with high speed spindles, I just don't know anything about it.

You will be spending $2-3K minimum on the mill and more on the gantry. Possibly much more.

Steve

[bostosh]

Just bumping around the Zone site and have to comment.
this is how I think,

Own the data, the geometry, the program, the tooling, the final product.

Rent a machine capable of doing the job properly.

Too easy to get bogged down in building a machine with limited capabilities when the real machines are so cheap to rent.

Think of swimming pools, yachts and private jets,
They are great as long as someone else owns them.

[stevespo]

That advice is great for certain types of work. Do you mean rent the physical machine, or rent time on someone else's machine? There's no machine shop that I know of that would let someone off the street near their equipment. Too much risk, liability, etc.

I regularly pay my local machine shop to do jobs for me (at $60/hour) and it's well worth it for capability that I don't have. That's a great arrangement for special jobs, but I couldn't afford that for everything that I need to make.

Yes, it's expensive and time consuming to build (or buy) your own machine. But once you have it you can do all the prototyping, fixturing, tool paths, etc. It opens up a lot of possibilities because it's right there waiting for you, ready to go. I paid off my machine very quickly, in just a few months, and that was working part-time.

On the other hand, when you build your own machine it can takes months or years of research, sourcing parts, building, troubleshooting, redesigning, retrofitting, upgrading, etc. You just can't get everything right the first time. However, when it needs attention you know it so well there is nothing you can't fix if necessary.

Steve

[bostosh]

Rent time on someone's machine,
with/and the shop and their operator (the whole package with your designs and Gcode and tooling ,. )

Until the cost of owning, becomes practical.

I have no trouble with paying for time, machines are reasonable for the expertise utilized.

If you are oriented into getting the widget complete or
learn CNC are factors.

So many choices so many ways. to go with this
Doneumall