[LRShooting]

I have been looking into CNCs for the past few years and money has been restricting. I just realized that I spend way more on stupid things than I could on building a good CNC machine that I could do small projects and make money with. Ill be doing both wood and aluminum. I doubt I will ever do steel just because I my hobby stuff doesn't require it. Its possible though and Ill just have to slow everything down. That is ok considering the frequency of steel CNC machining will be almost never.

But heres the deal, I don't know what exactly I need. I can get by way way cheaper than most...I have access to tons and tons of metal (literally) in any shape and size as well as torches, welders, grinders, cut-offs, drill press, etc. here on the farm. Building a frame will be fairly easy. I also have a small foundry to cast aluminum and I have seen some pretty nice linear bearings cast out of aluminum with 6 quality skateboard bearings for every assembly. Therefore, a set of 4 linear bearing assemblies would be 24 bearings total and they are rock solid. Also, I have quite a bit of experience with electronics and have built a few circuit boards. I have fun with it and I have seen DIY tutorials on making breakout boards. This GUY in paticular is about the most detailed for driver boards that I have found so far. Also will try to keep my rail size at about 1 inch stock of regular steel as well as supports every foot to make it bullet proof from flex and therefore increase accuracy.Oil will be needed for rust reasons and functionality, but its worth the cost reduction.

So since Ive basically got the actual frame of the machine itself figured out as well as driver and breakout boards, the real questions come.

1.First of all, lets say I have a fairly large table like 24"x36". Would that be too big and start sacrificing accuracy or does size not matter if components are solid?

2. Motors are my big dilema and probably by far the biggest cost. What size stepper motor will I need. I don't want to use servos because 1) I don't need that kind of accuracy, 2) its my first cnc and cost is prohibitive. My gantry would be steel to keep accuracy high so weight would be pretty high. I don't suppose length of the table matters because it doesn't change the gantry unless you make the table wider. Would it be smart to use smaller motors on the gantry itself and a larger motor to run the whole gantry back and forth? Ive found packs of 3 NEMA 34 motors for 200$. Maybe thats overkill at 1600 in oz? Wantai sells NEMA 23 at 270 in oz for a slim 16$ if thatd be enough. Even if it only powered one axis like the Z axis for the router, its still a lot saved.

3. What router do you all use on DIY's? I will never use huge bits on this machine so thats not going to be too much of an issue. Ill probably stick to wood router bits and end mills that fit.

4. As far as software, is there a specific program I need? There are plenty of free programs that have been proven to work and I won't have complicated stuff.

5.Would water cooling be smart if I do much aluminum? I could set one up easy enough and just cover it up when wood routing.

6. What kind of screw am I going to need and what size? Ive been looking at ACME because its much cheaper and more readily available. As far as anti-backlash nuts, Ill be getting those to keep accuracy as good as possible. Remember, this is for a 24x36" table if it makes a difference.

Now that Ive probably bored you out of your minds, I just want to say thanks for any and all help. Feel free to ask questions if you are confused by my scrambles.

[vtx1029]

Spend the time and read, read and read here before you build something. CNCrouter parts Nema 23 are pretty powerful and do a great job. Accuracy comes with the quality of components you choose. $ goes up as accuracy does. There are tons of things to consider. For your first router I'd suggest spending $ on a decent controller and steppers that you could move to another machine if you upgrade down the road. Most likely your first design will have problems or features you'll want to upgrade down the road. For controller software you have the free LinuxCNC.org if you run Linux or $175 for mach3. Dry cutting aluminum is possible and or a mist coolant. I'd stay away from flood cooling if you have any wood on your machine.

[Devastator]

1.First of all, lets say I have a fairly large table like 24"x36". Would that be too big and start sacrificing accuracy or does size not matter if components are solid?

The bigger you go, the more rigidity you lose, so you have to compensate by making it stronger

2. Motors are my big dilema and probably by far the biggest cost. What size stepper motor will I need. I don't want to use servos because 1) I don't need that kind of accuracy, 2) its my first cnc and cost is prohibitive. My gantry would be steel to keep accuracy high so weight would be pretty high. I don't suppose length of the table matters because it doesn't change the gantry unless you make the table wider. Would it be smart to use smaller motors on the gantry itself and a larger motor to run the whole gantry back and forth? Ive found packs of 3 NEMA 34 motors for 200$. Maybe thats overkill at 1600 in oz? Wantai sells NEMA 23 at 270 in oz for a slim 16$ if thatd be enough. Even if it only powered one axis like the Z axis for the router, its still a lot saved.

NEMA 23's a fine for a machine of that size, but you'll want something in the ballpark of 300 oz. in. And they won't be your biggest cost, but good leadscrews and AB nuts might. Or possibly your driver and electronics. Steppers are cheap.

3. What router do you all use on DIY's? I will never use huge bits on this machine so thats not going to be too much of an issue. Ill probably stick to wood router bits and end mills that fit.

I use a Bosch 1617 EVS

4. As far as software, is there a specific program I need? There are plenty of free programs that have been proven to work and I won't have complicated stuff.

Most everybody uses mach 3.

5.Would water cooling be smart if I do much aluminum? I could set one up easy enough and just cover it up when wood routing.

You can cut dry if you use the right cutters, feeds and speeds. Flood or mist is great if you can keep the water out of the wood. You can go faster with more flutes that way. I found out that I don't care how long it takes with single flute if I can walk away from the machine. It is still better than standing there squirting cutting fluid on aluminum for three or four hours if I use three flute bits.

6. What kind of screw am I going to need and what size? Ive been looking at ACME because its much cheaper and more readily available. As far as anti-backlash nuts, Ill be getting those to keep accuracy as good as possible. Remember, this is for a 24x36" table if it makes a difference.

Multi-start ACME with delrin AB nuts is what most people use. I use 5-start. Single start will be cheap but SLOW. The answers you need are all easily available on cnczone if you just start doing searches, that's why the slow responses to your questions.