Newbie- Starting from scratch

[Superduper2010]

Hello everyone,
For the past couple of weeks I was looking into the DIY CNCs all over the internet, and found this forum to be the most informative.
After all this browsing I want to build my own CNC.
I want to do wood-working and engraving. ( on styrofoam as well) using this CNC.
I want a work area of 4'x4'x7",
That's 4 ft (x axis) x 4 ft (y axis) x 7 inches (z axis) ------ (reduce it down if it's too much, cuz my budget is a big constraint)
I would want to keep the cost of the project as low as possible, If possible then less than $1000.

My initial questions are:
Is this achievable? - if answer is yes... then continue.
What torque Stepper motors would I need?
What are good Stepper motors? (please explain what Nema is to me)
What is the best design plan on the internet for the CNC, which is easy to make but very rigid?
Is there any free CAD/CAM software out there for windows/linux?
What is a good Electronics kit for CNC out there, i.e. cheap and good. Should include the power supply and the Driver board.
What should i make it out of?
What kind of movement system should i make -- i.e. chain, belt, screw etc

These are the things I already have:
i) tools and equipment
ii) 6'x 4' Plywoods - 2 cm thick - about 3 of them
iii) Assorted small wood pieces.
iv) Aluminum sheets
v) Computer with a parallel port running windows xp
vi)

Thanks alot,
superduper2010

[Crevice Reamer]

Hi SD. Welcome to the Zone! That's an ambitious first post.

Some of this Basic CNC info may be helpful to you:

http://crevicereamer.com/Page_2.html

I recommend these electronics:

http://crevicereamer.com/Page__57.html

CR.

[Superduper2010]

Thank you so much for your quick reply, I'm going over the links you listed.
Meanwhile... I don't mind other ppl offering their advice

[Superduper2010]

I was phoning here and there, and i found a kit for some stepper motors,
I think they are kind of weak but you proffessionals may have some recommendation on it.
The kit includes the following -
4 stepper motors 0.9 Nm Torque --- 56 mm
1 driver board (for the 4 motors)
Power Supply --- Including cables....it costs approx $340

Do you think this price is ok, and that a stepper motor with that much torque is good enough, Please let me know if there is anything else you want to know about the stepper motor

[Zygoat]

we would need to know what the specs are for the power supply and the driver board to know if it is a good price or not.

the steppers are on the weak side for a machine as big as yours. but the real important factor is weight. you need to know how much weight the steppers have to move before you can decide if they are good or not.

nema is an organization that creates standards. when they refer to a stepper motor as nema 23 or nema 32. they are telling you the external size of the motor. (larger numbers are bigger) different motors that are both nema 23 can have different power outputs. that is why you need to look at the torque rating. normally in oz. in. or n. m.

hope that makes sense.

[Superduper2010]

Originally Posted by Zygoat we would need to know what the specs are for the power supply and the driver board to know if it is a good price or not. the steppers are on the weak side for a machine as big as yours. but the real important factor is weight. you need to know how much weight the steppers have to move before you can decide if they are good or not. nema is an organization that creates standards. when they refer to a stepper motor as nema 23 or nema 32. they are telling you the external size of the motor. (larger numbers are bigger) different motors that are both nema 23 can have different power outputs. that is why you need to look at the torque rating. normally in oz. in. or n. m. hope that makes sense.

Thanks for replying. It makes perfect sense.
Apart from that, The weight of the machine is dependent on the material I use, which was one of my questions, so you can estimate the weight. I think I'm most probably going to make my build out of MDF, or out of Plywood.
It's pretty cheap to do so.
Also for the "cutter" I have 3 choices -
Either a router, or a dremel, or a drill ---- found this one at a nearby shop http://www.saco-ksa.com/product_deta...i=5072&lang=EN the tool is from a company named skil their website:www.skiltools.com
What do you guys recommend for good cutting in wood and styrofoam.
that also contributes to the weight.

** I attatched the datasheet of the stepper motor i was talking about
the power supply is a 24 dc supply (for 4 motors as well as the driver board)
The controller board picture is attatched.

[ger21]

A lot of these questions are personal choices, and dictate the answers to the other questions.

I would want to keep the cost of the project as low as possible, If possible then less than $1000. My initial questions are: Is this achievable? - if answer is yes... then continue.

Possibly, but very unlikely. $1000 just doesn't go very far, and the larger the machine gets, the more it costs.

What torque Stepper motors would I need?

Depends on how much weight you're moving, how your moving it, and how fast you want to move it. A rough guess is 350-450oz-in.

What are good Stepper motors? (please explain what Nema is to me)

Nema is the size of the motor frame. The larger the number, the larger the size. Most affordable steppers are made in China, and are all very similar, regardless of where you get them.

What is the best design plan on the internet for the CNC, which is easy to make but very rigid?

You might want to look at www.joescnc.com, but it'll cost much more than $1000.

Is there any free CAD/CAM software out there for windows/linux?

There are lots of free programs available. Search here using the Google search.

What is a good Electronics kit for CNC out there, i.e. cheap and good.

You rarely can have both cheap and good.

HobbyCNC makes a decent product at a low price. But, the Gecko G540 is a much better package, for a little more money.

What should i make it out of?

Totally up to you, and what you have available, and what you're comfortable working with.

What kind of movement system should i make -- i.e. chain, belt, screw etc

Screws are probably cheapest and easiest.

[Zygoat]

Originally Posted by ger21 Screws are probably cheapest and easiest.

im gonna have to disagree there. chain drive is by far the least expensive option i have found while researching my own build. screws can be cheap if your travel is short. but once you get to any kind of length they become prohibitively expensive.

[ger21]

How many chain driven routers have you seen?

[Zygoat]

Originally Posted by ger21 How many chain driven routers have you seen?

oh god, here we go. i just said that chain drives are cheaper. and they are.

[ger21]

I was just saying that you won't find many builds here that used chain. It probably is a little cheaper, but I think it's more difficult to build the chain drive system than using a screw. And acme screws are not that expensive. Although in Saudi Arabia, pricing may be a bit different.

[Zygoat]

ok. since your being polite. i know that the build yourcnc.com machine uses a chain drive.

i think the price is more than a little cheaper. especially when you get into larger sizes. i know he is using a 4x4 table which is not huge but it is big enough.

a 4 foot piece of normal acme threaded rod from mcmaster is around $40.

i can get 10 feet of chain for $15 and the sprocket to run it for another $4. so for half the price of just the rod i can have a complete axis drive system.

the rod would still need mounting nuts, couplers, bearings ect.

add to that, in my research, a chain should be able to be about as accurate as a rolled ballscrew, and to me it makes more sense.

chains are simple, put a sprocket on the motor shaft, probably and idler sprocket and go. they seem less complicated than screws to me.


just my thoughts.