Newbie- Thinking about Building a CNC Needs some input and pointers!!

[CnCustoms]

So I've been on this board for a lil while.Finally decided that I'd like to build a cnc machine.Something to cut some mdf,plastic,wood,and some aluminum.Looking to buy a kit more than likely a joescnc 2006 or a 4x4 hybrid.I have some questions.I see most of you are running these machine with parallel ports what would be the major difference between parallel and running one with a usb port?trade-offs the good and the bad???Also where can plans be found to build such a machine and where does one purchase all the bits and pieces you need to build one??Budget is another thing.Id like to stay within a $1000 budget.I have access to software so thats not an issue.Just looking for pointers and ideas.This will be my first build.I'm a Mechanic by trade and pretty handy.Any help and infomation is greatly appreciated.Thanks.

[dkirtley]

It depends on what you want to play with and your goals. The USB and parallel port ideas are not really mutually exclusive if you want to play with the programming and hardware. I have stuff for both. It is also a tinkering that will make for a long time before I have a usable system. I am not really in a hurry and honestly, have no reason for a CNC machine other than I want one to play with.

Controlling individual steps over USB is a lot of information over one connection. The only real feasible way to use a usb connection is to have an embedded controller that will handle the timing. The current answer is to have a g-code interpreter installed on the controller (or something similar.) The embedded controllers don't generally have as much memory or a very fast clock speed. Makes it hard to have really sophisticated code. Going with the parallel port route has fewer lines of communication and provides a lot more cpu power. Parallel ports are dying out and will eventually have to be replaced with something else. You can also incorporate a lot more information on screen with a computer and parallel port. You can get by with pretty cheap computer. A mini-ITX can set you back less than $100 new. Without memory, I think I paid $50 for my mini-ITX board and $60 for my Arduino Mega. Not much of a savings in that area.

My own personal experiment plan has hardware that cost about $250 for the power supply, 4 steppers, parallel board, and some shaft connectors for the motors. The more problematic part is the linear motion components. Lots of choices for motion components, threaded rod, ball threads, gears, chain, belts. The tradeoffs are power transmitted, friction, accuracy and repeatability.

As far as the kits, you trade off sourcing parts and making choices or your money and time. The two areas that are the greatest expense: linear motion and drive system. If you source a lot of different items from different places, actually shipping can rank pretty high as well.

As far as where to buy, there are some suppliers that advertise here on the forum and many others. Some are building only from hardware store components. One more option is to do a CNC conversion for a manual machine.

Just depends on what you want to play with and what you want the machine to do.

[ger21]

I see most of you are running these machine with parallel ports what would be the major difference between parallel and running one with a usb port?trade-offs the good and the bad???

Most of us Use Mach3. If you want to use a USB port with Mach3, you need to buy a Smoothstepper, which is an additional $150. Warp9 Tech. Design - Home of the SmoothStepper - Home

You're budget is gonna be tough to stay under. No way you can build Joes 4x4 for $1000. If you buy the 2006 kit, you'll have a hard time staying below $1000, as the Kit eats up half that, and that's just the MDF and plastic parts.

If you're handy, and have decent woodworking tools, you may be able to make those parts in the kit yourself for $100-$150

Plans for the 2006 are here.
RapidShare AG, Cham, Switzerland

Some parts can be bought at Lowes or Home Depot. McMaster Carr has everything.
dumpsterCNC - anti-backlash solutions for home and industrial linear motion

Plenty of others.

[Benonymous]

Sounds like you need to go with an aluminium frame if you're going to cut aluminium. Some judicious shopping on eBay will probably get you the frame materials. If your budget is $1000 I think you'll be going with the round rails or plate rails and skate bearing trucks. Whatever, they'll need to be fully supported. I personally think you'll blow the budget by around 2 to 5 hundred by the time you're finished but I'd go for the best structure and linear parts you can afford as a priority. Motors and electronics can be upgraded later if necessary but the structure should be as good as possible so you can set it up once and then worry about other things.

Happy building

[CnCustoms]

I was thinking about using some 80/20 aluminum extrusions for the frame as it seems that stuff is pretty durable and ive seen a few people on here using it.As far as stepper motors go i was thinking about some nema 34's. either 640oz or the 960's.As far as drivers go I am clueless.Seen alot of people using gekodriver but my question is which one would be best for me??Also how do i go about powering my cnc steppers and of course is there motherboards out there that are still made that have a parallel port???Id like to use a parallel port to control the steppers however I am not sure if i will be able to find a motherboard that has a parallell port on it.Also as far as computing power goes.What kind of processor would I need and ram and what comes into play.Suggestions welcomed.ideally I believe I will end up going with a 2'x4' cnc machine.I believe that Will be best for me at this time.

[bobsch]

The NEMA 34s your looking at are overkill for a 2'x4' machine. Check out the kits here: Page Title

The third kit (G540 3 axis package (One G540 + Three NEMA23 KL23H2100-35-4B (1/4” Dual shaft with a flat) 381 oz-in + one KL-350-48 48V/7.3A 115V /230Vpower supply: $455.95) is a popular choice.

[ger21]

You can get dual Core Intel Atom motherboards with processor for about $75-$100, with parallel ports.

[CnCustoms]

as far as ram goes and requirements to run one these machines what do you all recommend????Also What kind of router is a good choice??

[wcarrothers1]

I typically look for a Pentium 4 3 ghz machine with a meg of memory and I run either Windows 2000 or XP. Although I would admit that my nearly favorite machine I've run mach on was a P3 machine which was very nice for running Mach but was under powered for drawing things up quick..

Parallel port is simple and tried and true. I have both SS and paralle which I can switch between to run my gecko's (servos) and I tend to choose to run with the paralle more then the SS. Although I've never had any miss haps with the SS and it's basicly drop in (you would have to be a complete idiot) not to be able to get an SS to work.

I'd go paralle and see. You can always drop in a SS real easy after getting things working on parallel and see how you like that.

Probably more important then anything to get things to run right is going into bios and disable power save or any option which might try to throttle CPU rates on their own or to save power based on what it thinks you need. just turn all that off. specially look there if things are not working smooth. When I moved fromy my P2 and P3 to my p4 I ran into this and took a while to figure out how to get things smoothed out.

b.

[CnCustoms]

Sorry it's been a while,I've been very busy at work and after hours.So after doing some research and some homework.I've decided I will be building either a 3'x4' machine or a 2'x4'.I was thinking about using the plans you can download from finelineautomation. Using 8020 aluminum extrusions for the chassis of the machine.Can anyone tell me if this would a a suitable way to go??considering I am planning on machining some aluminum pieces??Or it there a more sturdy design perhaps that I should use??and which extrusion should i use?30x30mm or 40x40mm extrusions???That would be a big help.

Also im sure the advantage of rack and pinion setup is speed.But considering this will be a machine mostly for personal projects and some tinkering.So is it worth spending the extra money on a rack and pinion setup or should I stick to lead screws???Also what would be the ideal steppers id need for a 2x4 machine or a 3x4 machine??

[dkirtley]

I have not been making any progress on mine either. Not in any big hurry myself. Lots of projects and little spare time.

The system from Fine Line Automation seems fine for general purpose. I bought a set of their bearing blocks and like them. The design is at least as rigid as any 80/20 would make. I don't think 80/20 is particularly rigid but close enough within the constraints of light cuts in softer materials. It's only real benefit is having the t-slots for attaching stuff and for permanent installation it is not that hard to drill and tap holes. I might feel differently if I didn't have a manual mill, lathe, and bandsaw.

I have been thinking about the drive system a lot. Unless you are machining foam, I really don't see the point to high speed feed rates for a CNC machine unless you have a monster spindle that can cut that fast. I like the simplicity of rack and pinion but as you decrease the mechanical advantage of the drive, you will need higher torque motors to move stuff. There is no free lunch. I am assuming that you are discussing steppers so there is one benefit. As you speed steppers up, you loose torque. They work better at lower speed.

I personally decided to stick with leadscrews. 1/2-10 acme to be exact. I picked up an acme tap and am making my own anti-backlash nuts (much like the system that Sherline uses) I have made up two leadscrews so far but have been putting off buying some more stock until I finally make the decision of what I am going to do for the linear bearings. That and I have been unable to commit to a size as well. I was originally going to go with a 2'x4' work envelope but I don't know that I really would be doing anything that big at present.

As far as motor size, that depends on what you are doing with them. The amount of weight and friction on the stuff you are pushing around, the speed you want it to go, and the strength of the spindle you are trying to keep positioned will decide the motors you need. This is also a matter of the mechanical advantage of the drive system as well. Your choice is to go with what similar machines use or experiment. Personally, I am experimenting. I am starting with 1NM steppers for mine for a similar size machine.

[CnCustoms]

Thanks for your input.I am having a hrd time deciding on what size extrusion I should use?maybe 60x60mm or larger I don't know.The only reason why I am looking at building a 2x4 machien is because I could use it to make some parts for my rc cars,and also some engraving on different pieces.That's It really, possibly making some other cool projects later down the line.