First Post - Some Beginner Questions

[tvdbon]

Hi Everybody,

I've been lurking around on the forums ever since I heard about cnc machines and the possibility of building my own. I never did much than reading on forums mostly due to time and money restraints. I've decided that I will start doing to the research and then to actually build the machine. At the moment I'm looking at JGRO's plans, but it still looks a bit advanced for me so far. I'm also very limited to tools and currently own a jigsaw and a drill press. I'm still contemplating if I should build my own machine from scratch or if I should buy a basic frame kit. So Hi! and I'm sorry if I'll be asking dumb questions in the next couple of months.

Some basic questions:

(1) With my limited set of tools would it be better to buy a frame kit or should I take the punch and try building from scratch? Does anybody know where I can buy wooden frame kits on the internet ?

(2) ... I had more questions, but now I can't remember them

Anyways, I'm hoping I won't give up along the way, but I'm willing to give it a try.

Thanks for reading ...

[tvdbon]

OK, i've decided to rather go the build from scratch route to get things started. At the moment I'm thinking of maybe doing a kind of concept model first, small and basic - won't really be able to route anything but it would be a great way to get the concepts going. I'm thinking of using some basic supplies from old printers. With a bit of luck I'll be able to build something that will in the very least be able to hold a pen instead of a router and draw some stuff on a piece of paper. Can anybody suggest any good books on building your own cnc router ?

[Rance]

[Can anybody suggest any good books on building your own cnc router ?]
CNCZone is better than any book you could ever find. It's dynamic rather than static. You can even ask it questions and it will give you an answer.


As far as printers goes, I assume you are referring to HP Laserjet printer parts, then go for it. Bubble jet printers don't have much in the way of usable parts from what I've found. I see 3 possible choices for you:

1) Very small machine for learning how to build a CNC -- Salvage 5.25" floppy drives for the steppers and their controllers. [Cost: $50-$100] A reasonable 1st machine.

2) Small to medium machine to cut some useful parts -- Salvage HP Laserjet printers for their 100oz steppers, build one of the "Kit" controllers and build a wooden machine. Wood is easy to work with and cheap. Use skate bearings and pipe for the same reason. [Cost: $150-$600] A good 1st machine.

3) Build using aluminum (8020 or similar) or welded steel frame. Use THK slides or other costly "stuff". Also pay through the nose for Gecko controllers. Buy lots of software, some you may not ever need or use. [Cost: $500-$5000] Definitely NOT a 1st machine.

And there's a managerie of options in between what I've laid out here. Keep in mind that there is lots of conjecture & opinion here. I'm sure some of the more experienced may balk at all of this (and for good reason). But most importantly, GET STARTED, and rottsa ruck!!!

Rance

[tvdbon]

Thanks for the reply. At the moment I only have a couple of inkjet printers from which I wanted to take apart from some parts. I've got a lot of old floppy drives lying around so I could start there, anybody have any more information on using floppy drive motors ?

I'll still shop around for more parts, but don't want to spend too much since I'm only building a small concept machine. I'll save the money for my 2nd machine when I've got the idea of the innerworkings figured out. Guess I'll have to do some more research ...

[Rance]

TV...,

Look at the following:

How to use Disk Drive Stepper Motors:
www.epanorama.net/circuits/diskstepper.html (Tomi Engdahl)
...or
Floppy Stepper Motors
Lookup www.nhcad.com/flpystpr
www.hobbycnc.hu

Usually only the Teac Teac Floppy Drives have the bigger stepper motors. Here's their Part #'s:
FD-55BR
FD-55BR-566-U
FD-55B-01-U 19307110-01
FD-55FR-511-U
FD-55BV-11-U 19307200-11
FD-55FV-13-U
FD-55GFR

The original Tandon TM-100 or IBM 171172 will also work.

FYI: HP Laserjet II & III printers can be had for a song($5 or less) if you wish to go that route. However, then you have to have a real (ie. $$$) controller board.

[tvdbon]

Wow, thanks for those links - some nice information there. I noticed the following cd plotter



from this site : http://www.nhcad.com/cdplotter/index.html

and I'm thinking that this might be the perfect project to start with. It has the basic cnc approach but only smaller and not as powerfull. I'll have to start messing with the floppy drives this weekend.

[Rance]

TV,

Along those same lines I really had fun building an Egg Bot for the same reasons you are building your "cheap" machine. Not too much detailed info but you can get the idea from http://www.taomc.com/studio_machines/egg_plotter.htm . Other things at taomc are interesting too. I ended up buiding a controller using unc5804's but the controllers that come with the motors work well too. One note, you should be able to make them more powerful by supplying more than 12v to the motors but I've not tested that yet.

Have fun!

[tvdbon]

wow, the egg bot seems pretty cool too. I guess you can make pretty neat cnc-like things with some basic materials and tools. I can't wait to begin. I'm planning to play around with the steppers this weekend and then start to build something similiar to the cd-plotter. Quick question though, the lead screws used in a cnc machine are they specialized screws ? I know I can get some of those at the local hardware store. Basically a long bolt but without a head and on which you can screw a nut. Will that work or does one use something else which is similiar ?

[tvdbon]

I was thinking of using something like this:



Will this work or am I missing something ?

[Rance]

Looks like that's exactly what the CD plotter guy used. Yes, it will work but you'll have to learn about backlash and how to fashion an anti-backlash nut (sometimes referred to as an AB nut). For the bigger machines, folks usually use Acme rod or better. But even some of the decent machines use simple threaded rod like you've shown.

Rance

[kiltjim]

That is exactly what the DIY machines start with.

It's called allthread. Most of the DIY machines start with it, and migrate to heavier duty, more precise threads (if the machine gets upgraded, redesigned, etc.)

A cheap, easy to work with, introduction.

[tvdbon]

OK, I know what backlash is (did some research), but I'm not sure how create a anti-backlash nut. I'll search the forums and see what I can find. Also , how would one connect the stepper motor to the threaded rod ? Sorry about all the questions, but as soon as one concept becomes clear, the next part confuses me.