total newbie

[peggsydaly]

Hello everyone. This is my first Post.Thought I would introduce myself to you all. I am a 50 odd years young old fashion trained signwriter, yet I have worked with cnc flat bed Matcam routers for many years, as an employee of course. Operation of this equipment has always been graphically orientated through cadcam and I have been interested in what makes these things work the way they do. Up until this time I have had only a very basic understanding of steppers and servo motors. I logged onto the WWW for the first time at home only a couple of years ago. Since then I've been learning about electronics and how they work. I want to build myself a small hobby cnc router, but want to do it the hard way and not go buy controllers and boards. To me its all about the learning experience and the fun of it. I have built some driver boards using only descrete components for unipolar steppers and am building a few for bipolar stepper motors. Have had a few meltdowns with the transistors on the bipolar circuits though, until I realized they come with different pin arrangements for possibly ease of board making. The math knocks me around a little, but will continue anyhow. So far as step, direction decoding goes I've managed to sort through. I find the 1/0 logic ok. Need to sort out a descrete interface from pc to my steppers but won't be easy.Want to stick to the KISS principle with everything that I make even though "simple" seems often to lead to its own compexity. Have read a bit about Gcode and that there are many variations. I'll have lots of questions for you all. Hoping thats ok. Will try and post my primitive stuff here for all to have a chuckle about when I have something worth the view. Some may find my electronics amusing.

[Robin Hewitt]

Hi

I went down the same stepper route, (also 50 something), thought all I had to do was use lots of volts, control the current and add a lesser hold current option so things wouldn't get hot.

It worked okay until the mains surge when all 3 drivers failed the smoke test simultaneously. Fortunately I had already got curious about black box commercial stepper drivers and had a set of 3 c/w a 40 volt power supply. The top speed difference was amazing, they must do something real clever in those little boxes.

The usual PC interface is the parallel port which can be written to directly. Opto-isolators are good, that way you don't have to share a common ground between PC and stepper driver.

I have rambled enough

Best regards

Robin

[watchman]

Hi Peggsy, welcome to to community....
I'd second the idea of using commercial stepper drivers, there are several microstepping drivers on Ebay regularly which are not only better that you can build but also much cheaper - been there, built my own and wasted both time and money on it!!
I'd also recommend having a play with EMC2 as the driving software - its FREE! Go to www.linuxcnc.org and download a disk image. It is linux based but that's nothing to be worried about. The image burns to produce a live CD which will boot up and run straight from the CD - albeit quite a bit slower than an installed version but you don't need to change your PC at all to try it. If you do decide to install it, it will install alongside Windoze as an alternative boot option and won't interfere with anything else you have on there. If you have never played with Linux, its now just like a different version of windoze (except that it and a lot of its software if totally free). Good luck...

Ian
Sheffield, UK - (Who only started really getting into this when he was 60!)

[solodex2151]

Peggsy,

It's always good to see new faces in the community. Robin and Watchman have given good comments. I would consider taking the following approach. Design the router first. Build it and use a cheap commercial package like HobbyCNC to get your router running. Use EMC2 for the software and figure out how the whole process works. You've been doing Matcam work for many years but I can guarantee that you will learn a lot of the internals from this approach.

After you have everything up and running, then focus on your electronics. Stepper motor controllers can range from somewhat simple to relatively complex, depending on the performance envelope you want to achieve. I would suggest going over to the electronics section and searching for "Mardus-Kruetz stepper drive". Mardus and Kruetz designed a stepper drive with a performance envelope similar to the Gecko units. That is the complex end of the spectrum. Check out www.pminmo.com for the simpler end.

If you need help with specifics, feel free to PM me.

Nate L.

[itel933]

Hi Im new to the site and even newer to CNC. Im an inventor and would like to start using a CNC to make things.....the only problem is that I am completely and totally lost. I keep reading on multiple sites to make one yourself and on other sites that have "diy starter kits" Can anyone help this newbee in starting his first CNC.

[solodex2151]

Originally Posted by itel933 Hi Im new to the site and even newer to CNC. Im an inventor and would like to start using a CNC to make things.....the only problem is that I am completely and totally lost. I keep reading on multiple sites to make one yourself and on other sites that have "diy starter kits" Can anyone help this newbee in starting his first CNC.

You can't go wrong with a kit CNC. It'll take some more work than a completed unit but far less than designing one yourself from the ground up. Since you seem to be a little overwhelmed, it is probably best that you go with either a kit or buy some plans so that you don't have to do any design work.

Regards,

Nate