[High Seas]

Greg - Not to drive (poor choice of terms --hehe) the design - and backing up to the number of pins discussion -- you could add a second parallel port and increase the the numbers of pins - but it probably doubles the costs of that section of the board! but greatly enhance the modularity aspects.

Regarding the type of motor - bipolar, unipolar, servo - you'll "know" what meets your needs and sharing the results with all will be most kind - and keeping within the OpenSource -- thanks for that!
AND, certainly at some point you just gotta say, "Pencils down - time to turn in your papers!"

Great effort in creating the spec and good luck! I'll most likely be saying later, "Wish I had one of those"
Cheers - Jim

[gregmary]

Phil,

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I did a little consolidation of the files I have been working on:

http://webpages.charter.net/pminmo/cncelectronics.htm

Always looking for colaboration and help. It would be really good if there is somebody at the zone that could build a mill file for the 5804 copper board.

Phil

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Could I get a zip file of your Eagle schematic and board files for your 3977 design and your parallel port interface board. It looks like you have done the lion share of the work already.

Thanks,

Greg

[pminmo]

Greg,
You have a PM with the details.

Phil

[vladdy]

It looks like you use Eagle PCB software already, do you have to 'pcb to gcode' conversion ulp..??
Easy to use.. either top or bottom [flipped] nc code generation..
imports easily into Kcam [haven't tried others]..
If you don't have, I can shoot a selction of different type over, including drill and outline generators..

I use 4.08r2
enjoy

[pminmo]

I updated my webpage with the lastest files:

http://webpages.charter.net/pminmo/cncelectronics.htm

I've taken the L297/298 board as far as I plan to. I can't say I plan on building that board. But I did put some effort into cleaning it up. I think it's good to go. My thought would be to ask the admin here if once we get into the publishing phase of the open source stuff to build a webpage rather than just a downloads area.

Phil

[joq]

what about the squematics in this site???
motherboard and driver

[pminmo]

Nothing strikes me as terribly incorrect. On the positive, there is a driver onboard for an off board relay, thats good. Pull up resistors correct.... Power on reset circuit, (something I hadn't thought about) I like the modular design, and I wish I had found it it would have saved me some work getting his eagle files for what I want to do. My concern would be lack of signal conditioning. If you know what you are doing wiring wise, you maybe ok. Be carefull of wiring gnd, 5v and 12v as they all interconnect. And wire routing to avoid noise coupling. I would have liked to see the 4584 used to condition at least the step line for each axis.

Phil

[gregmary]

Why use Bipolar motors instead of Unipolar motors?

Stepping motor-based systems offer an economical method of motion control. Different types of drives (or controls) expand step-motor performance for added versatility.




For the greatest wiring flexibility, the motor's eight leads are connected to the ends of the four coils that make up the phase windings. The coils can be connected in series or in parallel to operate with a bipolar drive, or in series with a center tap to run from a unipolar drive. Relationships between motor parameters when using these connections are summarized in the Online Extra item.

Use half or all the copper

Unipolar drives supply current to a given motor phase in only one direction. These simpler drives use only half the copper available in any phase at a given time. The result is less torque at low speeds than with the same motor operated from a bipolar drive of the same input power.

Bipolar drives supply either positive or negative current to a given motor phase. Drive electronics are more complex here, but using all the copper in the phase windings results in about 40% more torque at low speeds than from a unipolar drive with the same motor.

Unipolar or bipolar drives can be further divided into voltage (L/R) type and constant current type (which includes a chopper or PWM).

Voltage (L/R) drives apply rated voltage to the motor phases and rely on winding resistance to limit current. The least costly drives in this class have the poorest speed performance Adding a power resistor in series with each winding, and using a higher supply voltage to maintain rated voltage at the motor, can enhance high-speed performance somewhat. This effectively lowers the motor's L/R time constant, allowing more rapid current build up. Due to large power losses in the resistors, this approach is practical only for resistor values up to a few times the motor resistance.

Performance of a bipolar voltage drive is the same whether the windings are connected in series or parallel, because the L/R time constant is the same. But the unipolar connection has higher speed capability than either bipolar connection because the unipolar L/R time constant has half the value.

Constant current drives use a much higher supply voltage than the rated voltage of the motor (typically 10 times higher or more). They also use current-sensing circuitry and apply pulse-width modulation (PWM) to the supply voltage to maintain the motor's rated current and keep it from overheating. As noted earlier, a higher supply voltage allows the motor to run at higher speeds. Advances in integrated circuits and power-switching transistors have made this a very popular type of drive, even though it is relatively complex.

The bipolar constant current drive is the most popular drive type today for high-performance applications. When the same supply voltage is used a bipolar parallel connection will result in about twice the speed of a bipolar series connection. However, the parallel connection requires twice the current of the series connection. Unipolar constant current drives are less common and their low-speed torque performance is lower compared to bipolar drives.

Understanding the relative performance of a step motor with various drive types will aid users in selecting the most suitable control for a given application, or provide insight on how to increase performance of a stepping-motor system.

[venomx999]

Post some plans of the board...
I want to make it