cnc winder controller board

[David King]

I think the solenoid is already too much trouble, just a thumb screw and a spring over the felt is more than enough here. If your windings seem a bit loose, just tighten the screw 1/4 turn and try again. If anything goes dead with the solenoid system then the whole tensioner becomes useless.

I really like the feedback loop on the DC generator, that's probably overkill but just so cool. Use a DC motor with lots of poles and very low inertia. Probably a disk drive motor, the spinning disk armature kind.

Why not just use a passive dynamic brake with a potentiometer? It's got to be more reliable than the felt. You want a motor that's not too "notchy"

Swiss made Escap tape-drive motors have the magnet inside a spinning armature. Totally smooth and 60-75% efficient despite having brushes...

[-Elepro-]

i'm working on tensioner....
Escluding the load cell because it is not cheap...

...I am undecided about:

- a solution with felt tensioner controlled by a solenoid driven by a pwm pic output..... but without any kind of controll feedback.....

- a solution where the wire wraps a turn around a pulley on the shaft of a DC generator... a mosfet controlled by pwm signal from pic adjusts the load on motor (and brake torque).... voltage on load go at A/D converter and value compared with set tension value.... comparator output adjusts pwm duty cycle....


first solution is simple and easily doable

second solution has feedback.... but it's too hard to find perfect generator with right brake torque and with linear current/ brake-torque characteristic curve (at speed variation too) ....

I'm afraid that a complicated solution like second could be worse than first....

suggest?

[-Elepro-]

that system is good but not cheap.... wait and check ebay every day

for power supply is enough a transformer with a diode bridge rectifier and smoothing capacitor..... motors don't need stabilized voltage.....

about voltage, 24 volt is enough (but more is not worse ).... (motor speed depends on voltage)

did you receive my reply private message?

bye

[David King]

2 axis stepper kit?

Im thinking that maybe one of these stepper kits from probotic might be a reasonable and cost effective starting point.

2-Axis CNC Stepper Motor Driver Kits

It's two 2 Nm (280 in/oz) steppers with a pair of stepper drivers (3A @24V) and a power supply.

I'm not sure you could do the whole bit yourself for less using new equipment and I don't see much used equipment for sale on ebay these days.

Any reason to up grade to the 32 or 40V systems?

[David Schwab]

Yes I will email the original color pdf that I scanned at the U of Mich Eng Lib. It was too big (10MB), so the post is a scan of a copy Anybody else need the color version, email me at mootej@aol.com.

John

Thanks for that John.

I reduced the size of the PDF to about 1.5MB and emailed it back to you.

It's interesting, but it looks like it's made for heavy gage wire. You could never have a spool of 42AWG on its side like that and expect it to de-reel without breaking. But there could be some tidbits to glean from it.

[-Elepro-]

Please note that driver in that article other than it has not minimum features of all common stepper drivers (and it has serious design errors.... that mosfet never can has complete saturation with 5v at gate.... and many lpt have tension of about 4v or less ) it has not any protection for computer motherboard!!!!!
that software can use only that driver....
therefore with that solution you can have 100(???) rpm max, many heat and maybe a burned out PC.....

[mootej]

Looks interesting. Did you scan that? Can you rescan it as grayscale and not bitmap? It's hard to see the photos.

Thanks.

Yes I will email the original color pdf that I scanned at the U of Mich Eng Lib. It was too big (10MB), so the post is a scan of a copy Anybody else need the color version, email me at mootej@aol.com.

John

[-Elepro-]

and this is default settings branch

next time something more interesting


YouTube - cnc pickup winder - configuration menu

[salvarsan]

l297 is a controller..... SN754410 is a quad driver.........

My error.

I meant the L293.


-drh

[-Elepro-]

Try Texas Instruments' *SN754410 instead of the L297.
It is L297 pin compatible and has built-in snubber diodes.

-drh

l297 is a controller..... SN754410 is a quad driver.........

[salvarsan]

Try Texas Instruments' *SN754410 instead of the L297.
It is L297 pin compatible and has built-in snubber diodes.

-drh

[-Elepro-]

The full wave chips L6203 on ebay for $5 ea and up
The stepper chip L297 is $12.5 at digikey

in europe it is possible to find l297 at 3€!!!!!
watch this and this (same store)
....enter in ebay from .co.uk and try to find better price..

[David King]

Elepro, Thanks, that looks better and 4 amps @ 40V ought to be more useful for some other small CNC projects I'd like to do (like a small engraver).
I found the following two links:
Schematic: http://i20.tinypic.com/2emdkx0.png
PCB: http://i23.tinypic.com/28lg9c8.png
I'm hoping that those chips aren't too expensive, or maybe someone has made a kit already. I can etch the PCB if necessary, some experience there.

The full wave chips L6203 on ebay for $5 ea and up
The stepper chip L297 is $12.5 at digikey

[-Elepro-]

Would this driver be enough?
2 AXIS CNC Stepper Stepping Motor Driver Board - eBay (item 300312066747 end time May-31-09 22:30:23 PDT)
I see that 2A is maybe enough for Nema 17 motors
4A is needed for nema 23 motors?
I suppose amperage and torque go together so the nema number doesn't mean too much

nema is dimension... but you can find nema17 with more torque of a nema23...

about the driver on ebay, i have not experience with TA8435 but the datasheet says that reccomended operating current is 1,5A max (not 2A of auction specifications)... anyway, with a large heatsik (and fun?) and 2 high efficiency 2A motor you should have good results..... and it has a good price....

if you have experience with electonics assembly you could search project of a L297 + 2X L6203 driver that can supply 4amp @ 40 volt....

[David Schwab]

An interesting article for a coil winder project in Nut and Volts June 2005 p. 40 (attached).

Looks interesting. Did you scan that? Can you rescan it as grayscale and not bitmap? It's hard to see the photos.

Thanks.