[stokessd]

I designed and built my own stepper drivers based around the Allegro 3977 chip (the same as zylotex uses). I also have a limit and relay board for spindle and coolants etc. I used the mill to build the box and engrave it. Pictures are here:

http://www.quadesl.com/albums/stepper.html


My completed mill and lathe are here:

http://www.quadesl.com/albums/taig/taig_done.html

I made them portable because my bench is also an electronics bench, woodworking bench and photographic darkroom.

Sheldon

[cncadmin]

That is one sweet shop set-up you have there! Wow I love your controller box, nice and clean!

[pack rat]

very professional job. Tidy and neat wiring too.

[anoel]

Nice.

How was the "cost : Benefit" of building your own drive boards? The Xylotex are priced reasonable, was it worth it to build your own? I ask cause I'm considering cobbling together a chopper board of my own, just haven't decided on the chipset.

Those Sescom boxes are very nice Pricey but nice. That's what I used for my Gecko box. (That I'm selling )

[pminmo]

stokessd, shop is way to clean! I too have done a board on the allegro chip, a coworker has done the limit board. Currently off to olimex for board fab. Any gotcha's on the 3397?

Phil

[WOODKNACK]

Looks alot like mine. I need to get out in my shop! Just too cold right now. Going to be -30 tonight!! with wind chill around -60.

[pminmo]

anoel, the reason I didn't go with the Xylotex or thk was the lack of input conditioning on the step and dir lines.

[stokessd]

Originally posted by anoel


How was the "cost : Benefit" of building your own drive boards? The Xylotex are priced reasonable, was it worth it to build your own? I ask cause I'm considering cobbling together a chopper board of my own, just haven't decided on the chipset.

Well, the allegro chips were free samples, so I built my 3 axis board for about $30 or so in parts. I also use the case side for a heat sink and don't need a fan. I also use a 7805 regulator for the logic level voltage without some sort of "power steal" kludge. The boards offer 8 amp switching of spindle and coolants as well as inputs for limits and home switches. The real benefit was that it was cheap, an fun to build my own driver. That's part of this hobby right? Building things...

Originally posted by pminmo
anoel, the reason I didn't go with the Xylotex or thk was the lack of input conditioning on the step and dir lines.

Yes, that's the biggest problem with those chips. I have 10K resistors in series on the input lines and a 47 pF cap to ground. that does a nice job of filtering the grunge out.

Originally posted by pminmo
stokessd, shop is way to clean! ... Any gotcha's on the 3397?

YES, I like a clean workspace. The floor is painted with two part epoxy paint and my cars are spotless behind the photos (highly polished too). the biggest gotcha is the input are very noise sensitive, and are millimeters from a huge noise source (the outputs). Input filtering is a must, I also used inverters to buffer the parallel cable lines on the board before the filters. IF you aren't careful the steppers will wander around from spurious input. The filters described above solved my problems.

That allegro chip is way too fast and as a result is sensitive to the same RFI it generates. What stepper needs 500KHz pulses?!

Sheldon

[pminmo]

Yes my board has 40106 cmos schmitt trigger inverters. I figure with the hysterisis inputs combined with the slowness of the cmos, plus a lower impedence pull up on the input. There is a spot for a cap just in case.

[stokessd]

Originally posted by pminmo
Yes my board has 40106 cmos schmitt trigger inverters. I figure with the hysterisis inputs combined with the slowness of the cmos, plus a lower impedence pull up on the input. There is a spot for a cap just in case.

I thought something similar, that's why I put the inverters in my design and that wasn't enough. I ended up putting those RC filters right next to the chips.

Make sure you have provisions for them, my exerience says you'll need them.


Sheldon

[kfong]

We designed one as well, went with the lmd18245 chip set.
3amp 55volt microstepping chopper driver board, all parts can be found at Digikey. Works great and the software is open source. At 8 microsteps, it seems like a servo motor. Very smooth and fast. All info and schematics are posted on our web site. National gives out samples as well.

http://www.embeddedtronics.com/microstep.html

Kin Fong

http://www.embeddedtronics.com