On Saturday 14 April 2018 22:05:25 jeremy youngs wrote:

> Good day gents, probably for pcw Andy or Gene. Any pointers on
> selecting mesa cards as needed? I'm looking for inexpensive and
> versatile. I don't have a lot of spare funds to contribute.

I have 2 fav cards, mainly because I have zero experience with the 
others.

If a pair of parports is enough to get it done, the 5i25 is a good 
choice, using Sainsmart BoB's.

If you need more than what the 5i25 can do, the next step up would be a 
7i90HD, which can be written to use an spi channel, or can be driven by 
an epp parport. It has 72 gpio's, and can handle in some configs, up to 
8 axises.  Both of these cards are 3.3 volt cards, but the Sainsmart BoB 
handles to real world noises well in the case of the 5i25.

The 7i90HD has 3, 50 pin headers, and to protect it from surge noises 
that can blow the 3.3 volts gates in it, needs 3 7i42TA's and 3 short 50 
pin cables to do that protection job. That also gets you the usual green 
plastic stick the wire in the hole and tighten the screw interface to 
the real world. These effectively function as the BoB's, so you don't 
need them if using the 7i90HD and a triplet of 7i42TA's.

If using hi-res omron encoders, you may have to bypass the opto's in the 
Sainsmarts inputs to get enough speed, but it has no slow opto's in its 
outputs. I bought a 1000 line omron, and put it on the rear of the 
spindle motor, so its before the mills back gears, so I wrote a hal 
block to determine the gears, and put some switches on the rim of the 
knob to switch the spindle scale so it works and the tach reads 
correctly in either gear. The index still comes from my original home 
brewed optical encoder on the spindle.

There's more that would be TL;DR, for right now, but suffice to say I 
have VERY stiff speed control on the spindle motor now.

My 2 cents. ;-)

> I'm thinking 7i43 ran by epp at this time. I have a pair of servo 
motors
> with renco encoders and an inexpensive hbridge (36v15a) . I've tried
> sorting through everything and just seem to end up confused. I'm
> looking to get x/y under servo power and get away from these steppers
> . The big issue for me is having to build the timing belt drive mount
> and not desiring to do it twice as these servos are roughly nema 42
> and my steppers are nema 34 .
> I'm basically looking at being expandable and controlling the h bridge
> while keeping z stepper driven for the moment. ( I do have service for
> that as well, I am likely to just convert all of them to omron encoder
> down the road) . Also I would like the ability to drive my selema +-10
> drive and brown boveri motor as an a axis with a lathe headstock I
> have lying around in the very near future.
> Thank you for your time .
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-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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