long term reliablity computer boards

I'd suggest you take a closer look at Mach3 as well as the couple external pulse generator modules that work with it which eliminate the need for parallel ports as well. As you see you're already having difficulty maintaining a system that requires ISA slots, better to prepare for a newer setup that will work with more modern components. Remember that Mach3 is free in code limited trial mode (~1000 lines IIRC) so you can very easily try it out. It is also very reasonably priced in full mode (~$150/unlimited for non commercial and ~$150/machine for commercial).

Most desktop motherboards aren't built to specification for long term reliability. I know some motherboards have operated for many years without failures, but long life isn't the average life.

Reliability is spec'ed in server machines that are intended to run continuously over a long period.

The ISA bus is already old, and so are the individual special ISA hardware cards/boards. I'd imagine that ISA backplane boards exist, but I don't recall ever seeing them. There may be a ISA backplane module that adapts to another buss or port type.

There is a specialized class of industrial-duty computers similar to desktop construction, but cased in 19" rack cases, which are airtight and cooled without room air passing thru the cases. These systems may still be being built with the ISA buss.

Hoarding old motherboards will only work until a failure wipes out the ISA cards that the machines need to run on.

You can still buy machines with ISA slots, but they are not typical consumer machines.

One route that I often see used in industrial environments is PC/104 bus computers with a converter to the ISA bus. This was once useful as a transition step when an ISA card was available that didn't have a PC/

104 equivalent yet. Today it is extremely unlikely to be that combination; it's far more likely that the PC/104 card is available new yet the ISA card hasn't been made in years.

The hardware lifecycle for PC/104 is quite a bit less frenetic than for consumer PC stuff. Peripheral cards are likely to stay in production for years and years, not just a few months. At work we bought a large quantity of PC/104 stuff 7 years ago; today when the manufacturers change board revisions they still send us updates and often tell us which new versions are backwards compatible with the old ones (they want to make sure we don't switch to a different manufacturer I think!)

Tim.

It's nothing more than a wag, but I would say new stuff every three years, providing you keep the machines cool, clean, and turned on. Nothing seems to hurt electronics more than heating and cooling cycles from turning them on and off.

It also assumes a good power system to avoid low and spike voltage conditions.

Have you checked out the industrial computer suppliers? There's a lot of folks in your shoes; I would expect that someone at least makes a PC-104 carrier with a regular ISA slot.

Search on "embedded PC" and "ISA", if you haven't already.

Look up the specs on the electrolytics used on the boards. Most have a 2000 hour life rating at the specified temperature. After that, the ESR starts to rise, causing the boards to fail.

BTW, my background is in mission critical electronics.

Around machine tools?

The Geckos are a kluge that allows you to run servo motors from the step and direction signals more commonly used for driving steppers. Convenient under the right circumstances, but you'd sacrifice quite a lot of the functionality that the Galil controller offers by going that route.

What functionality? It's still closed loop, still flags an error and shuts down the control if the servo is overloaded and can't hold position, you can still tune the parameters, etc. I can't think of any feature you loose that is relevant for the class of control.

83 days?????????

Sure, why not?

You and Michael raise good points on the computers and ISA bus. Looks like this route is out of business in 5 years or so. Right now Galil PCI cards are $1000s each while the ISA units go for cheap on eBay. Maybe I'd best start saving.

My hesitation with Mach is based on the frustration I see with folks trying to install commercial scale needs. I worked with a guy on a hardinge CHNC like mine. He's done three previous refits and is having a terrible time with tool changer.

maybe you can change my mind. The devil is in the details:

My machines all home on startup. Not just a home switch but encoder index pulse after making the home switch. pretty standard commercial stuff. Do you know a Mach user doing this and how he done it? I'd love to see a video.

I need rigid tapping on my mill. I've not seen this done under Mach. Again how it was done and pics would be nice.

my lathes do Fanuc G76 multiple pass threading with definable infeed angle, rough passes, finish passes, taper threads, ID or OD threads, number of leads to pull out at end of thread, more. Again, I've not seen a successful Mach machine doing this let alone going at high speed to hypercritical specs.

For that matter, I think keyboard control sucks. It must be doable but I've not seen a Mach control using a standard operator panel that you see on any commercial machine.

Karl

Not quite what the Nichicon spec sheet here says:

After 2000 hours at the specified conditions, leakage and ripple are still under initial specs.

That said, the cheap electrolytics on consumer motherboards are what usually goes bad the quickest, given otherwise good power and environmental conditions. I just had to pull one and stick in a spare, it'd been in service pretty much continuously for 5-6 years. The big caps all had bulgy ends. I'll try reviving it with some new caps, they're cheap and it's a fairly quick fix, if it works.

So for the O.P., I'd figure on a max lifetime of NEW boards at about 5 years. Used ones are a crapshoot. You might improve things with better-quality caps, assuming you have the facilities and ability for changing same.

Stan

The first thing you'd lose is the Galil controller itself, unless it's a newer card than what I imagine it is. Some of Galil's newer controllers can be configured for either step & direction or +/-10V, but not the older generations.

But setting that aside, the first couple things that occur to me are, since the gains are now set in the amp rather than the controller, you'd give up: the auto-tuning routines available for the controller; the ability to replace a drive without going thru a manual tuning process(with the Galil board the setup parameters can be stored in the motion program); and the ability to change the loop gains on the fly in software. Also, the Gecko is missing integral gain.

Unless you were able to set up a second feedback loop from the encoder to the controller board, you wouldn't get the "digital 'scope" utilities that Galil supplies, and the motion program wouldn't have access to real position and velocity numbers.

One of the long term storage problems you'll face is that electrolytic capacitors will eventually dry out and fail.

Ok, and exactly how relevant are those features to the day to day operation of this class of machine? We're talking old used retrofitted iron here, not the latest $1M machining centers. Nearly all of what you indicated is only relevant to one time setup. I believe Mach3 can also read encoder positions in some configurations so it does get to see the "real" position, but even so, that makes little difference for this class of control and machine. You're trying to put a Ferrari engine in a Chevy truck.

Yes, the same homing routine as the commercial machines I used to work on.

I don't know anyone who is doing this, but I also don't know many folks period. I do know that I can readily get Mach3 to work with this type of precision homing and can give you the demo and details once I finish re-retrofitting my mini mill.

I'm not sure on this one. Mach does have the capability for a spindle index pulse and I know this is used in the lathe threading mode. I'm sure the Machsupport forums could provide answers on this.

Check on the forums on that too.

There are a number of pendants and "real" control panel setups available, complete with real jog encoder wheels and "hard" buttons for the key functions.

Actually, here are the details:

Use separate home and limit switches and inputs to Mach. Route the encoder index signal through the home switch to the home input on Mach for the axis. Set Mach for 0 home offset and a reasonably slow home speed. The axis heads towards home, eventually runs up the home switch ramp, the home switch trips and then Mach homes when the next encoder index pulse comes along. Same sequence as your current setup, home is the first encoder index pulse past the home switch.

Looking quickly on the Machsupport forum, I see references to semi-rigid tapping as well as indications that the SmoothStepper (SS) external USB connected pulsing engine is going to support better spindle sync.

May need to condition / pulse stretch the index signal if it's real short. I think the SmoothStepper can handle short index signals better.

AMI made almost bulletproof boards way back. Whatever you get you will want to replace the Low ESR filter caps on the boards.(Generally a set of 8)