MONSTER - A learning experience... pyVCP machine

Sorry, i replied without reading the rest of the thread, now i can add more,
Gecko servo drives will instantly die if you push the estop on a machine with no back EMF suppression ( dump resistors ) if it is moving fast, there is a nice easy to do schematics on Gecko website.
Then again, you said earlier that mosfets AND opto couplers died in the same drive, that is for sure a wiring problem.
Again to late, but it might help.

Have you seen these encoders?
www.digikey.com/product-detail/en/cui-in...V/102-1307-ND/827015

I have these on my servo mill, they're fantastic. Impressive noise immunity too.

Noel

The opto is what was suspected the first time in St Louis a few years back... this time... when I send the reset signal... the micro responds... but the MOSFETS don't lock in... so i think they are toast. I ordered new MOSFETS and the OPTO simply because if you are in there changing parts... what's 81 cents more right?

As your post stated tommylight, my calculations were probably off... the the current draw is very close to the max... plus the issue of instant MOSFET death if the motor coasts due to an ESTOP or similar. Changing the encoders is a $300 adventure... and if I'm going to drop that much... and still potentially have some wire / current / spike issue... then it's probably better to drop $700, replace all the 35 year old motors, redo the wiring, and replace the single mongo (40 pound) transformer with independent power supplies.

Plus... the new controllers have built-in optocouplers on every input... that's going to isolate the parallel ports. Then... I'll add optocouplers to the inputs for every magnetic switch... because they all have a 9v input... and if any leaked... that could have been the cause of the parallel port zap. The outputs to the 120vac have always had industrial opto units on them... so this way every input and output will be protected.

As for the encoders I was using cncnoel... these are what I was using...
usdigital.com/products/encoders/incremental/rotary/shaft/H1

They have an integrated shaft that I connected to the existing upper shaft. It originally had a 50-year old design of resistors and cam followers. (I regret not photographing or video recording the old units... all brass workings.) At the time... this was a HUGE upgrade.

I know that with steppers there is the potential to miss steps... but if it is adjusted properly... with modern microstepping... the chances are low. I said the MONSTER was a learning experience... not just for you... but for me too! I'm hopeful that this really improves the machine. I have not played with steppers this big before... I hope they are enough... I'm committed now.

In the context of the money you are talking of spending, using the parallel port seems like s false economy.

andypugh said...

In the context of the money you are talking of spending, using the parallel port seems like s false economy.

Yes and no... I understand the parallel port completely as I have been using it for years. I'll get the machine operational and figure out the resolution, maximum speed, acceleration, and other factors. Then, once I have all those configurations saved, I can install and play with a MESA card... something I have never done before.

Better to take one unknown step with five known steps to look for errors than to dive into a totally unknown situation and hope for the best.

I just now pulled the first motor off... the great news is that it has a 2:1 tooth belt in there so I'll double my power and resolution with a lower microstep setting. The bad-ish news is that the plate does not fit the current motor... I'll have to machine a new plate. But... this is a perfect job for the new Frankenlab CNC that I am working on.

Shameless plug and playlist here!

Stay tuned... hoping to get this first motor installed today. (maybe??)

Hi, Jerry

How was your INTRO_GRAPHIC working? Is it showing up every time you start the MONSTER ?


Wenbin