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Author Topic: 0-10v spindle control convert to +/-10v spindle control  (Read 1250 times)

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Offline mark4

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0-10v spindle control convert to +/-10v spindle control
« on: October 01, 2017, 06:55:34 PM »
hello has anybody made or found a converter to convert a 0-10v signal to a +/-10v signal. it would work like this relay output fwd or rev then 0-10v convert so output is 0 to +10v for fwd or output is 0 to -10v for output that would open the way to control some of the older spindle controls that only have +/-10v i will probably make one it depends on an update to the controller i want to use if the update comes through as promised all will be well. if not then this will be my answer short term. i dont want to reinvent the wheel so if anybody has seen or done this??
thank you
mark
Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #1 on: October 02, 2017, 06:07:49 AM »
Hi Mark,
how about this idea, about as simple as I can make it. Two opamps (LM358 dual), one as unit gain voltage follower the other as unit gain
inverter, selected by contacts of a double throw relay. The relay when de-energised connects 0-10V to the output terminal and when REV is
active the relay connects -10V-0 to the output, easy. Haven't bothered with too much logic, surely you can cause Mach not to have conflicting
FWD REV signals. I have shown a 5V to -15V-0-+15V DC to DC converter for power supply. I have become quite a fan of these little units, dual
rail supplies from 5V, galvanaically isolated for $10-$15, whats not to like?

Craig
My wife left with my best friend...
     and I miss him!
Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #2 on: October 02, 2017, 06:11:50 AM »
Hi Mark,
just as a matter of interest do you actually need the spindle to go backwards? You'd need it if you were doing rigid tapping but then you'd
probably have a more sophisticated spindle altogether.

Craig
My wife left with my best friend...
     and I miss him!

Offline mark4

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Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #3 on: October 02, 2017, 09:59:47 AM »
thank you for your reply and circuit. the reason i might need to do this is i have a cincinati milicron that i am upgrading from the original crap computer. i want to use a csmio/ip-a as this will do +/-10v drives which the original are. however the csmio/ip-a hasnt gotten its firmware upgrade yet and the one on the web site wont do +/-10v spindle just drives and 0-10v spindle. i have been told that the update would be coming out last week or this week then just a couple of days. i really want to do this with the csmio/ip-a but i have been told updates were coming before. the controller i am trying to use doesnt have an autotune feature and just wont work for me i have tried everything i could think of and every time i believe i got it problem. i have used csmio/ip-a in the past with mach 3 (which i dont want to go back to) successfully. i also upgrade using ac servo drives. love them easy setup. and i am looking at a moriseki lathe in my future if the csmio/ip-a will do as i want good but if it wont i could replace the X and Z drives and motors with ac servo however as you know the spindle motors on lathes are huge and require big vfd and are usually old but they are the heart of a lathe so with this kind of circuit i could use a ethernet smooth stepper for the motion planning with lets say a mach bob2 take its 0-10v signal and convert to +/-10v. that about covers my thinking let me know what you think.
thank you
mark

Offline mark4

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Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #4 on: October 02, 2017, 10:05:39 AM »
ps as for the spindle going backwards some cutters require reverse rotation i believe dont know for sure and with the setups i have outlined i believe rigid tapping to be possible. i dont know how well this circuit will function but the milicron has an encoder and a index for tool changes ect.
mark
Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #5 on: October 02, 2017, 10:38:14 AM »
Hi,
this circuit will work for a spindle but would be inadequate for an axis servo, the linearity required for servo use is another ball game altogether.

Craig
My wife left with my best friend...
     and I miss him!
Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #6 on: October 02, 2017, 11:09:05 AM »
Hi,
my only other concern would be its linearity around 0V. If your lathe spindle required 0V to stop for instance and any bias voltage of even a few
millivolts would cause the spindle to creep when the operator had intended that the spindle be stopped. That would constitute a safety concern.
When I first started sketching this circuit I had a mosfet to short the output to earth when the spindle is stopped to counter this very thing.
Rather than complicate the situation I omitted it. I assume, and the simple circuit I have sketched would require, a relay contact to disable the motor
when it is intended to be stopped.

Craig
My wife left with my best friend...
     and I miss him!

Offline mark4

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Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #7 on: October 02, 2017, 09:58:09 PM »
hi i wouldnt know how to add a mosfet i know it is a field affect transistor but that is only a name not knowledge of how it works. here is what i know or think i know when running a spindle +/-10v  0 volts stops and brakes the only time you get creep is if you dont have 0v and i am thinking a narrow deadband around zero will be built into most vfd the question would be how to adjust if necessary. i will have to build a bench version and see what it puts out to a scope building wont be a problem figuring out how to read the scope might be. on the vfds i have worked with the lathes stop incredibly fast and so do the mill spindles thats old vfds new vfd require resistors for fast braking circuits. thing is there is a relay to run but that is more of an enable i am not thinking you want to disable every time you change stock. this is something i want to take further but for right now if csmio/ip-a gets the update as promised i am going to build with that. however in the future i can see lets say a fanuc with yellow cap motors. from experience scrap the motors and drives and fanuc computer add two new ac servo drives and motors now you have a fuji vfd that takes +/-10v for the spindle we could run that from a machbob2 with ethernet smooth stepper which if i read that correctly at warp 9 it is capable of lathe threading so already knows what to do with the spindle encoder and index pulse. the lathe i am going to do in the future is a moriseki and it has yaskawa drives that are easy to talk to. a word to the wise dont try to use fanuc drives for anything. the main reason i am going down this path is if a okuma howa lathe for example comes up for cheep or auction i might be interested to upgrade but the spindle problem would stop me and i want the option. so thanks for all you help.
mark
Re: 0-10v spindle control convert to +/-10v spindle control
« Reply #8 on: October 02, 2017, 10:38:54 PM »
Hi Mark,
the reason I considered a Mosfet (or some other transistor) was to pull the output to zero volts when stopped, within a few
millivolts. The natural bias offset voltage for these little opamps is about 50mV. It may not cause any problems but then
again it might. Try it and see...if it needs to be more sophisticated thenit can be done.

Craig
My wife left with my best friend...
     and I miss him!