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Where to start
« on: May 09, 2011, 03:18:58 PM »
Hi,  I have a commercial cnc lathe I'm thinking about running with Mach3.  I have done searches with no results, and other than reading every thread,
is there anyone who could answer some basic retrofit questions?

1: I have analog dc servo's with resolver encoders and need to figure out exactly what or what kind of servo interface card, motion controller, breakout board,
    quadrature encoder, etc., I need to get them to work with Mach3.

2: Can I use my existing operater panel for all the buttons, switches, jog wheel, etc. (manual functions - spindle off/on, collant off/on, tailstock fwd/rev, jog x z,
    home, work light off/on, tool changer)

Thanks for any help, or point me in the right direction.

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Re: Where to start
« Reply #1 on: May 09, 2011, 03:32:13 PM »
Not really easy to answer these questions without being a bit vague I am afraid.

1. There are several motion controllers for Mach that can integrate with analogue servo amps, Galil, DSPMC, Kflop/Kanalog and then there are  the YASPC cards which I believe are kind of DIY boards.
I think for all you will have to replace the resolvers with encoders or get resolver to encoder interface cards which would likely be more expensive than just replacing the encoders.

Depending on your motor type/specs you may be better to replace the drives with ones that can accept Step/Dir input but whether that is the best option or not all depends on what you actually have.

2. You can most likely use the panel again but it will need rewired to interface with your chosen motion controller, so basically you can use buttons but probably not the way they are connected at the moment.

Hood
« Last Edit: May 09, 2011, 03:37:14 PM by Hood »
Re: Where to start
« Reply #2 on: May 09, 2011, 03:48:17 PM »
Hood,  thanks for the reply.  If I just replaced the servo's with steppers, where would I be?
Would I still need an encoder to guarantee proper position? 
Would I still need motion controllers or does Mach3 do that? 
Do I understand correctly that a breakout board is optional but offers protection to your pc.
Thanks.
Re: Where to start
« Reply #3 on: May 09, 2011, 04:15:10 PM »
Hi
 Here is a link to my Colchester refit.

http://www.cnczone.com/forums/viper_servo_drives/82579-colchester_master_anilam_viper_200_a.html

My refit was not as complicated as your lathe with turret and tailstock but may give some ideas.

I kept the brushed servos. The old thyrister drive exchanged for step / dir drives  - the resolvers were replaced with encoders.
Any of the control gear / contactors / breakers etc were re-used too.

I wouldn't exchange to steppers, as you would need new motors and drives - I think you would be better off keeping the servos already fitted and go for new drives.
Much of the wiring "should be" back to the panel already.
Some photos of your lathe would be great.
ATB
Derek

You can "chop it off" but can't "chop it on"

Offline Hood

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Re: Where to start
« Reply #4 on: May 09, 2011, 04:15:31 PM »
Hood,  thanks for the reply.  If I just replaced the servo's with steppers, where would I be?

That to me is a backward step. Steppers have their place but I am presuming your machine is a medium sized mill and for that servos are superior. I have had a Bridgeport CNC with steppers but also have a Beaver NC5 with servos. The rapids are 4 times greater and could be more and the  acceleration (most important in my opinion) is 8 times more with servos.

Would I still need an encoder to guarantee proper position? 

Mach is open loop and to guarantee your axis is in the position Mach tells it to be is to have servos with encoder feedback and the motors/drives need to be tuned well to allow a small following error to be set. If you had steppers then as long as they are properly sized they are accurate but there is no real guarantee that they will be where Mach thinks they are. But as said if they are properly sized then the likelyhood of them not being where Mach thinks is very minimal, the only time that has happened on my Bridgeport was when I tried to rapid through the vide ::)
There is a board sold by Ron Rogers which allows you to hook up encoders to monitor the commanded position and the actual position and fault Mach if it is outwith a user set following error but to me it is not really a great idea. Sure it will stop if you are out of position but if that is the case then your steppers are not up to the job so thats all that it is really telling you. Of course others may have different opinions on that ;)


Would I still need motion controllers or does Mach3 do that? 

If using steppers then the parallel port could be used, this could also be used if using servo drives that can accept step/dir input but if your encoders are high count then rapids could be limited. I get over this issue by using the SmoothStepper, it pulses externally to Mach and is a very smooth pulse of up to 4MHz per axis.

Do I understand correctly that a breakout board is optional but offers protection to your pc.
Thanks.

Depends on the way yougo, if using one of the cotrollers mentioned in the first post they will likely need some form of making easy connections. If using the parallel port or the SmoothStepper then again a BOB makes connections easy. Most BOBs can also buffer the parallel ports voltage which means you can use the modern computers 3.3v ports and the BOB will buffer it to 5v.

So to answer your question, a BOB is probably best but not always needed but is a big convenience.

Hood

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Re: Where to start
« Reply #5 on: May 09, 2011, 04:16:23 PM »
Oh sorry see its a lathe ;D but my points probably still apply.

Hood

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Re: Where to start
« Reply #6 on: May 09, 2011, 04:18:54 PM »
BTW what size/type/make lathe is it. I have done a Churchill Computurn 290 lathe which is around about 3000Kg and can swing 500mm.
Hood
Re: Where to start
« Reply #7 on: May 09, 2011, 04:51:06 PM »
Thanks everyone for the reply.  My lathe is a 1986 Mazak QT10 Universal with Mazatrol T2 controller. (Universal means it has a tailstock)
It's rated at 10" swing, 20" between centers, 8 position turret, programmable chuck and tailstock.  The whole problem started when the
spindle controller went out.  Apparently it shot some high voltage back through some of my controller boards.  I replaced the spindle
controller with a VFD and can run the spindle manually, but with bad boards I cant get the rest of the machine to function properly. I
have replaced some of the boards, but obviously not the right one, and they all are going out one by one anyway.  It has dc servo's on
X and Z axis.  I think 25 years is enough for the controller electronics and it's becoming a money pit.  The pc controller looks like it would
do the job and appears simple enough.  I just want to make sure I know what I need before I start buying stuff.

A list of everything I need would be helpful.  I already have the pc with Mach 3 running good on it. Next step is to deal with the dc servo's.


Thanks.

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Re: Where to start
« Reply #8 on: May 09, 2011, 04:56:59 PM »
Sounds like you are thinking of replacing the amps(analogue drives)? If so then Specs of DC servos would be needed to advise which drives may be suitable.

Depending on which controoler you choose or if PP or SS then it will be likely you will need a PLC for the extra I/O you will need for things like chuck, turret etc.
I have two 6 position turrets on my lathe, originally it had a rear 6 pos turret and a front 4 position toolpost but I replaced the toolpost with a turret I aquired from a friend who was scrapping a fire damaged bullard lathe.

Hood
Re: Where to start
« Reply #9 on: May 09, 2011, 05:25:41 PM »
Hood,  Is it possible to keep the analog drives I have now and the board in my existing controller that sends the signal to them
and add a step/dir to analog converter card in my computer.  My drives still work good.  I can home and jog just fine with them
now.  I guess I would just be replacing the brains and plc of my controller with the pc running mach3.  That would control
my spindle, turret, tailstock, coolant, chip conveyer, chuck, and send a signal to my drive board. I could add the external plc
if i had to.

Thanks.