Messages

7461

General Mach Discussion / Re: Question about encoders and missing steps, G540

« on: June 15, 2016, 05:38:14 AM »

Hi,
just had a look at the board in your link. Don't think its anything like smart enough to
'close the loop'.

The Chinese manufacturer I was thinking of was Leadshine. They look to be the real deal.

I use Vexta 5-phase steppers and low backlash planetary gear drives, consequently can't
use Geko stuff. If I were using 2-phase motors I would and from the feedback on the forum
don't think I would use anything else, they are very good.
The Vexta drivers I use are like most Japanese stuff, expensive but superb.

Craig

7462

General Mach Discussion / Re: Question about encoders and missing steps, G540

« on: June 15, 2016, 05:13:58 AM »

Hi,
given that you have steppers then encoders are not going to help much. Stepper motor drives
are typically open loop. With a drive of that description and I believe the 540 is an example
then it cannot correct missing steps even if you had an encoder to detect it.

At best with the drive that you have you might be able using an arduino or similar is detect
when missing steps occur and enter some fault state so that you could correct it.

I understand there is a Chinese manufacturer, Longs maybe, that offer a closed loop stepper
drive. While cheaper than a genuine servo still quite a premium over open loop drives like the 540.
Have heard that Tormach have adopted them as standard on their new equipment.

Finding out why your steppers are getting out of whack maybe a better bet. The only few times
I've had issues is when I was pushing too hard, usually overfast rapids with a heavy workpeice
and then they stall and whine, no guessing required as to the cause!

Given your description I would guess that you are suffering from intermittent noise where a noise
impulse surreptitiously adds or subtracts a pulse. It can happen in bursts. If it occurs on the direction
pin during a rapid it usually produces a stall. I would be looking at the step lines. It not unreasonable
to pass the control lines thru a ferrite ring, one or two turns, supresses some RF without affecting
the pulses much.

Craig

7463

General Mach Discussion / Re: Motors won't change direction

« on: June 15, 2016, 04:43:01 AM »

Hi sparky,
a good BOB is really worth its weight in gold, some if not most have LED's on the outputs. Makes diagnosing
faults and setup issues SO much easier and less prone to slipping with a multimeter probe and wrecking
something!

Craig

7464

Mach3 under Vista / Re: Mach 3 and STDR-4C HELP PLEASE

« on: June 13, 2016, 08:10:27 AM »

Hi edfire4,
not sure what the problem/problems are so best start at the beginning and work your way thru.

While its not an absolute test a good indication as to whether Mach is producing pulses to which your
motor controller can respond is the "mach3 driver test'. Does it operate and what sort of report does
it give you? Note that unless Mach3 is licenced as opposed to demo then you are limited to 25khz.
If licenced it is worthwhile to run the driver test at higher speeds just to see what sort of capability
your PC has. I run my mill at 25khz but occasionly test up to 100khz just to see. If you do change speeds
you will need to shut Mach down and restart before the driver will 'read' the new speed.

Second step would be to see if your controller is getting pulses. I have no idea what an STDR-4C is, can you
post a manual? Do you use a breakout board? Quite a few of them have LED's on the outputs and are
a godsend when diagnosing things. The other alternative is to use an oscilloscope but unless you or
perhaps a friend has one and know how to use it possibly of little use to you, brings me back to the
LED's on the breakout board... marvellous things!

Craig

7465

General Mach Discussion / Re: Hydraulic engine controled by mach3

« on: June 11, 2016, 08:02:43 PM »

Hi Pablo,
how does your hydraulic engine work? The type I'm most familiar with are controlled with a valve which
allows fluid to pass in one direction for CW and the other direction for CCW and blocks all flow for
no rotation.
Depending on the size of the hydraulic motor the valves required are pretty big and electrically
operated valves are pretty expensive. If you have the required valving the Mach could probably
be induced to read an encoder and control the valves. Mach can 'close' a servo loop but it is
not its primary function.
The vast majority of posts on this forum use Mach as a step/direction generator to a dedicated
motor controller and it is the motor controller which closes the loop.

Craig

7466

General Mach Discussion / Re: Help me mach3 on T42 IBM

« on: June 08, 2016, 04:43:35 AM »

Hi,
don't know if this will help...
Used to be that when I turned my machine on it would default to a federate of 6mm/min. If as I usually do, do
a few manual moves just to check everything is working before homing it would take a long time at only 6mm/min.
Then I read that on the 'General Config' page that I can put an initialisation string, I added an 'F300' to the string
and now when my machine fires up it has a useful federate for me to jog around and focus my mind on what I want
to accomplish.

Craig

7467

General Mach Discussion / Re: Mach3 Home switch question

« on: June 08, 2016, 04:29:08 AM »

Hi algba,
been quite awhile since I setup my home switches but on the 'home/limits' config page the 'home off' setting is used
to cause the axis to back off a specified amount,

Craig

7468

General Mach Discussion / Re: Motors won't change direction

« on: June 08, 2016, 04:20:18 AM »

Hi,
another possibility along the same lines as Tweaky is that some drives require an active direction input, for instance
if the pin is left floating it will naturally go high and therefore turn CW say. It will require your BOB to pull the direction
pin low to get it to turn CCW.
Careful reading of the drive and BOB manuals are required, my experience is that they are not plug and play!

Craig

7469

General Mach Discussion / Re: Z axis will not go up

« on: June 08, 2016, 04:12:41 AM »

Hi Jimch52,
sounds like the 'soft limits' have triggered. On the 'program run' screen there is a button to turn soft limits on and off. I you turn
them off then you should be able to jog all axes in any direction. With the limits on Mach will restrict your jog/move options to
those that are in the limit zone ie either direction but disallow any direction movement on any axis that takes you outside of the of the
zone or further out of the zone than you already are!
The soft limits are configured on the 'homing/limits' configuration page. Without home switches and referencing at turn on soft limits
are a bit useless.
For a time I was blaming my handheld jog controller for not being able to drive my Y axis in the negative direction when in fact it was
the soft limits trying to prevent me from crashing the axis. Once I realised what was going on I turned the limits off and crashed
the axis ALL BY MYSELF!!  LOL.

Craig

7470

General Mach Discussion / Re: Table size

« on: June 08, 2016, 03:52:06 AM »

Hi Daveleg,
on the 'input pins' configuration screen you can assign a port and pin number to Xhome, Yhome, Zhome, etc.
Clearly the pin you assign must be input capable.
On the 'homing limits' configuration screen you can assign things like the direction to approach a home switch
and the speed as a percentage of traverse speed to approach at.
A home switch is usually a microswitch or some equivalent and can be anywhere on an axis but it is common
practice to put it at one end, aka a limit switch. When you hit the RefAxis button the machine will drive in the
preconfigured direction and speed until the switch operates, stop and back off a small distance and 'zero' the
machine coordinate for that axis. The machine will maintain the machine coordinate for that axis for the remainder
of your machining session or until you repeat the 'referencing' because of an axis stall or worse a crash during the
session.
Note also that on the 'home/limits' page you can assign your soft limits which define the safe operating area of your
machine and is seen in the toolpath display as table limits.
You can use the home switch as a limit switch by disabling the limit function (usually an Estop and/or drive power
disconnect) while homing and the re-enable the limit for the remainder of the session.
For the purposes of a home switch a device which can repeatably trigger at a precise location is required. Inductive
proximity switches can be a bit vauge for this purpose. I use top quality roller plunger microswitches, Omron is
the manufacturer but indentical units are made by others, Allen Bradley certainly and if memory serves Honeywell as well.
Look at the specification for the switching limits usually mentioned 0.02mm /0.05mm or similar, the price also gives them
away.
For limit switches less precise units suffice including proximity switches. I prefer seperate limit and home switches, I find it
reduces confusion and have had less 'operator induced crashes' since I adopted the idea. All the limits (x++,X--,Y++,Y--,Z++ and Z--)
are in series and if any one operates then my machine is in trouble and Estops immeadiately, no exceptions. The home switches
trigger about 2mm short of the limit and so homing never operates the limits unless there is a fault in the home switch wiring/components/
software/logic.


Craig