Messages

2431

Mach4 General Discussion / Re: Any Lua programming consultants out there?

« on: June 07, 2019, 09:18:10 PM »

Hi,
which is equivalent to a constant surface speed.

Craig

2432

General Mach Discussion / Re: Motors stalling /growling

« on: June 07, 2019, 08:48:09 PM »

Hi,
it is far from certain what the problem is, there may in fact be two or three problems which are compounding things and
making it hard to diagnose.

You have bought yourself an ESS which is a good step to ensure good pulse streams to your BoB and stepper drivers,
yet the problem persists. It is not impossible that there is a problem with Mach/ESS/BoB but being able to eliminate
Mach/ESS/BoB altogether is the only real way to test the capability of the stepper/driver combination.

I suspect, but cannot be sure or prove, that the issue is with the steppers and drivers.

Electronics is my thing and I have a digital signal generator. Were this my installation I would drive the step input
of a driver direct from my signal generator. I could then be ABSOLUTELY certain that Mach/ESS/BoB have no part in the
test.

One of the challenges of testing steppers and their drivers is that it is not possible to just turn on the signal generator
and expect the stepper to be able to accelerate instantly. It is necessary to start the generator at a low frequency,
maybe a few Hz, and then increase the frequency taking note the frequency at which  the steppers start to lose steps
or stall. The frequency at which the steppers stall is the uppermost limit that your steppers will perform. In a CNC machine
there will be loads induced by cutting forces and the torque necessary to accelerate the mass of the axes. Thus the ultimate
top speed that you have determined may be much less in practice.

Do you have access to a signal generator that could perform such a test?

The number of posts and the duration of this thread suggest to me that you must be getting very frustrated with the whole
thing. It might be time to enlist, even pay for, the help of a electronic technician. A stepper/driver test like this should not
require much more than half an hour for a technician. You really need to nail down where the fault is: either the stepper/driver
OR Mach/ESS/BoB.

Craig

2433

Mach4 General Discussion / Re: Any Lua programming consultants out there?

« on: June 07, 2019, 04:52:20 PM »

Hi,
there is an API that allows you to change the steps per unit:

LUA Syntax:
rc = mc.mcMotorSetCountsPerUnit(
      number mInst,
      number motorId,
      number counts)

One concern that I would have about using this API is that once you changed the steps/per for your rotary axis it would
have to be flushed out to motion controller.

I broadly understand what you want to do and why but I'm not convinced that changing the steps per is the right approach.

Imagine you have a car that has a fixed throttle. To go fast you stop and bolt on large diameter wheels or to go slow
you bolt on small wheels. That is the equivalent of changing the steps per unit.

You may have seen discussion on the forum about CSS, (constant surface speed). It is generally thought of as a lathe feature.
The idea is that the spindle increases its speed as the diameter of the cut reduces so that the surface cutting speed remains the same.

Craig

2434

General Mach Discussion / Re: Motors stalling /growling

« on: June 07, 2019, 04:33:05 PM »

Hi,
there is a small variation there but I would have thought well within bounds.

One possibility is that if when an axis, X say, is accelerating it will draw significant current from the supply and that will
cause a variation in the supply voltage. The variation could be construed by the Y axis driver as an input pulse and it would
therefore react. You could say that it is an example of 'conducted noise'.

Some people try to use the one high voltage supply to provide the stepper drivers but also feed a voltage reducer to provide
low voltage for your controller and BoB. It is not recommended as any variation in supply voltage is likely to be impressed on the
low voltage thereby introducing noise into your controller/BoB.

Do you have a separate low voltage supply for your controller/BoB combination?

Craig

2435

General Mach Discussion / Re: Servio motor Delta adas b2 Software and electronic gear ratio

« on: June 07, 2019, 07:37:47 AM »

Hi,

If P1-46 defaults to 2500, then this guide would be incorrect if P1-46 actually set the encoder count that the drive uses.

That is exactly the same train of thought that I went down......but as you see P1-46 does default to 2500 for an effective
10000 count encoder. Have a look at the manual that OP posted, my reading of leads me to conclude the P1-46 sets the
effective count of the encoder, not just the digital outputs, but the primary encoder loop. Pretty kool!!

Craig

2436

General Mach Discussion / Re: Mach program and an industrial pc with com ports questions

« on: June 07, 2019, 07:17:29 AM »

Hi,
my suggestion is start at the cutting tool and work backwards.

By this I mean you need to determine what materials you want to cut and what tools you want to do it.
That will in turn define the power, torque and speed of the spindle. Then you need to decide on the maximum cutting rate
and possibly also on the traverse rate.

Those decisions will in turn determine the required rigidity of the axes and therefore the technology you use in them,
be it round rails and linear bearings or rectangular rails and recirculating ball bearing loaded cars or some other method.

The same decisions will determine what size steppers  are required, or if the speed requires servos rather than steppers.
The cutting forces and acceleration/deceleration forces will determine the torque required of the stepper/servo.

You will have to go through the decision tree several times because you might decide for instance that you want to cut steel
but as you progress through the decision tree you realize that the cost has just blown out and its un-achieveable.

I need to point out that I did not really do this when I designed and built my mill....but I rather wish I had. I tended to
settle on those components that I could get reasonably priced second hand. Its very easy under those circumstances
to find an 'overkill' part or assembly there but only a sub-standard part there. Trying to keep the design balanced and
prevent the budget from blowing out making decisions from the tool backwards in invaluable.

Craig

2437

General Mach Discussion / Re: Mach program and an industrial pc with com ports questions

« on: June 07, 2019, 06:24:27 AM »

Hi,
you really want low inductance steppers. First time buyers tend to look at the holding torque as the only metric and
would choose a 450oz.in stepper despite the 400oz.in stepper having very much lower inductance and therefore being
a much better choice for CNC. Look for less than 1mH in 23 size steppers and less than 2mH in 34 size.

Second is you want a high voltage supply and a high voltage driver for your steppers.

Toroidal transformer type power supplies are rugged and tolerate abuse that a switchmode supply will not. Aim for 72V or 80V
and then use Geckos or Leadshine AM882's as drivers.

Another area that is poorly understood is the difference between strength and rigidity. Any flexure of your machine is the
equivalent of inaccuracy. What's the point of having really fine resolution, lets say 0.005mm, only to find that the frame of the
machine flexes by 0.1mm when cutting? When you've designed something to be rigid, double its rigidity....and then double it
again.....and you might get to about half the rigidity that you need!

The spindle is the costliest single piece of any machine. Buy a decent asynchronous spindle with a good VFD, not some el-cheapo
Chinese one. Having said that I do like Delta VFDs, they are strictly speaking, Taiwanese.

Good luck.

Craig

2438

General Mach Discussion / Re: Mach program and an industrial pc with com ports questions

« on: June 07, 2019, 05:44:37 AM »

Hi,
industrial PCs like Avantech are good but pricey, very pricey.

I bought a dual core Atom mini-ITX board and ran Mach3 with a couple of parallel ports for two years without problem.
Then I upgraded to Mach4 and an Ethernet SmoothStepper with the same underpowered Atom PC, and it runs like a trooper.

The truth is that Mach, either 3 or 4, is not a power hungry application. What really upsets Mach is when the PC skives off to do
some other task and the motion controller runs out of data and stalls. Mach's parallel port, which lives in the kernel and runs
in the same PC as the Mach application is particularly susceptible to stuttering/stalling/stopping as a result of other software
and/or services on the PC. For this reason an external motion controller, being VERY much less susceptible, is highly
desired.

May I suggest don't waste your money on a flash PC, it wont make your machine any faster, more powerful, more accurate
or anything else. Use your money to get the things that do make a difference starting with a decent (no Chinese rubbish)
motion controller. As I have stated I now use Mach4 and comments hereafter refer to the status of controllers that have a Mach4
plugin.....Hicon Integra, ESS, PMDX-424,UC300,57CNC.

My favorite is the Ethernet SmoothStepper by Warp9. Warp9 have released over the last few months Backlash Comp,
Lathe Threading, Spindle PID, Laser Rastering/Vectoring and Torch Height Control in addition to all the other standard realtime
supports its always had. These new features make it the stand-out performer in Mach4 in its price range.

There are others like the UC300 and 57CNC which are economically priced, good quality and plenty of features......just not all
that the ESS has.

There is a wider choice of controllers for Mach3, including all those I have already mentioned that have Mach4 plugins, and
includes a wide range of Chinese controllers, some of which seem to work...mostly. Do your homework on the forum,
.....ask.....ask....ask......BEFORE you buy. Its too late once you've already paid for something to find that its not as good as
you thought.

If you want a groovy little PC to run Mach try this:

https://www.dfrobot.com/product-1585.html

Craig

2439

General Mach Discussion / Re: Servio motor Delta adas b2 Software and electronic gear ratio

« on: June 07, 2019, 03:23:11 AM »

Hi Gerry,
I discussed this in reply #7 of this thread.

The parameter P1-46 allows you to set the lines per rev, the range is 4 to 40,000. At the upper end, ie 40,000 lines
equates to 160,000 counts because of quadrature.

Craig

2440

General Mach Discussion / Re: Servio motor Delta adas b2 Software and electronic gear ratio

« on: June 07, 2019, 02:56:34 AM »

Hi,
well how do you explain it then?

Craig