Messages

4361

Mach4 General Discussion / Re: mach 4 demo setup and try.

« on: June 07, 2018, 02:59:49 PM »

Hi,
you can download Mach4 and if you use the Sim(ulator) plugin and run for as long as you like all for free.

The Sim plugin will not drive any motors. If you actually want to experiment on a live machine you will have to install a motion control plugin and
select that plugin as the active motion control device. There is a parallel port plugin for $25. It works but it will never be fully featured, lathe threading, THC
and that sort of thing. It was meant for people to have a cheap way into Mach4, if your serious you will need an external motion controller.

There are half a dozen manufacturers of external motion control devices which are Mach4 ready, ranging from about $120 to $650 or even more if you want a
Gallil controller. At this time there is only one Chinese manufacturer of Mach4 capable controllers and it doesn't work very well at all. If you see someone advertising
cheap Mach4 controllers be very suspicious.

With ANY active motion control plugin (other than Sim) Mach4 runs in Demo mode, that is to say it runs exactly as a licenced version for about six minutes before you need to restart
the program.

Thus to experiment with Mach4 you will need to spend some dollars, $25 as a min for the Darwin Parallel port plugin for which you require a PC with 32 bit OS Windows 7 or earlier.
Other than that you are up for say a UC100 or ESS as a min. The UC100 is $120. Don't be tempted by the cheap UC100s you see on Amazon or EBay, they are Chinese ripoffs.
Buy direct from the manufacturer or their nominated distributor. With an external motion controller you can use just about any PC you want to run Mach4, it will run on even
very small and low powered PCs for instance.

Craig

4362

General Mach Discussion / Re: Really basic "beginner advice" needed please !!!

« on: June 07, 2018, 02:57:02 AM »

Hi
in addition to those that I recommended in my previous post I should mention three other devices that you will hear talked about.
The UC100 from CNCDrive, the PMDX-411 from PMXD and the 57CNCdb25 by PoKeys.

They are all USB connected to your PC and have a motion controller embedded within the housing that contains a DB25 parallel port socket. You might
even consider them a 'USB to Parallel Adapter', they in fact have an FPGA chip embedded in them and are way to clever to be called an adaptor, but none-the-less
serve that purpose. Given that they have but one DB25 socket they have 'one ports worth' of IO, that is  13 outputs and 5 inputs.That is enough to run a simple
machine however if you want extras like a probe or a spindle index then you will run out of IO, inputs in particular. If you feel that you may want more than the absolute most
basic machine then you will need more IO and the devices I recommended previously are the correct choice.

Given their simplicity they are the cheapest style of motion controller out there...excluding the questionable products from you where. Just beware that there are Chinese knockoffs
on Amazon and Ebay. I recommend buying direct from the manufacturer or their nominated distributor, don't be tempted by cheap prices....get the genuine article or you will be back
to where you are now.

Craig

4363

General Mach Discussion / Re: Really basic "beginner advice" needed please !!!

« on: June 06, 2018, 03:21:36 PM »

Hi,
there is almost a bewildering array of choices for a motion controller. To try to slim down the list I'm going to exclude anything Chinese on the
basis they don't support their customers. I'm also going to include only devices that have Mach3 AND Mach4 plugins, it means you could use either.

https://warp9td.com/ The ESS is the model of choice, ethernet connected for minimum latency Mach3 and Mach4 ready.
https://www.poscope.com/product/pokeys57cnc/ The 57CNC is the model of choice, complete, flexible and competitively priced.
https://www.cncdrive.com/ The UC300 is the model of choice, five ports worth of IO, note the Mach4 plugin is new and not as developed as others in this list, excellent record with Mach3
http://www.vitalsystem.com/portal/index.php The HiCon is the model of choice. The Mach4 plugin is the best developed of all in this list, also the most expensive especially with addons
https://www.pmdx.com/ The PMDX-422 is the model of coice but for Mach4 only.
https://en.cs-lab.eu/ Has a good reputation with Mach3 but patchy with Mach4, this company has gone off the boil when it comes to support, expensive.

All of these devices, with the exception as noted, are superb quality and backup. I personally use the ESS but would be happy with any of these units.

Craig

4364

General Mach Discussion / Re: Pulse per turn

« on: June 06, 2018, 09:42:12 AM »

Hi,
I assume you mean 1.8 degrees per step, that is the norm for a two phase stepper. If so that means 200 steps are required for ne revolution of the motor.

For one revolution of the output shaft of the gearhead:
200 x21=4200 per rev.

You don't mention microstepping, its a common technique to improve the smoothness of rotation. So if you employ '8 step microstepping' your calculation is:
4200 x8 =33600 per revolution.

Note that if using for an A axis the units of an A axis is degrees:

33600 / 360 =93.333 steps per degree. This is the figure you would enter in the 'steps per unit' value of the A axis motor tuning page if using an 8 microstep regime.

Craig

4365

Mach4 General Discussion / Re: ESS + Mach4 + Clearpath = Motor error input goes where?

« on: June 06, 2018, 05:22:30 AM »

Hi,
just noticed a mistake with the bias and load resistors.

Craig

4366

General Mach Discussion / Re: Name of this controller? Manqls for it?

« on: June 06, 2018, 04:57:10 AM »

Hi Guys,
forgive my ignorance but I'm guessing that you are talking about 'ShellBack' and its some naval term or tradition.

What does it mean?

Craig

4367

Mach4 General Discussion / Re: ESS + Mach4 + Clearpath = Motor error input goes where?

« on: June 06, 2018, 04:21:51 AM »

Hi,
this is a quick sketch of an inverter.

I perceive some problems with it however. If for whatever reason any of the three HLFB inputs de-asserts itself it will propagate an ERR and so Mach will Estop.
If the HLFB de-asserts because it has lost the plot and no longer following its input this is exactly what it supposed to do. What happens however if for instance you turn
the power off to that servo. The HLFB will de-assert itself, not as a result of a following error but a power fault. Worse this will be an enduring Estop event, each time you attempt
to Enable Mach it will immediately fault because one or more of the servos is unpowered.

Is this what you want?

It occurs to me that this is a nuisance fault and I suspect that as you were powering up Mach and the servos there would be multiple occasions where one or more HLFB de-asserts
itself and cause an Estop.

This comes about because the Geckos when they fault go active high, whereas the Clearpaths are inactive high in fault condition AND various other conditions among them  being unpowered.
No amount of fiddling with the circuit diagram is going to change it.

The only solution then is to apply some logic which permits a genuine HLFB following fault to cause an Estop but prevents nuisance Estops. In which case the ERR/RST input is not useful as it always
causes an Estop. The best way to apply that sort of logic is to use the programming capability of Mach, but if you are going to do that then why bother with this wee inverter cicuit, just do the whole
damn thing in software along the lines of my previous post.

I think you will have to read and understand the various HLFB modes, the reverse logic will have implications as the machine is powered up that does not occur with positive logic of the Geckos.

Craig

4368

Mach3 and G-Rex / Re: Can't Get Soft Limits To Work Without "Soft Limits Out Of Range Error"

« on: June 06, 2018, 03:34:04 AM »

Hi,
you will find more people read your posts on the main Mach3 Discussion board and get more and varied answers .
This is another thread related to your enquiry:

http://www.machsupport.com/forum/index.php/topic,37334.msg256370.html#msg256370

Craig

4369

General Mach Discussion / Re: "Goto Zero" getting Soft Limits Error

« on: June 06, 2018, 03:30:48 AM »

Hi,
that may be happening also but the basic problem it without accurate and repeatable referencing SoftLimits are useless.

Question: 'When Mach is first powered up how does it know where the machine is?'
Answer: 'It doesn't know where the machine is'.
Explanation: Mach is an OPEN LOOP controller. It has no real facility to accept feedback from the machine as to where it is and even if it were to be pressed that way
our machines DO NOT HAVE ABSOLUTE ENCODERS. Such things are available but they are rare and expensive well beyond the means of hobbyists.

Say you have boundaries programmed into the Soft Limits page, your machine has 1m travel in X and 1,2m travel in Y. It might be reasonable to have the X- softlimit = -500mm
and the X+ softlimit=500mm, the Y- softlimt= -600mm and the Y+ softlimit=600mm.

When you turn your machine on if it were perfectly centered on the table the SoftLimits would be fine, Mach would know that the X+ boundary is 500mm to the right and the X- boundary 500mm to the left.
What happens however when you turn your machine on and its not in the center, lets say its 200mm to the right of center. If Mach assumed that the boundary is X+ is 500mm to the right
your about to crash because you started not in the center but somewhere else and the soft limit data is correct if Mach starts in the center only.

This is the secret to how SoftLimits  work, the boundary data is relative to a particular point and at the beginning of each session you must jog to that location and tell Mach, 'This is the sweet spot,
all the boundaries are relative to this location'. Mach is very good about tracking where it is ONCE you've told it where it started from and it can keep in mind where the boundaries are IF AND ONLY IF
it knows where it started from. This is the reason for home switches, and good, accurate home switches are worth their weight in gold.

Craig

4370

Mach3 and G-Rex / Re: Can't Get Soft Limits To Work Without "Soft Limits Out Of Range Error"

« on: June 05, 2018, 05:57:27 PM »

Hi,
you need home switches for soft limits to work.

If you have an alternate solution I look forward to it. Good luck.

Craig