Messages

4711

General Mach Discussion / Re: Continual issue of Z zero being automatcially changed.

« on: April 27, 2018, 09:50:53 PM »

Hi,
I see you've posted on this exact same topic before. Did you do what was suggested last time?

http://www.machsupport.com/forum/index.php/topic,36707.0.html

Craig

4712

General Mach Discussion / Re: Continual issue of Z zero being automatcially changed.

« on: April 27, 2018, 05:18:56 PM »

Hi,
when this happens what do the DRO's show?

Do they reflect that controlled point is a couple of inches lower than you expected or do they show that they are where you expected
but the controlled poit is lower than it should be?

Craig

4713

General Mach Discussion / Re: REF All home

« on: April 27, 2018, 04:27:07 AM »

Hi,
yes that's correct, it doesn't really matter where the Z axis is referenced, at the top or somewhere else. You seldom look at the machine coordinates, Mach does that and keeps track of them.
You and I are more interested in how far we are from the corner of the workpeice, work coordinates as opposed to machine coordinates.

Craig

4714

General Mach Discussion / Re: MK-IV Mach3 motion card setup

« on: April 27, 2018, 04:16:06 AM »

Hi,
trying to understand Chinese instructions is tough, and be thankful that you have some instructions at all, most of the Chinese stuff doesn't and once they've got your money
they don't care.

Craig

4715

General Mach Discussion / Re: REF All home

« on: April 27, 2018, 03:56:19 AM »

Hi,
John is right you don't have to reference your machine however if you do it means that soft limits now work as intended.

Like John I did not bother referencing my machine and operated like that for nearly a year. Then I got around to fitting home switches,  just three home switches, not limits....and have never looked back.
Fitting good quality home switches and therefore having useful softlimits has reduced the number of crashes from a few every so often to once in last four years, and that one time was when I got
confused and did not home my machine prior to starting some code.

I use roller plunger microswitches and get 0.02mm repeatability. It means I can stop a job part way through, turn the machine off and come back tomorrow, reference the machine and take up from
within 0.02mm from where I left off yesterday, real REAL handy.

I highly recommend good home switches and preference is that they be dedicated for just that one job, ie homing. Leave limit switches to be just that...limit switches alone.

Craig

4716

General Mach Discussion / Re: REF All home

« on: April 27, 2018, 03:42:42 AM »

Hi,
yes there is, look on the Homing/Limits page.

Referencing requires home switches. For instance if you have a switch on the X axis, it doesn't really matter where, just somewhere on the axis, when the carriage activates the switch Mach can
say 'I know where I am on the X axis', or as we say, 'referenced'. Thereafter Mach can keep track of where it is but it needs some definite point to start from.

Its common to put  home switches at or near the end of the axis, its not required but it is common. Its also possible to use a limit switch as a home switch. In the early days of Mach when everyone had a
parallel port with only five inputs is was common to have limit switches double as home switches. Today with external controllers with lots of inputs we don't have to do that anymore but lots do.
I personally think it causes a lot of confusion all to save an input or save mounting another switch.

What happens is that when you hit 'Ref All Home' Mach ignores the limit switches and treats them as home switches. Once the machine is homed then it turns the limits back on and turns the homes
off. It means that while your machine is homing, just when you need it, you don't have any limit switch protection. I think that's dumb. Anyway that's exactly what a lot of people do. If you chose to do
the same and crash your machine just remember you chose to do it this way.

Set the 'Home Order' so the Z axis moves first, ie 1. When it goes to the top limit it will call that home and will set machine coordinate DRO to zero, or whatever number you set as home offset.
I would recommend not to worry about Home Offsets to start with, just have the machine coordinate go to zero. The next axis in the 'Home Order' will now drive to its limit, or because Mach is ignoring limit
switches, its actually a home switch at the moment. When it gets there it will set the machine coordinate for that axis to zero. The last axis will do the same thing.

Once all three axes have 'homed' the contolled point (usually the spindle) is at machine coordinates 0,0,0. Now you can shift anywhere, usually to the corner of the workpeice and 'zero the axes'.
Zeroing in this instance means the work coordinates, not the machine coordinates.

Craig

4717

General Mach Discussion / Re: Problem to setup a belt driven 4th axis

« on: April 26, 2018, 04:40:35 AM »

Hi,
a rotary axis is tuned to so many 'steps per degree'. Thus if you have your stepper set for 8 microsteps or 8 x200 =1600 steps/ motor revolution.

With a belt reduction of 4:1 then 4 motor revolutions or 4 x 1600 = 6400 steps per A axis revolution or 6400 / 360 = 17.77 steps per degree. You will have to round to
18 steps per degree but that would result in an error of 1.2%. Not bad.

If you work backwards you may be able to reduce that error a bit. If you assume 18 steps per degree then a full A axis rotation would reuire 360 x 18 =6480 steps.
With the same 1600 steps per motor rev you would require a belt reduction of 6480 / 1600 =4.05. Thus if you have a belt reduction of 4.05:1 instead of 4:1 your steps
per degree would be perfect.

A pulley of 20 an a pulley of 81 teeth would do the trick.

Craig

4718

Mach4 General Discussion / Re: Lua file operations

« on: April 26, 2018, 12:37:26 AM »

Hi,
maybe a file has to have one character...an EOF character?

Craig

4719

General Mach Discussion / Re: Replacement Computers

« on: April 25, 2018, 06:40:53 PM »

Hi,
if you are keen on a UC100 beware there are a lot of Chinese counterfeits out there, Amazon , Ebay etc.
Buy direct from CNCDrive or their nominated distributor.

Craig

4720

Mach4 General Discussion / Re: output on/off from same button

« on: April 25, 2018, 06:35:01 PM »

Hi Danilo,
I've used that API too, it works well. Be aware though it works only with input signals numbered 0 to 63,
ie ISIG_INPUT1 through ISIG_INPUT64.

Also it is highly advisable to test the return code for all possible returns, its easy to get caught out by a return
that you did not expect.

Craig