Messages

491

General Mach Discussion / Re: stepper motor direction/s

« on: April 23, 2014, 11:46:34 AM »

by the sound of it you have dodgy connections on your DIR chain somewhere.

492

General Mach Discussion / Re: Machine wont zero after Homing

« on: April 23, 2014, 11:30:39 AM »

Power supply is 24V / 20A.
Gantry is waiting A Axis driver. Only have 3 at the moment. 4th in transit.
Will Check the voltage using the forumla you supplied and see if its somewhere near. Where do i put my meter to measure the Vref ?

Hmmmmm. Your power supply is not ideal - problem is you're already running your motors at little more than half their potential. Not enough V, but more Amps than you could shake a stick at.

It's not MY formula - don't be blaming me when it all lights up - it's right there on YOUR board. If not then the piccy you linked to is different. Check the manual.

there are 2 points just under the pot on the board

Hmmmmmm. are you sure they're the points you need to be measuring? Again from the piccy - there's two terminals on top of the board marked VRef and Gnd. You may be right - they may be the same thing - You guys have the boards and manual. Just checking.

493

General Mach Discussion / Re: Spring loaded touch plates for Z auto-zero

« on: April 23, 2014, 11:14:56 AM »

What -  all 44 pages of it Gerry? 

Just a comment about the code presented on the first page.

The line:

Code "G4 P0.25" 'Pause for Dro to update.

would be better replaced by a while isMoving loop. The problem is I'm pretty sure that using a G4 for temporarily blocking the macro is version dependent and anyway, the wait is needed by the macro thread not by the Mach thread. A while isMoving() guarantees it's the CB that waits.

Ian

494

General Mach Discussion / Re: Spring loaded touch plates for Z auto-zero

« on: April 23, 2014, 10:03:29 AM »

OK first that particularly nasty macro!

1) Its accuracy is totally speed and accel dependant because it doesn't handle the actual trip point and instead ATTEMPTS to store the stop point.

2) Perhaps worse though is that because its attempt to store the stop point may well fail, the retraction will be pretty random/un-predictable and in worst case could seriously crunch your tool tip/plate.
Could be worse, you could have a Renishaw which could be destroyed by this little piece of macro genius.

The probe speed and the accel you've posted will not show the errors behind 1) but faster probing or less accel certainly will. You will however more than likely see the effects of 2).

I'm left guessing then that the pitting you're seeing is probably down to not getting good electrical contact until you've pushed hard enough against the plate. If this IS the case then a sprung plate is not going to help for obvious reasons. Either way - I'd junk that macro if I were you.

495

General Mach Discussion / Re: Spring loaded touch plates for Z auto-zero

« on: April 23, 2014, 07:43:14 AM »

OK - That is ONE of the MANY macros out there that is just plain wrong. However I need the other info I asked for also to explain why you're seeing the pitting.

496

General Mach Discussion / Re: "run from here" problem

« on: April 23, 2014, 07:36:45 AM »

IN plasma when you are doing TOM routines  that may contain certain calls such as G28.1  the Run from here does not work correctly. Never has never will . You can get it to work IF the TOM routine is in MACRO form BUT that also may cause problems with macros that contain Gcode.

Just for Terry because you said you were bored the other day. Here's your challenge should you decide to accept it. There IS a way to get RFH to work across G28.1/G31 GCODE TOM routines, i.e. WITHOUT putting your TOM in M codes.

Ian

497

General Mach Discussion / Re: When is a circle not a circle? When it's 4 arcs!

« on: April 23, 2014, 07:15:40 AM »

Sounds good. So is it now cutting the same for a 4 arc circle as a 1 arc circle?

Is it seeing that there is a join in the arc and thinking about it?

It shouldn't be if CV is doing what it's meant to. Just to re-state: If CV is working properly there should be absolutely no reason for it to cut 4 tangentially meeting arcs any different to a single arc. i.e. there is absolutely no need for a speed change OR for any rounding at the "joins".

Is that a characteristic of stepper motors?

Not sure what you're meaning. Is what a characteristic of stepper motors?

The look ahead is set to 200 lines as recommended by mach handbook.

Hmmmmm. Where does it say this? My default was 20 and my manual says it shouldn't need changing and indeed I never have.

Lookahead tells the planner the maximum number of sequential feedrate moves it should consider at any given time. The maximum number of sequential feedrate moves in the whole code you posted was only 20. I think you can see where I'm going...

I realise that I may be barking up the wrong tree here but would a smooth stepper improve the performance?

With Mach I've learned never to say never. But if we're still concentrating on why a 4 arc circle cuts differently to a 1 arc circle, then personally I can't see how it could make a difference.

Anyway - things seem to be improving so that's good.

Cheers

Ian

498

General Mach Discussion / Re: Spring loaded touch plates for Z auto-zero

« on: April 23, 2014, 06:40:04 AM »

If a good macro is used correctly a spring loaded plate should not affect accuracy but will also be pointless. Perhaps you could post your macro(s) along with details of how fast you probed, your steps/per and accel settings of the Z axis.

499

General Mach Discussion / Re: Machine wont zero after Homing

« on: April 22, 2014, 07:32:05 AM »

You shouldn't need to be guessing things.

your (Nema23) motors rated currents are 3A so that is what you should set your drives to. From what I can see on the pictures you linked to you should do this by monitoring Vref as you turn the pot - is this what your documentation says?. The formula appears to be I=(vref*1/3)/0.151 from what I can see so for 3A you should be looking for a vref of 1.359V if my maths is correct.

You haven't given info about your Nema17 so I can't comment.

From the info you posted about your N23 motors, they ideally need 43V however your drivers have a max of 36V so that is what your power supply should be - is it?

Your power supply should be able to source at least 2/3 of all your motor requirements added together. i.e. your two N23s will need 6A*2/3 + 2/3 of whatever your N17 needs - can it?

From your pics it looks like you are only driving your gantry from one side - is that correct?. If so then you're going to suffer from racking so you can't expect much in terms of accurate cuts.

As has been said earlier (and I agree) your homing issues are more than likely down to your external motion controler/plugin.

When you're using an external controller, what's running on Windows is not particularly of any concern as it would be if you were using the parallel port.

500

General Mach Discussion / Re: When is a circle not a circle? When it's 4 arcs!

« on: April 22, 2014, 06:19:03 AM »

you want your accel as high as possible. However it will be limited both by your motor power and jerk. From what you say it would seem you have rigidity problems if an accel of 1200 is causing wobble.

However, concentrating on the difference between your 4 arcs and a single arc try your accel at 1200 and slow your feed down - 9m/min is pretty fast if you a) have rigidity issues and b) your accel is not so good.

Using a single parallel port you have 5 inputs of which your e-stop should be one. Pin 2 is an output, as are 7 and 8. Look at the bottom of the input/output dialogs - it tells you the valid input and output pins.

accel and decel are the same in Mach.