Messages

1391

General Mach Discussion / Re: Power Supply Unit

« on: January 16, 2011, 01:06:07 PM »

If the fuse on the DC blows while the machien is moving, the back EMF frpm the motors can blow the stepper drivers.

Ray - This just caught my eye whilst browsing. I wonder if this is why this fuse arrangement has been taken out of geckodrives's current version of their "step motor basics guide". I have the older version on file and saw that the DC quick blow fuses (between PS and drive) had disappeared on the latest version. Surely Mariss didn't make a mistake - oh no is nothing dependable any more

Ian

1392

General Mach Discussion / Re: Power Supply Unit

« on: January 16, 2011, 12:11:46 PM »

Kolias - Don't know if anyones raised this yet but it looks as though you have a double primary and double secondary transformer there. Wiring is not complicated but you need to be aware of how they need to be configured. Generally speaking it looks like you'll need your primaries in parallel (for 120Vac) and your secondaries in series (for 24Vac). Also you'll need to establish the phases of the windings or that fuse might well come in handy (hopefully there'll be some marking or whatever). To cover my *rse Please check it out - don't take this as instruction - just a cautionary heads up.

Ian

1393

General Mach Discussion / Re: Help ! "Radial Cut with Zdepth" toolpath from mastercam makes Skip steps ??

« on: January 14, 2011, 09:10:35 AM »

yes I did, kind of to check the xy only.
what I did is make a 0,0 mark before I cut.
after finish cutting sphere, it was offset like 0.5 mm.

So would it be fair to say that cutting in air with spindle off results in less error? Do it a few times and see.

but the result.. looks fine to me.

Curious comment as you're still out by 0.5mm

btw, when I do cutting air, it's very rare to get lost step.
so I got to test cutting some wood.

why do you think I asked you to cut air?

1394

General Mach Discussion / Re: THC axis selection?

« on: January 14, 2011, 09:03:39 AM »

What I want is to be able to jog all the axis freely while running a G-code program

Can't see you being able to do that - why would you want to do this?

something similar to what happens when you use THC up/down function assign to keys.Mach interprets this beautifully and recalculates all the G-code relative to the new position from what I saw

I think you may be misunderstanding something here (or I'm misunderstanding you). Mach doesn't recalculate anything as such. It just moves the Z axis as prescribed by the THC up/down signals (and of course keeps track of Z position in the DRO). During this time Mach can not simultaneously perform Z axis gcode i.e. commanded movements. In fact I just tested this out before posting and if you command any Z movement, simultaneous THC up/down is ignored. (which is kind of what I'd expect - if you don't want anarchy)

Ian

1395

General Mach Discussion / Re: Help ! "Radial Cut with Zdepth" toolpath from mastercam makes Skip steps ??

« on: January 14, 2011, 07:35:56 AM »

Have you tried your datum check in air with spindle off as per my post #59?

1396

General Mach Discussion / Re: Help ! "Radial Cut with Zdepth" toolpath from mastercam makes Skip steps ??

« on: January 13, 2011, 10:59:38 AM »

when I see the result of cutting sphere, the Z depth cut is exactly in the right measurement.

I'm not sure what you mean by this. If when you've finished you have a "ding" in the surface of the sphere, how do you know whether it was X/Y or Z?
i.e. if you start at the pole and XY takes you radially to the equator as Z descends. THEN if X/Y miss steps then "correct" Z movement will cause the ding. BUT if X/Y move normally and Z erroneously drops you'll get that same ding.

I'd suggest you arrange a datum somewhere off model for XY and Z, do your job and return to datum. Try this both for real and in air with spindle off.

Ian

1397

General Mach Discussion / Re: THC axis selection?

« on: January 13, 2011, 10:39:06 AM »

Hi Shorty - welcome.

As far as I know - and I'm happy to be corrected, the THC control of the Z axis is hard coded and can't be moved to another axis. You could of course wire the Z pins to any physical axis you want or you could use swapaxis(). But I'm guessing that's not really what you want. I'm also guessing you want to run XYZ gcode whilst you manually control the 4th (rotational?) axis. Can you explain in a bit more detail - someone may have something.

Ian

1398

General Mach Discussion / Re: Power Supply Unit

« on: January 13, 2011, 10:25:14 AM »

No one can help with my previous post?

I would like to know if the transformer looks ok
If the capacitor selection range is ok
Bridge rectifier selection

If no answer, perhaps I should go to another forum to finalize this projects?

Thanks

Kolias - I'm going to put my mod hat on just for a second. Your last post is unfair to all the very knowlegable people who have spent a lot of time helping you. Whilst people love to help as much as they can it's also up to you to try to do as much as you can for yourself. Your first two questions have been answered several times by several people and your third... I just typed PIV Bridge Rectifier into google and I got over 7000 results with the 1st on the list telling me all I could ever want to know.

You are of course free to go to any other forum if you think this one isn't good enough but I doubt VERY much that you'll receive as much help and patience as you have here.

mod hat back off 

1399

General Mach Discussion / Re: Can a slaved axis have different steps/mm in motor tuning

« on: January 13, 2011, 07:28:04 AM »

Not sure how or if you could handle homing.

Greg - Using your scheme above (very creative) I'm wondering if maybe a refCombination for X and A would do it.

Ian

1400

General Mach Discussion / Re: Help ! "Radial Cut with Zdepth" toolpath from mastercam makes Skip steps ??

« on: January 13, 2011, 07:06:32 AM »

I'm with Terry here when he says:

HOW are you determining that the XY are loosing steps?

I've just read the whole thread again and there is abosultely nothing here that SHOWS us that it's X/Y that is losing steps. You MAY be right, but the way I read this it looks more likely to me that it's Z.

BTW - did you change the step pulses for Y and Z to active low?

Ian