Messages

7321

General Mach Discussion / Re: Mach3 and laser?

« on: January 14, 2011, 12:38:00 PM »

Hi Dan,

There is little point in using Mach to control the PWM as this is far better achieved with a seperate, external controller.
A simple circuit is all that is necessary to actually switch the laser from the Z direction signal (Z+(up) turns it off and Z-(down)turns it on). The actual Z movement needs to be small (0.001 or less) to reduce the time delay but editing standard GCode to achieve laser control is easy once you get the hang of it.
Have a browse through my webpage here http://www.cooperman.talktalk.net/files/27.htm this may answer some of your questions.

Tweakie.

7322

General Mach Discussion / Re: Why is there no effort for the true closed loop control on the mach3 level

« on: January 14, 2011, 02:02:30 AM »

kf2qd

Seems that some folks are just finding a way to say that closed loop is a waste of time.

Just to pick up on this one point - "If you have a good machine, of small size, closed loop is totally unnecessary". If you doubt that go to my website and take a look at some of the stuff I have made. OK I can improve on all of it by using higher resolution, smaller cutting tools etc etc but no improvement would be gained by me using closed loop.

The debate between servo's and steppers will go on forever and it is "horses for courses". Mach has proved to be good for driving both.

Tweakie.

7323

General Mach Discussion / Re: Rogue step pulses when system idle

« on: January 13, 2011, 11:49:37 AM »

Keith,

Electrical noise can be generated by (or from) the PC parallel port and on the ground return rather than any particular pin. This could easily be triggered by a mouse click as well as other things so noise should not be ruled out too easily. You could perhaps check for earth loops as an initial source of the problem.
Connecting a small 0.1uF capacitor from each input (limit switches, estop etc etc) to ground (at the breakout board) is well worth trying (inputs only).

Tweakie.

7324

General Mach Discussion / Re: Why is there no effort for the true closed loop control on the mach3 level

« on: January 13, 2011, 05:51:54 AM »

I agree and anyways if a position error occurs and is subsequently corrected (by closed loop) there is a good chance that the job has already been spoiled (obviously this, to a certain extent, depends on the 'steps per' or resolution of the machine). The secret to success is no error in the first place.

Tweakie.

7325

FAQs / Re: RESET- E-stop & Limit switch's issue

« on: January 13, 2011, 05:26:02 AM »

Bruce,

Sounds like you know what to look for, ground loops are so easy to create and cause so many problems. Noise spikes can be extremely narrow and although of high amplitude are still sometimes quite difficult to spot.

Tweakie.

7326

General Mach Discussion / Re: Why is there no effort for the true closed loop control on the mach3 level

« on: January 13, 2011, 05:08:50 AM »

Some have been able to use it successfully in production environments, but it is still a "hobby" control.

A bit more than 'hobby' today. One can do serious production with it IF you know how.

Cheers

I second this, in fact there are a great number of people using Mach3, in it's present form, for serious production.

Providing a CNC system is designed and built reasonably well there really is no need for closed loop operation - yes it would be nice but accurate, reliable and repeatable work can be achieved without closed loop.

Tweakie.

7327

General Mach Discussion / Re: Newby needs advice

« on: January 13, 2011, 04:54:22 AM »

Mikka,

I have seen adverts on eBay for spring loaded, rotary engraving tools (to fit most engraving machines) that are designed for engraving on curved surfaces but they do have limitations to character height / surface curvature etc. A rotary axis is another possibility, quite easy to set up within Mach but the mechanical aspects of fitting one to the machine (length of barrel etc.) may need some thought.

Tweakie.

7328

General Mach Discussion / Re: Mach 3 and CorelDRAW.

« on: January 13, 2011, 04:43:27 AM »

Kerry,

Do you use the standard DXF Tool or the Professional version ?

I am thinking that at $190 the professional version does seem a little steep. 

Tweakie.

7329

Mach SDK plugin questions and answers. / Re: Impact engraving plugin

« on: January 13, 2011, 04:20:55 AM »

Stitos,

Having tried with a portable oscilloscope, it is obvious that a much more fancy digital, recording piece of equipment will be necessary here.
All I have been able to confirm, so far, is that the pulse width is indeed 40uS and the Pulse Repetition Frequency at white is 0% increasing with shade to approx 90% at black but I have been unable to accurately measure the gap (pause) between the edges (join) of each pixel in the image but this does vary with feedrate.
Not much help really but I will try with another scope when time permits.

Tweakie.

7330

Mach SDK plugin questions and answers. / Re: Impact engraving plugin

« on: January 13, 2011, 04:18:53 AM »

Ntlaser,

Looking forward to seeing the pictures of your new machine.

Tweakie.