Messages

7671

General Mach Discussion / Re: not circle that is a polygon

« on: August 25, 2010, 06:41:12 AM »

It is not possible to cut a true circle with a flatbed X-Y-Z CNC machine. Because the machine can only move in straight lines the circle must be comprised of straight lines and so is really just an approximation of a circle. (A CNC lathe would, of course be entirely different).
Mach outputs step and direction signals which are also a series of straight line moves - that is the way it works.
The circle quality starts to improve as you get more (shorter) lines up to the point where the GCode gets too long to be practical.

From tests using acrylic and relating to the optical quality of the edge I have found that a 50mm disc comprising 400 straight lines is about the minimum I would like to use. If the diameter of the disc is increased then so does the number of lines used and so on...

One trick with CAD is to draw many times full size then scale the GCode at run time.

Hope this helps.

Tweakie.

7672

Show"N"Tell ( What you have made with your CNC machine.) / Re: Gertrude Gets Some!

« on: August 25, 2010, 04:11:23 AM »

thanks guys, things been slow actually, may need to jump into another industry at some point in the future.. any tips? hints, what can i do other than jewelry that I can apply my skilset too guys?

I think we have been here before Chris.

Nobody ever got rich working for the man and nobody ever got rich working with their hands.

Sorry buddy but you just have to use your head.

Tweakie.

7673

General Mach Discussion / Re: Mach3 and Boxford Duet

« on: August 24, 2010, 03:37:05 AM »

Boxford are unwilling to provide any information which would help with the use of their machines once they have left the education loop and come into the 'second user' domain.

The only really practical solution is to replace the internal electronics driver card etc. with a new driver card which is Mach compatible (I used a cheap Chinese board bought on ebay). Some of the details here may be of help. http://www.cooperman.talktalk.net/files/14.htm

This approach may seem a little extreme but it is not too difficult to do and at the end of the day you finish up with a good machine.

Tweakie.

7674

General Mach Discussion / Re: Spindle delay

« on: August 23, 2010, 08:40:24 AM »

Hi Jim,

Here is a link to the thread and video.  http://www.machsupport.com/forum/index.php/topic,15465.0.html

This has no movement delay whilst the spindle is running up because the spindle only starts / stops when the Z axis has changed direction. This can be achieved by using the Z axis direction pin to switch the spindle rather than the pin associated with the M03 / M05 command.

Tweakie.

7675

FAQs / Re: I do not understand

« on: August 22, 2010, 02:25:01 PM »

Mijn Genoegen.

Tweakie.

7676

FAQs / Re: I do not understand

« on: August 22, 2010, 11:17:09 AM »

Hi Thomss,

The X,Y,Z,4 DRO's are in Units.
If you have selected native units as mm then the DRO's are in mm. (If you have selected native units as Inch then the DRO's are in Inches)
The units for the 4 DRO is usually always Degrees.

Hope this helps,

Tweakie.

7677

Show"N"Tell ( What you have made with your CNC machine.) / Re: Gertrude Gets Some!

« on: August 22, 2010, 04:52:16 AM »

Mach3 has a limit of 10,000,000 lines of Gcode even after licensing.

Still a way to go Chris. 

Tweakie.

7678

General Mach Discussion / Re: Spindle delay

« on: August 22, 2010, 02:12:15 AM »

Hi Jim,

There was a video posted here a little while back which showed exactly what you are asking.

I think it was done by using the Z axis direction pin to switch the spindle motor.
A Z minus move turns the motor on, which stays on until a Z plus move is encountered.

I switch my laser on / off this way (but using the B axis direction signal).

Hope this helps,

Tweakie.

7679

Show"N"Tell ( What you have made with your CNC machine.) / Re: Gertrude Gets Some!

« on: August 22, 2010, 01:21:13 AM »

Keep this up Chris and you will be the first person to exceed the licenced Mach maximum line limit. 

As always excellent work.

Tweakie.

7680

General Mach Discussion / Re: error code

« on: August 21, 2010, 09:10:49 AM »

Interesting information there Guys.
Perhaps this will get taken up by the development team.

Tweakie.