Messages

111

General Mach Discussion / Re: Mach3 & bobcadcam

« on: July 30, 2011, 07:35:13 PM »

CAD to create a drawing of what you want to make.
CAM to generate the g-code.
Mach to run the g-code to move the machine.

Sage

112

General Mach Discussion / Re: Circuit board isolation routing and probing

« on: July 30, 2011, 02:16:20 PM »

I'm not sure how you are generating your circuit boards but I use Eagle PCB. There is a free Eagle User language program (ULP) written by Johnson called PCBGCODE which runs in Eagle and takes the Eagle PCB file and outputs g-code to do the isolation routing. It works very well.
 John Johnson has a user group called pcb-gcode on yahoo groups.
 Also in that group is another gentleman named esseel1 who has (I believe) recently modified the original ULP by John Johnson to do the auto-levelling. His posts started on Jul.22 under the topic "auto-pcb levelling and a few other things"
I'm not sure (yet) how he generates the array of Z heights to be used by the ULP. I'll have to start reading from the beginning to figure it out.
 If you use Eagle I would suggest joining the group.

Sage

113

General Mach Discussion / Re: Circuit board isolation routing and probing

« on: July 30, 2011, 07:28:09 AM »

I have to admit I've only ever isolation routed a couple of boards and I didn't like the results. Mostly because the Z axis on my machine (CNC modified mill/drill) is not very accurate because of the slop in the rack and gearing. I'll have to modify that even for my machining efforts.
  My main reason for asking is that I follow a forum on homebrew PCB making and there is someone working on some software to pre-probe the whole board and modify the G-code with a post processor before milling. He's having some some success.  But, after reading about THC it seemed that Mach was already equipped to do on-the-fly height adjustment - something that PCB group may not have been aware of. So I thought I'd investigate it more for my own interest mostly but also on their behalf.
 Now I realize it may not be up to the task. I suppose in plasma cutting several  thou or more of height error makes very little difference whereas even a thou or two can mess up a PCB route.
 I'll go by the experience of others here and now think about something else but any other suggestions would be welcome.
 I did make a machined flat surface plate for my machine to put the PC board on but I found the double sided tape in itself added error or did not necessarily pull the board down flat enough to the surface. A vacuum table might be better but I prefer to do the toner transfer method anyway so I haven't persued it. I have no problems with the toner transfer method.

Thanks

Sage

114

General Mach Discussion / Re: Circuit board isolation routing and probing

« on: July 29, 2011, 10:00:43 PM »

Well, lots of things to think about here.
Do you have any idea what Dave3891 was having problems with in the post I made reference to above?
 Seems like he might be touching something (maybe the torch tip) to the work and automatically resetting Z=0. This would be similar to the auto tool zero addition I already have for Mach. Although it requires touching the tool to a touch plate connected to an input pin on Mach.
 I'm thinking now that maybe an insulated tool connected to an input could work in conjuction with some added code to implement an auto zero move before each tool down command.
  Implementing that would depend on the ability to easily modify the existing G-code or perhaps the post processor could add a Mcode before all Z down moves.

Still thinking...

Sage
 

115

General Mach Discussion / Re: Circuit board isolation routing and probing

« on: July 29, 2011, 09:01:46 PM »

I can see your points - all reasonable especially the one about the swarf messing things up. I guess that's not an issue for THC in plasma cutting?
 SO, not knowing much about it,  how does THC work? From what I've read a separate controller measures voltage from somewhere - I guess across the plasma arc?  and provides UP/DOWN inputs to mach which responds in real time? So real time is possible based on that assumption.

I can see your idea about a linear encoder feeding a controller similar to THC controller to provide the signals to Mach. This might be the best approach. The tricky part will be the probe and how to make it follow the cutter while not getting in the swarf. A good continuous air flow perhaps?


Sage

116

General Mach Discussion / Re: Circuit board isolation routing and probing

« on: July 29, 2011, 05:50:06 PM »

 There are typically lots of raising the bit and repositioning commands in the isolation routing G-code. What I envisioned was some sort of macro to modify or add a procedure to the z moves to go through a typical probing routine first. The idea was a routine to touch the probe to the work which resets the z-axis DRO just before doing the z-axis move thereby adjusting the zero point and therefore the depth.
 I was thinking the proble could be spring loaded and right along side the engraving tool tip so it touches first and the routine adjusts accordingly.
 Not sure how this could be implemented in Mach. That's why I'm looking for ideas.

The idea came from this recent post. I'm not sure what it was all about.

http://www.machsupport.com/forum/index.php/topic,19117.0.html

(sorry not sure how to insert a link)

Thanks

Sage

 

117

General Mach Discussion / Circuit board isolation routing and probing

« on: July 29, 2011, 05:03:17 PM »

 I could use a bit of insight.
 I'm sure most are aware that there is a method of creating circuit boards using isolation routing. Special software creates the gcode. An engraving cutter removes the copper from a blank circuit board leaving the familiar copper traces.
 One of the difficulties with this is that the blank circuit boards are not always perfectly flat so the routing depth varies as you move across the board which makes the remaining traces vary in width (sometimes leaving nothing at all if they are thin or close together).
 Various approaches have been used to minimize this problem. I'm aware of most of them, even one attempt to pre-probe the whole board to build up a z-axis map and use these values in a post porcessor to modify G-code to adjust the Z-axis moves to compensate.

After reading a recent post on Plasma cutting using Mach I realized that apparently some sort of "pre-probing" is done for proper depth on-the-fly before every Z move of the plasma cutting head.

I'm wondering if someone can explain this to me (Mach software mods required, how it works) and if they think this might work for the circuit board milling process. I've tried searching on this but it pretty difficult to find all the info all in one place.

Thanks

Sage

118

Newfangled Solutions Mach3 Wizards / Re: Taskbar and NFS wizards

« on: June 02, 2011, 09:37:31 PM »

I assume what your saying is that your screen resolution is set at something like 1280x1024 and you run mach and size the window to only take up 1024x768?
 Can't argue with that if you have a big screen but it might be useful to test at the designed full screen resolution so you can see what (most) others are seeing.
I run a full screen 1024x768 on my laptop development computer (whch is where I noticed the issue). Any higher resolution and things get too small. No problem on my actual CNC display since, like you, I run it at some really high resolution and only use part of the screen.

P.S> I did fix it myself. I found it necessary to move the button and description over to the right under the preview screen since there was not enough room for it to fully display clear of the task bar if simply moved up a bit.

Sage

119

Newfangled Solutions Mach3 Wizards / Circle cutting direction description wrong

« on: June 02, 2011, 08:49:04 AM »

I'm using V2.86 wizards.
In the circle cutting wizard I select:
Groove
Inside
Clockwise (climb mill)

The code generated is correct in so far as the tool IS climb milling but it moves COUNTER-clockwise to do so.
CCW is the correct direction to climb mill inside a circle. Therefore only the description in the wizard is incorrect.
The choices will need to be re-thought since selecting inside or outside also affects the description of the direction.

Sage

120

Newfangled Solutions Mach3 Wizards / Re: Taskbar and NFS wizards

« on: June 02, 2011, 08:29:00 AM »

It's nice to know that I can fix it myself and I might give that a try, but I guess the point was to point out the problem so it can be corrected at the source for future releases.

Thanks

Sage