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Author Topic: Circuit board isolation routing and probing  (Read 7956 times)

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Offline Sage

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Re: Circuit board isolation routing and probing
« Reply #10 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

Offline BR549

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Re: Circuit board isolation routing and probing
« Reply #11 on: July 30, 2011, 11:39:19 AM »
Sage I will keep this on my mind to see IF anything comes along that might be of help to yall. You never know when an idea might pop up.

One of thebig problems that alwys pop up is that MACH's monitor loop only updates at 10 cycles per sec MAX. That is not anywhere near fast enough to do anything constructive for live height comp.

Is there a Site where the Probing comp software is available for reveiw?

(;-) TP

Offline Sage

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Re: Circuit board isolation routing and probing
« Reply #12 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

Offline BR549

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Re: Circuit board isolation routing and probing
« Reply #13 on: July 30, 2011, 03:53:45 PM »
I am not a PCBer. I just help develope functions for other MACH users to use.(;-)

(;-)TP