Hello Guest it is August 18, 2019, 10:09:20 PM

Author Topic: Pocketing and Island avoidance issue, need help  (Read 14717 times)

0 Members and 1 Guest are viewing this topic.

Re: Pocketing and Island avoidance issue, need help
« Reply #20 on: April 21, 2009, 09:48:12 AM »
I'm not in the big league yet either that's why I'm here too.

I shall no doubt be shot down in flames but routers generally do not work at high precision, for that you need a milling machine.

Have you access to a DTI you will then be able to see by putting the DTI on the spindle and pushing on each axis how easy it is to move out of position.

THIS IS DONE WITH THE SPINDLE OFF.

The only way to confirm is to check this way.

The other test is to remove the motors disconnect the screws and manually push the axis this way you can feel for any binding/crabbing.

In my case i use a mill is is s****e in quality but by fettling it is now unbelievably accurate and i did know it would be s****e BTW

I believe all your troubles are mechanical
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline 2bits

*
  •  24 24
    • View Profile
Re: Pocketing and Island avoidance issue, need help
« Reply #21 on: April 21, 2009, 10:23:48 AM »
The hard part for me to understand if there is any 'slop' or binding, runout from the router, gantry etc, I should see the same margin of error on the outside of the pocket, not just the 'island'.  It doesn't matter what bit size I use, and I can get the same error cutting .020 deep versus .08 deep on a single pass.  I'm only cutting acrylic and a .020 deep pass with a brand new bit shouldn't put any strain on the motors, etc to cause this deviation especially when it seems to occur when pocketing.
Hell, I accidentally hit a clamp once and it almost ripped it out of the track.  So the system has some torque behind it.

Last night, I ran a test, I cut a .5 circle, no pocketing, just cut it to a depth of .0625. it measured .5007.  I then told it to pocket a 1" circle around it and avoid the .5 circle.  It created a 1" circle and ground the island to .485.  Why can I cut the circle accurately, but not pocket with island avoidance?  It's like the system changes the radius and doesn't take in or drops out the additional distance for the bit to leave a .5" circle. 

I don't know, that's why I'm posting this stuff here, because I'm a novice at this, I believe I understand how it's supposed to work, but it's beyond me as to why I'm experiencing what I am. 

Re: Pocketing and Island avoidance issue, need help
« Reply #22 on: April 21, 2009, 11:37:43 AM »
What happens if you cut say a 1" outside diameter circle in only one pass with say a 1/4" bit. Does the inside circle be exactly 1/2" smaller than the outside circle?

Next test, cut a 0.8" outside diameter circle in the exact same center as the first circle. This cut will of course be mostly air. Does the inside circle be exactly 0.2" smaller now than after the first cut was made?

Offline 2bits

*
  •  24 24
    • View Profile
Re: Pocketing and Island avoidance issue, need help
« Reply #23 on: April 21, 2009, 12:00:20 PM »
I'll give it shot tonight when I get home and see what it does.
Re: Pocketing and Island avoidance issue, need help
« Reply #24 on: April 21, 2009, 03:10:48 PM »
When you say "Pocketing with Island avoidance" do you have a program that is creating your G code by giving it the parameters for the pocket and island?
If so, what program is it?
Re: Pocketing and Island avoidance issue, need help
« Reply #25 on: April 21, 2009, 03:27:39 PM »
Another question, your file is labeled "hole test conventional" does the conventional part mean conventional milling as compared to climb milling?
That is what it looks like to me running your program. What happens if you re post the program in climb mode?

Offline 2bits

*
  •  24 24
    • View Profile
Re: Pocketing and Island avoidance issue, need help
« Reply #26 on: April 21, 2009, 04:48:28 PM »
Correct, it was to designate that it was configured as conventional.  Climb the normal default, made no difference.  Using a finish pass made no difference.

As far as creating the job, yes, I select a Area Clearance pocketing function, select the toolpath, bit, depth etc, optionally pick toolpaths of the 'islands' to avoid and generate the gcode.
« Last Edit: April 21, 2009, 04:53:31 PM by 2bits »
Re: Pocketing and Island avoidance issue, need help
« Reply #27 on: April 21, 2009, 07:28:01 PM »
Looking at holetest.tap and adding or subtracting .118 for the tool size your G code gives me .175" hole, a .5" hole with a .1752" island and a 1" hole with a .5" island.
The G code is correct. Do you have any numbers plugged into the tool window?

Offline 2bits

*
  •  24 24
    • View Profile
Re: Pocketing and Island avoidance issue, need help
« Reply #28 on: April 21, 2009, 07:46:27 PM »
I agree, the gcode is correct and looks fine, just don't get how I can adjust and get a 1" outside dia as anticipated and have the island off.

If I understand your question, I only specify the bit, the depth, climb or conventional, an optional finish pass, inward or outward on pocketing (neither make a difference by the way) the clearplane height etc.  Nothing that overrides the toolpath dimensions.  If you mean the tool window in Mach3, no.
Re: Pocketing and Island avoidance issue, need help
« Reply #29 on: April 21, 2009, 09:12:04 PM »
Ok, just for me, run both of these programs. If the sizes are still off, Uninstall Mach 3 and re install it.