Difficulty with full depth pockets...

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glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Difficulty with full depth pockets...

Postby glockpod » Wed May 16, 2018 7:04 pm

Hi,

I've searched the forum, but found nothing recent like what I am experiencing. I think I am doing this correctly, but I have only been building and playing with freeCAD for 6-8 months, or so.

I have a simple sketch that is a rectangular object with three round holes in it. Two are 10mm in diameter. I padded out the sketch to 25.4mm, and on the top surface, created another sketch, this time with two 16mm diameter round holes, coincident with the 10mm holes. I then created two pockets out of the 16mm holes, 24.0mm deep... leaving 1.4mm of the original 10mm holes at the bottom.

Next, I went into path, and created a job, made a tool holder with one 6.35mm, 50mm long end mill, and selected the side surfaces of the two 10mm through holes. I entered the pocket function, and used the spiral path to "drill" the holes through the part. My stock was set to be 1mm larger on all sides, but 0mm on top and bottom (z axis).

The little green paths are created, but they stop 6.35mm from the bottom of the part.

I have tried changing the finish dimension, but it has no effect on the path... well, nothing good.

If I change the Z-axis waste on my stock to 1mm up and down, the path moves a little closer to the bottom of the part, but is still a couple of cm from the bottom.

The extra pocket operation (16mm dia. x 24mm deep) seems to have something to do with the problem

How do I get my holes to go through the part, like they shown on the body object?

I can include the fcstd file if that would help.

Thanks!

-Chuck


OS: Debian GNU/Linux 8.10 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13714 (Git)
Build type: Release
Branch: master
Hash: 46a91630b6568b3bcf46f51c19474645c4356e6c
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.1.0
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cahlfors
Posts: 63
Joined: Tue Jan 24, 2012 8:27 pm
Location: Sweden

Re: Difficulty with full depth pockets...

Postby cahlfors » Wed May 16, 2018 7:57 pm

I have seen the same thing. Unfortunately, it resolved itself and, embarrassingly, I don't know what I did... :oops:
FreeCAD-daily/Ubuntu or Mint
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Optimum BF20L mill
glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Re: Difficulty with full depth pockets...

Postby glockpod » Wed May 16, 2018 8:44 pm

The problem has been 100% repeatable, and has been going on for several weeks worth of github revisions that I know about.

-Chuck
chrisb
Posts: 22532
Joined: Tue Mar 17, 2015 9:14 am

Re: Difficulty with full depth pockets...

Postby chrisb » Wed May 16, 2018 9:06 pm

glockpod wrote:
Wed May 16, 2018 7:04 pm
I can include the fcstd file if that would help.
Yes, it would help.
glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Re: Difficulty with full depth pockets...

Postby glockpod » Wed May 16, 2018 10:02 pm

chrisb wrote:
Wed May 16, 2018 9:06 pm
glockpod wrote:
Wed May 16, 2018 7:04 pm
I can include the fcstd file if that would help.
Yes, it would help.
I'm new here, where and how?

-Chuck
glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Re: Difficulty with full depth pockets...

Postby glockpod » Wed May 16, 2018 10:14 pm

glockpod wrote:
Wed May 16, 2018 10:02 pm
chrisb wrote:
Wed May 16, 2018 9:06 pm
glockpod wrote:
Wed May 16, 2018 7:04 pm
I can include the fcstd file if that would help.
Yes, it would help.
I'm new here, where and how?

-Chuck
Ok, I went exploring a bit, and I think I found the how.

The fcstd file I have included is currently in a mode where only the path, and an outline of the stock is showing. You will have to turn on the other parts to see the original figure, of course.

-Chuck
Attachments
Winder-Mechanism-BearingBlock.fcstd
file with view of bad path in pocket.
(41.41 KiB) Downloaded 28 times
chrisb
Posts: 22532
Joined: Tue Mar 17, 2015 9:14 am

Re: Difficulty with full depth pockets...

Postby chrisb » Wed May 16, 2018 10:32 pm

Works perfect here:
Bildschirmfoto 2018-05-17 um 00.29.53.png
Bildschirmfoto 2018-05-17 um 00.29.53.png (43.51 KiB) Viewed 857 times
OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13651 (Git)
Build type: Release
Branch: (HEAD detached at 4604bd9)
Hash: 4604bd9456688e6108b1b5f1a0dcc7f8d205555f
Python version: 2.7.14
Qt version: 5.10.1
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)
glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Re: Difficulty with full depth pockets...

Postby glockpod » Wed May 16, 2018 10:53 pm

chrisb wrote:
Wed May 16, 2018 10:32 pm
Works perfect here:
Bildschirmfoto 2018-05-17 um 00.29.53.pngOS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13651 (Git)
Build type: Release
Branch: (HEAD detached at 4604bd9)
Hash: 4604bd9456688e6108b1b5f1a0dcc7f8d205555f
Python version: 2.7.14
Qt version: 5.10.1
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)
Looks to me like it doesn't. Your path appears to stop above the bottom ring in the pocket. It should go all the way down through the material. Turn the part visibility off, and look at the front view.
Screen3.png
Screen3.png (122.57 KiB) Viewed 853 times
-Chuck
GeneFC
Posts: 1025
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Difficulty with full depth pockets...

Postby GeneFC » Wed May 16, 2018 11:11 pm

The default stepdown is very coarse. Change the stepdown to a much smaller value and the pattern will look like you want. (If I understand the issue.)

I don't know if the actual result will change, but the visualization will defInitely change.

Gene
glockpod
Posts: 31
Joined: Tue May 23, 2017 7:06 pm

Re: Difficulty with full depth pockets...

Postby glockpod » Thu May 17, 2018 12:01 am

GeneFC wrote:
Wed May 16, 2018 11:11 pm
The default stepdown is very coarse. Change the stepdown to a much smaller value and the pattern will look like you want. (If I understand the issue.)

I don't know if the actual result will change, but the visualization will defInitely change.

Gene
My milling machine says the pattern exactly matches what the FreeCAD shows in its view window.

The path is supposed to clear the entire depth of the hole. It stops at depths without any discernible reason. For instance, if I change the waste area above the part to 2mm, then the path goes closer to the bottom of the hole. If I change it top and bottom to 2mm, then it gets farther away.

My expectation was that path should adjust the stepdown so that it could reach the final depth. Is that not true? It does when it is doing the contour paths, and the profile paths around objects.

It also divides the space properly when I am using spiral to carve out holes that don't have any pocket objects incorporated with them.

And yet, I have found that if I have any pockets that are less than full depth, anywhere on the part, then it will screw up pockets that are full depth.

As a programmer, it feels a lot like a variable that isn't getting properly initialized, and is starting with a wrong value.

-Chuck