[SOLVED] Slot profile issue

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ceandraka
Posts: 32
Joined: Sun Dec 27, 2020 11:24 pm

[SOLVED] Slot profile issue

Post by ceandraka »

I am continuing to try to machine my small part with a slot.

For this particular version, the slot has to be 0.015" wide, but I have a 0.013" milling cutter. Therefore I need to "spiral" around the slot. I have tried profile and pocket with identical results.

My actual part will have a larger slot partway through, and a smaller slot through. The path for the tool ought to be an oval that follows the edge of the slot. However, if we look at the larger partially-through slot, each end has the radius offset a little, and a small diagonal line joining it to the straight sides. Looking at the smaller through slot, the shape is quite funky, not resembling an oval at all.

Finally, I made a sample file with just a small through slot, and it shows similar.

In the cases I am attaching I am using profile. However, if I selected the sides of the slot (two straight sides, two half circular sides) and did a pocket, I get virtually the same path.

Am I using these wrong, or is there a bug? Any suggestions to get this right?

Thanks
Chuck

OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.23756 (Git)
Build type: Release
Branch: master
Hash: 9c6e9184930a52b165a0b7274e3a45d1006bfe67
Python version: 3.8.6
Qt version: 5.12.5
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/United States (en_US)
slotdeviation.jpg
slotdeviation.jpg (25.59 KiB) Viewed 702 times
SmallSlotDeviation.jpg
SmallSlotDeviation.jpg (34.13 KiB) Viewed 702 times
JustSmallSlot.jpg
JustSmallSlot.jpg (35.11 KiB) Viewed 702 times
Attachments
DemoSlotMillProblem.FCStd
(43.46 KiB) Downloaded 24 times
DemoSlotMillProblemB.FCStd
(30.44 KiB) Downloaded 26 times
Last edited by ceandraka on Tue Jan 26, 2021 12:52 am, edited 1 time in total.
GeneFC
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Posts: 5373
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Slot profile issue

Post by GeneFC »

I did a recompute and the shapes look OK.

CaptureA.JPG
CaptureA.JPG (51.83 KiB) Viewed 676 times

CaptureB.JPG
CaptureB.JPG (35.18 KiB) Viewed 676 times

Not sure why, but sometimes things don't update on their own.

OS: Windows 7 SP 1 (6.1)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.23756 (Git)
Build type: Release
Branch: master
Hash: 9c6e9184930a52b165a0b7274e3a45d1006bfe67
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)

Gene
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sliptonic
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Location: Columbia, Missouri
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Re: Slot profile issue

Post by sliptonic »

You need to set your geometry tolerance and curve accuracy lower.
2021-01-25_18-48.png
2021-01-25_18-48.png (107 KiB) Viewed 673 times
ceandraka
Posts: 32
Joined: Sun Dec 27, 2020 11:24 pm

Re: Slot profile issue

Post by ceandraka »

Gene: Tried recompute, did not fix it.

Sliptonic: That was it. Changed tolerance, and then forced recomputed.

Thanks guys! Marked as solved

Chuck
GeneFC
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Posts: 5373
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: [SOLVED] Slot profile issue

Post by GeneFC »

ceandraka wrote: Tue Jan 26, 2021 12:52 am Gene: Tried recompute, did not fix it.
I always keep tolerances super tight. That would explain why it worked for me.

Gene
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