Rough edge quality on baltic birch plywood arcs

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ryanjg11
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Rough edge quality on baltic birch plywood arcs

Post by ryanjg11 »

Newish CNC router, using Acorn with SDSK servos and AVID Pro4896 mechanicals with a Jian-Ken JGL-80 3hp ATC spindle.

Getting great results on baltic birch when taking cuts in the X and Y directions, but I've noticed pretty poor edge cut quality after cutting some 4" diameter arcs, making some throat plates for my tablesaw out of 12mm baltic birch plywood. Router bit is a Vortex downcut 1330xp 1/4" spiral bit, still quite sharp.

I'm thinking the issue has to do with the toolpath, as slowing the speed down (from 250 ipm to 50 ipm) doesn't result in any better quality.

The CAM was done in Fusion 360 with smoothing enabled of 0.0004 inches, conventional cutting (right compensation), with a full depth finishing pass.

I enabled/disabled "Radius arcs" in the Centroid Milling swissi post properties, but it didn't seem to make much of a difference.

Anything else I should look into?
IvanVelchev
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Re: Rough edge quality on baltic birch plywood arcs

Post by IvanVelchev »

Try to disable "smoothing edges". I had the same issue and I fixed this way.
ryanjg11
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Re: Rough edge quality on baltic birch plywood arcs

Post by ryanjg11 »

IvanVelchev wrote: Tue Aug 30, 2022 6:41 pm Try to disable "smoothing edges". I had the same issue and I fixed this way.
Where is this? I don't see it in the CAM post settings. Nor do I see it in Fusion.
ryanjg11
Posts: 39
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Re: Rough edge quality on baltic birch plywood arcs

Post by ryanjg11 »

Figured it out - smoothing was never enabled in CNC12. Setting it for Router Contour seems to help a lot.

Is there any reason to enable smoothing in Fusion 360 if I have it enabled in CNC12 as well?
cnckeith
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Re: Rough edge quality on baltic birch plywood arcs

Post by cnckeith »

post a fresh report.zip and the offending g code then we can give you real advice.

best not to have two different smoothings fighting each other.

shortest vector length should be around .010" (not to be confused with tolerance) in the g code for centroid smoothing to work best. no need to go finer than this, it just causes problems.
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ryanjg11
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Re: Rough edge quality on baltic birch plywood arcs

Post by ryanjg11 »

@cnckeith - I've attached the offending gcode. I had to split this into three NC files as I was using different cutters and the free version of Fusion360 doesn't support tool changes in the same program.

Note this was before I enabled Contour Routing in CNC12, which seems to have solved the problem, mostly. I'm still seeing some rough undulations on cuves with radii of 10" or less.

In Fusion 360, I've usually kept the "Tolerance" and "Smoothing" option under the "Passes" tab both checked and at their default values of .0004" each. Though that seems like a very small number for woodworking. :) Let me know if I should dial that up.

I'm wondering if it would be best, in general, to keep Smoothing disabled in Fusion and just have CNC12 do the work?

My machine is an AVID 4x8-foot gantry-style router, and I'm using their mechanicals but with custom electronics.
Attachments
NC.zip
(25.9 KiB) Downloaded 20 times
cnckeith
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Re: Rough edge quality on baltic birch plywood arcs

Post by cnckeith »

thanks, now i need to see the current cnc configuration of the machine. post a fresh report.zip
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
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cnckeith
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Re: Rough edge quality on baltic birch plywood arcs

Post by cnckeith »

yeah some of the vectors in that g code are .004" long. which is silly for such basic geometry. this shape should consist of two lines and two arcs and instead Fusion is outputting approx 260 lines of code.
slot sillyness.png
slot sillyness.png (10.12 KiB) Viewed 1252 times
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
ryanjg11
Posts: 39
Joined: Wed Jun 23, 2021 2:17 am
Acorn CNC Controller: Yes
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CNC Control System Serial Number: 402E71ED62A8-0322214540
DC3IOB: No
CNC12: Yes
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Re: Rough edge quality on baltic birch plywood arcs

Post by ryanjg11 »

cnckeith wrote: Thu Sep 01, 2022 8:56 am thanks, now i need to see the current cnc configuration of the machine. post a fresh report.zip
Keith, sorry I've made it so hard for you to help me! Attached report.zip here.

Things have improved since enabling smoothing in CNC12, set to Contour Routing right now. Still some minor undulations. Pretty easy to sand out, at least on the outer contours. The inner contours are a bit more challenging.

Here's a pic of a blade holder I made for the tablesaw.

Some of these files were originally created in Solidworks, then converted to STEP to import into Fusion. Wonder if that might be part of the issue with the line segments/polylines?
Attachments
report_402E71ED62A8-0322214540_2022-09-01_22-20-27.zip
(773.9 KiB) Downloaded 15 times
PXL_20220902_052225287.jpg
PXL_20220902_052252544.jpg
cnckeith
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Re: Rough edge quality on baltic birch plywood arcs

Post by cnckeith »

This type of geometry should not have any smoothing applied. It is unnecessary by having smoothing on. What you're asking fusion 360 to do is break up what should just be a nice straight line or an arc into tiny little pieces, lots of them causing problems. Then turning in CNC 12 smoothing then tries to turn those tiny little pieces back into smooth bigger arcs. Simple geometry like straight line squares circles arcs don't need any additional smoothing applied to them. The same with rigid tapping and drilling cycles. I would turn off any smoothing functionality in fusion 360 (or at least make the vector length controls much much larger. ) The subject comes up at least once a month on the forum where newbies misunderstand when to apply smoothing and when not to and what It is designed for I'll put together a diy smoothing paper as soon as I find some time to explain everything with graphics.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
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