SOLVED: Still getting 'air cuts' after autolevelling

Help for setting up and using
WoodWorkerB
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Joined: Thu Nov 28, 2013 2:51 am

SOLVED: Still getting 'air cuts' after autolevelling

Post by WoodWorkerB »

KiCAD: 4.0.7
FlatCAM: 8.5
Autoleveller Version: 0.9.3u1
LinuxCNC (current)

PCB mounted with double-stick tape, 3 peices, full length of the board. It is damn-well stuck down

I put a dial indicator on my machine and ensure the PCB is level across all 4 corners the lower-left corner (0,0) reads Zero on the dial indicator. The area with the air-cuts also reads 0 the top right is .003 high. I actually measure ON the PCB itself, not mounting board.

Probing at 0.15". Probing proceeds without incident. I use the actual cutting tool as the probe, so there is no tooling change between probing and milling.

The 80% of the board that milled correctly is perfect.
aircuts.jpg
This has happened several times now, and I'm starting to get frustrated ruining PCB stock.

Ideas?
Last edited by WoodWorkerB on Thu Nov 22, 2018 4:49 am, edited 1 time in total.
daedelus
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Re: Still getting 'air cuts' after autolevelling

Post by daedelus »

It sounds like you are doing everything correctly but have you tried the 'Generate PFG' button? This will allow you to probe without etching / milling and stores the resulting probe values in a file (RPF). See section 5.1 here: http://www.autoleveller.co.uk/autolevel ... art-guide/

As this is just the probing part, you dont need to waste any more boards by milling them, and allows you to inspect the probe values for errors. Any wild spikes in probing can throw the autolevelling process off so this may be one cause of the air cuts. If you try this, please attach the RPF here.

Feel free to chip in anyone with other ideas.
http://www.autoleveller.co.uk/. Software to probe and adjust a GCode file for PCB's or any probe-able surface.

http://www.autoleveller.co.uk/cnc-probe-guide/. A short guide to setting up the probe.

-James
WoodWorkerB
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Re: Still getting 'air cuts' after autolevelling

Post by WoodWorkerB »

I will do that! I wish I'd have actually RTFM sooner. This looks like it would have addressed several of my issues at one time.
I'm off to the SEMA show in Las Vegas, so I'll be out for the rest of this week.
Will do this upon my return.
BrianV
WoodWorkerB
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Re: Still getting 'air cuts' after autolevelling

Post by WoodWorkerB »

So, I THINK the issue was the double-stick tape approach.
It lifted a bit at one corner/end. The probing applies no pressure, so the probing couldn't detect any deflection.
Upon milling, however, the pcb just 'flexed' away from the tool.
I intend to try with a different, more secure clamping technique.
Having problems with AE-0.9.5u1 right now, no time to diagnose at this moment.
Will advise!
daedelus
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Re: Still getting 'air cuts' after autolevelling

Post by daedelus »

Thanks for the update. Let me / us know if we can help with 0.9.5.
http://www.autoleveller.co.uk/. Software to probe and adjust a GCode file for PCB's or any probe-able surface.

http://www.autoleveller.co.uk/cnc-probe-guide/. A short guide to setting up the probe.

-James
WoodWorkerB
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Re: Still getting 'air cuts' after autolevelling

Post by WoodWorkerB »

Okay, here's the latest.

Issue #1: Aircuts. I happened to visit a high-end cabinet shop. He has a large-format CNC router (like 6 x 12 feet). He used HOT GLUE (yes, hot-freakin' glue) to secure some smaller parts for milling - parts too small for the vacuum system to hold down.
So I put a weight on my PC board and used some globs of hot glue at each corner. Easy to remove, no clamps, no screws.
WORKED PERFECTLY. No air cuts. I intend to continue the Hot Glue Clamping System.

Issue 2: Problems with 0.9.5 were operator error. I was fooled since I could use my probe to zero my Z-axis on the PCB surface. In StepConf (LinuxCNC), I had the probe connected to Z-Home and not Probe-in. Made the change and all was good with the world.
daedelus
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Re: SOLVED: Still getting 'air cuts' after autolevelling

Post by daedelus »

Think I saw something like this before but with superglue. When the etching was done, the guy used ISA to remove the glue. Seemed to work well but never tried it myself.
http://www.autoleveller.co.uk/. Software to probe and adjust a GCode file for PCB's or any probe-able surface.

http://www.autoleveller.co.uk/cnc-probe-guide/. A short guide to setting up the probe.

-James
mohoram
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Re: SOLVED: Still getting 'air cuts' after autolevelling

Post by mohoram »

What is ISA?
daedelus
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Re: SOLVED: Still getting 'air cuts' after autolevelling

Post by daedelus »

Sorry, I meant IPA (Isopropyl Alcohol)
http://www.autoleveller.co.uk/. Software to probe and adjust a GCode file for PCB's or any probe-able surface.

http://www.autoleveller.co.uk/cnc-probe-guide/. A short guide to setting up the probe.

-James
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Country_Bubba
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Re: SOLVED: Still getting 'air cuts' after autolevelling

Post by Country_Bubba »

Still think there might be a slight error here.

IPA (Alcohol) is an activator for CA glues (eg makes it cure faster)
To remove or breakdown the CA glue you use Acetone
Art
Country Bubba
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