Shapeoko 3 cutting too deep

Shapeoko 3 cutting too deep

Postby C J » Wed Aug 08, 2018 3:11 am

I've been pulling my hair out for 5 days on this one, maybe someone can help.

I'm using Vcarve to create and export tool paths to carbide motion so that I can make inlays.

I have no idea why, but for some reason the machine cuts deeper (almost.33") than my flat depth setting (.2"). When I view the gcode in a simulator, everything looks just fine..

Support gave me a link to proper homing set up. I'm not sure if it's outdated or not because it says when homing ($h) the machine will move off 1mm. Mine moves off 5mm.. Could this 4 mm be part of my issue???

Here's my workflow:

1. Create pocket with Vcarve tool path: start depth=0, flat depth=.2". Tool edited pass depth to .1"
2. Export Gcode as Shapeoko (inch).gcode
3. Open Carbide Motion, home the machine.
4. At home I clear offsets, they now read -5 -5 -5
5. Next I jog the bit to the stock, near middle or wherever I'm actually cutting, touch it down with a piece of paper in .01" increments until it grips. Zero Z.
6. Raise Z, move machine to lower left corner of stock. Zero X,Y and click done.
7. Load file, Run. Pull hair while watching the machine dive into the wood. It goes down to almost a third of an inch by the final pass.

On top of the depth issue, there seem to be some accuracy issues as well. The one inlay I got to sort of work ended up having a few gaps on one side. Unusable.

There are also some places where the bit wavers along the cutting edge, causing uneven lines.

I'm cutting into end grain with a Makita router set to 3 for the 60 degree 1/2" V bit, and 2 for the .250" end mill. The machine is set to move at 30-35"/min, which from what I gather is fairly slow.. Plunge rates are 25-30"/min. During cutting, I've had to slow the process by 30% because the pass depth is so deep the router starts bogging down.

I'm trying really hard to like this stuff, but so far it's been nothing but a headache. Any help would be appreciated!
C J
 
Posts: 2
Joined: Mon Jul 09, 2018 8:13 pm

Re: Shapeoko 3 cutting too deep

Postby WillAdams » Wed Aug 08, 2018 1:32 pm

If you're having trouble with depth, and the simulation is okay, most likely this is either a job setup issue (are other elements also cut at the wrong depth?) or a mechanical problem.

You can verify the preview using a third party tool such as Camotics.

For mechanical, this should be one of the following:

- belt tension --- Z-axis needs to be guitar string tight (but careful not to bend the motor shaft) see: https://www.shapeoko.com/wiki/index.php ... ko_3#Belts which links to: http://www.shapeoko.com/forum/viewtopic ... 075#p53075
- pulley set screws: http://docs.carbide3d.com/shapeoko-faq/ ... et-screws/
- eccentric V wheels: http://docs.carbide3d.com/support/tensioning-eccentrics

Also check your feeds and speeds, and safety/retract height --- if you bump against the top stop and lose steps the Z-axis will be off by the number of steps lost thereafter.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)
WillAdams
 
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Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15

Re: Shapeoko 3 cutting too deep

Postby C J » Thu Aug 09, 2018 3:06 am

Thanks for your reply. Some good info there.

So far I've been instructed to run a couple of tests using only Carbide Create and Carbide Motion.
First,I did the chuck test. Cutting different depths for various lettering. All good.
Second, the circle/square/diamond test. Not only were the depths spot on, but the shapes were also near perfect.

This leads me to believe that I'm having an issue with either Vcarve, or the file output from Vcarve to Carbide Motion.

On the mechanical side, one thing I did notice while performing these tests is that I'm getting horizontal lines across the X axis. They aren't terrible, but definitely noticeable, and I don't get them running vertical along the Y axis.
I'm guessing the cutter is pitched either forward or backward a tiny fraction.

I wonder if this issue is causing minor deflections while V carving, leading to inaccuracies in the final shape of my pockets/inlays.
C J
 
Posts: 2
Joined: Mon Jul 09, 2018 8:13 pm

Re: Shapeoko 3 cutting too deep

Postby WillAdams » Thu Aug 09, 2018 3:39 am

Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)
WillAdams
 
Posts: 8361
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15


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