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+-- Thread: CNC, Talk me out of it or not (/showthread.php?tid=7342009)
RE: CNC, Talk me out of it or not - Gary™ - 09-05-2018
It's alive and did the "Hello World" project they request. It worked after I fixed the Z axis limit switch that I goofed where to plug it in. I spent a couple of hour extra truing & squaring the machine this morning. It slides much smoother now.
[attachment=12762]
RE: CNC, Talk me out of it or not - Phil Thien - 09-05-2018
Now make sure you can slide a playing card between the steel pulleys and the extrusions. Otherwise what tends to happen is that the steel rides on the aluminum and causes a slight distortion to movement, and the steel wheels can eventually even wear a grove into the extrusion they're riding (eventually causing even MORE distortions).
I've worked on two Shapeoko units and seen a third, all required loosening the steel wheels on the carriage and shifting them up ever-so-slightly in their holes, so keep them from contacting the extrusions.
RE: CNC, Talk me out of it or not - Gary™ - 09-05-2018
(09-05-2018, 06:48 PM)Phil Thien Wrote: Now make sure you can slide a playing card between the steel pulleys and the extrusions. Otherwise what tends to happen is that the steel rides on the aluminum and causes a slight distortion to movement, and the steel wheels can eventually even wear a grove into the extrusion they're riding (eventually causing even MORE distortions).
I've worked on two Shapeoko units and seen a third, all required loosening the steel wheels on the carriage and shifting them up ever-so-slightly in their holes, so keep them from contacting the extrusions.
"There ain't no stinkin steel wheels"
The v wheels look like nylon of similar substance.
RE: CNC, Talk me out of it or not - Phil Thien - 09-05-2018
(09-05-2018, 09:35 PM)Gary™ Wrote: "There ain't no stinkin steel wheels"
The v wheels look like nylon of similar substance.
I'm talking about the pulleys around which the belts wrap on their way to the stepper motors. These steel pulleys can ride very close to the extrusions, so close they often ride directly ON the extrusions, especially those on the z-carriage. You want to be able to slide a playing card between them, and the extrusion.
RE: CNC, Talk me out of it or not - Gary™ - 09-06-2018
I played around and cut this today. It's a prototype for a box.
[attachment=12803]
RE: CNC, Talk me out of it or not - Lumber Yard® - 09-06-2018
(09-06-2018, 05:56 PM)Gary™ Wrote: I played around and cut this today. It's a prototype for a box.
For the most part I think it's a good start.
With that much clean up work I would look at bit sharpness, cut speeds, and potential z axis deflection. There appears to be some bit chatter so, I would troubleshoot some. Another thing that helps with tear out is doing a hog-out cut first and then making another shallow pass for a final cut. (this also helps if you encounter burning)
As far as design I would make the center star have a maximum (flat) depth cut with an endmill and then do a edge v-carve instead of the deep v-carve.
HTH
RE: CNC, Talk me out of it or not - Gary™ - 09-06-2018
(09-06-2018, 06:34 PM)Lumber Yard® Wrote: For the most part I think it's a good start.
With that much clean up work I would look at bit sharpness, cut speeds, and potential z axis deflection. There appears to be some bit chatter so, I would troubleshoot some. Another thing that helps with tear out is doing a hog-out cut first and then making another shallow pass for a final cut. (this also helps if you encounter burning)
As far as design I would make the center star have a maximum (flat) depth cut with an endmill and then do a edge v-carve instead of the deep v-carve.
HTH
I switched to Vcarve Desktop today. Carbide Create used in this test didn't offer a flat depth setting and I wanted that. The top will only be 0.250" thick so the carving can't be too deep. The bit is a brand new Whiteside. The actual image I'm using has some roughness in it. I'll double check the setups again to verify everything is good
RE: CNC, Talk me out of it or not - Phil Thien - 09-06-2018
(09-06-2018, 06:34 PM)Lumber Yard® Wrote: For the most part I think it's a good start.
With that much clean up work I would look at bit sharpness, cut speeds, and potential z axis deflection. There appears to be some bit chatter so, I would troubleshoot some. Another thing that helps with tear out is doing a hog-out cut first and then making another shallow pass for a final cut. (this also helps if you encounter burning)
As far as design I would make the center star have a maximum (flat) depth cut with an endmill and then do a edge v-carve instead of the deep v-carve.
HTH
Switching to a downcut bit will nearly eliminate any need for cleanup.
RE: CNC, Talk me out of it or not - Lumber Yard® - 09-06-2018
Looking at the image in full size leads me to believe that there is more going on then just bit selection. I can't really tell what bit was used to complete the carving but my guess is that the whole thing was cut with a v-carve bit. The detailed pattern is kind of garbled with bit chatter as well as tear-out if you look at it in full size.
What bit(s) were used for the carving?
RE: CNC, Talk me out of it or not - Gary™ - 09-07-2018
(09-06-2018, 09:33 PM)Lumber Yard® Wrote: Looking at the image in full size leads me to believe that there is more going on then just bit selection. I can't really tell what bit was used to complete the carving but my guess is that the whole thing was cut with a v-carve bit. The detailed pattern is kind of garbled with bit chatter as well as tear-out if you look at it in full size.
What bit(s) were used for the carving?
brand new Whiteside 1550 60 degree v bit. I interrupted and restarted the cut a few times so that's why some are more ragged. The safe height was 12mm and it was taking forever so I lowered it to 2mm once I was confident.