Is this normal? Finish pass is scalloped

Questions/answers/discussion about initial setup of your CNC Shark

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mdcavanaugh
Posts: 53
Joined: Tue Jun 19, 2012 4:24 pm

Is this normal? Finish pass is scalloped

Post by mdcavanaugh »

I finally ran my brand new SharkProHD after spending two weeks carefully setting it up, tightening screws and leveling everything. I ran the "bowl" tutorial - the one that's shaped like a leaf. I followed the tutorial to the letter copying the speeds, feeds and tool choices of the tutorial. The roughing pass was awesome. The finish pass had the gantry jerking and wobbling. Is that normal or do I need to slow something down? The finish is kind of divoted/scalloped. Advice? Normal?
leaf.PNG

drueth
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Joined: Sat Jul 09, 2011 7:09 am

Re: Is this normal? Finish pass is scalloped

Post by drueth »

mdcavanaugh

I was hoping some one that has use cut3d and had more experence than I do would post a reply. I have only use ct3d one time and had the same problem. What I have learned from using Vcarve pro is I belive you have your step over to high. In step 4 finishing toolpath you can select the bit you are going to use. Select the tool and the program will open the tool database. Pick the tool you want and look for stepover . When I tryed this mine was set at 40%. This is way to high. Set is down to about 15% . Calculate the tool path and look at the estimated time to cut It should be a lot higher that it was.
When you get step 6 preview Machining you sould be able to see a difference in the finising toolpath preview. These previews are very acuret. If you want to see the difference open the program and step all the way to step 6 and press the finishing toolpath preview now go back to step 4 and change the step over recaluate the toll path and step back to step 6 Reset the preview and than request the finishing toolpath again.

If all else fails press F1 and the program will open up the help menu page down to step 4 and look for the part that talks about step over.


Good luck

drueth
drueth
Shark Pro Plus HD
new to CNC 12/2012

tonydude
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Joined: Tue Aug 17, 2010 9:23 am
Location: Buffalo,NY

Re: Is this normal? Finish pass is scalloped

Post by tonydude »

Slow down your speed. I run mine around 75 to 80 always when doing 3d work. I have vcarve pro, cut3d, photo vcarve. My stepover for rough cutting is 40 percent, and for ball nose bits I have between 8 to 10 percent stepover.

Tony
Buffalo,NY

"What will matter is not what you bought but what you built; not what you got, but what you gave”

Aspire 12.010, photo vcarve, cut3D.cnc mako shark extended bed with the new upgraded HD 5 gantry with Led pendent.

ohiococonut
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Location: Central Ohio

Re: Is this normal? Finish pass is scalloped

Post by ohiococonut »

My first attempt at the maple leaf plate was a disaster so now I keep it as a reminder of what NOT to do. My second attempt went very well. I ended up decreasing my finish step over to 20%. I believe 3-D Cut recommends 10-20%. I also slowed the FRO speed down to 75% in the control panel to eliminate the jerky motion. It took much longer but the results were very nice with minimal sanding. Your picture looks like pine with all of the symptoms mentioned. My first cut was with cherry and it was a learning experience.
Del

"It's not what you take when you leave this world behind you, it's what you leave behind you when you go."

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Bob
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Re: Is this normal? Finish pass is scalloped

Post by Bob »

One more observation...It looks like you may not have reset your Z zero after changing bits. It's the kind of thing I do once in a while.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

mdcavanaugh
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Joined: Tue Jun 19, 2012 4:24 pm

Re: Is this normal? Finish pass is scalloped

Post by mdcavanaugh »

Bob, you are correct, my zero was off but I'm not sure why because I used a gage to find the new Z after the tool change. I ran the tutorial again and when it finishes roughing the Z has .100 inches added to it. Am I crazy?

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Bob
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Re: Is this normal? Finish pass is scalloped

Post by Bob »

My usual mistake is to locate the cutter exactly on zero...then forgetting to set it.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

4DThinker
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Re: Is this normal? Finish pass is scalloped

Post by 4DThinker »

Since most bits aren't designed to plunge like a drill bit, a bit that isn't extremely tight in the collet will ofter push up during a cut. That might be where the .1" Z height came from.

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wooddude
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Re: Is this normal? Finish pass is scalloped

Post by wooddude »

I've seen the same thing on my Pro Plus, and found one of the possible culprits is slight flexing of the router platform during the cut. Since the router is mounted to one side of the gantry assembly, travel along the Y-axis during the cut can cause the slightest tipping during the cut as the mechanism flexes. The quick solution I found was to first set the raster angle for the final pass to follow the X-axis, and then adjust my feed rates and step-over as needed for best cut quality.
If it's too small, use Bondo. If it's too big, use a belt sander. If it moves and it shouldn't, use epoxy. If the above doesn't help, build a bonfire with it and make s'mores!
{|;-) David

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wolffie
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Location: Far North Queensland, Australia

Re: Is this normal? Finish pass is scalloped

Post by wolffie »

I made the mistake when I set up mine, that I used the highest setting of the gantry and it was rocking like a ship in a heavy storm.
Set your gantry at the lowest setting and only use the highest if you are making something that requires very very deep cutting or is very thick.
In other words, set the gantry at the lowest your material allows.
The lower you set the gantry, the more stable it is.
Cheers
Wolffie
I am never going to die, I live in Paradise already

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