Performance Test (1 year in)

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sharkcutup
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Performance Test (1 year in)

Post by sharkcutup »

I ran a performance test on my CNC Shark Extended Bed after a year of operations. I ran a 2" Square Pocket .250" deep, 2" Diameter Circle Pocket .250" deep and a 2" Triangle Pocket .250".

With the .tap file G64 P .005 as my post processor setting.

All above was performed using Virtual Zero on a 3/4" Common Pine Board. My Touchplate is .375" thick with the thickness noted in the Virtual ZERO Preferences of the Control Panel Software.

The only thing that was not to my liking was the triangle SIZE. Instead of it being 2" it came out to approx. 1.875". So I ran two additional triangles -- one sized to 2.125" and one sized to 4.125" and both cut to 2.000" and 4.000" respectively. All other measurements and depths were satisfactory (some were even within the G64 .005" .tap file setting).

Not too bad for cutting wood, acrylics, or plastics --- but would definitely have to look into the matter if cutting any metals!!!

Have a Nice Day EVERYONE!!! :)

Be SAFE around those AWESOME machines!!!! ;)

Sharkcutup
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Kayvon
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Re: Performance Test (1 year in)

Post by Kayvon »

How are you measuring your triangles? It's really odd that everything else is perfect, but the triangles aren't.

Rando
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Re: Performance Test (1 year in)

Post by Rando »

Kayvon wrote:How are you measuring your triangles? It's really odd that everything else is perfect, but the triangles aren't.
Yeah, I wonder if he's ignoring that the bit radius means it can't get all the way into the corners. Such as in this diagram, where the vector is in red, and the purple shows where the bit actually cuts. Might this be what's going on?
traingleFail.JPG
That's a great idea to periodically check that the machine is still put together after a lot of hard work :idea: .

If you're going to measure triangles, you might get better information checking for smoothness along the hypotenuse. Another test would be a very slightly angled slot, say 0.010" displaced in the Y-axis, over 10" in the X-axis. And then another one in the other direction. Make the slot a little deeper than you might. Plunge a tiny divot with the bit just off the two ends, then cut the full slot, with a slow plunge. Two things to look for: if you can see the 0.001" increments in the small-excursion axis. make sure that these increments are evenly spaced. Also, if it's like a normal shark, the center of the at-depth slot will in fact NOT be in a direct line between the two divots, due to bit, carriage and gantry deflection. Keeping a watch on that can catch if there might be loosening bolts in the structure of the gantry and Z-axis carriage.

And, of course, check that your pocket depths are accurate; I didn't notice you testing any of them, but maybe you did.

If you have the ability, check the roundness of the circles. If you have something you know is round, make the hole exactly that size, and see if the circumference is actually round. There will "always" be "some" backlash in the system, even if it's under 0.001". If you can detect any flatness on the X-parallel or Y-parallel portions, this will indicate the amount of backlash in the lead-screw following anti-backlash T-nuts. One might argue that if you can see a flattening, that's too much backlash. But, your projects will decide how much inaccuracy is too much.

One final note: (kindly ignore if you're already using a "finishing pass") you saw the mention of deflection above, right? If you're really, truly needing thousandths-accurate holes, then you're going to want to cut it in two passes (at least): a primary pocketing path that leave ~0.005-0.015" inches of material margin, and then a finishing pass to take that last little thickness. Those are very useful in real work as well, but for testing machine dimensional accuracy, you're going to get the best results when the last pass, that establishes the final edge, has almost no cutting stress on the system. Trust me, I work in metals with the Shark, and deflection in the range of 0.020" and more is not uncommon when the cut is especially hard.

Regards, and thanks for the idea!

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

sharkcutup
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Joined: Tue Mar 08, 2016 5:23 pm

Re: Performance Test (1 year in)

Post by sharkcutup »

Yes I did check depths and all were fine thanks to Virtual ZERO!

And yes I do use finish passes. They save a ton of dremel work cleanup along with what Rando also said about smoothness, concentricity, system hardware deflections and the like!!!

And yes I also have tools available for checking roundness and the like with my past profession (retired) in Industrial Quality ControI I have many inspection tools I can access.

I will admit though I was using a .25 down cut spiral when running my cnc tests and I did not account for it when measuring my triangle! My bad!!! I will use age as an excuse, lol!

My cnc tests were run to check for wear & tear and I found that my cnc is still in Great shape except the spoilboard may need changing soon though!!!

Great Advice there, Rando!!!

Sharkcutup
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Rando
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Re: Performance Test (1 year in)

Post by Rando »

Oooh....mind if I keep your former role in mind, sharkcutup? Sometimes I'm at a loss as to how to measure somethings...sounds like you have the experience that would expose my head-scratchers for the eye-rollingly obvious solutions they really are ;-).

Cheers!

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

sharkcutup
Posts: 408
Joined: Tue Mar 08, 2016 5:23 pm

Re: Performance Test (1 year in)

Post by sharkcutup »

Now that my CNC Shark is no longer under warranty I have finally added an item that I have been longing for (a fan inside my control box). Now I no longer have to be concerned with the control box getting to hot during the summer months in my workshop.

After fan installation I ran the same performance tests again to make sure I have not messed up something else in my install process. Checked out AAA OKAY!!!

Sure is Grand when everything falls into place!!!

Have a Great Day Everyone!!! :)

Be SAFE around those AWESOME machines!!! ;)

Sharkcutup
V-Carve Pro Tips, Gadget Tips & Videos
YouTube Channel - Sharkcutup CNC
V-Carve Pro 11.554

Rando
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Joined: Tue Jan 06, 2015 3:24 pm
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Re: Performance Test (1 year in)

Post by Rando »

sharkcutup wrote:Now that my CNC Shark is no longer under warranty I have finally added an item that I have been longing for (a fan inside my control box). Now I no longer have to be concerned with the control box getting to hot during the summer months in my workshop.

After fan installation I ran the same performance tests again to make sure I have not messed up something else in my install process. Checked out AAA OKAY!!!

Sure is Grand when everything falls into place!!!

Have a Great Day Everyone!!! :)

Be SAFE around those AWESOME machines!!! ;)

Sharkcutup
Uh Oh.....he's caught the "modding" bug! :mrgreen:

It's an irresistible slippery slope to making it work juuuuust the way you like. Welcome the club, sharkcutup.

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

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