Topic for Forum Member Rando

Discussion about the CNC Shark Pro Plus HD

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sharkcutup
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Re: Topic for Forum Member Rando

Post by sharkcutup »

Wow! A lot of information here give me a bit to soak up what you already have provided!!! And Thank You!! :)

Thanks that has been very informative!!!

2" Boss .5" high in center of 5 by 5 block

2 hp spindle and I can control speeds at the inverter.

Cheers!!! :D

Sharkcutup
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Rando
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Re: Topic for Forum Member Rando

Post by Rando »

Then those parameters would work just fine. After all, that cut only consumes 0.0053 horsepower. The Sharks handle VERY light cuts, but they still have to be in the valid range of SFM, 900 to 1200 for Aluminum 6061. A 1/4" bit at 16500RPM gives 1080 SFM, a perfect amount. Then you just have to make sure you neither cut too much nor too little, and keep the total system torque so low that the HDPE doesn't bend, and things will actually work. I have actual aluminum product, in-market, that I regularly make and sell from my Shark HD2+. Well, it's a modified one now, but that's very recent.
=====================================================
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: Topic for Forum Member Rando

Post by sharkcutup »

Thank you Rando

Appreciate your advice/comments/input!

Valuable information which not only I will get from this but anyone else who reads your posts.

Sharkcutup
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Rando
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Re: Topic for Forum Member Rando

Post by Rando »

You're welcome. HowEVER....just so you know...the ONLY reason I write these posts...is so you and others benefit. Knowledge that is not shared has no value.

TL/DR: Machines have operating envelopes and sometimes we don't get out of them all they can do because we don't understand how to move within that operating "space".

====================================================

Giving just attribution, the guy who runs cnccookbook.com, in my working with him to get his excellent F&S calculator to include the features necessary to characterize a machine like the cartilage-based sharks, once told me "I don't think you're pushing your machine anywhere near hard enough."

Well, he was partially right. That is, I was babying the machine....somewhat...maybe by 50%. But, the problem wasn't weak drive motors, or worn leadscrew backlash, or lousy controller capabilities. It was HDPE. But not "just" the HDPE.

In any system like a 3-axis CNC, all the three axes have to act very similarly in "compliance", that is deflection under load. You don't want X to be really soft while Y is rock solid and Z is some other value. They work best when they are close in compliance, rigidity, even primary resonant frequency. And the HDPE in the sharks are actually somewhat matched to the rest of it.

So, that becomes a problem when you say "to heck with this weak router, I want a SPINNNNNNDLE!!!!!" Well, a spindle weighs 12# and a router weighs some other amount, far less in my DeWalt D618 long ago. Young's Modulus says those different weights make the system move differently. C'mon...we've all seen this. Tramming these beasts is a nightmare because there's compliance at each joint in the system that has to be individually compensated.

Yikes!

People get dixie-billet clamps, and that solves the holding-tight problem, but adds to the weight sag.
You can shim up the spindle mount, but that just doesn't fix the z-axis slide rails also not being perfectly vertical.
You can then fix what holds those slide rails, but that is only the same in the middle of the gantry.
Yup, as you move from end to end, the sag in the gantry changes.
So sure, you can stiffen the gantry (yes, I have a kit for this ;-) ),
But that then transfers that torque down the gantry arms.
The first thing you notice (no, really...do this...you'll freak) is that if you watch the cross-wise drive plate underneath the bed while you tug at the top of the gantry ALONG the length of that gantry...you see an S shape.
Okay, fine...you can use the crane hoist and temporarily move the bed off, get underneath, and totally beef up that with very little weight...I'm on it.
Oh...but then, you're left with the plate that joins the top of those long linear bearings to that under-bed drive plate.
And you realize that ALL of the former deflection is STILL in that member.
Sure, the underside doesn't move
And sure, the gantry is stiff as heck
and for me, it's now pure metal all the way forward from those bearings...well, alloyed metal anyway ;-).
And yet, still, I'm f*cked by a 3/8" plate that really should have been 3/4" thick, all the way across, which is now the ONLY flexing element, and boy does it.

I've done every one of those things except that final fix.

The machine is now a BEAST, and moves with the same movement dynamics, because I've added less than a pound.

Material removal rates?

Okay, remember how I said I was babying the machine?

I decided fine...I'll do better! And I did...scary, sometimes failing, but stronger and harder and better, but well over double what I was getting before. Stupid deep cuts for this machine. Toolpaths that took an hour then took 20 minutes, and three depth-passes instead of five.

Which then allowed me to feasibly make those upgrades to the gantry system. 10 different precision components that ('cause I's poh!) reused the precision components already in use on the Shark. That's right....can't assemble the final unit until it's not only all cut, but the machine is so far disassembled there is NO going back. Yeah, well I'm an in-gin-err, and my sh!t works...which it did :D.

And now? OMG....cuts an ORDER OF MAGNITUDE harder faster, and more accurate at those. That's right, I can now PUSH the bit....Yeah, I DARE you to push a full slot on a shark. I can now, with no bit diving, and no deflection....except in that one damned joint :evil:.

Seriously...those cut parameters I recommended earlier yield 0.0275 cubic inches per minute. I've gotten (in a torture test) 0.866 cubic inches. Yes, nearly 32X :D

On a shark that electronic configuration-wise has ZERO changes. That's right, if you had the systems I have, or rough equivalents (chip BLOWER as in with a nozzle, not a vacuum, and a pulsed mister...maybe $30, two components and a power supply on eBay) you'd be able to do WAY more than anyone imagined using these machines.

Yes, other machines are way better, and I'd love to have a $150K machine, but for nearly all projects, ±0.005" is well within customer and product needs. And asking for more than that should be questioned, anyway.

So now, those toolpaths that took an hour that then took 20 minutes? Yeah, one maybe two passes, 8 minutes, and don't stand near the machine because the chips are HOT, and go flying down my shirt and burn me :cry: ....again :evil: . If I want to watch, I use the web-cam :D

Sharks are cool. They're all capable of SOMETHING. Getting what you want out of any robot is all about convincing it to make it for you. Success requires this, and cannot be achieved without it.

I'm always envious of the 12,000# "Big Blue Beast" here in the 8,000 square foot metals-fabrication shop...that hasn't moved in three years. Why? Because a while back, it sh!t its brains, and manually keying in 2K lines of ladder code (ew!) is not really something I'm willing to do. After all, every single CNC-requiring job that's come in has been capably handled by the Shark. So, Pbbbbbbbtttt on you big boys.

As I was once told by another engineering mentor, "good tools can make a good engineer better. But even great tools can't make a bad engineer good."

And as I tell my clients, "my sh!t works."

Cheers, y'all. It's been bizarre listening to the #1 presidential debate during the typing. What a 4 year-old.
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

sharkcutup
Posts: 408
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Re: Topic for Forum Member Rando

Post by sharkcutup »

AWESOME!!!

I have had my Shark now 4+ years now. I have made many wood carvings on it and thoroughly enjoyed using it. You are so right that the Shark is not rigid and yes you cannot push the machine. But with the right adjustments/settings you can produce acceptable projects. When I was researching CNC machines back in the day (early 2016) I was looking for something that would carve wood (a specific material) and had settled on the Shark HD3 Pro Plus machine with a water-cooled spindle.

After machining the spoil board I noticed some minor carving lines (which would sand out) but I was determined to find and solve that issue. It was making an adjustment to the carriage assembly that holds the Router/Spindle. After making that minor adjustment I resurfaced the spoil board again, problem solved lines gone!

Where I see the most flex in my machine (Router/Spindle Carriage) is on the y axis when drilling holes. But I have since changed that approach to using a v-bit and just drill starter holes for drilling at a later time with drill press or hand held drill. Or slowing down the plunge and adjusting the Spindle speed on the CNC machine. Drilling technique varies depending on the type of projects being carved.

Being retired - time is not an issue so I adjust the Feed/Speed rates to accommodate the projects thereby producing acceptable carvings. Sure by doing so some jobs take longer but as I said time is not an issue and besides it sure beats carving the projects by HAND!!! After 4+ years I am still getting acceptable WOOD projects from my Shark machine!

Oh and By the Way --- My Sh!t works too!!!

Kudos and Cheers,
Sharkcutup
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YouTube Channel - Sharkcutup CNC
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Rando
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Re: Topic for Forum Member Rando

Post by Rando »

My experience was similar, stymied at first by a dead controller board and their lame grounding scheme.
I also noticed the issue with facing the spoilboard, and from there the can of worms was opened!

But, I think we can both agree: regardless of any shortcomings, there are plenty of amazing things that can
be created using the machines, with overall surprisingly little technical trickery required.
=====================================================
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: Topic for Forum Member Rando

Post by sharkcutup »

Agreed!!!

Well Yesterday my first Spindle has died. Services next Wednesday :lol:
Got over 4 years and many projects out with that first spindle. I was carving a Monte Carlo Style SKS Gun Stock when it decided to crapped out.

Replacement spindle is on its way.

In the meantime I am and have been working on another SKS Gun Stock design - Thumbhole version

Sharkcutup
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cromag27
Posts: 29
Joined: Fri Apr 20, 2018 10:13 am

Re: Topic for Forum Member Rando

Post by cromag27 »

Rando wrote:
Thu Oct 01, 2020 4:37 pm
My experience was similar, stymied at first by a dead controller board and their lame grounding scheme.
I also noticed the issue with facing the spoilboard, and from there the can of worms was opened!

But, I think we can both agree: regardless of any shortcomings, there are plenty of amazing things that can
be created using the machines, with overall surprisingly little technical trickery required.
just curious your opinion on rpm and feed rate for the following:

cast acrylic, cut through, amana o flute plastic bit
1/8” w/ 1/8” bit
1/4” w/ 1/4” bit
3/8” w/ 1/4” bit
1/2” w/ 1/4” bit

tried to search for your previous posts regarding feed rates and couldn’t find this specific info.

also, are you still using a plastic shield around your unit? do you have a photo?

thanks!!

Rando
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Re: Topic for Forum Member Rando

Post by Rando »

Well, you kinda stumped me! It's been a long while since I've done acrylic....

Oh, no, wait....

DANG I love these electronic notebooks! (I use Microsoft OneNote, but there capable others)....

If the great forum gods will let me upload a PDF.....
SharkHD2OriginalCutCatalogHDPEandAcrylic.pdf
My original cut-catalog for HDPE and acrylic.
(669.13 KiB) Downloaded 256 times
Looks like it might 8-)

That was back when I was just learning, so those will be VERY conservative, and possibly
even BAD numbers. Looking back, that was a time of very little "knowing what the f*ck I
was doing" if you know what I mean, WRT feeds and speeds. ;) ...and fighting the battle
of finding out just where the capable working envelope of the shark was. My crayons were
veering wildly outside the lines during those days, so to speak. :)

That is my old cut-catalog that has something of what you're looking for in the top table.
If there's any confusion, let me know...I do tend to over-analyze and over-record
technical data. :roll: But, that's how we learn, right?

Hope that helps!

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

cromag27
Posts: 29
Joined: Fri Apr 20, 2018 10:13 am

Re: Topic for Forum Member Rando

Post by cromag27 »

i'll take a look, thank you.



Rando wrote:
Fri Dec 25, 2020 2:00 pm
Well, you kinda stumped me! It's been a long while since I've done acrylic....

Oh, no, wait....

DANG I love these electronic notebooks! (I use Microsoft OneNote, but there capable others)....

If the great forum gods will let me upload a PDF.....

SharkHD2OriginalCutCatalogHDPEandAcrylic.pdf

Looks like it might 8-)

That was back when I was just learning, so those will be VERY conservative, and possibly
even BAD numbers. Looking back, that was a time of very little "knowing what the f*ck I
was doing" if you know what I mean, WRT feeds and speeds. ;) ...and fighting the battle
of finding out just where the capable working envelope of the shark was. My crayons were
veering wildly outside the lines during those days, so to speak. :)

That is my old cut-catalog that has something of what you're looking for in the top table.
If there's any confusion, let me know...I do tend to over-analyze and over-record
technical data. :roll: But, that's how we learn, right?

Hope that helps!

Rando

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