I would hardly call changing from CV to exact stop a "workaround." I do however agree with you on the flex issue. See my last post, I've added to it since yours...
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I simply meant that with a rigid machine, you do not have to fuss with the CV settings or Gcode. If you do have to mess with it, it is a work around. That is unless you update the post processor in your CAM package to handle it every time. That said, the action of modifying the PP is a work around.
That wasn't actually the point of my post though. Rather than a work around, lets call it less optimal.
Lee
I hear you, but unless you or anyone else can get a motor to instantly accelerate, isn't it all a "workaround?"
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Btw, you don't have to modify your PP to do it... I just edit the file and insert it. Kinda old school, I guess...
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Getting someone else to machine and ship you parts for less than you can make them for is ideal for me. That is optimal.That is what I have going on with one of my suppliers currently and I could not be happier. It is like hiring another guy without having to pay his insurance.
That is definitely getting around work.
Lee
Sounds like you've got it all figured out. I build guitars, but someday I would like to have someone working at the shop while I drive around and buy cool looking wood. It's a dream for sure. For now I'm stuck programming for machine shop and building guitar parts in my spare time...
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I started part time in 03. Stick with it. I still don't have time to do much woodworking, but I can buy nice wood when I see it.
All figured out? Not hardly. Maybe next week.
Lee
use the drill function, and use the bit the size hole you need. for small holes anyway.
^ I just need to get the machine some rigidity as mentioned and go from there. I will try the direct mode and cut some circles.
But as stated before, I agree that everything would be a workaround until I upgrade / "fix" the machine.
I appreciate all the help and CNCRouterparts is behind their product all the way which I am happy about.
If the circle code is a single G2 or G3, they'd both cut exactly the same.If you are wanting the cut as perfect a circle as you can, use G61. If you want to cut it fast, use G64. You ain't gonna get both
However, since his g-code is cutting with 4 arcs, G64 would be preferable imo. With G61, his code will stop 4 times as it cuts the circle, magnifying any flex he has. G64 will cut the 4 arcs as one continuous circle.
Arcs and circles are not normally an issue with CV mode. Code made up of short straight segments or sharp corners can cause issues.
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
If his CV settings are out of whack with his motor acceleration settings, they will cut sloppy. This isn't hard to do with Mach. But the reason why I said what I said was because someone was telling him to make all kinds of changes to his settings to test, when all he had to do was put a G61 in his code and cut circles for test purposes. I would agree with you totally if the circles he was trying to cut were bigger, but they are tiny. I would agree that flex may be an issue, but it's more than likely that something is loose somewhere. I highly doubt that given the fact that he's using a CNCRP setup, he actually has a flex problem... Unless we're referring to something being loose as flex. Those machines are more than stiff enough to cut a good circle.
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I value both of your input. I you are right, there all kind of flexing things. My gantry risers have some play in them, I tighten the motor and it helped a bit.
I cut a 1.5" circle pocket and it came out pretty well. Much better than this weekend.
I read somewhere about the "pull test" I engaged the motors (power on the machine) and started to tug at it. And I noticed there more play on the risers than on my Z carriers and Z axis.
Once I tried to tighten everything (Still some play left) I run a circle pocket. I also used HSM express (I am an inventor user) to make the G-code and the results were quite acceptable. I really bought is the G-code that made the different.
I just really need to get my upgrades and loctite all the bolts.
Here is a pic.
I'm glad you're getting it straightened out. Good luck! When you start getting some projects cut, post some pics
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You have no idea how much I want that BuckN. I have been sturggling with this machine / learning through hard knocks since Nov 2013. I have yet to cut anything "real" But I know that with the support from you guys and CNCRP I will be up a running in no time.
Re: Is anyone else having problem cutting circles?
More than one way to shine a turd. Make a rough cut and come back with multiple finish passes so it will deflect less. Use a shorter tool, buy quality tooling, and know the limits of your diy machine when programming.
Washington state
Re: Is anyone else having problem cutting circles?
Thanks, it's all sorted out.
Re: Is anyone else having problem cutting circles?
Good to hear!
Washington state
Re: Is anyone else having problem cutting circles?
I've been reading through this thread, and i hate to tell all the "Flex in Machine" Guys that you may be wrong, but "You May Be wrong" you see i have always had this problem as well, and i thought is was that, but i just completed a Plasma Cutter and guess what? you got it oblong circles. the plasma cutter never touches anything. i think it might have something to do with the way mach interprets I s and J s in mach.
No solution yet
Re: Is anyone else having problem cutting circles?
This is not a problem with Mach whatsoever if your circles are coming out oblong, you either have not calibrated your x and y correctly of you have backlash issues.Originally Posted by jonmessenger
Re: Is anyone else having problem cutting circles?
Calibration does mean a lot on some machines. You cannot just punch in the numbers that should be there after doing the math. You need to actually measure the travel to confirm or adjust the steps to get the target length. Mach 3 has a calibration aid for adjusting the steps per inch or MM and it will let you dial each axis in. Once you know that the machine travels 5.75" when you call for that distance, then you are farther along in troubleshooting the cause. You may find that the issue disappears.
On a plasma, just because the torch isn't inducing any cutting forces into the machine, doesn't mean that all the other axes aren't either. Especially given the speed needed for some materials. A gantry traveling at 150 IPM may suddenly need to go back where it was coming from. It has to stop all that momentum instantly. Any slack at all will show itself right there. Consider how many times the machine may do that during a job. Mach 3 does try and lessen that type of impact with CV.
Lee
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