Hello Guest it is August 07, 2020, 06:30:15 PM

Author Topic: 4th axis  (Read 8041 times)

0 Members and 1 Guest are viewing this topic.

Re: 4th axis
« Reply #10 on: August 07, 2009, 02:13:02 PM »
OK some of the settings I did or didn't have checked, now it's working in a more normal way. What confuses me is the motor tuning I came up with 13.3547 steps per degree. After I set my accel and velocity the velocity reads 47,470 and the acceleration reads 3450, and when I jog in normal more it says the FRO is 449. I don't care if it's high if that's just a bug but I want to make sure that's normal?
Re: 4th axis
« Reply #11 on: August 07, 2009, 03:19:46 PM »
OK, some success. I did get the 4th running and figured out all the weird things you have to do. I actually engraved a test piece, but as Alenx suggested it is cutting a mirror image, why would that be I have a feeling it must be in Rhino, I don't think Mach would have anything to do with that. Any suggestions to why that happens?

Also the cuts are not bad but the lines are not super smooth as when I engrave the same text on a flat bar. They seem to have hesitation marks. Is there some setting such as CV that I should do something with to make it come out smoother or is that just the nature of using a 4th axis. I mean if the timing or something else was off it would be noticeable, right?
Re: 4th axis
« Reply #12 on: August 07, 2009, 03:40:12 PM »
OK I figured out what I think are the problems, first I reversesd the motor and everything comes out normal, this is good but why would Alenx's come out mirrored too, if reversing the motor was the cause? Is Alenx's motor revered too or is there a bigger problem?

Next I think the hesitation marks are from the Z axis moving up and down just slight per the Gcode, when I engrave from my other CAD program the Z, once making a pass, doesn't vary up and down. Why is this program making it go up and down slightly, is it trying to form somthing like when you do 'V' carving and it has to form the tips of letters. Possibly I have a setting wrong in my CAM program. If changed all the Z that are moving slightly to what the final depth should be would that solve the problem?

Offline alenz

*
  •  137 137
    • View Profile
Re: 4th axis
« Reply #13 on: August 07, 2009, 05:30:33 PM »
Yes, I would do exactly what you suggest. (I was only trying to work with the code as presented).
Sure, set Z-zero on the surface of the cylinder and the cut depth to minus .005. Enter the actual radius (to split hairs it would be the radius less .005) of the cylinder in the DRO and it should work fine. The error that I referred to earlier will now be when Z is positive and cutting air, so no problem. In fact, this is how I should have suggested in the first place. Your cylinder is constant diameter so no need for mach to recalculate new angular feeds based on dia change. If the cylinder is not constant diameter for the full length, then mach does have the ability to compensate, that is, it keeps track of the Z value and the angular feed in deg/min is decreased as the diameter increases. It only needs one small tweak to be useable and that is to recognize that a change in Z is NOT a change in diameter but a change in radius.

I’m not familiar with RhinoCam but the code does (IMHO) have a few rough edges. I took the liberty of modifying a few lines to illustrate what I’m referring to. It should run faster. That doesn’t make it right or wrong, just a personal preference. The code is not optimized, that is, it jumps back and forth from place to place.

In regard to the mirror image comment, I had to rotate the view in the tool path window so that it could be read from inside the cylinder looking out <grin

Al

PS Try the modified snippet and see what happens.
Re: 4th axis
« Reply #14 on: August 07, 2009, 06:11:07 PM »
I just tried to set the top of the part at zero instead of at the radius and RhinoCAM doesn't like that, it has to be set at the raidus for center. But I don't care cause I put the actual part on and I crashed the machine hard, oh well a ton of work down the drain. What I did was pause cutting for the last part so I could reset the height because it was cutting a hair to deep, fine for what it was cutting but the last part has to be shallower. When I did "run from here" and the box popped up it said 1.72, OK, then I hit cycle, but it wanted to go to Z-Zero first instead of Z1.72 and it blew right through my part and broke my bit. WTF!!! the pop up box said move to Z1.72 so why did it go to Z0 first????????????

Offline alenz

*
  •  137 137
    • View Profile
Re: 4th axis
« Reply #15 on: August 07, 2009, 06:59:35 PM »
That pop-up box has a 'Rapid Height' setting which appears to be zero by default. Set it to a value greater than your current height and it will go that position instead.
Al Lenz