I’ve been cutting a lot of acrylics lately and I’ve had to cut some things and assemble them accurately. My Altmill has never given me any problems before but not Im noticing that when I’m cutting a 4.5 mm piece of acrylic. The first cut doesn’t align to the second step down cut. The material is well placed.
So what I’ve observed was that whenever it started the other pass and runs down the Y axis there’s a very slight pause in the machine when changing from X to Y direction of the cut. Can you guys please help me identify what’s going on.
I can’t tell you if what is happening is deflection due to something losse or not (holding the tip of a mounted endmill between two fingers and wiggle it around might help identify if you have a mecahnical problem in that direction. )
I do have some wiggle in my machine that results in visible deflection marks. Not as profound as you have, but still enough to be visible in cutouts (especialy at engagememt points) and pocket bottoms.
Instead of hunting down the wee slop in my machine (that’ll probably needs me to take it apart, reassemble it with no guarantee of improvement, let allone if it will be permanent ), I changed my cutting strategy to hide the imperfect cutting. I engage cutouts like a spiral toolpath and use a shaving final pass in pockets.
I choose to not go into the rabbit hole of trying fixing the machine because I figured that I can easely worsen the situation, instead of improving, leaving me with a problem I cannot hide using alternative cutting strategies.
I know this isn’t realy a helpfull post, because your deviation clearly is way beyond tiny, but it might help you mitigate problems in running projects untill you get feedback that will identify your problem.
my bit is well secured and the workpiece is. But for some reason I notice that it occurs only when changing from a cutting in the x direction and as soon as it turns the corner to cut in the y direction there is a very very slight pause. Could it be the motors? Not sure I’ve never encountered this.
@A13x Is this cast acrylic or extruded? I’ve cut both, but cast is much better for CNC work. I don’t know what speed you are running your spindle at so my suggestions may not work for you. I run my Makita as slow as it will go = 10,000 rpm. I would go slower if I could. I run at about 80 IPM. Any slower feed than that results in melting or at least distortion. If that happens, the swarth can distort a 1/8” mill. For best results, you should consider getting o-flute mills. They are single flute and remove the swarth much more efficiently.
I don’t believe that it’s a hardware issue for some reason Im feeling it has to do something with communication or my code or gsender or something with the motors.
Also I’ve noticed too that since I upgraded the gsender to the newer version after homing I’ve always had to reset the jog normal mode.
I will however try the lower rpm’s as you advised as I’ve never done it before.
@A13x If I were you, I would ignore my suggestion. If you have a process that has been working well, look to see what has changed to cause your issue before throwing out your entire process and adopting mine.
That said, I respectfully disagree with your conclusion. I don’t believe that it’s a gSender or gcode issue. Again, if the same code has been working, there is no reason to believe that is the problem. It may be something as simple as a dull end mill from cutting a lot of acrylic. That mill is working harder and maybe flexing.
@TDA would be a good source of information on this. Search his posts here. He includes an email address that you could write for his expert advice.
I do appreciate all your suggestion guys, as I’m just happy I can come here for help. Here in Belize its very rare to find people around who knows about CNC.
Here a video I took when I was cutting and as you can see whenever it changes from x motion to Y motion there’s a very very slight instance of a pause. Please take a look and what you think?
When I look at this footage, I do not directly notice a pauze, what I do see is the stock getting pulled up, and by the looks of it, quite a large amount. That might at least contribute to the inconsistent cutting.
@A13x That’s a good call by @Spamming_Eddie . However, looking at the chips you are getting, I would say that your settings are fine. Your hold down method is not. If the material can flex, you need to use double-sided tape or blue tape and ca glues to hold it down. Clamping the edges is not working.
If you have a process that has been working well, look to see what has changed to cause your issue before throwing out your entire process and adopting mine.