DIYLILCNC

1. EqualsP
   Member

   I finally got around to finishing my build nearly 2 years after I started. I am experiencing an accuracy and a possible noise problem with the Y axis. Below is a movie of the router trying to draw the arcspiral sample from EMC2 as well as a video. When the router is attempting change direction along the y axis it is making a horrible noise. There is no slop that I can tell in any of the axis and the marker is held firmly in place.

   the final output printing the spiral: http://dl.dropbox.com/u/257902/DiyLilCNC/Y-Error-Example.jpg

   a video while the machine is drawing the spiral, pay close attention to the noise the y axis is making. I'm not sure this is right. and there is a noticeable lag as it tries to change directions (67Mb .wmv file) http://dl.dropbox.com/u/257902/DiyLilCNC/y-error.wmv

   thank you, any help will be greatly appreciated

   Posted 1 year ago #

2. Taylor
   Key Master

   @EqualsP,

   Sorry to hear about your problems! Let's see...

   Video: Believe it or not, that's how a healthy rig sounds! Arcs in particular make crazy noises, especially when you run at a slow feed speed. You could look at changing your microstepping settings if you're noticing crunchy output - but I don't think this is your issue. See the HobbyCNC documentation about jumper settings for more info.

   Image: I know you've stated that the marker is held firm, but in our experience zip ties will always lose out to stepper motors. Your spring clamps are a second opportunity for wiggling. Note that the overall spiral does appear to be consistent in position - this tells me that you're not losing steps, so it's probably a marker shift that's hard to see.

   You can verify this by strapping a laser pointer to the sled, setting zero, and marking the laser point on the bed with a pen. Next, go ahead and run the same file a couple times in a row. Finally, return to zero and check to see if laser dot lines up with your pen dot. If it does, you're all set (though you will need a beefier marker attachment). If it doesn't, try to isolate the funky axis by running squares. You can write the Gcode for a square by hand, and it also has the benefit of showing you directly which axis is off.

   Posted 1 year ago #

3. EqualsP
   Member

   I was able to fix the problem. The issue was the set screw connecting the shaft from the y motor to the y drive shaft was slipping slightly when the motor changed direction. I had to remove the drive shaft and grind a flat spot into it so the set screw would be able to be tight and not slip on the shaft.

   Posted 1 year ago #

4. Taylor
   Key Master

   Well done! We'll integrate your solution into future documentation.

   Posted 1 year ago #

5. gera229
   Member

   Don't all shafts on motors from hobbycnc have a flat spot?

   Taylor do you guys cut parts for CNC builds out of your own CNC machines (I see they are laser cut, but still do you do it the way I asked)?

   Posted 1 year ago #

6. EqualsP
   Member

   Gera229, the motor's shaft had the flat spot from the manufacturer, but the 1/4" rod used as the drive shaft for the y axis did not.

   it should probably be done for the x-axis shaft as well.

   Posted 1 year ago #

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