Banding lines in one area

[agron zeka]

Dear members,

Need help with my mercury laser, when engraving photos (see attached pic) there always banding lines in one area somewhere between inch 1 until 10 then they disappear I never had this kind of problem before, I've checked the belt it's ok, any suggestions. See forehead.


DSC_0179.jpg
best regards,

[Craig Matheny]

Check your lens

[Kev Williams]

The banding is at the top- Is the material you're engraving at the very top of the table? If so, try moving it and starting at 3 or 4 inches below the top-

Just speculating on a possible cause here, but while doing extensive testing of my Triumph last month to locate my erratic engraving and cutting problem - which I thought was a bad X stepper but turned out to be a broken wire TO the stepper- I discovered another issue that was causing my X stepper to vibrate, causing the whole machine to 'sing' at certain speeds... The issue is belt tightness. My machine is 1300 x 900, so the X belt is very long. I adjusted the belt tension right after I got the machine based on free play with head at the extreme left or right ends of the axis. What I wasn't noticing was how brutally tight the belt was on the SHORT side of the belt! The belt remained quite tight on the short ends for about 6 to 8 inches from extremes. I loosened the belt in small increments until I got zero vibration from the stepper during full X sweeps. The short sides of the belt are still nice & snug, but not 'brutally' tight, and my engraving quality is great!

So my speculation is, that the belt teeth & cog engagement when the belt was very tight must have been adding stress to the gantry movement to cause the vibration...

So, since your banding is at the top of your engraving, which is where the short sides of your Y belts would be at their tightest, it could be belt tightness is mechanically creating your banding. Testing from a more central Y coordinate may confirm this...

Of course, all this means zilch if you're engraving from the center of the table! But thought I'd throw this out there!

[agron zeka]

Thank you Mr. Williams for your reply, I've done that but still the lines remain, and they start at inch 1 until 10 approx, it's very frustrating. Even if i do a double pass still the same.