step-6-laser-backlash-correction

Battle of the Backlash

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Backlash – “Recoil arising between parts of a mechanism.”

A problem i am almost guaranteed to find on 90% of the machines i visit. Backlash occurs whenever the laser head changes direction, mostly apparent on the X axis of the x700. When the head changes direction a couple steps are lost taking up the slack in belts and pullys.
This can be corrected to some degree mechanically but due poor design considerations of the x700 it cannot all be eliminated.

I have written the following guide for backlash compensation, less then 0.2mm Backlash compensation is normal, if you find your machine needs more after belt tension i suggest consulting a Laser Service Engineer.


Step 1 – Download Backlash Test file


Step 2 – Load Test file into RDWORKS use two power levels or speed settings. Make sure that the x lines start at the sides and the y lines start at the top or bottom.

 

step-2 rd works backlash


Step 3 – When sending the job to the laser make sure path optimise isn’t ticked or it will change the start points for each circle.

See under the user tab, (Backlash X(mm)) and (BacklashY(mm)) that’s where you will enter backlash settings. Remember to do a read first then enter your backlash and write back to the machine.

 

When sending the job to the laser make sure path optimise isnt ticked or it will change the start points for each circle. See under the user tab, (Backlash X(mm)) and (BacklashY(mm)) that;s where you will enter backlash settings. Remember to do a read first then enter your backlash and write back to the machine


Step 4 – Send Test file to machine and run.

I couldn’t enter a negative value to show but here is an example of too much backlash compensation.

 

step-4 backlash laser


Step 5 – Any circles that start at the top and don’t meet up need the Y backlash tweaking. Any circles that start at the side that don’t line up need the X backlash tweaking.


Step 6 – Use thermal labels or paper to get it as close as you can, then when you think you’ve got it perfect use a piece of dark acrylic, rub over with a white pastel crayon and use a jewellers loupe. You’ll find another 0.01 to 0.005 easily that you didn’t notice before.

 

step-6-laser-backlash-correction

 

After successfully following these steps your machine should be almost completely Backlash free.

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