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# MG New installation & results

Hi Paul / Dam and others ...and A HAPPY NEW YEAR!

Finally my MG arrived via EU warehouse and installed yesterday

Everything went fine (according to Pauls installation guide)

Motors worked smoothly without any parameters correction. (I will also check motor speed limit )

I noticed when trying to engrave with LB a simple TEST logo I got the following results in A with default \$28=0

Changing pwm frequency I got the following res B.\$28=1 C.\$28=5 D.\$28=10

Is it normal?   speed is around 200mm/s

I have also one question: I cannot calibrate max laser limit

With S=1000 and \$31=1000 MG sends 30mah (!!) to laser tube (out of range!)

I played with the values S=900 and \$31=1800 and managed to get max around 12mah.

I am trying to figure out a ratio to set the limit to around 15-16mah for 100%.

Is it correct or I am loosing pwm resolution?

Alex

Hi Alex,

Happy new year to you too! Well let's get straight into it.

Changing pwm frequency I got the following res B.\$28=1 C.\$28=5 D.\$28=10

Yes this is normal because the PWM freq gives different outputs. \$28=1 is 120 Hz so you get a lot of rough dots. \$28=10 is about 10kHz and probably the max that the K40 PSU can process. The default freq is 1.5kHz (setting 5).

Setting the \$31 needs a bit of explanation in order to set it. The S parameter is is value of the G code program setting the laser  strength. The user set this in the laser program (e.g cutting at 30% power). So the max S output from the g-code for 30% is S300 when S1000 is full power. See S as a refence pointer.

As you described, \$31=1000 gives you 30mA. \$31 is the power range in the controller. For the K40 it is set to 1000 and S and \$31 just happen to match. So you \$31 should be 2000.

30mA equals \$31=2000 so S1000 equals S1000/range 2000*max current30=15mA.

Note: However for the curious ones, of course you could set the S reference point as 500 in Lightburn and lease \$31=1000. S500/range 1000* max current 30mA=15mA too! However 500 points for engraving is rougher than a 1000 so you loose resolution here.

Hope this makes sense. Let me know your findings.

Cheers Paul

ps. try to run the tube at 80% max to extend its lifespan.

Cheers, Paul awesome.tech

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