Confused

[Mike Christen]

Hello all

I have a epilog summit (1996) 25 watt laser still going strong. I have always had problems cutting material of any thickness greater than 1/8". I was playing around the other day and lowered the frequency (the summit refers to it as "rate" 1-100%). I set the rate at 10% (always used 100%) and now i can cut 1/4" acrylic without a problem at 10 speed and 80 power. Does this seem strange? Seems to me the more pulses of the laser per inch the greater the cutting capabilities. I'm not sure if there is any hardwire issues that may have been reversed over the years.

Am I missing something?

Thanks
Mike

[Rob Bosworth]

Mike, oh man it's too early on a Saturday to get into this. But here goes. When you lower your pulsing rate, you actually are increasing the peak pulse power at the front end of the pulse. Your laser averages 30 watts of power over time. If you look at how the power in a pulse is generated, or profiled, it will help understanding. If the power distribution in a single pulse from your laser is shaped like a bell curve, the power starts out as 0, ramps up to say 35 watts, then drops back down to 0, the average power of that pulse will equal 30 watts. If you lower the pulse rate, it allows the beginning of the pulse to start 0, peaks very rapidly to say 60 watts very quickly, then drops quickly back down to 0 quickly. You still will average 30 watts of power through the duration of that pulse. However, since you have such a high spike of power at the front end of that pulse, you get more penetration in that spike, and then get a "tag along" effect of that extra power as the power drops off towards then end of that pulse.

Sorry about that explanation. Too early on Saturday to for my numbed brain to be working. Also, put 700 miles on yesterday, and four hours installing a machine. It didn't help that we left at 5 AM, and it was snowing and raining. It snowed and rained all day. Arrived home at 11:30 and it was still snowing and raining. When I was younger, that would have been a piece of cake. Not anymore!

[Dee Gallo]

Rob, I'd hate to see your brain turned on at full speed!

That was a really good explanation, one even an anti-techie like myself could understand. So why do my manuals tell me to max out the frequency? Is is not more efficient to take advantage of this "bell" effect and go lower? Is it the smoothness of the cut that requires the high frequency?

Thanks for the lesson, dee

[Mike Christen]

Thanks Rob

I understood your explanation perfectly, thanks a lot, the light is on.

Now go back to bed or have some coffee, and take it easy. Your work is done for the day, I Hope.

Thanks again
Mike