Mode burn?

[Joseph Leavell]

So, just curious, but does Russ do his mode burns without any lens? If so, what do you guys think of mine... The left was 80% for 10 seconds, and the right was 60% for.... 45 seconds... Also, whenever I do a quick pulse there's almost 2 completely visible 'orbs' of power. Thanks!
(50W tube supposedly)

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[Gene Uselman]

This is below the laser head with no lens installed? Also it would be helpful to have some reference as to size- it is hard to guess how deep the burns are actually going.

almost 2 completely visible 'orbs' of power

- I have no idea what that means, picture would help.

When we post pictures, we know all the details but members looking at them do not and often have no idea of the context of what they are looking at. We all do that, of course, and we should get in the habit of adding more details.

[Joseph Leavell]

Sorry, I had edited a reply but then forgot to post it, so may as well here.
1:Yes, below laser head with no lens installed.
2:The circumference of both is about 5mm or so, the left is 2.8mm in depth, and the right is 8.2mm in depth.
3:As for the "orbs" I speak of, it does this sort of thing on the initial pulse (I can get the exact photo if required, but I hate the smell of burning acrylic so I do it as little as possible):

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Also, if I look into it as it burns, there's like a cone in the center where it isn't really hitting or something? Not sure, just that there's maybe .5-.75mm 'volcano' peaking up while the laser is turned on

[Joseph Leavell]

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[Gene Uselman]

Is the last picture a side view of the first picture you posted? The first pict looks normal for no lens- the main power in the beam is in the center and it lessens as you go out.- the last pict looks like it has flat bottoms [could be your inverted volcano reference, hard to see].

The 'Orbs' that you drew... is this sentence referring to them or to the pictures?

Also, if I look into it as it burns, there's like a cone in the center where it isn't really hitting or something? Not sure, just that there's maybe .5-.75mm 'volcano' peaking up while the laser is turned on

I am not trying to be obtuse... I'm just old and not understanding the question.

[Joseph Leavell]

So in this the left is the 80% for 10 seconds, the middle is the 60% for 45 seconds, and the right top is the pulse where it's almost 2 distinct points of power. I tried to explain the volcano's as well, so the bottom left has like a mound at the bottom that comes upwards, and the middle has like a point from the center coming up. The main question I guess I was getting at, is
1: is 2.8 / 8.2mm what you would expect for an acrylic mode burn for 80%/10 sec and 60%/45 sec on a 50W tube?
2: does my tube seem funky in that it's forming 2 points of power instead of one central, or if you do a very short pulse on yours does it also kind of make that double burn?
3: I'm bad at explaining, you're definitely not obtuse! I appreciate the help and am more than glad to explain anything I'm not clear on

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[Gene Uselman]

That is strange- I suspect that after going thru the lens it will cut/engrave alright- how does the machine perform?
I actually have two 130w Reci W6 tubes that have a donut shaped burn pattern [which you appear to have] instead of a concentrated 'dot' and unfortunately there is so much divergence in the beam that by the time the beam gets to the far corner [a 900x1300 and a 1300x1800 machine] the donut shape is so large that I cannot center it on the 25mm mirror in the laser head. These are expensive tubes and I am quite disappointed as you might imagine- I have since bought a SPT 130w tube from LightObject in Calif, which works as expected.

[Joseph Leavell]

It does both of those "ok", but it seems I'm getting vastly sub-par results to what people with similar setups get. I also think that since it's less conical more more donut shaped like you said, that it's attributing to my cutting being limited since the high power is moved further out, thus it loses focus quicker and scorches the edges more. I do notice that my lower-right corner has less power, so I tend to only cut top-left

[Joseph Leavell]

Are you able to do a mode-burn test on that good tube so I could compare? If you ran at like 32%/10 it would be equivalent to my 80%/10sec

[Gene Uselman]

I do notice that my lower-right corner has less power, so I tend to only cut top-left

That is almost always a mirror alignment problem. I don't have access to my acrylic blocks right now and I am in the middle of cutting out pieces for a new rotary device [my last one is going with my 1300x900 laser next week].

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