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View Full Version : Question for the Pro's; Laser out of focus? Or something else?



Ben Levesque
12-24-2006, 12:03 PM
I am trying to engrave tiny lines, but I can’t get my laser to create great looking lines (by vector).
My laser is an Epilog mini 35 Watts, 2 months old.

My current material is wood; it is maple veneer and maple cards, mostly 0.02'' thick.
Also the 1/32 Birchwood plywood gives me the same results.

I've included a small picture to show what tests I'm currently doing.

In brown is some 1/64” thick Birchwood plywood (the good lines), and the not painted wood is a .02” thick maple card (the bad lines).


Since my current issue is to try and have the thinnest lines, I tried to create theses with higher speed and lower power. But the lines are too large anyway, as you can see in the photo.

I've tried with auto focus, which everyone tell me to never use, had also tried manual focus with the gauge, and I got the same results.
I use a 2"lens kit, so I also tried focusing with a ruler using the real 2” from the underside of the lense to the top of the material, which I discovery was 1/8" to low when using the gauge (wow!), but I get the same results at the end.

Lenses look ok, no apparent dirt on them,

Alignment with the little black X disk and the red pointer seems also ok.

I don’t know what else to try. Or I’ve reach the limit of the Epilog laser regarding thin lines?



Any suggestions?

Ben

Joe Pelonio
12-24-2006, 12:23 PM
Ben,

Those Epilog focus gauges are adjustable (2 screws). There are other factors that can cause problems with thin lines, dirty lenses or mirrors, dirty x-axis sensor strip. Also, the harder the wood te better the result, any chance you can try it on Oak? Something must be wrong because I've never had a problem doing thin lines even on wood with my Epilog Legend 24tt 45W.

Dennis Perry
12-24-2006, 12:56 PM
Here is a easy focus test. With say a 6 inch long piece of wood raise one end up 1 inch and focus to the center of the wood or the 3 inch spot. Vector a line the full length and at the point you have focused to should be the thinnest. The thinnest part of the line is your focus lenght.
Looks to me like a problem with optics damaged or dirty.

Cheers Dennis

Richard Rumancik
12-24-2006, 1:37 PM
I would tend to blame the optics as well - which was your first hunch. Since you have ballparked the focus using a physical measurement and it still seems to be marking out of focus something else seems at play. I don't have your machine so don't know what the lens holders look like. Hopefully the lenses only go in one way and it is not reversed. Are all the mirrors properly seated and tightly secured? Do you have a second lens to experiment with? That might help track down the problem.

By the way - for fine work I would suggest a 1.5" lens if you have it. I know they are expensive to buy, but for .020" and 1/64" material I would not use my 2" lens. I cut and mark .062" basswood with the 1.5 inch "engraving" lens. I can get .004-.006" kerf on the front and less than .004" on the back side (a piece of paper will bind in the cut on the exit side).

Dave Jones
12-24-2006, 7:26 PM
In your photo you say the "good" lines are birch plywood. Did you laser those? Or are those something you got somewhere else?

There's nothing in your photo that gives it a sense of scale. For example, how far apart are the vectors that we are seeing?

What frequency is your driver set to for vectors? Maybe try turning it down to a frequency of 300 or 500, if it isn't now. That reduces the heat affected zone around the vectors. I'm assuming that was done in vector mode, and not raster mode.

As Joe mentioned, try other types of wood. Some woods do always end up with thicker lines because of the oils/resin in them and how soft/hard they are.

Have you tried doing very low power lines on the surface of index cards? Do it low enough that it doesn't go through.

BTW, the autofocus on my Mini-24 seems to work very well.

Ben Levesque
12-24-2006, 8:04 PM
In your photo you say the "good" lines are birch plywood. Did you laser those? Yes, I had lasered birch wood too = same result as the mapple in picture Or are those something you got somewhere else? The brown piece (birch) was lasered on another brand of laser, but I was told that the Epilog could do the same fine details.

There's nothing in your photo that gives it a sense of scale. For example, how far apart are the vectors that we are seeing? I've put another pic with a measure, to show scale.

What frequency is your driver set to for vectors? Maybe try turning it down to a frequency of 300 or 500, if it isn't now. That reduces the heat affected zone around the vectors. I'm assuming that was done in vector mode, and not raster mode. I had tried different freq, including the one suggested = same result.


As Joe mentioned, try other types of wood. Some woods do always end up with thicker lines because of the oils/resin in them and how soft/hard they are. Like I said I had tried Brich plywood, and mapple, and also basswood.
same result.

Have you tried doing very low power lines on the surface of index cards? Do it low enough that it doesn't go through. I am at 3% that's pretty low, lower than that, nothing appears.

BTW, the autofocus on my Mini-24 seems to work very well. I tought mine was too, but to get fine details there's an issue.

I just took the lens appart and cleaned them, put everything back, and I get the same quality.

After Xmas I will send a request to Epilog about this, I don't know what else to try.

Since the start I had nothing but issues with my Epilog mini.
Chage the button screen, then change the main bus card were the drives chips are, the drive that lift the table up was faulty.

Thank god I'm not counting on this machine for a living.

Ben

Dave Fifield
12-25-2006, 4:55 AM
Ben,

Now that we have some scale (your 18 mil measurement in the photo) to compare things with, blowing the picture up and taking measurements off it, I see that your Epilog Mini's lines are about 4.5 mil wide. This is about normal for your laser with its 2" lens. The lines that the "other" laser engraved measure just over 1 mil wide.

You will not be able to acheive this fine a line width with an Epilog Mini 18, sorry. You will need a different model laser (one with interchangable lenses like the Epilog Legend 36EXT model - like wot I have) fitted with a 1.5" lens to acheive fine line width in the 1 mil range.

Sorry! :mad:

Dave F.

P.S. What is the item you're trying to engrave - I'm very curious - it looks electronic in nature....???

Dave Jones
12-25-2006, 10:41 AM
Your image with the scale speaks volumes. With a 2" lens on a Mini you should expect a line width of about .004"-.006" at best. It can be wider if you are going deep into soft materials.

If you run the angled material test that was described a few posts back, that will show the laser going in and out of focus as it goes along the angled material. At it's sharpest you will see your minimum width for that material. The reason I asked specifically about index card stock is that I've been able to get very fine lines marked on them if the power is low enough and speed high enough to not cut all the way through. I'm just trying to seperate what the laser beam width is vs what any specific material can handle.

Do you know what kind of laser the "good" lines were made on, and what type of lens it had? Also, if it was painted, the paint could have filled in the lines a bit, making them look thinner.

Ben Levesque
12-25-2006, 2:28 PM
Do you know what kind of laser the "good" lines were made on, and what type of lens it had? Also, if it was painted, the paint could have filled in the lines a bit, making them look thinner.

The brown part was made using a Laser Pro 12x8 upgrade to a 35 Watts with a 2'' lense.

So if the Epilog mini 35 Watts can't beat that? What else?
And no, the paint did not fill the groves, they were very well done with a speed of 100% at lower power.

I'll do an angle test and see what it gives.

Ho! and Dave is asking what it is :) (an indice: Roofwalk)


Ben

Ben Levesque
12-26-2006, 12:28 PM
I did an angle test, and the best it did is a 0.006" line. Bummer!

The mini 18 can have a 1.5" lens installed, but will it do the job? And it is probably selling for another 650$ or more? Very discouraging in deed! :(

Ben.

Mike Null
12-26-2006, 12:48 PM
If you're considering the purchase of a new lens you might want to try this company. http://www.iiviinfrared.com/index.html

Dave Jones
12-26-2006, 12:53 PM
I'm just curious if you were there watching while the other one was engraved. If so, I'm wondering if maybe they had a mask on the material when it was engraved. Or if the wood was sanded after engraving.

Ben Levesque
12-26-2006, 6:07 PM
I'm just curious if you were there watching while the other one was engraved. If so, I'm wondering if maybe they had a mask on the material when it was engraved. Or if the wood was sanded after engraving.

Dave: No mask or primer was used, neither the wood was sanded. It was done by one shot with the Lasr Pro model.

Thank Mike for the link: , but my optics physics is pretty far away for me right now, I'll quote Epilog for a 1.5 kit since I surely could't find the right one to install on my Laser from the infrared lists.

Ben

Dave Fifield
12-26-2006, 6:20 PM
If you just change the lens from 2" to 1.5" focal length, the focus will be 1/2" nearear the work surface. This may cause issues with focussing (manually/automatically) with the auto-focus plunger hitting things etc. My 36EXT overcomes this problem by mounting the 1.5" focal length lens 1/2" nearer the work surface.

I wasn't previously aware there was a 1.5" lens option for the Epilog Mini, but I see from here (http://www.epiloglaser.com/mini-helix_1.5_lens.htm) that it is now available! This will please quite a lot of people I'm sure! It looks like they do the same thing for this lens - it's mounted 1/2" closer to the work surface so the standard focus gauge and auto-focus will work just fine. Let us know when you get a quote please Ben. It should be $300 or less IMO.

:Dave F.

Jim A. Walters
12-26-2006, 6:47 PM
There is a SMC member that sells lenses: www.oemoptics.com (http://www.oemoptics.com). He did a FreeStuff drawing a while back.

Jeanette Brewer
12-27-2006, 10:44 AM
Let us know when you get a quote please Ben. It should be $300 or less IMO.

:Dave F.


Good guess, Dave! The 1.5" lens for the Epilog Mini is $300

Ben: Touch base with your local Epilog distributor and he can get one ordered for you.

Richard Rumancik
12-27-2006, 11:47 AM
There are a few things that confuse me about this thread. Ben said the brown sample was done on a LaserPro 35 watt with 2" lens. Meanwhile Dave F. estimated the beam width on the LaserPro sample to be .001" wide. How is it possible to get a .001" beam width with a 2" lens? I didn't think this was possible. With a 1.5" lens I can maybe get .003" cuts in really thin material but that's about the limit. I'd like to know how to get .001" cuts . . .

It was my understanding that the Epilog with the "Radiance Optics" option could achieve smaller spot sizes. But if Ben buys the 1.5" lens assembly, he will still be limited to about a .004" beam - Correct? (I'm assuming he doen't have Radiance Optics.)

Dave F: do you have the Radiance option on your Epilog? I'm guessing you have it, because you suggested a 1.5" lens would provide a .001" beam, and I thought that would only be true if Radiance Optics was also installed.

Roy Brewer
12-27-2006, 12:51 PM
I am trying to engrave tiny lines, but I can?t get my laser to create great looking lines (by vector).
My laser is an Epilog mini 35 Watts, 2 months old.
Ben,

To tie up a few ends, the Mini 18 does not have the Radiance Optics(TM) which yields a smaller spot size. I'd agree with Richard's estimate that even with the new 1.5" lens you're not going to get below about .004" even optimizing your speed/power/frequency/focus.

Beginning with the Mini24, all larger Epilog systems have the Radiance Optics(TM).


I've tried with auto focus, which everyone tell me to never use, had also tried manual focus with the gauge, and I got the same results.
As Dave Jones confirms, I know of very few Epilog owners who do *not* use Autofocus. I suspect the people suggesting you not use it are using other lasers(?). You may, however, want to discuss with your distributor or Epilog tech support the process they use in adjusting AutoFocus for maximum value.

Ben Levesque
12-27-2006, 1:16 PM
(I'm assuming he doen't have Radiance Optics.)


No, and I don't have the least idea what a Radiance optic is!

Ben

Tim Goldstein
12-27-2006, 4:29 PM
Radiance optics is a fancy marketing name for putting a beam expander in the machine. They mount it at the output of the laser tube on the ones I saw at the factory. By expanding the beam it then focuses to a smaller point. Doen't make sense, but it is a normal optics concept. Best as I can tell from reading the patent the Universal HPDFO add on is about the same thing.

Dave Jones
12-27-2006, 5:35 PM
Tim, here is my understanding, based on something Rodney said (and a little guesswork).

The very center of the beam that goes through the center of the lens is changed very little by the lens. Basically passed straight through. As you get further out from the center, the curve of the lens focuses the wider part of the beam into a small spot. The further out from the center, the more curved the lens is, the more the beam gets bent by the curve and focused.

So with a narrow beam a large amount of the laser power is passing through the center and not being changed much. And a portion of the beam that is wider gets focused into a spot that combines with the part in the center.

With a much wider beam, carrying roughly the same total power, a smaller amount of the power is going through the center and a larger percentage is being focused by various points on the curve of the lens into a spot in the center of the target. I would also guess that since the lens is thinner at the edges, the beam that travels through that part loses less energy to the optics than the part passing through the thicker parts of the lens.

Also, with the expanded beam, you are using a larger surface area on each mirror and on the lens, which means less loss from each of those and from any imperfections they each have.

As I said, there's a certain amount of guessing here, so take this with a grain of salt.

Ben Levesque
12-30-2006, 7:55 PM
Ben,

To tie up a few ends, the Mini 18 does not have the Radiance Optics(TM) which yields a smaller spot size. I'd agree with Richard's estimate that even with the new 1.5" lens you're not going to get below about .004" even optimizing your speed/power/frequency/focus.

Beginning with the Mini24, all larger Epilog systems have the Radiance Optics(TM).


As Dave Jones confirms, I know of very few Epilog owners who do *not* use Autofocus. I suspect the people suggesting you not use it are using other lasers(?). You may, however, want to discuss with your distributor or Epilog tech support the process they use in adjusting AutoFocus for maximum value.

I wish I had the Aztec Calendar Corel file to see if my laser can acheive this kind of details.

I will have to seriously re-think my options here.

Ben

Dave Jones
12-30-2006, 8:50 PM
Here, try this:

www.redtengu.com/images/raw/Aztec.eps

Richard Rumancik
12-30-2006, 8:50 PM
Ben, I didn't want to see you buying a lens thinking you would get .001" lines/cuts when it doesn't seem possible with "normal" optics.

Someone on the forum had an Aztec calendar file, but when I searched, it seems like it was not posted - at least I did not find the file. (I wouldn't mind trying it on my laser as well, just to see the difference.)

But you originally said the sample you were copying was done with a LaserPro. I don't know if they have any special optics kits like Epilog and Universal - I have not heard of it - but you need to talk to that laser owner if possible and see exactly what they have.

I have never seen Epilog or ULS say what the spot size is with the special optics. They use different methods but the end result is that both systems are supposed to achieve finer resolution than normal optics.

Synrad says that a beam expander/collimator and aspheric lens (the method Epilog Radiance Optics implements) can reduce spot size from .004 to .002". So that's a ballpark estimate.

I have to admit I was impressed with the Epilog version of the Aztec calendar (don't have the ULS version). If you have a lot of potential business doing fine work then maybe the special optics would pay. (For most users the advantage hasn't been so clear.)

Let us know how you make out with this . . .

Vicky Orsini
12-30-2006, 9:07 PM
I have to admit I was impressed with the Epilog version of the Aztec calendar (don't have the ULS version). I have seen Epilog's, Universal's and Trotec's versions of the calendar. Epilog and Universal had theirs pre-made and ready for display when I arrived at the demos, so I don't know which machine produced them or whether or not they had any special optics on them. Trotec's sales rep made one for me on the spot. He didn't say whether his machine had any special optics on there. It looked like a standard 2" lens to my untrained eye. All three seemed to be quite comparable in detail. Definitely not as "off" as the original poster's pictures would indicate. I haven't seen LaserPro's version. Once I get my exhaust fan set up, get a little more practice under my belt and I can get hold of a decent graphic, I'll gladly show you what the machine can do. ;)

Bill Cunningham
12-31-2006, 12:54 AM
I had posted a picture of the aztec Cal. cut into a piece of pine, to show that pine 'could' have some colour.. That file was just a 300 dpi lineart .tif file I found someplace on the web.. it was definately NOT good enough to have the software trace it to a .cdr file, so I never even tried..
If anyone wants it let me know, and I'l post it in a .zip file..

Dave Fifield
12-31-2006, 6:38 AM
Richard - yes, I have a 45W Epilog Legend 36EXT (just a few weeks old) :) I bought the optional lenses with it too. It's very much like my old Mini 24 in many ways, but the larger working area and tiny kerf (in my marquetry veneer cuts) are features that I wouldn't want to do without now!

Roy & Richard - I think you guys nailed it - unless Ben's laser has the Radiance Optics (TM), the 1.5" focal length lens isn't going to help much.

Dave J. - I think you captured the essence of the advantage of beam expansion nicely. As I recall from my university optics labs (many years ago!), it's all about minimizing path losses and maintaining coherency in the beam at the final focus point - in addition to the lens loss effects you noted, a high-power concentrated spot-size laser beam tends to heat the air through which it's running causing a refraction index gradient across the beam width that causes loss of beam phase coherency and excessive beam divergence (if the power is high enough). The beam expander/collimator/aspheric lens system keeps the beam as wide as possible for as much of the path length as possible, minimizing path loss and phase spread, resulting in more power delivered in a smaller spot at the work surface.

Ben - I have a Corel file of the Epilog Aztec Calendar (kindly supplied to me by another SMC member some time back). I will email you a copy of it.

Cheers

Ben Levesque
12-31-2006, 1:48 PM
I will see what Epilog answers me back regarding my query on fines lines and the 1.5’’ lens option.

We are still in holiday’s period, so I’m not hopping for any answers soon.

But I’ll keep an update on my researches here.



HA! yes! For everyone questioning on the Laser Pro results, I'm confirming that no special lens was used, just the ordinary 2'' lens, BUT alignment was work and rework badly to be able to attemt such results, which on my side with the Epilog I'm too green to try to play with lens aligment, the black puck is way not presise enought to do a real nice aligment, the cross has line of 0.014'' in width and the red dot is almost 0.050", I will need something else.


Ben

Peck Sidara
01-03-2007, 5:17 PM
Dear Ben,

We received your message yesterday morning upon our return from the holiday. Your email was forwarded to one of our tech reps, Brian Denileon. Unfortunately we haven't had a chance to address this yet as we're still catching up from the long weekend.

From the attached picture, it looks to be beam size related or focus related. Please note that the focus length isn't always exactly 2". I thank everyone that has replied with their ideas and suggestions and do beleive it's best that we discuss via phone.

Please give me a call at 303.215.9171 to discuss. I will have your email ready for review.

Regards,
Peck Sidara
Epilog Tech Support

Ray McAlister
01-04-2007, 2:38 PM
Are you sure it's not the software? Do you have a Hairline selected in the art?

Ray

Ben Levesque
01-04-2007, 7:56 PM
Are you sure it's not the software? Do you have a Hairline selected in the art?

Ray
Hi Ray, I may be green with laser optics alignment, but what you are asking is going a little too far behind, I am more advance than that, but a huge thanks for the care. :)

Ben