Bad lens - but not at first glance... Epilog Helix

[Doug Fennell]

Well, looks like my banding errors on photos may very well not be a bad tube after all - I may have to replace it in the end, but there is no question that this lens and the mirrors are causing compounded errors.

You can't see the damage by looking through the lens assy... gotta take it off to see what's really going on. Easy to do, just 2 screws and the entire assy comes off for inspection.

Dosen't look bad from this angle -

645.jpg

But from here..
646.jpg

and here...
647.jpg

The mirrors all have a uniform haze that won't come off, so replacing those as well. The good news?? Well, if you're on the fence and thinking about buying 3rd party lens and mirrors because Epilog's are to expensive, think again... the lens from Epilog is $104, and only one of the mirrors is over $35. Total for the one lens, 1 pass through and 2 mirrors was just a bit over $200! Not bad at all.

[Chris DeGerolamo]

So did the swap fix your banding issue?

[Doug Fennell]

We'll see - I'll have the parts on Tuesday. I hope it will fix it, but I'm not necessarily counting on it. I very well may have to buy a tube as well, but this is the first logical step in the repair.

[Joe Pelonio]

I normally take off the two screws for routine cleaning but then every 3-4 months take the lens out of the holder to inspect more closely. That gold coating does wear off in time.

[Rodne Gold]

That lens doesnt look too bad , the lenses we use are often a lot worse and they still work ok. Im pretty sure banding is not a result of lens issues , why would a damaged lens where the beam path is constant thru the damaged bit cause banding which is not a constant type of distortion?

[Frank Corker]

Don't mean to dampen your concerns, but my lens on my Helix looks far worse than your and it works fine. I certainly have not had banding errors nor unusual reactions to the engraving by using it.

[Dan Hintz]

I hate to burst your bubble, Doug, but a new lens will not resolve your problem. What you're showing will not affect the beam in that manner. If you have jobs in the hopper and are expecting the new lens to solve the problem, best start making alternate plans now.

[Craig Matheny]

I just replaced my tube on epilog and had the pass through lens real bad like yours and took some advise from others "Dan" clean with acetone yes epilog says stay away from it but I took acetone and a lens cloth to the lens and got the lens spotless. I would try some elbow greese on them being yo have put them out to pasture nothing to loose.

[John Noell]

The good news is as Doug says, Epilog's prices and policies have come down to earth! No longer do you have to buy lens/mirror/mount as one over-priced piece. I just ordered a second mount and new mirrors for about $100.

[Craig Matheny]

Also if you have a laser built from 2005 forward and is 30 w - 60w with a coherent tube if it goes out you can know buy the epilog brand replacement for alot less. Just replaced my 45 watt saved about 2200.00 and the tube is hotter and cuts 20% faster then from day one.

[Zsolt Paul]

I had the same exact problem a few months ago. I was doing 3D carving and it was leaving bad lines, just like banding. As much as it didn't (and still doesn't) make any sense, it was the lense. I did everything BUT change the lense, because as Rodney pointed out, why would a constant problem (bad lens) produce a not-constant issue such as banding. Banding is generally a mechanical problem that shows up on one direction of the axis more than the other. Yet, when I changed the lense, it went back to working fine. Go figure! So, do keep your hope up!

See my thread:
http://www.sawmillcreek.org/showthre...d!!!&highlight=

[Dan Hintz]

I had the same exact problem a few months ago. I was doing 3D carving and it was leaving bad lines, just like banding. As much as it didn't (and still doesn't) make any sense, it was the lense.

I'm not sure I agree with your assessment that it was the lens, Z... here's a quote from that thread:

What I did is rotate <the lens> within the lens holder (I dont mean upside down) and thankfully, the beam is currently missing the spots and is working fine.

The beam covers a large portion of that lens, so rotating it would have little to no effect on the beam hitting the spots or not (not to mention you're rotating a round lens, which just changes where on the incoming beam the spots hit, not if they hit). The more likely explanation to the disappearance of your problem would be to you fiddling with the lens holder, applying pressure to the rails, the connecting band and cogs, etc.

[Martin Boekers]

Would it be possible if the lens did have an issue, plus the alignment was a bit off on the X-Axis
so that when the lens carraige moved back an forth that the beam would be at a different spot on the lens
depending upon the placement of the carraige as it moves left and right. Could this maybe have an effect on
the quality of the beam as it exits the lens?

[Dan Hintz]

Would it be possible if the lens did have an issue, plus the alignment was a bit off on the X-Axis
so that when the lens carraige moved back an forth that the beam would be at a different spot on the lens
depending upon the placement of the carraige as it moves left and right. Could this maybe have an effect on
the quality of the beam as it exits the lens?

Anything is possible... but the pattern would likely be different as it traveled across the axis (i.e., no repeating patterns).

[Martin Boekers]

Anything is possible... but the pattern would likely be different as it traveled across the axis (i.e., no repeating patterns).

But would it? The lines may be vertical instead of horizontal as it would be consistant as the carraige moves left to right
as the beam would be say defracted at the same position