Preemptive Tube Replacement?

[Ed Maloney]

Laser is cutting fine, but the engraving quality is degrading. Mostly the near left side (surprise to me) and the far right side. Last week though the laser did stop firing during a run, but a power off/on took care of the issue. Tube is about 3 years old running each day about 5 hours. Usual cleaning and table leveling shows no problem.


In the past I replaced the tube when it just stopped firing. I am thinking this time to be ahead of the curve and order a tube instead so I have no downtime. Comments?

[Martin Boekers]

I'd talk with Epilog support to confirm it's a tube and not something else, maybe an amplifier? It's strange that its missing at the same spot on the X-axis.
What happens when you engrave the whole area and not just text? Have you noticed having to kick up power or slow down speed lately? Make sure magnets
for the lid are working. I've had issues in the past that the magnet safety switch was going bad and I stopped it from firing.

[Ed Maloney]

Hey Martin - Yes I talked to Epilog and they suggested the usual stuff. Clean your optics, encoder strip, table level, etc. About a month ago I had to replace the power supply (since the laser shut off after about 15 seconds) and that didn't help things with the engraving quality.

When they stepped me through the trouble shooting for the supply the interlock lights were OK. Power and speed are normal with no variations.

What do you mean about amplifier? Is it on the mother board?

[Martin Boekers]

Granted I have 75 watts EXTs, there are two amplifiers on mine, one behind the motherboard and one by the x-axis motor.
You can see pictures on this thread. http://www.sawmillcreek.org/showthread.php?221448-Amplifier-Boards-on-an-Epilog-EXT

[Rodne Gold]

600 days x 5 hours is only 3000 hours , a RF tube should last WAY beyond that....

[Ed Maloney]

600 days x 5 hours is only 3000 hours , a RF tube should last WAY beyond that....

Rodne - Not to hijack my own post, but I think I remember a post that said even if the laser/tube is idle and not turned on the tube would degrade over time.

[Rodne Gold]

It should not degrade significantly in 3 years... you should have gotten more useage from the tube...just saying

[Mike Null]

I agree but had a similar experience. My UlS tube gave out in the 36th month and ULS sent a new one in warranty.

[Dave Sheldrake]

RF tubes are often advertised as UP to 30,000 hours.

I've seen them last 10 years +, I've also seen them die in 100 hours.

cheers

Dave

[John Noell]

Three epilog tubes dead in four years. YMMV.

[Kev Williams]

Seems to me that a bad tube would misfire somewhat or mostly randomly. In this case the worst spots occur on the taller letters or other letters where there's much open space on either side of them, which isn't very random. I don't know the technical terms for it, but the higher-to-lower-to-higher power changes aren't happening correctly. My bet is this is a controller, tickle or similar issue.

[Kevin Gregerson]

Honestly even from universal I've seen tubes last 15 years and still put out more power than they were rated for. I've also seen them fail in two weeks.

[Ed Maloney]

I agree with you Rodney. Funny thing is that I can engrave small text 12x6mm with no problem (leaving 2" on the left and right of the sheet.) But larger engraving areas are streaked. As I mentioned for now it's cutting fine. I already turned down a job because of this. Just want to get as much life out of the tube before I spend the big money.

[Ed Maloney]

Another example of what's going on with my laser for those that have been following this thread. Any new comments or suggestions?


297248

[Jerome Stanek]

That looks like your mirrors need to be aligned or out of focus lens

[Ed Maloney]

That looks like your mirrors need to be aligned or out of focus lens

I will re-check that. The funny thing is the laser is cutting with no problem at all. In the past when the laser wasn't aligned, it won't cut the far right front areas.

Ed

[Dave Sheldrake]

Check your wiring, that tube looks to be missing initiation signals

cheers

Dave

[Ed Maloney]

Check your wiring, that tube looks to be missing initiation signals

cheers

Dave

How would I do that Dave?

[Dave Sheldrake]

Have a look for lose wires Ed, I've seen it happen on DC pipers but it's rare on RF units. Possible though and free to rule out :)

Trace all the wires that go to the tube unit from the control / psu and make sure if they are socket types that they are all fully home, if screw types make sure they are all tight (but don't murder them up)

cheers

Dave

[Jed Lawrie]

Another example of what's going on with my laser for those that have been following this thread. Any new comments or suggestions?


297248

Any update? The odd thing about this picture is that it engraved all of the outlines of the letters perfectly. The only parts that were left untouched was the fill inside the letters. To me that doesn't say its the tube. That is too much of a coincidence. Maybe it could the be control card?

[Ed Maloney]

Thanks for your comments everyone. Jed's observation is correct. Notice though the the failed engraving areas are mostly between large areas of white space. The laser isn't coming back to full power fast enough after the spaces.