Warning: Tube damage when using Home made Power Meter

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Stephen Eaton
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Warning: Tube damage when using Home made Power Meter

Post by Stephen Eaton » Tue Jan 03, 2017 5:11 pm

Hi All,

These photos were taken after I did a test using home made power meter like Russ's Dohickey, so Just a warning when using a power meter on output of beam and not to reflect back into the tube, even though the thermal mass was coated in what I thought was a non reflective paint it obviously reflected a portion of it back up into the tube. Before the test beam was concentric as you would expect, now I'm getting a split beam.

This occurred when measuring 80W tube at 60% and what I think has damaged the Tubes primary exit mirror. Now I'm getting a split beam on direct output to mirror 1.

My machine and Tube (red sail clone) is less than a month old so am in talks with supplier for a replacement.

So please be careful when using a home made power meter making measurements before mirror 1
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IMG_5976.JPG (1.45 MiB) Viewed 276 times
Stephen...

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Doug Fisher
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Re: Warning: Tube damage when using Home made Power Meter

Post by Doug Fisher » Tue Jan 03, 2017 5:35 pm

Did you carefully take a Q-tip and some lens cleaning fluid to clean the lens on the end of the tube? Then take a curled up corner of a lint-less microfiber cloth (glasses cleaning type) to remove any leftover gunk? I had a similar problem and the Q-tip alone didn't help but the combo did. If you have a Giotto Rocket Blower or similar, a few puffs from that are a good occasional maintenance.

I learned about the potential for junk on the end of this lens from reading the forums. If you have had gunk on your mirrors, you probably have gunk on the lens at the end of the tube so it is a good idea for everyone to give this lens a cleaning. I know my mirrors in my laser needed a cleaning right out of the shipping crate.
80 Watt 700mm x 500mm Ke Hui KH-7050 Laser (Similar to the Red Sail),T.R.
LaSea/EFR F2 Series laser tube, RuiDa RDC6442G EC controller, 2" lens, RDWorks v8.01.18, CW 5000 chiller, Chuck type of rotary attachment
Doug

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fred ungewitter
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Re: Warning: Tube damage when using Home made Power Meter

Post by fred ungewitter » Tue Jan 03, 2017 5:39 pm

With respect to using some form of a dust blower, be sure if you use compressed air in a can, do NOT turn it upside down or very far past vertical. If the spray is ejected as liquid, there is a risk of thermal shock if the liquid should contact the laser tube.

I hope the OP is able to clean the aperture and restore normal operation as D. Fisher has suggested.
fred

Redsail clone 60w 700 x 500 REAL 60w Puri tube
home upper right, chuck type rotary 15000 pulse setting
RDW 8.01.18
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Chris Berry
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Re: Warning: Tube damage when using Home made Power Meter

Post by Chris Berry » Tue Jan 03, 2017 5:46 pm

The best dust blower is the compressor you already use with your engraver - it won't add any more dust than it would in everyday use with the machine.
I just pull mine off the nozzle to blow everything from mirrors to lenses. I'm thinking about adding a T piece to bleed off some air when engraving and also provide convenient lens cleaning!
--------
Chris
--------

Weike 130 x 90 100W RECI Laser TR
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Doug Fisher
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Re: Warning: Tube damage when using Home made Power Meter

Post by Doug Fisher » Tue Jan 03, 2017 6:06 pm

The rocket blower I described is a big bulb blower. Since you are pumping by squeezing your hand, you control the flow. I have found it useful for many different problems. The large is the best investment because you can always squeeze softly if you just need a little air. So much cheaper than canned air without the risk of shooting out liquid like Fred warned.

https://www.bhphotovideo.com/c/product/ ... lower.html
80 Watt 700mm x 500mm Ke Hui KH-7050 Laser (Similar to the Red Sail),T.R.
LaSea/EFR F2 Series laser tube, RuiDa RDC6442G EC controller, 2" lens, RDWorks v8.01.18, CW 5000 chiller, Chuck type of rotary attachment
Doug

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Stephen Eaton
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Re: Warning: Tube damage when using Home made Power Meter

Post by Stephen Eaton » Tue Jan 03, 2017 8:04 pm

Yes was the first thing I did :(
Doug Fisher wrote:Did you carefully take a Q-tip and some lens cleaning fluid to clean the lens on the end of the tube? Then take a curled up corner of a lint-less microfiber cloth (glasses cleaning type) to remove any leftover gunk? I had a similar problem and the Q-tip alone didn't help but the combo did. If you have a Giotto Rocket Blower or similar, a few puffs from that are a good occasional maintenance.

I learned about the potential for junk on the end of this lens from reading the forums. If you have had gunk on your mirrors, you probably have gunk on the lens at the end of the tube so it is a good idea for everyone to give this lens a cleaning. I know my mirrors in my laser needed a cleaning right out of the shipping crate.
Stephen...

eBay 80w (70w) Chinese laser, 700x500mm, T.Right Home
RD Works V 8.01.19

User avatar
Stephen Eaton
Posts: 29
Joined: Fri Nov 25, 2016 7:29 am
Location: Bunbury, Western Australia
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Re: Warning: Tube damage when using Home made Power Meter

Post by Stephen Eaton » Tue Jan 03, 2017 8:11 pm

Lenses have been spotless since commissioning my machine in Late November, this has only occurred when I did some power reading test over the weekend. So is the only thing I can think of what caused it. Power meter held on a stand was used but placed 1/2 way between tube and 1st mirror so wasn't right on tube output.

I've got a small inspection mirror and a visual inspection was going to be my next step.

I will try the blower as I'm into photography and have a good lens blower and lint free lens tissue
Stephen...

eBay 80w (70w) Chinese laser, 700x500mm, T.Right Home
RD Works V 8.01.19

Doug Fisher
Posts: 464
Joined: Sat Aug 20, 2016 12:42 pm
Location: Atlanta, Georgia, USA

Re: Warning: Tube damage when using Home made Power Meter

Post by Doug Fisher » Tue Jan 03, 2017 8:17 pm

Unfortunately, if you have tried fluid and a Q tip, using the blower at the point most likely isn't going to improve anything.

I am sorry you are having the problem. Was your mass of metal reflective silver or similar?

Let's hope your inspection via mirror shows something you have missed during your cleaning! It wouldn't take much to create a split like that. That round lens is not the easiest to clean thoroughly with a Q tip.
80 Watt 700mm x 500mm Ke Hui KH-7050 Laser (Similar to the Red Sail),T.R.
LaSea/EFR F2 Series laser tube, RuiDa RDC6442G EC controller, 2" lens, RDWorks v8.01.18, CW 5000 chiller, Chuck type of rotary attachment
Doug

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fred ungewitter
Posts: 335
Joined: Tue Aug 16, 2016 2:55 pm
Location: East Central FL, USA
Country: USA
Real Name: fred ungewitte
Nickname: fred
Laser Machine Make or Type: Redsail Clone
Laser Power: 60W
Laser Bed Size: 500 x 700
Home Position: TR
RDWorks Version: 8.01.18
Accessories: Chuck style rotary, 30 ma meter, home-spun office water cooler mod, muffin fan anti-condensate blower
Windows Version: Windows 7

Re: Warning: Tube damage when using Home made Power Meter

Post by fred ungewitter » Tue Jan 03, 2017 8:34 pm

Stephen Eaton wrote:Power meter held on a stand was used but placed 1/2 way between tube and 1st mirror so wasn't right on tube output.
An alert pops up in my grey matter with this expression. All the videos I've seen of the power meter use, and all the limited use I've had of mine shows the black puck being moved within the beam, to spread out the energy over as much of the surface as possible. This is also to prevent a burn through of the black anodizing, creating a reflective surface. Two points here. Movement means it's not going to be easy to "aim" the reflected beam back at the exit mirror, and movement reduces the chance of burning a reflective spot.

Still hoping for a happy answer, but it doesn't look good for the good guys.
fred

Redsail clone 60w 700 x 500 REAL 60w Puri tube
home upper right, chuck type rotary 15000 pulse setting
RDW 8.01.18
Win7

Emblaser A3 4w diode laser
BCN3D Sigma Dual Extruder 3d printer
LMS Mini-mill
Cube 3rd gen 3d printer, universal filament mod
Under construction: OX CNC 1000x750 router

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