HeNe laser removing outer tube thingy :D

hi all,

i have a HeNe laser i got off ebay for $25 w/ pwr supply i was wondering if there is any way of removing the outer tube thingy its in revealing the laser tube in all its laser tubey good ness
oh yeah i have pics!

Almost never.

That's an old Hughes, so it may just be mounted with set screws, but usually the metal outer tube has the glass tube potted in with RTV silicone.

And there's no way to get rid of that. (Not really, at least.)

Really, I'd just enjoy the laser as-is, since it looks like it works, and get a bare tube from someone on the forum here if you want to see plasma.

There are marks that seem set screws, on the tube, so it can be tried, but the possibility is low ..... worth the trial just if the laser is non working, and you want the tube for a plasma lamp ..... popping out with care the caps, loosing all the screws and trying to see if it come out or move .....

Benzine or acetone can take care of silicone, but it can require days, if not a pair of weeks, if the whole tube was glued inside ..... and can potentially ruin the end mirrors, so as said, if it's not lasing at all, may try, but if it's working good, don't worth the risk .....

I have slipped dead tubes out that had gobs of silicone AND set screws..

The best way usually requires a tad more effort, so making a special tool is of course a must

Take an old hacksaw blade and grind off the remaining teeth. Next smooth the edges so as not to scratch anything.

Now sharpen one end / tip of the blade, into a blade. You basically use this tool like a narrow razor blade with a long handle.

Keep it tight to the aluminum body, and slowly work your way through the glue. Hopefully in your case the bead of glue wont run the length of the shell. Its usually pumped in through holes in the outer case, and should just be little blobs.

I haven't seen the inside of your specific laser, so attention to care may need be greater depending on how much space is in between the glass and the wall. Also some tubes / shell's are not flat on the inside and have grooves that may be somewhat in the way.


Oh and BE GENTLE!! :can:

I've removed the aluminum casing from 16" HeNe tubes with some
success...
The dots around the circumference at the ends of the tube that look
like set screws are actually fill holes where silicone was injected to
hold the Glass tube centered in the Aluminum protection casing..

You will need a few long box cutter blades in a holder similar to this....

2 Utility Knife Set Box Cutter 7 Snap-off Razor Blades on eBay.ca (item 290300723730 end time 29-Apr-10 10:54:15 EDT)

You will need to remove the end caps...(they may be glued or have
a set screw.
Then remove the Ballast resistor and wireing... The Ballast resistor
if not visible is sometimes potted into the End Cap..

Using your Razor Cutter blade fully extended and locked... cut the
silicone blobs holding the Glass tube to the Aluminum tube using
a sawing motion.. Change your blade as required...
This worked for me...

BTW... I can see wanaburn's method working as well....
and like he said BE GENTLE... it is a thin Glass tube...


Jerry

thanks for the advise i just came across an old handheld scanner so fingers crossed that i can use that tube for some plasma ill let you guys know i'm taking it apart today

SUCCESS! any tips before hooking it up? ballast resistor? can i use my old pwr supply for this little guy?

If the ballast resistor was not on the tube already, it probably incorporated into the HV leads or P/S, maybe hiding under that red plastic cap.

If it aint broke, dont fix it, in the pics it was working before, so you should be okay as is.
Without the resistor the tube will flicker or misbehave. You should be g00d without adding anything.


Nice clean extraction, congrats. Just keep in mind how delicate these are, and avoid touching the ends, or coming near them during operation... zzZZap! Not lethal just startling.

this isn't from the tube i just got it out of a scanner i decided not to risk breaking the other one and came across this thing so yeah lucky me but i mean the tube is way smaller than my other one so will my other supply work for this?

It would be nice to be able to say, "This is the way to do it." Unfortunately, different tubes are different.

Some have plastic set screws, some do not, some have a combination. Some have enough room along the side for the saw blade to fit, some do not. I use a combination of 4 or 5 different techniques. Somtimes ONLY the judicious and careful use of a dremel and a cutting blade will do it. Sometimes all you have to do is push the tube out with a piece of PVC pipe.

Experiment. You will break some. So what? If you are going to get into salvaging old lasers, you are going to have to get creative AND accept that you are going to incur some loss.

I have a dozen of the inner, glass, plasma tubes sticking up out of a pencil holder on my desk. I shine my lasers at them and watch the light "dance' on the wall behind them.

Remember, it's a hobby

TheTeslaWarrior said:

this isn't from the tube i just got it out of a scanner i decided not to risk breaking the other one and came across this thing so yeah lucky me but i mean the tube is way smaller than my other one so will my other supply work for this?

Click to expand...

That little tube probably only needs ~1.2KV to run. If you use a higher voltage PSU, you have to use a higher resistor (and it WILL heat up). I don't know what the voltage is on the PSU you've got, but I would probably look to pick up a smaller PSU for this little tube

Peace,
dave

LOL, I thought it looked small, was scratching my head on that one.

The power supply shouldnt be much different and should be okay. If the tube doesnt like it, it just wont operate properly.
Try a few different resistors...

I have used a PC monitor flyback to drive a smal tube once. The voltage was way higher than the tube was originally operated at. A single tube would not work, but two tubes wired in parallel worked fine.

In other words, it wont hurt to try..

Why not just use the P/S that it came with? You had the complete scanner yes?

it did work



used 120kohm resistor

But now you can only use 1 he/ne at a time. Need to get another P/S.

There is also a trick to get more power out of he/ne tubes using a bunch of magnets. A member had posted the technique a while back when I was selling off some tubes, but cant find the thread.

agreed

As for running a supply without a ballast, that is not a good idea, nor is running a supply with out a tube attached. Both conditions will kill most hene supplies after a few minutes.

When in doubt start with 100K and work your way down to 47K, while monitoring the current by putting a floating voltmeter across a 1K resistor in series with the tube. A plastic cased DMM setting on a block of foam works fine. Its best to only clip on the voltmeter leads once the tube is lit and stable. Most tubes are sized for 5 to 6.5 mA anyways.

The easiest way to remove tubes is a milling machine with a end mill. If you dont have that, I find for most tubes:

The second easiest way is gently pull the end plugs so you can save the ballast resistor and see where the tube ends are. Then drill out the fill holes, and then to cut around the tube either side of where the fill holes were. When drilling the holes it helps if you use a flat end mill instead of a drill, that way it just spins on the glass if you go too deep. So you end up with a tube with bare ends and a piece of AL casing around the middle. You can then see whats holding it in the casing and use a hot wire inserted along the tube to remove the remaining silicone. Nichrome and a argon laser cathode transformer with a variac works just fine for the hot wire. Avoid the fumes though..

Steve

Another trick to remove a tube that's stuck inside an asluminium tube with plain silicon is to use an old tape measure (a broken one because you'll sacrifice it) and cut a 5 or 6" lenght of the steel ribbon and cut one end in a point with 2 45 deg. bevels .

This "tool" will have a curve that will be flush with the tube so you can gently (and patiently) work your way through the silicon without exerting pressure on the tube itself.

Oh and resist the temptation of pushing on the tube with your bare finger, a fingerprint on the end mirror or aperture is never a very good thing for a laser tube. a little piece of lintless tissue or cotton will be perfect to protect the optics. Don't try to force it either (even if it moves a little bit) because enough pressure might even f**k up the optics alignement and then your tube probably won't lase anymore!

- Robert