How to; Remove a HeNe tube from a Silicone Potted Head

Hey guys... so today, I got a HeNe laser head from Gren, as he has gotten 4 of them for really cheap a while ago.

However, I wanted to be able to see the beautiful plasmas inside of the tube... and it was sealed inside of a metal enclosure, with silicone preventing easy removal.


Was the laser head I had gotten, but mine was made in 1991 as opposed to Fretwrecker's, which was made in 1988.

So what did I do? I thought about it, and came up with a relatively simple solution.



One of these, and careful patience. You go around it slowly, and once you finally get through the aluminum, stop there.

You must then get hot water running from a faucet, and run the tube under the water for a while. This causes the metal to expand enough to allow you to gently pry the tube out!

Be careful, and go slowly! I successfully removed the above tube, and will test it soon once Gren gives me a PSU to use.

Good luck!

Nice picture you got there

Neat tutorial. Maybe you could get some pictures of the bare tube?
Is your model the LHR-911 as well? I love mine. I need to get some bare tubes, but the look of my HeNe is just so... soo..... so 1988-ish. And I love that.

To me, it feels like removing the casing of a HeNe is kinda like cleaning a really old tarnished coin. I'm not scolding it, I'm just saying it takes away from the vintage/old-school/retro feel of it.

Good job though!

I'm rather surprised. The tube looks brand new... the bore is spotless.

Also, fret, the cords to the tube were cut, so the tube would have been inoperable without me removing it anyway.

And yes, it's the same model, just made in a different year.

That actually looks pretty great, right there!
Good point about the power cords. I suppose this is a great solution for those with severed cords!
Are you gonna put your liberated tube into a nice display?

I once did this by putting a slight bend longways in a hacksaw blade and sawing through the potting material around the tube. Worked reasonably well.

Your way seems... um... safer.

Trevor

Fretwrecker94 said:

That actually looks pretty great, right there!
Good point about the power cords. I suppose this is a great solution for those with severed cords!
Are you gonna put your liberated tube into a nice display?

Click to expand...

Not sure what I'm going to do with it just yet. I need to make sure it still works, and then I'll probably make some sort of small stand for it.

i read a post by dave saying this was really hard. looks like you got it easy!
btw where is dave? haven't seen him about lately.

I've "decanned" a lot of these LHR-911 heads actually, and some aren't nearly as stuck in there as others. One method is to bend some thin aluminium strips to contour to the ID curve of the bore and sever the silicone plugs from either the tube or the shell body. Another method if you can get both ends off is to use piano wire to slice through the silicone, nice aspect of this method is no chance of damaging the tube. Another method involves boiling the entire head at high temperature/pressure to soften up the glued joints and silicone to the point that you can yank/push the tube out, but this one risks the most damage to the tube.

I've done all the above methods with varied success. Some heads the ends pop right off and the tube comes right out. Others are damn near completely potted internally with silicone and will not budge. Others still have epoxy holding on the caps instead of glue.. and those are a nightmare to remove nondestructively.

In quite a few I've been able to de-pot and reuse the ballast resistor which normally resides in the end cap!

Wow, you guys did it the easy way. . I took a dremel with a cut off wheel and managed to extract one. I just kept cutting through the aluminum very carefully. This one only had a little bit of glue along each injection point.

I put a tiny scratch on the tube, but it made it out intact. I still need to hook it up and see if it works. Although I'm not sure this one worked in the first place.

Trevor said:

I once did this by putting a slight bend longways in a hacksaw blade and sawing through the potting material around the tube. Worked reasonably well.

Your way seems... um... safer.

Trevor

Click to expand...

Yeah... I've used the same hacksaw blade method but I
sharpened the blade to a razor's edge to cut through the
silicone shock absorbing mounts in the tube.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

Nice job! Here's another thread on the matter: http://laserpointerforums.com/f51/tutorial-melles-griot-hene-head-disassembly-49073.html