HT wire to tube

Discussions on optics for laser cutter/engravers

HT wire to tube

Postby bush flyer » Thu Aug 27, 2015 1:48 pm

I have come to the point that I will be fitting my Co2 laser tube, Having a look on Youtube I see a lot of the HT wires being connected by wrapping a thin wire round the connector then soldering the HT wire to that. I have also seen the HT wire been connected with a crocodile clips. and another way I have seen is to just twist the wire round the post and hold it on with silicone paste and a 2inch length of silicone pipe pushed over the connector. I even found one that was held on with plumbers tape the kind for sealing pipe threads.
What is the best way to do this, It does say in the box the tube arrived in that No soldering iron allowed on connection or warranty voided, so this leaves the crocodile clips or twist the wire or could I use a terminal block, the plastic covered one with the brass inside and two screws to hold it on, then cover that with Scotch 23 Bonding electrical tape. It would have been nice if the seller of the tube would have put some instruction how to connect this along with the do not solder note.
I look forward to any better Ideas or the best one out of the bunch?
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Re: HT wire to tube

Postby Techgraphix » Thu Aug 27, 2015 2:58 pm

One of the best ways IMHO is to take out the brass part of a terminal block like this:
TB2.JPG
TB2.JPG (11.77 KiB) Viewed 16873 times

Best to shorten the screws a bit so they won't stick out too much when it's mounted.
You can solder the HT-wire to the brass outside prior to mounting it on the Lasertube's connectorpin.
Slide a piece of silicon tubing (wide enough to fit over the brass terminalblock-part) over the wire (before you screw it in place ofcourse)
and fill it with siliconekit (no-acid type).. Wipe off the excess with something like white-spirit and leave it dry for a couple of hours..

When you want to replace the tube, just cut off the tubing and tear off the siliconekit lose the screws etc etc..

Oh euh... DON'T use to much force when tightening the screws.. a tube is made from glass and it might crack when you apply brute force!!

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Re: HT wire to tube

Postby bush flyer » Thu Aug 27, 2015 8:51 pm

That's Great, That is exactly what I will do. That's the terminal blocks I was talking about but I never thought about removing the plastic bit, your way makes much more sense,
Thanks Techgraphix I appreciate the help.
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Re: HT wire to tube

Postby mpeele » Mon Aug 31, 2015 12:28 pm

I just stripped the power supply wires to the length of tube leads. Wrapped leads with 30 ga wire and tied a knot in 30 ga. Used self fusing siclone tape to insulate.
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Re: HT wire to tube

Postby bush flyer » Wed Sep 09, 2015 2:33 pm

Well The laser is up and running, But I have concerns about the mA. I have a 40 watt tube that the max Operating current(mA) is 18 but when I'm only at 75% power the reading is 18mA when I go to 80% power I then get a reading very near 20mA which I stopped as I did not want to damage the tube. There is nothing getting hot that I can find and the connections at the laser tube are also not getting hot.
Should I buy another mA meter or is this pointing to another fault some where? Other than that it all seems to be working fine.
Thanks For any advise, Mike.
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Re: HT wire to tube

Postby Techgraphix » Wed Sep 09, 2015 3:54 pm

I don't think it's a defect.. You can check the current meter with another (multi)meter in series but if the value is the same on both meters, you can be quite sure it gives the true value..
It can be your powersupply is somewhat overrated. No problem, just tell your software that 75% is the maximum value..
I have seen another solution with two potentiometers.. somewhere.
Your tube starts firing at about 10-15% normaly. With these potentiometers you could set the minimum value of ~13% to be 0% and 75% to be 100%.. so from 0-100% is actually 13-75%
Simple but smart circuit.. if only I know where I had seen it.... :? (I thought of making that in my machine too)

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Re: HT wire to tube

Postby bush flyer » Wed Sep 09, 2015 4:21 pm

Ok I will test it with another meter and I'm using AWC708c controller I will set the maximum value to 75% I appreciate your help. Mike.
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