Taking Sharplan 720 to pieces !

[greybeard]

I've now received my Shaplan 720 in working condition, with half a tank(2 litre?) of CO2 mix.
Unfortunately it's on the ground floor, and I need to take it up a flight of stairs to my work room.
I intend to create my own manual for future use by others along this same path, so stripping it down to major units, photographing as I go has already been decided upon.

I'm familiar with the hazards of high voltage equipment, and of disassembling optical and vacuum equip., but this is my first laser.

Has anyone already been here, done that, who could offer advice ?

I assume, for example that with the gas bottle removed, the laser tube inside its assembly is open to the atmosphere, so I can safely remove the gas connetion between the arm and the body of the machine.

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[KTP]

I am not exactly sure what the 720 has in the way of power supply, but a lot of the medical lasers have a very heavy isolation transformer that could be removed fairly easily and carried up the stairs by itself. Also, in the Sharplan 1060, the HV supply transformer is very heavy but modular with connectors, and easy to remove. Much harder to carefully remove the fragile tube with all of its gas and water fittings.

I suppose you could quite easily remove the vacuum pump, since it would only have power + a gas fitting. It probably weighs 15-30lbs.

You are still going to be left with ~150lbs for the frame, tube and electronics...get some help!

[greybeard]

KTP - thanks for coming back so quickly - I'd hoped you might be online.
I'll try taking some photos soon to see if we both think alike ie that with a good design you re-use your previous ideas

[greybeard]

I'm hoping this will turn into a "my first laser cnc" thread if all goes well.

As I'm finding very little specific technical info on this particular model, I plan to post photos of my initial attempts as a guide to others.

I've taken the covers off, and the first thing that appeared was some vac oil inside the base.
The 720 was delivered lying on its front face, and I found what I assume is the vac pump filler screw partialy undone !
Next, what I assume is the water cooler resevoir/expansion tank almost empty. That's the acrylic cylinder seen on the lower right side above the vac pump.
Should I use deionised water, or is tap water ok ?
I still need to think about separating the laser tube assembly with all the tubes. I'd be happier moving that around on its own, so I'll probably go for it tomorrow.

[greybeard]

Down the line, I'll be adding labels to the photos as I identify various parts, with a little help from my friends.

[KTP]

Coolness!

Ok, see those 2 glass tubes that look like they come from a late friday night sci-fi B movie? Those are the current regulators for the cathodes (pretty sure on this...I believe the tube is center anode with a cathode at each end). They are fragile, and worth a lot! (Ham guys pay about $100-$150 each for those...used). I know this because I just made that much selling some on ebay

Down near the bottom, it looks like we have maybe an isolation transformer and a HV transformer? I can't quite tell, but the HV transformer would have heavily insulated leads going to a rectifier section...

Yes that clear tube is the water resevoir. If you know the laser is not going to be stored anywhere below freezing, you can use distilled water (grocery store, 1 gallon containers), otherwise perhaps use the glycol stuff you can put in RV water supplies (it is like a child/animal safe antifreeze). If your laser was treated roughly (delivered on it's side sounds rather harsh), you might want to check to make sure the tube does not have any cracks in the cooling jacket before you apply power. Water and 20KV is not a great mix...normally the water is isolated from the high voltage.

Just put more vacuum pump oil in the vacuum pump. It may be a good idea to drain and change that oil anyway, as performance of the pump goes down as the oil gets old. Check places like Dunaway for cheap vacuum oil.

I still would try and leave the tube connected to all the hoses. It is probably safer inside the housing, and less chance that it gets misaligned which would require some work to realign. Did this thing come with some sort of articulated arm with lots of mirrors in it, or do you eventually have to take the tube out anyway to make some sort of flying mirror gantry laser cutter?

[KTP]

Oh so just to motivate you a bit (or make you jealous), here is a 45 watt medical laser I rescued from the dump pretty much instantly blasting a 3/8" hole (unfocused) in a piece of 1/8" balsa. Short video, but it didn't take long!

http://www.skyko.com/shizlaser/burn.wmv

You can just see a faint glow in the glass tube when the laser fires...that is the plasma discharge. Note that this is a sealed tube, so doesn't require gas flow, vacuum pump, etc. The downside is that eventually it will require a recharge.

[greybeard]

Couple more photos - this time the tube with just the cover removed, and the articulated head.
The 720 is working, as I was given a quick demo on delivery by the previous owner.
Perhaps it was just as well it was brief and I didn't know about the possibility of water sloshing about inside!
However, as he had said in his ebay advert, it only seems to run at reduced power. It indicates a maximum beam current of 10ma, but happily burnt a lump of pine as a demo.


Re removal of tubes etc. What I have to decide is what is the minimum I can take off in order to get it safely upstairs.
First step might be to get it on the bathroom scales and see what the problem is .

I think I have two options to halve the weight. One is the remove the ht supply side as a mass of wiring looms and the two large transformers, or the other which is to remove the vac pump, cooling pump and the whole arm assembly.

The first option problem is several of the wiring looms(harnesses) go through holes in the chassis, and some of the bolts have difficult access. Those two glass diodes look a bit scary, as you say, so I'd like to avoid nudging those with a spanner.

The second option only requires removal of tubes between the arm and the various pumps/valves, and the ht supply leads. I could then remove the arm intact, along with a lot of the external hardware, making going up the stairs with the rest of it easier.
I presume that when I reconnect and start up, any air will be purged out in the first few seconds after switch on ?

Liked the video - must admit the motivation is now a bit green coloured(temporarily!).

The first target is to be able to cut complex paper profiles, then on to cutting ditto in wood veneer. After that, who knows.
I've got a lightweight xy assembly in the attic that may well move a piece of paper around, so I could avoid setting up moving mirrors. But it occurs to me that the articulated head may well contain the very items that I would need. Ever taken one of them apart ?