How to open a GSI Lumonics G120DT laser scanner?

[masterpj]

Finally recieved the proper allen wrench. It was 0.050inch for me and not 1/16
I am pretty sure this is what they mean with a broken torsion bar.

[absolom7691]

That would be it. And it is also typical for where it broke too. They normally break right at the base of the rotor. Not sure it is from thermal stress or from the wobble and jitter. Regardless, every broken spring from a G-series galvo that i have seen has always been right at the rotor.

[mixedgas]

Make a circular tool that fits over the shaft. Push the top bearing down thru the galvo. It only goes out thru the hub, do not try to push it out the top. See if there is a silver solder joint on the rotor. If there is, and if there is a silver solder joint on the base, with care, a new torsion wire may be formed from the proper high tension piano wire.

Perhaps some day I'll walk you thru it. The rezeroing process is quite involved. Best to get a new one.

Steve

[masterpj]

Make a circular tool that fits over the shaft. Push the top bearing down thru the galvo. It only goes out thru the hub, do not try to push it out the top. See if there is a silver solder joint on the rotor. If there is, and if there is a silver solder joint on the base, with care, a new torsion wire may be formed from the proper high tension piano wire.

Perhaps some day I'll walk you thru it. The rezeroing process is quite involved. Best to get a new one.

Steve

I got a working one underway that I can use along with the already working one I have.
(Thank you so much DZ!)

I had opened up the unit *without breaking it further for learning from it* and had talked to Brian Bennington about the process. I tried to grip on the shaft to pull it out at first but with a bit of carefull trying I assumed that this wasn't possible.

I had a tool which perfectly fit to push/tap out the entire shaft assembly (the antenna of a cheap portable FM radio) and put it back together for storing purposes.. you never know really and spare parts are never a miss.
I heard about a piano string before as well but had never seen it when I removed the back cover to take a look what was inside.
* removed the glue bond with a small flathead screwdriver scraping away the glue on each side.

[masterpj]

I'm looking in ways to see if both ends can be joined back together.. maybe one of the jewelry welding methods would work?
Right now I'm thinking of micro tig welding or laser welding... though both methods likely are very expensive.. but it's an interesting thought.


I think the enviroment and tools needed are factory level though.. I think it should unlikely to get a hold off but it would be cool to weld a whole bunch of torsion bars and have those as spares or parts to repair others.

Possibly welding on some kind of jig could work. I'm just brainstorming for something I might try sometime with a homebuild setup.

[mixedgas]

Welding them at the break is bad, it adds many extra resonances to the scanner. BTDTGTS.

Ordinary butane-air or propane-air torch melts the silver solder just fine.

The Wire is common and easily replaced. You straighten it by hanging a weight from it, over night.
Then you solder it in.

Steve

[masterpj]

With the wire you mean the snapped off piece from the torsion bar?...
Wait so the torsion bar is attached with solder? Its not actually snapping off it's the solder joint breaking?
If so that's rather interesting!!!

Edit: removing torsion bar again to look for silver joint

Edit #2: I think I know what the silver joint is.. its not a very small blob but rather a very precise circular part where the thin metal "wire" is soldered into but perfectly straight.
I hope I'm not completely mistaken here.

[mixedgas]

Its silver soldered at the rotor and either welded or silver soldered at the hub. You grasp the rotor with a heat sink when soldering, so you do not cook the oil in the bearing. All that is required is symmetry, when installed the torsion bar is under moderate tension.

Steve

[masterpj]

Thanks I get it now!
I will give this a go later today! But first: time to get some sleep.
I really apreciate your time and patience Steve I owe you bigtime for this.