WTB - Coherent Sabre Passbank Delrin 'Core'

[dsli_jon]

Hey Kats -

Just puttin' a 'feeler' out, to all the 'Ion-Boys', here, that I am in very *urgent* need to find an old / used (even-if electronically-fried) Passbank (or entire PSU) from a Coherent Sabre...

...Went to fire it up last week (in-prep for a week-long run of shows in, like, 2 weeks!) and see WATER dripping-out the back-panel of the PSU... took-apart last-nite (sorry, guys - no pix for now - no time - will post-later...) and my worst-fears were confirmed - small, hairline crack on the side of the delrin/PVC Passbank-cooling distro-block - basically, in 'human-terms', the equivalent of finding an aortic aneurysm, slowly-leaking... (and as you might-guess, water and 480 3Ø @ 150A don't play too-well together.... not to-mention the ~580VDC in the PB

Anyhoo, hoping against-hope, that someone might know someone, who might know someone, etc, who has a fried one, especially you Silicon-Valley 'tech-dumpster divers' , with a good cooling-block- that is ALL I need - Passbank-itself, is fine...

...Yes, I am also formulating a back-up plan (repair) with some epoxy (make a 'crescent-shaped gap' via an offset, slightly-smaller-dia. tube, inside the 'aorta', / fill w/ poly-resin; dry; take-out 'mold' tube; hope like heck it holds... ) because sending to Coherent is NOT an option (time) but, ultimately, a replacement block is THE best solution...

So, lemme know, peeps... ....sad day @ DSLI...
peace...
j

[Laser Ben]

There are a bunch of sabre systems availavle around here. I will ask around for you.

[gottaluvlasers]

john-

i have used the 2 part epoxy "clay" shit on some SERIOUS high pressure leaks before. that stuff hardens like reinforced concrete. i would suggest that over regular epoxy.



just my .02 sorry it isnt the exact answer ya need though...

-Marc

[gottaluvlasers]

sorry for the double post, but i couldnt post the link under "edit" in my post above.

anyway...

i have some of THIS stuff now and it works EXCELLENT. its available at home depot. its designed for high pressure, and applygin to wet surfaces. even under water.

-Marc

[daedal]

sorry for the double post, but i couldnt post the link under "edit" in my post above.

anyway...

i have some of THIS stuff now and it works EXCELLENT. its available at home depot. its designed for high pressure, and applygin to wet surfaces. even under water.

-Marc

Sorry to hear about your troubles Jon...

I have also tried this stuff on similar applications... it actually dries hard enough that you can buff it!

Definitely great stuff!

--DDL

[GooeyGus]

How long is the crack? Is it something that you could put some rubber tubing around and hose clamp it? It sounds kinda 'iffy' but has worked for me in the past

If not, like Marc said, I've used some two-part epoxy on some high pressure stuff as well and it held great (think turbo 2.3L race motor @ 26psi, crack on an intercooler pipe, only needed to hold up for about a day at the strip until we were able to fix it with new parts, but it didn't give us any trouble at all for that day!)

[dsli_jon]

Hey Kats -

Thanks for the tips and ideas - and yeah, I know the 'putty-steel'-type epoxies-well - thing is, here, it #1, MUST be something that can take the thermal expansion / contraction, with never any-risk of a chunk 'breaking-off' when it is running-cold (think: CLOG @ 60psi... / MUST-bond to the Delrin (a tough material to bond-to..) and #2, it HAS to mold perfectly down the entire ~11 3/4" length of the INSIDE of the flow-tube - see pix...(you knew I couldn't resist...! - Kinda-difficult to ensure a perfect bond all the way-down the length of the INSIDE of a ~3/4" ID tube, with the putty...

So I am thinking possibly this 'potting' epoxy,

http://www.mcmaster.com/#7548a11/=18y7f9

...cause claims it can take expansion/contraction and is waterproof / sticks to plastics - will test on the outside of the delrin first...

I have to turn this unit 90˚, so the crack on the 'side' is now at the bottom, and flow-in a tube-length 'moat' of epoxy - when dry, and sitting at it's normal position, the tube-mouth will now look look a 'bloated "D" - and yes, I know, not SO-much as-to restrict flow too-much ...

This thing is a work of art - all those transistors - 'anyone care for a robo-chocolate'?? ... and just look at the cooling-plate chamber... quite cool, literally..

Anyhoo, thanks for the ideas, guys, and I'll try and post pix / report pf the repair... I DID-find a source for a 'fried' PB, (with a good core) but they want $3K for it so I will try the 'patch' first...

ciao
j

[mophead]

I may be waaaaay off base, but if it's PVC or a derivative, maybe dissolve some PVC in some tetrahydrofuran and chemically weld it.

Maybe??

[Laser Ben]

He said it was delrin. One thing you could do if you have a mill and are ambitious. Cut a slot and a piece to fit in it. Then glue the piece in.

[heroic]

He said it was delrin. One thing you could do if you have a mill and are ambitious. Cut a slot and a piece to fit in it. Then glue the piece in.

Gluing polyacetal is difficult. You need to mechanically abrade it, then etch the surface with chromic acid before epoxy will take.

What I'd do is to use a cutoff wheel to turn the crack into a V-shape, then etch the surface of the V shape with chromic acid, use tape on the inside to make a dam, and then pour in a good two-part epoxy slowly, carefully making sure there are no bubbles. When it has set, remove the tape and sand down the mating surface.

Be careful with the chromic acid, though; it's really nasty stuff. You can get it in brass instrument cleaning solutions but it's also commonly used in labs for cleaning glassware.