Why homebuild?

prharris

Is it "because it's there to be done".
Many of the homebuilders say that the project costs ae more that many commercial ones when they've finished.

Or is it for a specific application?

I've only just started with a Kiss and feel hapy to strip and re-build it, but know my engineering facilities (if not skills) fall short of building one from scratch.

So, fire away

Duncan Price

For me it was for a specific application. Cave diving.

Unless you get it right first time the build cost of a bespoke rebreather is not far from what you could buy a commercial unit. You've not just got to think of the materials but also labour. Its not only the bits you buy but also the bits you already have. If I wanted a conventional CCR then I could have financed it by taking an evening job and bought one with the proceeds.

If you want to make a cheap and cheerful O2 rebreather then you can knock one up for next to nothing. The running cost is 1/2 to 1/3rd breathing OC O2 so you soon get your money back quick.

IMNSHO SCR's are a waste of time. Great gas extenders but you need the right drive gases for the dive you are doing. Might as well make a CCR. Your options are:

1. Convert a O2 unit (like the excellent C-96).

2. Convert an SCR (like a Dolphin)

3. Make something from scratch.

Knowing now what I do I'd probably should have gone for 1. The O2 unit was a doddle but it took 2 years on/off and several prototypes before I came up with something I was really happy with. So happy, that I built four (at over £1000 each) and even sold two#. The design is in the public domain and people are copying from it. I didn't set out to make money or save money - if there had been an off the shelf solution I'd have used it (most of the components are off of someone's shelf) - because I just couldn't buy what I needed. In my day job* (making scientific instruments) I adopt the same strategy.

Of course, I like to tinker with stuff and have a set of rebreathers that I know inside out. But that wasn't the initial aim. I wanted an ultra low profile, versatile lightweight rebreather. It wasn't a case of reinventing the wheel.

Mind how you go.

Duncan

# A third one is now up for sale.
* BTW I'm still looking for a new job.

Digger

Well, for me cost was the driving factor. I couldn't, and still probably couldn't, afford to buy a new unit off the shelf. So I didn't. I don't like the idea of £5K of debt, so I thought sod it, I'll start getting the bits I need and go from there. So I did.

First buy was a drager scrubber, £40. That was ok for a week's spending, so I liked that, and I knew it would be ok. It turns out that it's the weakest bit of the final design bow, but if I treat it right it's ok. Just needed a bit of getting used to.

Next I bought a few bits, inspo counterlungs came in at £80 without the buttons, but I can live with that, and the fittings for the scrubber and moutpiece were £75, so not too bad. The mouthpiece is on of Duncan's old ones, which I reckon he might want compensating for sometime soon, but we've not talked turkey on that one yet.

Swagelok valve came next (cash being a factor you can rule out any fancy KISS jobbie) and with the on/off valve I got one secondhand for £40 worth of toys (which you need to get from Woz, Duncan)

The tanks were old 2l argon cylinders from all over, and 1st stages etc. all things I already had.

The ppO2 monintoring is the fancy bit which John (narkedat90) had custom made for this season, and he's had some very fancy new ones done, so he sold me the old one for £300. Reasonable price for a very nice bit of engineering. Everyone always notices it first, and it gives the whole prohect an air of credibility it doesn't deserve!

Final parts were inflator buttons from an inspo, and p-ports to plumb in the ppO2 cells, and inspo hoses and fittings for the T-pieces. All pretty easy to do, but I dont like the hose ends a lot.

Basically the build cost has been £750 for the bits I've used. I reckon I've spent £250 ish on bits I either didn't need or didn't work, so about a grand all in.

So I built a KISS for a grand. It's secondhand basically, but it's got all the features I like about the inspiration, KISS, and drager, as well as being mine all mine. And the Digspiration was born.

Other advantage is that it's the size of a set of twin 7s, and pretty light. It's about the weight of a set of 300 7s I think, and very manouverable.

Ooh, and shiny shell coming for the turtle in a few weeks.

Digs.

Duncan Price

Thanks for reminding me - I paid good money for that. Might even have another mouthpiece for sale when my next sidemount one rolls up from the US.

Got bits thanks. Being as I didn't actually pay for the Swagelok parts then I think I came off well. Still some more bits to get rid of...

BTW - the P1SS scrubber that you'd borrowed - feels like its still full of cat litter.

Digger

Not full of cat litter, it's got the doormat bits still in there, the weight will be the hefty bits of stainless steel on either end!!!

What mouthpiece are you getting rid of soon? I can put the word out might be able to get you some cash for it.

I didn't pay for the bits I swapped for the swagelok either! We are the magpies of the diving world. Take the shiny bits for the P1SS as a thanks for letting me use it for so long. It certainly got me started, but I don't know if I'd trust it for more adventurous diving...

Mdemon

I started with a pendulum O2 rebreather aka the maxwell house/fenzy - I got given the bits. Was all fired up to make a full-on CCR when I came across two things...

1) My utter lack of engineering skills or equipment

2) Duncan Price's sage words on cost - see above.

A post by DrMike about a 60m entrapment in a wreck tipped me over the edge and I bought a second-hand YBOD. And very sexy it is too!

So, I now have a basic unit built by someone who knows what they're doing. But the fun doesn't stop there...

Having got the unit sorted out, I can now mod and add the toys I've always wanted. In the pipeline...

HUD - realtime PO2 of all three cells, solenoid firing and CO2 monitor and alarm display
CO2 monitor
CO2 alarm

Since I'm bolting together commercially available bits, I don't need to be an engineer... And the bits are cheap - £50 or thereabouts?

And for the near future, a Bailout rebreather - full CCR with connection to primary HUD. (D5 looking good for this!!!!)

Does this count as homebuild or tweaking? Not sure...

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imdown

Mdemon,

What co2 devices are you considering? Can you provide me any info on co2 detection systems that are now available? Other than those that detect the exothermic reaction during scrubbing, I am interested in any new concepts.
CO2 monitoring is a hurdle I hope to see refined and cost effective to the ccr diver in the near future!
Thanks for any info!

jmurba

Is it "because it's there to be done".
Many of the homebuilders say that the project costs ae more that many commercial ones when they've finished.

The reasons i have re-built and transformed totaly my dolphin are:

- I want to be independant in terms of up keeping and repairing
- I want to understand perfectly the technical limits of my stuff to be able to evaluate it's reliability
-I want to adapt my gear to my Rebreather philosophy and to my needs

the results are

-i am independant,
-it is not reliable so i never low down my guard (((-:
-my gear is exactly wht i needed and it would have been totaly perfect if my bluddy oxymeter houssings could have not had transformed in acquariums (((-:


ok but i am a happy man (((-:

regards

jean mi

lizardland

I started because I thought I could build something as good as a KISS for half the price. It went through various guises, in the end I think it became kind of possessed like the car in Carrie. It tried to kill me at least three times in Landenouse cave in France, when I got the bastard detached from me it went for my buddy and attacked him. I'm sure he'll verify that it was deliberately following us around the pool.

Anyway, as for building something as good as the KISS then unless you have access to an engineering workshop or know someone who does then save yourself the headache and give your money to Jetsam. Unless you really do need Rebreather's for a specific application that aren't available, like Duncan's D5's.

It's easy enough to get the parts you need but the real skill is getting them all to work together in a coherent, holistic lump rather than a collection of bits. Gordon managed that through a process of evolution, being a clever engineer and having a sophisticated workshop on his doorstep. Being able to redo/replace/modify things easily is a big advantage.

I'd say my backmounted rebreather was a decent enough unit, cost about £1000 and did what a KISS did. After a year of diving a KISS I couldn't say that what I had was a KISS for a grand. For me homebuilding was money down the drain.

That said there are some very good homebuilds out there.

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jmurba

Anyway, as for building something as good as the KISS then unless you have access to an engineering workshop or know someone who does then save yourself the headache and give your money to Jetsam. Unless you really do need Rebreather's for a specific application that aren't available, like Duncan's D5's.

XXXXX My opinion is that it is not worth to buit the breathing loop, threre are so many second and dolphins and others scr around available for good prices.
on the other hand buying a few swagelock parts to assemble properly the kiss injection system is worth reliable and cheap.
On the other hand using a couple of pvc pipe to build a good sensor holder is worth
on the other hand building a good pic oxymeter circuit is very cheap and very reliable (except that i have ne ver managed to buit a decent houssing !!!)but as a matter of fact building a Rebreather from A to Z is not worth, exept for specials purposes like cave diving .