K1 project page INCLUDING publically-available files

Scuba_Vixen · 12th September 2006, 03:09

Quote: (Originally Posted by jradomski)

at your max injection rate, you can only inject about 4lpm.. I would raise the max inject time to 2.5 to 3.0 at a minimum.. Ideally at 135psi I would like to have the ability to have a 50% duty cycle available for ascents... That would yield a capability of around 10lpm +/- a bit...

Wow, how serendipitous,

I searched and searched for the thread where Joe mentioned some timing figures, but didn't connect it to this one.

Joe, your suggestions came out to be excellent, as usual.

My injection timings now run from 1/4 sec for PO2 below setpoint by .02 ata to 3.2 sec for PO2 below setpoint by .2 ata in 6 steps, and 3.6 secs for PO2 below setpoint by more than .2 ata.

Recovery to setpoint after a drop in PO2 is timely, and overshoot seems nill.

So far I'm a pretty happy camper. .... Here's a link to the write up and pics, if you haven't seen it. http://www.rebreatherworld.com/home-...in-builup.html

Karl,

The new parts are looking good. It's always fun to figure out how to do something new, and then make it work.

I'm curious as to what kind of control algorithm you're planning to implement.....

On / Off with selectable inject times or some sort of proportional?

Darlene

Genesis · 12th September 2006, 11:37

The inject algorythm in the GPL'd K1 code is somewhat different than the one in the "current" version, with the primary difference being that I have floating-point math in the current version.

It is an error-signal-driven event, with injection time being based on both the deviation from the setpoint and depth, with a minimum and maximum boundary. The interval between events is a user-controllable parameter.

How well it "fits" with reality is of course yet to be determined - calculations are great, but the only way I'll really know is when I get some in-water time with it.

Genesis · 25th September 2006, 00:47

Here's a pic on the T-pieces....

Its made out of 1-1/2" Sch80 PVC - Sch40 isn't thick enough to turn the O-ring grooves without seriously compromising the strength of the pipe.

The T itself will have two 1-1/2 x 1-1/4" bushings inserted, which then accept 1-1/4" hose barbs for connection to the scrubber can and mouthpiece. The MSR bags are an OTS setup. I'm waiting for the drysuit add valves to get here to put those pieces together, and I may add a 45 degree elbow off one or both of the T-pieces going back to the scrubber can to optimize the "exit" direction - thus, I haven't cemented them up yet.

The "stick" piece is just a piece of pipe into which I turned two O-ring grooves. The piece actually uses THREE O-rings, two thicker ones which seal on the MSR waterbag throat, and one thinner one above the two visible ones that acts as a crush seal and prevents withdrawal of the tube from the bag. The ring is the cap from the MSR bag with the center cut off on my lathe - I chucked it in and took a cut-off tool to it, then smoothed the edges (it doesn't cut cleanly as the plastic is REAL soft) with the dremel.

The piece sticks down about 1/2" into the bag to prevent its complete collapse when there is still air in the lung.

It cannot be rotated when in the bag, but that's ok..... its very solid in terms of a seal and I can pick up the entire kit mocked up by the T-pieces (all fastened up to my BP+STA+Wing setup). In my testing for pressure tolerance I exploded the MSR bag before the T-piece failed or leaked....

That ought to be good enough!

There is a sectioned piece of PVC cut and glued inside the T-piece that forces the air down so as to provide the water trap function - it cannot go straight through the "T"'s top, but has to go down and then back up.

DanFountain · 27th September 2006, 11:41

Quote: (Originally Posted by Genesis)

Here's a pic on the T-pieces....

Its made out of 1-1/2" Sch80 PVC - Sch40 isn't thick enough to turn the O-ring grooves without seriously compromising the strength of the pipe.

...

The piece sticks down about 1/2" into the bag to prevent its complete collapse when there is still air in the lung.

...

Nice simple solution to adapting MSR bags as counterlungs! I has a buddy turn some o-ring fittings that fit inside the MSR bag neck and glued them onto 1" thinwall pvc pipe:

Extending the tube into the CL is a good idea, but the CL material can still seal across the end of the tube even before the CL is exhausted. Easy enough to drill a few holes radially into the extended tube. (Idea blatantly stolen from Gordon Smith's KISS design). Heres a picture of this incorporated on one of my earlier Rebreather designs:

If you don't want the T-piece to stand so far out from the CL, remember that you really don't need the full 1" depth of the socket - you could easily trim 1/2" off and still have plenty of glueing surface.

I don't bother trying to use the CL as a water trap on my KISS-tribute Rebreather - I let any fugitive water go into the plenum/water trap at the bottom of the scrubber canister, whence it can be expelled thru the OPV/ manual dump valve.

Gotta love that PVC - as long as you can wait for the volatiles to evaporate...

Dan

Genesis · 28th September 2006, 22:44

Here's some pics of the scrubber can and head cage......

The cage picture has two sensors screwed into the ports (there are 4 total ports; 3 for the controller and one for my trusty VR3, of course). The solenoid is not yet mounted and the head board is there just for reference as well. Both will be mounted to the sensor plate. The through-bolts have O-ring seals on the top; you can change the sensors without having to disassemble the cage.

The seal with the can is made with a crush O-ring, much like a SS scooter....

As soon as I get the surfaces cleaned up its going to get bolted together. I'm getting quite close - cutting scrim holders next and fitting THOSE, and then its time to actually assemble this beast!

Genesis · 3rd October 2006, 03:58

Here's the top scrim piece, the face pointing up will be in contact with the 'Sorb.

The bottom piece and assembly (bottom lid, including the bottom scrim the locator tube) should be done tomorrow. That leaves me with potting up a head board and assembling this beast - she's basically ready to start dry testing at that point!

I'm sure I'll run into some "Oh !$#@!!s", but right now things are looking awfully good.....

The frame is made out of 1/4" HDPE, cut with a scroll saw and drilled with an ordinary drill press. Nothing fancy. The actual mesh material is from Industrial Supply, Metal Balls, and is a polyethylene mesh material that is quite strong and stiff. It is secured with six small stainless steel screws, so it is easily replaced. Its reasonably cheap - $20 buys enough to make a more than a half-dozen "faces" and leaves enough for a few mistakes as well. The easiest way to make a new one is to screw it down and then invert it and take a razor blade to the periphery.

A piece of polyethylene fabric (aka Inspiration) goes over the sorb, then this piece goes on the guide rod. A spring goes down the rod and is compressed to expose the locking pin hole, into which the pin is inserted. This keeps the top piece pressurized against the 'Sorb, and the fabric prevents any dust from getting through towards the inhale side.

On the bottom is another one of these, but with three 1/4" bolt holes for a triangular pattern bolt-up that holds it in place above the inlet and properly horizontal. The locator tube is attached to the bottom piece and is sealed at the bottom. The locator tube is open at the top so a suitable implement (screwdriver, etc) can be inserted into its bore to guide it into the top piece as the can is being packed. I intend to put two holes in the guide tube - one for a "full load" of 'Sorb and a second for a 'Half load' for use when you intend to do only a couple of recreational dives in a day, and don't want to load up a full load of rocks.

Genesis · 7th October 2006, 20:17

OK, update for the 7th!

Getting close enough now that I expect to actually be surface-breathing this thing as an oxygen rebreather (to check the cannister sorb use and linearity, no electronics actually in the loop yet, all manual add) either tomorrow or sometime early in the week.

Test fit for the counterlungs and alignment of all the pieces on the backplate is complete; all looks good there. I see nothing in the way at this point that looks like a major problem.

The cannister has the latches installed and O-rings fitted; its airtight; passes both a positive and negative test. The scrims are done, as is the bottom "plug" for the can. Here's a picture of the can with the bottom next to it - the top scrim is on the center pole, but in actual use of course you load that from the top after you fill the can with your sorb, then install the spring and the pin through the center tube to keep pressure on it and prevent channeling. The screws passing through the lid have a countersunk bore on the outside and an O-ring seal is used between the washer body and the lid, stolen directly from the tank neck O-ring crush seal on a steelie dive tank. Works great.

I have also received the poly felt that I am going to use for dust passthrough prevention (and also as an attempt to prevent a cocktail from getting above the scrubber bed if there is a leak) but have not yet tested its impact on WOB. It has a nominal 100 micron rating; it may have too much resistance, and I may end up going to something with a finer rating but less compressability - we'll see on that one.

Installation of the control system into the head will be taking place as soon as I have the mold issues for putting the head board verified - I'm having a bit of fun with that at the moment.

onetime · 7th October 2006, 20:43

Looks quite nice but the bottom latches give me pause. Crawling through an opening, snagging line from a reel, etc could cause one or more of them to unlatch, no?

Genesis · 7th October 2006, 20:45

No, for two reasons:

1. They're the "double catch" type; you have to push the release to be able to unlatch them.

2. I intend to put a piece of inner tube over them in use (aka the SS scooter trick to prevent the same sort of snag hazard), so as to remove the risk of snagging them on something (e.g line, etc)

I would have done a "hard bottom" for the can but PE pipe is basically impossible to glue. The only way to bond it is through heat fusion and the hardware necessary is expensive.

The can body is one of the places where, if I actually decide to make these (e.g. more than one) I will do something about this. One of the big issues with the PE pipe solution is that its NOT completely round, and the error is not small - it is quite common for it to be a tenth of an inch out of round!

One of the nice things about the scrubber can design I adopted is that it does not require anything more than a scroll saw and drill press, plus a sander. You could get by entirely with hand tools if you're careful. I'm likely to post the drawings as PDFs, which means you can go get some full-sheet labels, load them in your printer, then stick them on the stock and use that as your template - that's how most of the cannister parts were made.

onetime · 7th October 2006, 20:52

What's the diameter of the can (inner and outer)?

12th September 2006, 03:09	#31 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	Re: K1 project page INCLUDING publically-available files Quote: (Originally Posted by jradomski) at your max injection rate, you can only inject about 4lpm.. I would raise the max inject time to 2.5 to 3.0 at a minimum.. Ideally at 135psi I would like to have the ability to have a 50% duty cycle available for ascents... That would yield a capability of around 10lpm +/- a bit... Wow, how serendipitous, I searched and searched for the thread where Joe mentioned some timing figures, but didn't connect it to this one. Joe, your suggestions came out to be excellent, as usual. My injection timings now run from 1/4 sec for PO2 below setpoint by .02 ata to 3.2 sec for PO2 below setpoint by .2 ata in 6 steps, and 3.6 secs for PO2 below setpoint by more than .2 ata. Recovery to setpoint after a drop in PO2 is timely, and overshoot seems nill. So far I'm a pretty happy camper. .... Here's a link to the write up and pics, if you haven't seen it. http://www.rebreatherworld.com/home-...in-builup.html Karl, The new parts are looking good. It's always fun to figure out how to do something new, and then make it work. I'm curious as to what kind of control algorithm you're planning to implement..... On / Off with selectable inject times or some sort of proportional? Darlene
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12th September 2006, 11:37	#32 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files The inject algorythm in the GPL'd K1 code is somewhat different than the one in the "current" version, with the primary difference being that I have floating-point math in the current version. It is an error-signal-driven event, with injection time being based on both the deviation from the setpoint and depth, with a minimum and maximum boundary. The interval between events is a user-controllable parameter. How well it "fits" with reality is of course yet to be determined - calculations are great, but the only way I'll really know is when I get some in-water time with it. __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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25th September 2006, 00:47	#33 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files Here's a pic on the T-pieces.... Its made out of 1-1/2" Sch80 PVC - Sch40 isn't thick enough to turn the O-ring grooves without seriously compromising the strength of the pipe. The T itself will have two 1-1/2 x 1-1/4" bushings inserted, which then accept 1-1/4" hose barbs for connection to the scrubber can and mouthpiece. The MSR bags are an OTS setup. I'm waiting for the drysuit add valves to get here to put those pieces together, and I may add a 45 degree elbow off one or both of the T-pieces going back to the scrubber can to optimize the "exit" direction - thus, I haven't cemented them up yet. The "stick" piece is just a piece of pipe into which I turned two O-ring grooves. The piece actually uses THREE O-rings, two thicker ones which seal on the MSR waterbag throat, and one thinner one above the two visible ones that acts as a crush seal and prevents withdrawal of the tube from the bag. The ring is the cap from the MSR bag with the center cut off on my lathe - I chucked it in and took a cut-off tool to it, then smoothed the edges (it doesn't cut cleanly as the plastic is REAL soft) with the dremel. The piece sticks down about 1/2" into the bag to prevent its complete collapse when there is still air in the lung. It cannot be rotated when in the bag, but that's ok..... its very solid in terms of a seal and I can pick up the entire kit mocked up by the T-pieces (all fastened up to my BP+STA+Wing setup). In my testing for pressure tolerance I exploded the MSR bag before the T-piece failed or leaked.... That ought to be good enough! There is a sectioned piece of PVC cut and glued inside the T-piece that forces the air down so as to provide the water trap function - it cannot go straight through the "T"'s top, but has to go down and then back up. __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
(Offline)

27th September 2006, 11:41	#34 (permalink)
DanFountain Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Dec 2005 Location: Lake Superior Posts: 102	Re: K1 project page INCLUDING publically-available files Quote: (Originally Posted by Genesis) Here's a pic on the T-pieces.... Its made out of 1-1/2" Sch80 PVC - Sch40 isn't thick enough to turn the O-ring grooves without seriously compromising the strength of the pipe. ... The piece sticks down about 1/2" into the bag to prevent its complete collapse when there is still air in the lung. ... Nice simple solution to adapting MSR bags as counterlungs! I has a buddy turn some o-ring fittings that fit inside the MSR bag neck and glued them onto 1" thinwall pvc pipe: Extending the tube into the CL is a good idea, but the CL material can still seal across the end of the tube even before the CL is exhausted. Easy enough to drill a few holes radially into the extended tube. (Idea blatantly stolen from Gordon Smith's KISS design). Heres a picture of this incorporated on one of my earlier Rebreather designs: If you don't want the T-piece to stand so far out from the CL, remember that you really don't need the full 1" depth of the socket - you could easily trim 1/2" off and still have plenty of glueing surface. I don't bother trying to use the CL as a water trap on my KISS-tribute Rebreather - I let any fugitive water go into the plenum/water trap at the bottom of the scrubber canister, whence it can be expelled thru the OPV/ manual dump valve. Gotta love that PVC - as long as you can wait for the volatiles to evaporate... Dan
(Offline)

28th September 2006, 22:44	#35 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files Here's some pics of the scrubber can and head cage...... The cage picture has two sensors screwed into the ports (there are 4 total ports; 3 for the controller and one for my trusty VR3, of course). The solenoid is not yet mounted and the head board is there just for reference as well. Both will be mounted to the sensor plate. The through-bolts have O-ring seals on the top; you can change the sensors without having to disassemble the cage. The seal with the can is made with a crush O-ring, much like a SS scooter.... As soon as I get the surfaces cleaned up its going to get bolted together. I'm getting quite close - cutting scrim holders next and fitting THOSE, and then its time to actually assemble this beast! __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
(Offline)

3rd October 2006, 03:58	#36 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files Here's the top scrim piece, the face pointing up will be in contact with the 'Sorb. The bottom piece and assembly (bottom lid, including the bottom scrim the locator tube) should be done tomorrow. That leaves me with potting up a head board and assembling this beast - she's basically ready to start dry testing at that point! I'm sure I'll run into some "Oh !$#@!!s", but right now things are looking awfully good..... The frame is made out of 1/4" HDPE, cut with a scroll saw and drilled with an ordinary drill press. Nothing fancy. The actual mesh material is from Industrial Supply, Metal Balls, and is a polyethylene mesh material that is quite strong and stiff. It is secured with six small stainless steel screws, so it is easily replaced. Its reasonably cheap - $20 buys enough to make a more than a half-dozen "faces" and leaves enough for a few mistakes as well. The easiest way to make a new one is to screw it down and then invert it and take a razor blade to the periphery. A piece of polyethylene fabric (aka Inspiration) goes over the sorb, then this piece goes on the guide rod. A spring goes down the rod and is compressed to expose the locking pin hole, into which the pin is inserted. This keeps the top piece pressurized against the 'Sorb, and the fabric prevents any dust from getting through towards the inhale side. On the bottom is another one of these, but with three 1/4" bolt holes for a triangular pattern bolt-up that holds it in place above the inlet and properly horizontal. The locator tube is attached to the bottom piece and is sealed at the bottom. The locator tube is open at the top so a suitable implement (screwdriver, etc) can be inserted into its bore to guide it into the top piece as the can is being packed. I intend to put two holes in the guide tube - one for a "full load" of 'Sorb and a second for a 'Half load' for use when you intend to do only a couple of recreational dives in a day, and don't want to load up a full load of rocks. __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
(Offline)

7th October 2006, 20:17	#37 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files OK, update for the 7th! Getting close enough now that I expect to actually be surface-breathing this thing as an oxygen rebreather (to check the cannister sorb use and linearity, no electronics actually in the loop yet, all manual add) either tomorrow or sometime early in the week. Test fit for the counterlungs and alignment of all the pieces on the backplate is complete; all looks good there. I see nothing in the way at this point that looks like a major problem. The cannister has the latches installed and O-rings fitted; its airtight; passes both a positive and negative test. The scrims are done, as is the bottom "plug" for the can. Here's a picture of the can with the bottom next to it - the top scrim is on the center pole, but in actual use of course you load that from the top after you fill the can with your sorb, then install the spring and the pin through the center tube to keep pressure on it and prevent channeling. The screws passing through the lid have a countersunk bore on the outside and an O-ring seal is used between the washer body and the lid, stolen directly from the tank neck O-ring crush seal on a steelie dive tank. Works great. I have also received the poly felt that I am going to use for dust passthrough prevention (and also as an attempt to prevent a cocktail from getting above the scrubber bed if there is a leak) but have not yet tested its impact on WOB. It has a nominal 100 micron rating; it may have too much resistance, and I may end up going to something with a finer rating but less compressability - we'll see on that one. Installation of the control system into the head will be taking place as soon as I have the mold issues for putting the head board verified - I'm having a bit of fun with that at the moment. __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
(Offline)

7th October 2006, 20:43	#38 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 696	Re: K1 project page INCLUDING publically-available files Looks quite nice but the bottom latches give me pause. Crawling through an opening, snagging line from a reel, etc could cause one or more of them to unlatch, no?
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7th October 2006, 20:45	#39 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,396	Re: K1 project page INCLUDING publically-available files No, for two reasons: 1. They're the "double catch" type; you have to push the release to be able to unlatch them. 2. I intend to put a piece of inner tube over them in use (aka the SS scooter trick to prevent the same sort of snag hazard), so as to remove the risk of snagging them on something (e.g line, etc) I would have done a "hard bottom" for the can but PE pipe is basically impossible to glue. The only way to bond it is through heat fusion and the hardware necessary is expensive. The can body is one of the places where, if I actually decide to make these (e.g. more than one) I will do something about this. One of the big issues with the PE pipe solution is that its NOT completely round, and the error is not small - it is quite common for it to be a tenth of an inch out of round! One of the nice things about the scrubber can design I adopted is that it does not require anything more than a scroll saw and drill press, plus a sander. You could get by entirely with hand tools if you're careful. I'm likely to post the drawings as PDFs, which means you can go get some full-sheet labels, load them in your printer, then stick them on the stock and use that as your template - that's how most of the cannister parts were made. __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket Last edited by Genesis : 7th October 2006 at 20:51.
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7th October 2006, 20:52	#40 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 696	Re: K1 project page INCLUDING publically-available files What's the diameter of the can (inner and outer)?
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