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Post by antique diver on Aug 9, 2023 9:02:01 GMT -8
Yikes! I've had that happen with NOS Voit seats, but not a new blue seat. I hope this isn't the new normal quality from Aqualung (again)
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Post by duramax on Aug 9, 2023 18:27:24 GMT -8
Fibonacci
I have a similar outcome. I recently check the IP on my Kraken and found it not to lockup. I inspected the seat and looked very similar to your first picture. I had less than 15 dives on mine since I received it back in Feb of 2021. Makes me wonder if the base where the volcano orifice is square with the wall of the nozzle
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Post by Fibonacci on Aug 9, 2023 19:37:01 GMT -8
duramax That's the most bizarre part, the reg can work fine and be rinsed dried and put away... then fail months later when its next used! Makes me wonder if the base where the volcano orifice is square with the wall of the nozzleWith modern CNC machining I think that is unlikely, however the Volcano Orifice could certainly be wobbling around off-axis if the bore is oversize... causing that characteristic uneven engraving. I accurately 3D modelled the Kraken partly as an exercise during Covid lockdown and partly to try and get to the bottom of what was causing the last remaining but persistent issue with my Kraken. I simply cannot trust it any longer to not have a random IP spike! Bore ID was 11.70mm measured with a Mitutoyo telescopic bore gauge checked against a Mitutoyo digital vernier caliper. If I get time I will remeasure to confirm and also check the corresponding area of an AL Royal Aquamaster (RAM) that I know doesn't eat HP seats! HP Seat volcano orifice bore measured 1 by fibonacci101, on Flickr Volcano orifice OD 10.95mm HP Seat volcano orifice OD measured 1 by fibonacci101, on Flickr 11.70-10.95 = 0.75/2 = 0.375mm per side maximum theoretical clearance. However the Pin Support OD is 3.4mm Pin Support OD measured 1 by fibonacci101 , on Flickr The corresponding bore ID is 3.6 3.6-3.4 = 0.2 or 0.1mm per side maximum theoretical clearance which should centre the HP seat below it accurately. However, if the bore around the Volcano Orifice is too large to support it properly it may allow the actuating pin to flex as the orifice moves around during breathing cycles? Pin Support bore measured 1 by fibonacci101, on Flickr Turning now to one of the off-centre HP seats, its hard to measure accurately but the misalignment appears to be around 0.21mm to 0.37mm off-axis. HP Seat engraving measured 1 by fibonacci101, on Flickr HP Seat engraving measured 2 by fibonacci101, on Flickr Side clearance to the HP seat centre spigot is around 0.32mm so it would not take much misalignment due to tolerance stackup and/or an oversized bore to display the sort of off centre engraving on the failed seats and lead to a metal-to-metal clash and IP spike. HP Seat volcano orifice side clearance measured by fibonacci101, on Flickr
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Post by Fibonacci on Aug 9, 2023 20:43:26 GMT -8
OK found some RAM CAD I had prepared earlier...ignore the mismatched threads The RAM of course does not feature a removable Volcano Orifice, but its still useful to compare bore clearances with the HP seat. Bore ID is 11.65mm HP seat OD is 11.45mm so 0.20mm difference or just 0.1mm clearance per side. Much tighter! I think this is the area we need to concentrate on investigating... I will try to find and measure corresponding areas on an Aqualung Titan with removable Volcano Orifice to compare with the Kraken. RAM HP bore measured 1 by fibonacci101, on Flickr
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cg43
Senior Diver
Posts: 90
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Post by cg43 on Aug 10, 2023 2:52:44 GMT -8
Hello Fibonacci
You write : "I accurately 3D modelled the Kraken partly as an exercise during Covid lockdown and partly to try and get to the bottom of what was causing the last remaining but persistent issue with my Kraken."
First , the balance chamber has to be fixed to the Kraken body , otherwise it dont work . The Ram HP seat can't have a hole in its end otherwise the HP will leak HP to the IP side .
I understoud that this drawings are an exercises for you but if ou want us to see problems there must be a littel more accuracy . Thats brings me to this: You write "...
"That's the most bizarre part, the reg can work fine and be rinsed dried and put away... then fail months later when its next used"
Well , in store the first stage is open as wide as posibel . Turning on the valve (quick) may schoot the HP seat foreward with speed , and that may causes problems . But to look at that by drawings , the drawings must be accurate to an certain point . You are on the right track , go on !
Greetings Rainer
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Post by antique diver on Aug 10, 2023 4:49:46 GMT -8
I don't recall hearing anything about this seat issue in past years of the Krakens, and now several divers have just recently spoken up about the off-center damaged Aqualung seats. This makes me wonder if this was not a Kraken issue, but may have been was a later batch of the those seats that were sized a bit small on the OD.
I am very interested in an accurate comparison of the OD of the damaged seats that have recently cropped up as compared to some that have survived a longer life and have concentric impressions! Please check that out and let us know results.
I forgot to mention... could the bore size for the pin could be off in some of the seats, causing sloppy alignment?
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Post by duramax on Aug 10, 2023 6:40:02 GMT -8
Hello Fibonacci,
Given the damage to the seat is not only off-center but also not a a complete circle (u-shaped), makes me think the two surfaces are not meeting parallel. It could be the HP seat that is off or the volcano orifice. Maybe you can model this in your CAD to determine how off they have to be from parallel to knock it off center. The theory of wobble to me seems a bit more dynamic and would make me think that the damage would be more circular, instead of u-shaped. This is just me thinking here and could be totally off base. I am far from an engineer. Just a weekend mechanic at times.
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Post by nikeajax on Aug 10, 2023 6:48:53 GMT -8
I'm only responding to this because I'm trying to be proactive and participate. Also, I do have some pretty bad reading issues, so forgive me if I've missread some of the conversation: So, if the bore is too large, could it be shimmed/bushed as I had to do with my Divair? In theory, this will take the slop out any seating issues,should it not? Jaybird
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Post by Fibonacci on Aug 10, 2023 14:25:21 GMT -8
I have a similar outcome. I recently check the IP on my Kraken and found it not to lockup. I inspected the seat and looked very similar to your first picture. I had less than 15 dives on mine since I received it back in Feb of 2021. Makes me wonder if the base where the volcano orifice is square with the wall of the nozzle duramaxCould you please upload some pics of the failed seat so we can gather more data?
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Post by Fibonacci on Aug 10, 2023 14:32:28 GMT -8
I don't recall hearing anything about this seat issue in past years of the Krakens, and now several divers have just recently spoken up about the off-center damaged Aqualung seats. This makes me wonder if this was not a Kraken issue, but may have been was a later batch of the those seats that were sized a bit small on the OD. I am very interested in an accurate comparison of the OD of the damaged seats that have recently cropped up as compared to some that have survived a longer life and have concentric impressions! Please check that out and let us know results. I forgot to mention... could the bore size for the pin could be off in some of the seats, causing sloppy alignment? Yes the original thinking was that there had been a bad batch of aftermarket HP seats (Trident?) and issues were confined to that. However it seems the 2017 batch of Krakens have another unrelated issue that causes accelerated failure in HP seats, as both new Trident and Aqualung seats experience premature failure, just at different rates. Now duramax reports similar issues with his 2020/21 Kraken which must be using different HP seat batches. Quote from another 2017 batch Kraken owner originally posted on another forum: I too had issues with the IP spiking, resulting in the octopus beginning to free flow as a tell tale sign. The HP seat had similar markings (see photos below). I went through three OEM HP seats in total, over about 130 dives total. Two were brand new and one was a an old spare I had lying around that looked good to the eye, but failed after 2 dives. I dive most days so this isn't a case of the reg sitting in a cupboard for ages. These failures were after Jerrie at DiverdownDH did a full service and rebuild on the reg, including photos, so we can be sure it was assembled correctly since Jerrie is not just some random technician but comes recommended by Bryan (VDH was closed due to covid, and a message on his website directing servicing to Jerrie).In this failure, the engraved rings are more concentric... Kraken HP seat failure 3 by fibonacci101 on FlickrKraken HP seat failure 4 by fibonacci101, on Flickr
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Post by Fibonacci on Aug 10, 2023 14:48:48 GMT -8
Hello Fibonacci You write : "I accurately 3D modelled the Kraken partly as an exercise during Covid lockdown and partly to try and get to the bottom of what was causing the last remaining but persistent issue with my Kraken." First , the balance chamber has to be fixed to the Kraken body , otherwise it dont work . The Ram HP seat can't have a hole in its end otherwise the HP will leak HP to the IP side . I understoud that this drawings are an exercises for you but if ou want us to see problems there must be a littel more accuracy . Thats brings me to this: You write "... "That's the most bizarre part, the reg can work fine and be rinsed dried and put away... then fail months later when its next used" Well , in store the first stage is open as wide as posibel . Turning on the valve (quick) may schoot the HP seat foreward with speed , and that may causes problems . But to look at that by drawings , the drawings must be accurate to an certain point . You are on the right track , go on ! Greetings Rainer The 3D models are accurate. The RAM has a balanced first stage so air needs to bleed into the Spring Block #1053-24 Ockham's Razor applies I hadn't opened that CAD file in a couple of years, when it was last used some parts were simply not loaded... I was just measuring the bore so didn't update the assembly. I have now... RAM HP Bore and Seat Section by fibonacci101 , on Flickr
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Post by vance on Aug 10, 2023 15:05:20 GMT -8
Your diagrams are awesome, Graeme. You and James have skillz I can't imagine ever getting. I tried to learn this stuff, but I keep getting stuck at the simplest level. That made me understand that I'm strictly an analog guy.
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Post by vance on Aug 10, 2023 15:14:13 GMT -8
I am starting to think that there's something wrong with the HP seats AND there's a bit of misalignment or slop in the volcano orifices on some Krakens. It could be a confluence of problems!
When I was a car mechanic back in the day, I found that the successful diagnosis of a problem often included two or more issues.
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Post by Fibonacci on Aug 10, 2023 15:22:40 GMT -8
Hello Fibonacci, Given the damage to the seat is not only off-center but also not a a complete circle (u-shaped), makes me think the two surfaces are not meeting parallel. It could be the HP seat that is off or the volcano orifice. Maybe you can model this in your CAD to determine how off they have to be from parallel to knock it off center. The theory of wobble to me seems a bit more dynamic and would make me think that the damage would be more circular, instead of u-shaped. This is just me thinking here and could be totally off base. I am far from an engineer. Just a weekend mechanic at times. Yes it certainly does seem like the two surfaces are not meeting on the same axis or plane. Did a quick sketch model below... shows a 0.5 degree difference between axes with the same 11.70mm ID bore over a 26.60mm depth to reflect both the RAM and the Kraken, A 0.5 degree skew will mean the two axes will be out by 0.23mm at the face which seems close to what we are observing when you also add a machining tolerance of +/- 0.127mm (0.005") ... 0.5 deg off axis section by fibonacci101, on Flickr CNC accuracy tolerance for line boring a blind deep hole like this is typically +/- 0.5 degrees... with a form tolerance of +/- 0.127mm (0.005") unless special custom reamers are used. Unlikely for the Kraken which seems to have been CNC machined in small batches annually. Xometry table below is just an example. www.xometry.com/manufacturing-standards/Xometry CNC machining accuracy by fibonacci101, on Flickr
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Post by Fibonacci on Aug 10, 2023 15:27:15 GMT -8
I'm only responding to this because I'm trying to be proactive and participate. Also, I do have some pretty bad reading issues, so forgive me if I've missread some of the conversation: So, if the bore is too large, could it be shimmed/bushed as I had to do with my Divair? ~snip~ In theory, this will take the slop out any seating issues,should it not? Jaybird I guess it could be sleeved, if the bore being oversized was the only issue. Measuring the axis of the bore accurately will be very difficult... I would need to take it to a specialist metrology lab. As vance says the bore may be oversized AND a little off-axis... if true then I have a very expensive paperweight I will try to measure an Aqualung Titan in the same areas, they are very similar in design to the Kraken and have a reputation as being very reliable regs so a comparison of the bore diameter will be interesting!
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