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Author Topic: Engel Type 212A Build Log  (Read 27135 times)

Subculture

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Re: Engel Type 212A Build Log
« Reply #25 on: December 17, 2014, 05:16:13 pm »

You would need to make some mods for the aerial. Another alternative is to look at the higher frequency modules.

Jack D

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Re: Engel Type 212A Build Log
« Reply #26 on: December 17, 2014, 11:34:03 pm »

I have to admit I am tempted by the F-16's, they do look very good.
I don't have any experience modifying transmitters (just like I have no experience with submarines!) so I'd need a fair bit of help both sourcing a module for converting a 2.4Ghz and then installing it.

One of the next steps in construction is installation of ballast, for which it reccommends using decent fibre reinforced tape. I'm hoping that kind of stuff is available in hardware or home improvement shops. I'd like to follow the instructions and reccommendations by the manufacturer as closely as possible during this build.
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Subculture

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Re: Engel Type 212A Build Log
« Reply #27 on: December 18, 2014, 07:46:28 am »

Fibre reinforced tape- duct tape fits the bill.

If you're not confident tinkering about inside a transmitter, then your best bet is to source either a decent secondhand 40mhz transmitter, or get a new unit.

A synthesized set is the preferred option, but there isn't a whole heap of choice, and they tend to be upper end transmitters. An exception being the Multiplex Cockpit SX, if you can find one.

Jack D

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Re: Engel Type 212A Build Log
« Reply #28 on: December 20, 2014, 06:47:44 pm »

I've started working on the hull of the boat now, things are really starting to come together- it might even float soon!

I've added the main ballast weight into the hull. In the manual it said to do this after putting in the rudder linkages, motor, etc but I believe that it would make an already tricky job harder while putting in the linkages and motor won't really suffer from the very slightly reduced room.



The first strip in the forward section. Note the two brass pins as guides- this section must be 1mm off centre and those pins are it's guide rail, so to speak. Really very useful!



The second strip- this is where things have gone a touch wonky. The two pieces are supposed to be perfectly parallel and as close to the sealing ring as possible. They're out of alignment by a few degrees and are about 2-3mm back from the locking ring, which could cause some trim issues. Given that the opening here is just about big enough to accept my hand, it is much harder than it looks to get everything lined up- this took three or four tries.



The stern ballast- now this I'm MUCH happier with. It's as it should be more or less exactly. But, given that I can hold the back end while putting it in it is far, far easier than the bow.


Next up, the push rods for the rudders and the prop shaft!
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Mankster

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Re: Engel Type 212A Build Log
« Reply #29 on: December 20, 2014, 11:25:15 pm »

I have to admit I am tempted by the F-16's, they do look very good.
I don't have any experience modifying transmitters (just like I have no experience with submarines!) so I'd need a fair bit of help both sourcing a module for converting a 2.4Ghz and then installing it.

One I did earlier, works perfect, switchable between 40Mhz and 2.4GHz. Never use it as I moved to more exotic gear.


Jack D

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Re: Engel Type 212A Build Log
« Reply #30 on: December 25, 2014, 03:34:31 pm »

Well, last night the sub was ready for bath testing, but somehow overnight the O ring has developed the ability to leak air like nobody's business no matter how much its' cleaned or has sillicone lubricant applied.
Add to that the fact that after putting in the batteries there is woefully inadequate room for battery connectors you have the problem of said connecting block coming out and rubbing on the side of the hull, which causes the dual headaches of scraping the lovely yellow paint off of the lead ballast into great big chips which then get adhered firmly to the lube on the O ring AND breaks the battery compartment into it's respective bits trying to get the tech rack out.

It's the latest in a string of minor issues that have been popping up over the last few days which have been driving me to distraction. I actually had hoped this sub being small and easy to manage I'd be able to sail it often but if it keeps throwing wobblers like this it isn't going to happen.
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salmon

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Re: Engel Type 212A Build Log
« Reply #31 on: December 25, 2014, 09:45:09 pm »

Jack,
Take a breather. Rarely does everything go smoothly. I adopted the mindset knowing it will get frustrating and at times I had to walk away or there would have been more parts than original because I smashed things.
Not having built your sub or know which o ring is giving you problems, but on some of my subs, I had to wrap Teflon tape two or more times in the channel the o-ring goes in. This in effect pushes the o-ring out to fit tighter against the tube. If it is a shaft o-ring, it might need replacing. Although tolerances are good, I cannot imagine that it is perfect or that there might not be a nick or damage on the o-ring. Anyways, stuff happens and if it gets to you, take a break. You are doing great on this build.
Peace,
Tom
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Subculture

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Re: Engel Type 212A Build Log
« Reply #32 on: December 26, 2014, 10:20:58 am »

Are you sure the leak is on the main hull seal, and not one of the other smaller seals?

You shouldn't need to break out the Teflon tape.

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Re: Engel Type 212A Build Log
« Reply #33 on: December 26, 2014, 05:22:58 pm »

I've omitted a lot of the photos and details of the build since last time. I've put everything in the stern section together and immersed it in the bath prop down. There wasn't any leakage around the propshaft, rudder linkages or air/water lines. When put together and testing out of water air can be heard escaping around the bayonet lock holding the two sections of the boat together.

I have decided to leave it for a couple of days but I will add the other construction details later.
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Subculture

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Re: Engel Type 212A Build Log
« Reply #34 on: December 27, 2014, 04:13:18 pm »

That's surprising given that these parts are generally accurately made on Engel kits. I would use the old gas fitters trick of pressurizing the inside and brush some soapy water around the suspect areas, that will pinpoint the leak very quickly.

Mankster

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Re: Engel Type 212A Build Log
« Reply #35 on: December 27, 2014, 04:22:10 pm »

One part to pay attention to (given this was glued in the factory) is the inner part of the hull where the bayonet lock is glued to the hull. I found it was easy to get a little void.

Jack D

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Re: Engel Type 212A Build Log
« Reply #36 on: December 29, 2014, 04:56:53 pm »

I've just tested this with the soapy water technique and it confirmed a leakage around the bayonet lock. But it was inconclusive as to whether where was air leaking from the stern bulkhead so I filled up the bath, filled the ballast tank out of the water to increase the air pressure in the sub and immersed it. Tilting it every way I could I couldn't see any bubbles in the wet stern compartment (with the auto pitch control on the servos were wiggling about a fair bit to testthe bellows).

However, as I thought there is a constant stream of small bubbles coming from the bayonet ring, specifically in one place- on the port side where the 'hump' would meet the main cylindrical part of the hull.

Before doing the test I cleaned off the O ring of dust and grime as much as possible and the lock on the inside too then gave the whole thing a generous coat of universal silicone lubricant- less thick and sticky as the kind which came with the sub but easy to acquire and apply in liberal quantities, potentially before each sailing.
Tomorrow I'm going to take the O ring off completely for an absolutely thorough clean and inspection then try the bath test again. If it still leaks then it's probably as Mankster suggested and there's a void in the bow bayonet lock- while the hull was pressure tested before sale I've found it requires a generous application of force to initially separate the two parts of the boat so the factory seal may have given up under stress.
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Subculture

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Re: Engel Type 212A Build Log
« Reply #37 on: December 29, 2014, 06:01:00 pm »

You really shouldn't need much if any grease. I put a tiny smear on the seal just to reduce the friction, but it's the rubber that does the work. If you're having to ladle it on, then it's a sign there's a problem elsewhere.

Jack D

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Re: Engel Type 212A Build Log
« Reply #38 on: December 30, 2014, 12:36:38 am »

You really shouldn't need much if any grease. I put a tiny smear on the seal just to reduce the friction, but it's the rubber that does the work. If you're having to ladle it on, then it's a sign there's a problem elsewhere.

A problem elsewhere is the most likely issue. I'm glad you don't need a lot of grease- that would rapidly turn into a nightmare.

If the bond to the hull with the plastic part of the bayonet has got a void in it how would you reccommend sealing it? I'm thinking of using some silicone sealant if it isn't a big gap but I'm not sure if that would be a good idea.
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unbuiltnautilus

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Re: Engel Type 212A Build Log
« Reply #39 on: December 30, 2014, 09:59:17 am »

Epoxy, Stablit or Devcon Plastic Welder. Silicone has its uses, just not to waterproof a sub. I would locate the hole if possible and dig it out with a burr in a hobby drill before re-sealing the problem area.
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Subculture

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Re: Engel Type 212A Build Log
« Reply #40 on: December 30, 2014, 04:35:54 pm »

I was thinking may be Deluxe materials Fusion. Set's up very strong, and totally waterproof, but it's runny when mixed so it seeps into gaps better than some other acrylic or epoxy glues.

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Re: Engel Type 212A Build Log
« Reply #41 on: December 30, 2014, 05:19:46 pm »

Unfortunately I only just checked back here after Subculture made the last post and I've already done done some work here.

I've taken the O-ring out and thoroughly cleaned the mounting- there was a lot of 'gunk' for want of a better description, mostly fibrous trapped under or around the O ring which could have been causing the issue. I inspected the O-ring itself after cleaning and I can't find any damage, only very slight irregularities on the surface around the inner and outer edges probably as a result of moulding but nothing major.

I've started putting epoxy in the bow just in front of the bayonet lock to seal it. A big thanks has to go to whoever told me how epoxy works when hot (probably Unbuiltnautilus)- after carefully applying to the area and pushing it into the gap as much as possible with a spatula without getting any on the inner surface of the bayonet lock (which would cause serious drama!) I heated it up with a hairdrier. The epoxy went very, very runny very quickly, so I could actually move it around about half of the ring and it seems to have left a veneer behind and hopefully havs seeped into cracks. I let most of it pool where I noticed the leakage and it set hard in under five minutes.
I'm going to let it set for a few hours and repeat the process on the other side of the sub before testing the seal again.
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derekwarner

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Re: Engel Type 212A Build Log
« Reply #42 on: December 31, 2014, 12:10:25 am »

Jack....must agree with UBN here....Dow Corning Silicone type material may have uses if scientifically placed in a clean room environment with equally clean mating parts which were also designed for such adhesion

However the above I suggest precludes it for any general use  of Silicone GOOP  <*< in the modelling or home repair water proofing arena

O-ring's were designed to be a pressure energised seal element........they also necessarily rely on correctly dimensioned cavities, [compression] clearances & surface finishes to effect fluid tightness

One of the difficult things here is that both British & Australian Standards for o-ring cavities are based on a pressure application....[~~~200 Bar]...so are not necessarily suitable for static conditions of say 1 Bar or atmospheric conditions

I also agree that an epoxy sealant is the better plan for your rectification work, however maintaining the manufactures cleanliness of the surfaces to be joined is of paramount importance......Derek
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Subculture

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Re: Engel Type 212A Build Log
« Reply #43 on: December 31, 2014, 08:02:05 am »

Most problems with sealing o-rings on subs stem from either sealing against a surface like the Himalayas or dirt contamination.

I find 10% compression is about right if both pieces are machined or known to be concentric, and move up to about 15% if the sealing surface is bit indifferent e.g. when sealing against internal bore of extruded plastic tubing which is often quite wavy.

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Re: Engel Type 212A Build Log
« Reply #44 on: December 31, 2014, 03:34:21 pm »

Well, I'm pretty sure I solved the dirt problem and to be sure sealed the inner join to the hull with epoxy, but it's still leaking in the same place, in fact it's actually gotten worse (beforehand the periscopes would at least retract and it would take a while for the air to leak out). The seal seems pretty tight, it takes a lot of effort to get it together and apart. I'm pretty much all out of ideas now.I could try the teflon tape idea but since it's already a tight fit I'm not sure if that's the solution either.
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Jack D

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Re: Engel Type 212A Build Log
« Reply #45 on: March 07, 2015, 08:04:37 pm »

 Well, it's been a while since I last posted and a bit has been done in the meantime, although it still hasn't hit the water yet (I've been very busy with work). I also made an absolutely fatal error in the build which I will share here in case anyone else comes across the same situation.
 
 Where I left off with the pictures was just after putting the pre sealed ballast in the hull. After this the stern section starts having its equipment fitted. It starts off with the bellows which will take the brass rods for the tail planes.



 This was actually a remarkably fiddly job with a pair of long nosed pliers trying to get the bellows which are deeper attached. There's less room to work within that access hatch than you might think.
 
 
 
 Now here are the pushrods and the main drive battery, which is two 6v batteries linked in series to make one 12v unit. It's done this way to save space in what is a relatively small hull. The instruction manual says that the threaded rod ends should either be soldered or superglued. Here you can see that they have been soldered, but later one linkage did break so I then superglued it and it seems to be a good bond now. These rods are then passed through the bellows to be linked to the X-rudder linkages, which have been pre assembled.
 
 
 
 Here are the pushrods in their final positions. Note that the rod closest to the hatch is bent- this is to stop the pushrod from flexing when the rudder is moved, which puts pressure on the bellows and can cause the rod to seize in place. Judging the angle is difficult, especially since the bend must be done in situ, as it will be very difficult if not impossible to feed the rod in from the stern section (or was when I tried).
 
 
 Here's the dry side of the aft bulkhead after installation of the servo pushrods. Note that the clips put on the threaded end caps are out of focus.
 
 Now this next step is where things went badly wrong, installing the propshaft. I followed the instruction book to the letter as was recommended and so I missed a key step which came back to haunt me later. To prevent confusion, I'm going to put the next photos in the order in which you SHOULD install this thing, not how I DID the first time. The error I made was very simple and anyone with a little more experience probably wouldn't have made it, I'm pretty sure.
 
 
 Here you have the propshaft assembled but everything isn't quite put together. The coupling is very simple, just a piece of brass machined through with four grubscrew slots. Given the tech rack and stern bulkhead's precise machining, there shouldn't be any mis alignment of the motor and propshaft. Note you have to put the motor mounting plate on before linking the motor to the shaft, because that mounting plate is also where the shaft leaves the watertight compartment and has a rubber seal- if you push the threaded end of the shaft through, you will destroy the rubber seal and your boat will leak, a lot. Luckily the shaft is long enough that this plate doesn't get in the way when you're joining the shaft to the motor.
 NOTE: the prop and spinner are attached in this photo. In the instructions, the prop is attached after the shaft is installed and here it will need to be removed to fit into the submarine. However, I strongly recommend at this stage putting the prop on and giving the prop in one hand and the motor in another a firm tug. This ensures that your motor and propshaft linkage are on properly and the shaft won't come out if you go into reverse.
 
 It is important to do this check at this stage, because the brass linkage will fit snugly into the mounting plate and will be totally inaccessible without completely taking the stern to pieces if you do have a problem. I can't stress enough how much of a total pain that is. In my case I followed the instructions and essentially completed the entire sub. Then I had leak issues, which made me take the submarine to the clubhouse, where it emerged that my leak problems were caused by having too much silicone grease on the O-ring and it managed to go into the water, dive and emerge just as it's supposed to. Then I put it into reverse and the propshaft came loose. After taking the entire thing apart and putting it back together, lo and behold it's leaking again, caused by something I did taking it apart. If I'd tested the prop linkage at that much earlier point this sub would most likely have been sailing happily for a while (or something else might have come up, who knows).
 
 
 
 Here's the propshaft with the motor mounting plate on and greased. Note how the motor and propshaft linkage is now inaccessible. the green grease is also pretty cool- when it's no longer visible on inspection it is time to grease again.
 
 
 Now the motor is mounted, plugging the largest hull in the stern watertight bulkhead. I HIGHLY recommend a nut driver for this step, if you don't have one it is impossible to do by hand due to the depth and restrictive size of the compartment. I first put these nuts on with pliers and it took over an hour. With a good driver, it takes five minutes.
 
 
 
 The wet half of the propshaft. Note how most of the rotating part of the propshaft is entirely exposed to the water. It probably cuts down grief with keeping it greased but I can't help but wonder what the hydrodynamics are like inside that wet compartment when it's going.
 
 
 
 Next is installing the servos into the tech rack. Due to limited room and the fact you use the third hole from the centre, the end of the servo arm has to be cut off. Since there are two, here is a picture between an original arm and one I prepared earlier(tm). The servos then literally snap into place in the tech rack.
 
 
 
 Here's the watertight stern bulkhead with everything bar the tech rack support bars attached. The large pipe takes water in for the ballast tank. I found handy advice to run it under hot water immediately before installation to soften the end of the pipe, which makes it easier to slot over the brass collar by orders of magnitude. Again, due to depth and narrowness of the compartment you need to use pliers to do this which isn't the easiest thing in the world. The smaller tube routs to the pressure switch, which will hopefully return the sub to the surface if the model goes below 3m of depth, which runs the risk of pressure and other, more sinister unknowns killing the model and making it irretrievable under its' own power. This smaller lead is easier to install, but with pliers you do have to be wary of ripping it if you aren't gentle.
 
 At this point the tech rack is joined to the stern section. Here a lot of things need to be done simultaneously- the ESC must be linked to the motor (which given the positions of the two bits of kit and the length of cable provided means the pliers come out again and you have to be very careful. I also found that the bullet connectors didn't have quite enough rubber coat to completely cover the connection, leaving a small golden strip visible so I wrapped each connection with electrical tape to prevent any unlikely short circuits (as said earlier, you want to disassemble the stern as infrequently as possible so mitigating issues before they arise is essential). The piping is connected to the routing in the tech rack and then finally the pushrods are connected to the servos. This is done last because the reach of the arms only gets to the final position of the servos, so the tech rack has to be physically bolted on for it to work.
 
 There wasn't a lot of point trying to take photos of these steps because they're all pretty straightforward, even for a build as simple as this and given their nature getting photos of this work would be tricky.
 
 
 
 With everything installed, this is what the sub looks like from the outside. Which is to say, identical to when I started! Picking the model up however there is now a very healthy weight to it which is immediately apparent.
 
 
 
 
 Then the prop and spinner are screwed on and the dive planes are fitted. Take note, when the instructions say use only the tiniest drop of superglue, they mean it. Luckily, for most of these planes, the fit is tight enough that they can really go on without any glue at all, but if you do need to glue them as they're resin superglue will bond them to anything and in lightning time (something I somehow forgot from my many years of sci-fi modelling with resin). As a result, one of the tail fins (the lower starboard one) is about a millimetre further from the hull than it should be because it got momentarily stuck pushing it on and the superglue went off before I could push it in further. Every attempt to remove the fin have ended in failure so far and since it is only minor I probably won't try much more to fix it (unless there's a chemical I could use which doesn't harm plastic and resin but attacks superglue, in which case I might), for fear of damaging the submarine.
 
 At this point you are ready to test the submarine. This is where I discovered the leaks, found the solution to the leaks, lost the propshaft, took everything apart, fixed the shaft, leaked again, took everything apart again thinking one of the water lines had come off (they hadn't), still leaking etc etc etc.
 
 When I build up the will to go leak hunting again it will be time for trimming and I'll take photos of the trim weights and the completed tech rack et al.
 
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Jack D

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Re: Engel Type 212A Build Log
« Reply #46 on: March 09, 2015, 10:49:10 pm »

So, today has been a mixture of ups and downs.
I took apart the stern (again) on Sunday, discovered that the ballast feed had come loose, fixed it back in place and I installed the reciever for my shiny new MC-15 and got the Hall effect sensor put into action, then had a look at the tailplanes and servos and had a look to see if I could get them to change in all directions. In everything I was met with success. Here's how the tech rack looks.


The power leads need neatening up at the bow but that's all that's visually going to really change on this tech rack now.

I decided to power it all up, seal it and check for leaks on Monday evening and to my surprise, it passed in air, so I filled the bath and tested it in the water. It seemed that there was a minor leak from the O-ring on the starboard side so I took it out, cleaned it up and it appeared not to leak any more.


Amazingly for surface running the model seems to sit right in the water and it does look good.

The sub then managed to dive and surface multiple times using the piston and I was ecstatic. You can see the video of it doing this here:


https://www.youtube.com/watch?v=tvqEhNBnMk0
  (the video is unlisted, so only people with the link can see it).

Unfortunately, the problems started literally flooding in. As you can see in the video, one pair of tailplanes has become totally unresponsive to anything and I have the sinking feeling that the servo has burned out. Also, after being prompted to do a motor test the prop screwed itself into the back of the hull as there is no gap between the threading and the hull. After gently putting the prop back in it's original position spinning up the prop makes a very unhealthy noise (which I hope against hope is just the linkage inside coming loose again). Also the sub is trimmed with the stock trim weights and is nose heavy, so some of the trim weight will need to be removed (though that particular issue is so far down my list I'm not really worried about that at all).

There also seems to be some pretty major interference which crops up from time to time, which is annoying (but since I get odd servo chatter even on all of my 2.4Gz models I'm rapidly coming to accept this as an annoying fact of life), most worryingly which sometimes prevents the piston tank from emptying (though the auto bail on signal loss system is still working).
After taking the model from the water, I discovered everything in the bilges was wet and an alarming amount of water came out, so the leak is still there, it just doesn't show very well on leak tests.

I'm now getting that horrible sinking seeling that I'm horribly out of my depth here.

 
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Subculture

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Re: Engel Type 212A Build Log
« Reply #47 on: March 10, 2015, 01:49:49 pm »

Looking at your pictures, and going by your description, you have a leak on one of the seals, but it's possibly being masked by all the grease you're slapping on. You only need a very small amount of grease just enough to relieve friction. Water works and I would try that for initial bench tests.

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Re: Engel Type 212A Build Log
« Reply #48 on: March 10, 2015, 05:28:35 pm »

I didn't know water could be used to help seal the O ring, that will be useful for the tests.
You are almost without a doubt right about too much grease. That caused the leaks last time. I'm going to tackle the issues that came up in the test one by one, starting with the drive and rudders since I might have to order in replacement parts.
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Subculture

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Re: Engel Type 212A Build Log
« Reply #49 on: March 10, 2015, 06:29:11 pm »

Water doesn't seal anything, it just reduces friction. Course it dries out, hence why grease is used. But use it sparingly, you are ladling it on!

Do a leak down test, pressurize the inside and see if it holds air, You can use the piston tank to pressurize the inside. Ensure the tank is empty before you button up, put the hull halves together and operate the tank to full, that should put a one or two pounds of pressure inside, and leave it overnight. if it doesn't hold this pressure, then you're no good for diving.

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