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[irishcarguy]

I'm presently engaged in assembling my Robbe U47 and have acquired some aftermarket items. Before I start to permanently  affix them to the rear bulkhead in the WTC I'll looking for some experience for make sure I'm headed down the right path. I have Dream Arts (Has Closed his shop) shaft tube and seal It's a two part item. No issues in stalling them but anyone used them before and did you have any leakage there.

Also plan on using Norbert Brüggen push rod seal and will be using true 3mm brass rods, again any problems with his seals. Did anyone use any grease on the push rods, worried about attacking the rubber "O" Rings

Will be adding a servo to power the front diving plans and will in bow section of the boat. My question is, I will need a water proof connector for the servo wires in the rear bulkhead for removal of the stern portion of the boat

Finally have heard a lot of different thing about different ESC's thinking about Robbe will be driving two Graupner 400 6V and will most likely BEC.

Any comments would be welcomed

John

[eddieboote]

Hi, I'm rebuilding my U-47. Finally ditched the traditional system and gone for the bayonet system. I never used any grease or vasaline before on the large 'O' ring. This is because I always considerred vasaline would eat the rubber, being pure pertrolium jelly. For the bayonet system 'O' ring I'm considering to use something that is bio-degradable atleast nothing aggresive. Maybe some olive oil. However during a recent meeting I went to at St Albans most used vasaline. Seems the norm.Your mention about Dream-Arts shop closed. That's a pity. He had some good stuff. I bought a deck from him. Your last point for the front servo and waterproofing. Yes you will need a water tight connector. You could make one. You could have standard servo connection then installed into a small plastic can (screw top). Try to use something as small as possible not to have too much air, or then you might have trim problems. My boat will have a 40 contact connector that I've found on RS catalogue. I need this for various accessories I've added (speaker in conning tower, other servos for future torpedo launch system, waterproof camera, revolving 88mm). I made a connector before using 2 sub Ds, but this failed. RS do sell some smaller waterproof connectors with 2, 3, 8 connections. I'll post some pictures at the weekend of the status of my re-build. 

[derekwarner]

eddieboote ..... nitrile rubber ...or Buna N is a synthetic elastomer...it is totally compatible with general petroleum lubricants...& naturally petroleum jelly is a highly refined version of petroleum with minimal added modifiers  

Silicone grease, rubber grease...& a number of others are all totally suitable ...DOW Corning market tubes of such products specifically for the safe installation of nitrile o-rings & seals.......

To satisfy yourself   GOGGLE  nitrile rubber fluid compatibility   .......Derek

[Subculture]

Most o-rings you will find on submarines are made from nitrile. I belive that Buna-n is a trade name for nitrile, used primarily in the U.S. Here in the UK and in Europe it tends to be named nitrile or NBR.

One material you really need to be careful with is silicone rubber. This is attacked by petroleum or silicone greaseshese products. Silicone rubber seals tend to be a bit softer than nirile o-rings, and are often white or red in colour, but can also be black or transparent.

There are a lot of other polymers out there (viton and EPDM are two others that spring to mind), but they tend to be much more expensive and are a little harder to source. Most of them are overkill for model submarines.

A safe lubricant to use on all seals is vegetable oil/fat. Lard also works quite well.

Andy

[irishcarguy]

Thanks to everyone who responded I did go on a site to check for fluid compatibility and vegtable oil was rate as excellent

John