Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Submarines => Topic started by: g4yvm on July 04, 2011, 11:15:57 pm

Title: Piston tank build
Post by: g4yvm on July 04, 2011, 11:15:57 pm

Im trying to decide on one of two systems for my Type vii, water tank ballast or piston tank.   I'll probably go down the R and D route for both quite a long way before I actually decide as I am still getting the 3D concept of a submarine into my thick head.  On this basis, and as I am loath to repeat other's mistakes yet make my own path public out of interest to others who may tread this path, I shll attempt to ensure that my build is "in the open". 

When designing the piston tank I have found this company http://www.technobotsonline.com/index.php?dispatch=categories.view&category_id=189 (http://www.technobotsonline.com/index.php?dispatch=categories.view&category_id=189) which seems to supply gears.  But as far as correct threaded brass goes, will standard "M" threads do the job?  I.e. if I used M5 brass rod, will that type of thread be okay?

My initial thinking right now is to have (for each tank) a servo cam drive one of two microswitches -  one for "in" and one for "out" on the piston.  Add to this two end stop switches and I seem to have two independent piston ballast tanks with capability for fore and aft independent trimming.



David

Title: Re: Piston tank build
Post by: g4yvm on July 05, 2011, 08:28:51 am

Sorry chaps, just read a short article that declares M8 or similar to be fine/  Thats one issue sorted!

D

Title: Re: Piston tank build
Post by: Mankster on July 05, 2011, 10:27:36 am

I would go with a stainless steel threaded rod for the increaed strength, especially if it is a long tank. Brass or plastic is fine for the gears.

Title: Re: Piston tank build
Post by: andyn on July 05, 2011, 10:57:36 am

I'd go for stainless steel rod too.. Mainly cos it's cheaper %)

Title: Re: Piston tank build
Post by: g4yvm on July 05, 2011, 03:59:28 pm

Oh right, thanks.

I assumed brass would be best.  Thanks for the heads-up

D

Title: Re: Piston tank build
Post by: admiral donuts on July 06, 2011, 07:43:43 pm

If the threaded rod is going to extend into the W.T.C as per Herr Engel then I have nothing to add BUT if you attempting to have a fixed rod and a moveable piston then some form of gland packing will be required on the piston/thread interface
Ordinary M8 rod has a thread that is cut and as such is rough.this will reduce the service life of the packing
It would be better to use a rolled thread as this is smooth and will not cut the packing
Grab yourself a copy of the R.C submariner D.V.D in which a nice man shows you some piston tanks and you may save yourself a lot of
head scratching,sorry,development work
Regards Donuts

Title: Re: Piston tank build
Post by: g4yvm on July 09, 2011, 08:36:14 pm

Thanks Donuts.

Ill get the DVD too.

D