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[John W E]

Hi ya gingyer

The mould for the USS South Dakota is it a 3-way Split Mould?   As I noticed, as well as protrusions, such as the bilge keel and the prop-shafts there are also recesses along the deck edge - just out of curiosity that's all - as the mouldings themselves, going by the photographs, look like they have been moulded by professional laminators.    I cant see any evidence of any resin rich areas on the bottom of the mouldings in the areas of the bilge keels. 

The only thing that does concern me - is - if you have a good team of laminators, who are building their experiences up - try to avoid moulding on items such as the bilge keels to the moulds, due to 2 facts - one that has already been explained i.e. pure resin has the habit of chipping and breaking off easily - the other one is that polyester resins tend to shrink a lot, when they have no glass structure behind them to support.  So, you may find (if the bilge keels are pure resin) you may get distortion there over a period of time.

Long time ago when working in the moulding industry, we used to spray, using a fibre glass chopped spray gun and this gun was fed by roll material - that is chopped up by the machine and sprayed on to mould.    One of the cheats we used to do, if we had a tight area such as you have in the bilge keel would be to (after the gel coat had set) put a small layer of tissue in - gently stippled into the area; then roll some of this chopped strand up from the machine into a string and lay that into the area - then wet out with resin.   I have had a look at the website for fibre glass based here in South Shields and they now supply a string which might help you out.   I noticed that the price of the roll for the machine is a bit on the pricey side, compared to the string.    Somehow, though, looking at these mouldings; I am trying to teach me granny how to suck eggs here

https://www.ecfibreglasssupplies.co.uk/category/cloth-fabric-and-tapes

John

[gingyer]

thanks John 
every little tip helps

[ballastanksian]

I think your work is up there with the established companies, and your efforts to supply the superstructure units for customers to detail is a big thumbs up, as this makes the build a lot easier as we can then concentrate on making detailed bits. I completely appreciate you are on a budget and remember the experience when trying to set up a couple of ranges in the last twenty years, you have to make sure your outgoings do not eat more than your income even if you are ploughing it back into the company.

The Atlanta is fun, How many turrets can you stack up on one hull!

[gingyer]

thanks for the kind words 


The superstructure for the South Dakota mast has been cut where there is a deck level, to make it easier for building.
hopefully this will aid the builder

The Atlanta....   
8 Twin 5" guns, but they were top heavy...... so later ships were cut down to 6 Twin 5" guns
We have built a master 5" gun too, but I am unsure best way to proceed with this at the moment so have stopped to think about it.
If we made it just out of a big lump of resin then we have a weight issue, not a problem for the battleships but the Atlanta we need to be careful.
yes the buyer could core it out but think of the waste, hassle and DUST (its bad enough to have our better half moaning about a wee but of dust  )

The other option which I am looking to explore a bit further is using a light weight GRP structure with a resin base, but this is all to be thought out further before proceeding

[ballastanksian]

Manufacturers of resin military model kits manage to cast hollow hulls and (on larger scale kits) turrets so it is definitly possible to hollow cast such things. One method you could try that does not require resin injection systems is to sluch cast turrets. You make a two part mould that effectively has no ingate and you pour an amount of resin deemed enough to give a thick enough skin to the whole item in and then roll the mould in all directions so the resin coats all surfaces. If you can make a simple automated system to do this for you then it saves standing about rotating the mould when you could be doing other things. Do not rotate it too quickly as it will encourage bubbles in the resin 

If you are comfortable with using GRP then that is certainly a proven way to do it. I beleive Deans do larger turrets in GRP these days. Ron or Nick can probably tell you.

[gingyer]

thanks for the info 

[raflaunches]

If you are comfortable with using GRP then that is certainly a proven way to do it. I beleive Deans do larger turrets in GRP these days. Ron or Nick can probably tell you.

I can confirm that Ron Dean uses GRP turrets most notably in the Dreadnought kits and as a recent upgrade to the Hannibal/Magnificent kits too. They are moulded very cleanly with a lot of detail incorporated with minimal tidying up at the base. They are a perfect mix of lightweight of the vacform principle but have the detail of resin items without the weight issue.

[big_bri]

Picked up this well detailed 1/48 scale Oto Melara turret in Dortmund last year, layed up with epoxy resin and fine mat, it weighs in at only 11 grams.
Might be something worth considering mate?

[gingyer]

I know Bri, thats where I got the idea for the lightweight turret.


thanks Nick, I knew Ron does the GRP turrets what I need to do though is really watch the weights.
An Atlanta Cruiser has 8 turrets on it so CofG will come into play especially at about 68 x 6.5" its more
destroyer size