S.M. U-1 (a new RC project)

[DrSchmidt]

I applied a GRP backside to get an even and clean surface. The excess GRP was then removed using an angle grinder, my Dremel and some files and sandpaper. Nasty busyness, but now I have a nice tool and can start prepping the conning tower.

[DrSchmidt]

Pulled the modified deck section from the mold....no problems this time...and cleaned the seams. Tomorrow the backside will get a layer pf GRP so that the piece gets a nice surface on the backside, And thn I can proceed to get the master of the coning tower fit to the deck and prepped for making its mold....

[DrSchmidt]

The backside of the hull molds are done. Next will be the mold for the conning tower. As the deck is curved, a flat underside of the tower won't do. So the first step is to pull a decks section from the hull mold that will act as base for the sail mold. To make the interior of the sail mold accessible, I wanted to make an opening in the base, a slightly smaller that the sail contour. Therefore I designed and 3D-printed a plug. I adjusted the hight of the plug using polyester filler and then inserted two threaded insets in the base of the plug. Then I positioned the plug in the center of the deck using a cross made of 2 mm GRP sheet. The cross ws screwed to the pug and fixed to the mold using clamps. I used PVA as parting medium. Then I printed two bulkheads and secured and sealed them using putty. Again the plastic was coated with PVA. Then I applied a first layer pf surface resin and cotton flakes as coupling layer. After curing, I filled laminated the remaining voids using glass and carbon fibers and filled the remaining voids using resin soaked glass shreds .

[DrSchmidt]

Still finishing the molds. The backsides are laminated and cured, Now I have to cut the protruding GRP and clean the seams. Then the mold is done...

[DrSchmidt]

The backsides of the four molds is still open, just the sanded filling medium exposed to the open. So the next step is to apply a lid. Basically one takes a coated wood board, next one applies some parting wax, then one laminates the same GRP layers onto the board that were used to make the mold, then one applies a coupling layer of resin mixed with cotton flakes onto the backside of the mold, filling the gaps of the porous filling medium, and than one presses the mold onto the GRP using a plenitude of c-clamps. Done....

[He Who Shall Not Be Named]

A well fought battle, sir!

[DrSchmidt]

Opened the mold and removed the master of the U1. Did not go smoothly as the master got stuck, but in the end some persuasion with a hammer helped. Molds are O.K., not perfect, but I‘m confident that I‘ll be able to produce nice hulls out of it. Next is the application of the GRP backside and then we're in busyness.

[DrSchmidt]

Only when everything went well....still enough failure scenarioss. A stuck master, air bubbes, something got too hot dring curing....only when the master is out and all the seems look good, I'll be happy.

[redboat219]

This should be playing in the background https://youtu.be/e-QFj59PON4?si=idU9tC--x4lXW759

[DrSchmidt]

After a few weeks, 7 kg epoxy resin, 2 kg of surface resin, 2kg of glass fiber fabric and 22 liters of filling medium, the master of the S.M. U1 submarine, Germanys first military sub from 1906, is firmly entombed in its mold. Doesn’t look spectacular, but when everything went well, these will be excellent and robust molds to make a few hulls from. I‘ll wait a few more days to give everything a bit more time to cure before the most exciting part of the process is due: the opening of the molds.

[DrSchmidt]

History repeating...the same sermon for the fourth and final quarter of the mold. Setting the Indexing pins and thread insets, building the wooden box, putting down in the surface resin and then, while the resin still is sticky, apply cotton flakes to create a coupling layer for the GRP that will be laid down later.

[DrSchmidt]

Sanded flat, box removed, and the remaining quarter of the master cleaned. Seams look good. So ready for the final lap…

[JHapprich]

Weather conditions should be ideal at your place, too!

Looking forward to seeing pictures of the first hull!

Jörg

[DrSchmidt]

2,5 hours of laminating and 2 kg epoxy later, the third quarter is done....one more to go:

[DrSchmidt]

Set up the third quarter of the mold. I'll put down the surface resin tomorrow and then I'll laminate the box later this week.