Hi gents, the apatite is back….so the build is back on track.
A drill press was missing on my machinery list, and this was an item I needed for manufacturing the rudders and dive planes. I did not need a big machine but I wanted one with high precision. After streaming the WWW I found one for my budget I wanted to spent with a max clearance of 0.02mm on the spindle.
The masters of the rudders and dive planes were still were I left them…sitting in the modeling clay.
For the making of the sprue channels I modified a syringe so I got the desired diameter for the channels. Filled the syringe with molding clay an out came the channel.
I cut the cylindrical formed clay in half longitudinally and pressed them in place on the mold.
The mold were closed and the seams were sealed with modeling clay. The poor funnels I made out of paper, put in place and sealed with molding clay.
The silicone was degassed in my DYI vacuum chamber (works Great!) and poured into the molds.
After curing molds were opened up and master and molding clay was removed. The only thing I needed to do before pouring the other half is making new sprue channels in modeling clay and put them in place together with the masters……and apply release agent . Closed and sealed everything and poured the other halve. The mold worked out fine.
Next step is to pour the resin in the molds, again I made the pour funnels out of paper. After the molds were filled I placed the in my pressure chamber @ 3bar, and let them cure overnight. I was very pleased with the result.
The only thing I noticed is that the diving plane was slightly bent but the master was straight. Probably I applied to much force when I pressed the master in the modeling clay as the rudder is long and thin it is fragile (lessons learned
). The deformation small so I don’t need to redo it.
Next step was to cut the control faces out. Everything was marked in pencil. On the real sub all the rudders and diving planes are provided with trim surfaces these are supported by pintle bearings. I want to integrate these bearing in the model. So these were also drawn.
First I had to drill the rudderstock holes (drill press time). As the rudders and dive planes are double curved it is hard to clamp them in a machine vice without a sort of jig. As I had a lazy day I din’t want to make a jig, so I tried……….modeling clay. This works great, just put an piece of modeling clay on both sided and clamp it in the machine vice, the modeling clay squeezes itself in place wen pressure is applied. 2mm holes were drilled.
The yellow stuff is the molding clay
The surfaces were cut out with a scroll saw. Before I made the cut I had to level the planes in both directions in order to get a nice vertical cut. This was done with modeling clay (yes I seem to use this stuff for everything
). A recess for the pintel bearing was also cut in the control surface. All cut surface were sanded. A radius was sanded on the leading edge of the control surface.
The pintle bearings (3x5x5mm) were made out of a 3mm styrene sheet glued in place and provided with a 2mm hole.
The gaps between the control surface and the actual plane were filed up with the EUREKA putty but not before I thickened up the leading edge of the control surfaces by masking tape (4 layers approx. 0,5mm) and applied some release agent so the EUREKA putty will not bond with the tape.
pintle bearing in place and tape applied
EUREKA putty applied
Control surface removed
After curing all were sanded in shape resulting in a nice small 0,5mm gap. The upper and lower gap between the control surface and plane needed also attention. EUREKA putty was applied on top and bottom and after curing sanded in shape resulting in a nice small gap.
Bushings will support the rudderstock, I made them out of a 3mm brass rod, the all received a 2mm hole.
• 4pc for the pintle bearings (rudderstock runs through it) Ø3x3mm
• 4pc for the upper bearing (protrusion of the hull) Ø3x10mm
• 3pc for the lower bearing Ø3x3mm
These bushings will be placed in position in the molds prior to the casting process so they will be imbedded in the parts after casting.
That’s it for now,
Practical wisdom is only to be learned in the school of experience.