New IOM bulb moulds cnc-machined

Jari made these new IOM bulb-moulds over the weekend. CNC-milled in aluminium. Circular cross-section with a NACA0010-34 profile (similar to my 2005 design), length ca 360mm. Designed with a central stiffening brass rod. Check out rcyachttech.webs.com for more cnc-machined moulds and parts.

See also casting notes from 2003.

Deck Mould Modification


As I mentioned earlier, the flanges around the foredeck openings were very time-consuming to laminate around, and very hard to release from the mould. Here I've ground them down with a pneumatic dremel-type grinder, and then sandpapered a bit. Next I need to fix a few dents in the gelcoat, wet-sand, and polish. Then we should be ready to mould hull nr 5 next weekend.

Steel Fin Moulds

Jari machined these steel fin moulds for the PIKANTO over the weekend. The fin will be moulded with a clear glecoat, one 200g carbon layer as a surface layer, and one 250g/m2 UHM UD carbon layer. We are going to use either cnc-machined balsa cores, or a 2-component epoxy foam core. The bulb attaches with an M3 threaded rod which will be moulded into the lower end of the fin. At the boat end we'll insert a metal piece with M4 threads so the fin can be attached to the boat with an M4 hex screw.

RG65 Fin and Rudder moulds

We've done the CAD design, CAM-toolpaths, and CNC-machining for a set of RG65 model yacht (looks roughly like this) fin and rudder moulds. They will be shipped to the customer on Monday.

From time to time I get enquiries about making moulds like this, for fins, rudders, bulbs, etc., from people around the world. Usually by people who've gone to a professional mould-shop or cnc-workshop with their drawings, and suffered a bit of sticker-shock when they've seen the quote. For this set of moulds we asked 500 euros, which is not a lot I claim. Production and delivery in one week or less after the final CAD-drawings were available.

If you're interested in CNC-cut moulds in aluminium or steel, please send your ideas, preferably a CAD drawing, and I'll send you a rough quote. Keep in mind that our machine has a working XY envelope of ca 500x200 mm, so no single parts can be bigger than this. There are lots of examples of what we do in this blog, you might like: bumper mould (2010 Jan), Rudder mould (2009 Dec), IOM MDF plug (2009 Feb), Microscope part (2009 Sep), IOM Fin moulds (2008 Jun), Telescope rings (2008 May).

Jib support mould

This jib-support part which goes into the bow of the boat has about three or four different purposes. First, it stiffens the forward deck to take the loads from the rig, second it provides a 6 mm i.d. tube for a dyneema-thread type no1 rig swivel, third it provides a 3mm wide slot for recessed steel pins for the no2 and no3 jibs, and fourth it holds a block for the sheeting system. Here I'm trying a home-made block made from a 24 mm diameter 3 mm wide acetal-wheel (yellow) which is designed to rotate around an M2 bolt through the sides of the shaped jib-support.

Lester Gilbert's PIKANTO-page has pictures of how the SAILSetc equivalent parts look like. With an RMG winch there is no need for the 1:2-gearing in the sheeting-system, and a block is placed at the very front of the boat (see SAILSetc part 67RMG).

SAILSetc has a downloadable drawing with the sheeting systems: http://sailsetc.com/downloads/2006/67G.pdf

Jari has cnc-milled the positive moulds for this part:

Stock is a 200 mm length of 100 x 10 mm aluminium bar. There's a  2 mm hole in the moulds for the block-axle.


Next follows the negative moulds.

Polished PIKANTO hull mould

The PIKANTO moulds were polished first with "Oskar’s buffing and polishing compund M-50" and then with "Norpol Rubbing R-10", both from Terpol (www.terpol.fi) in Turku.

Shine mould, shine!


After sanding with 1200-grit and a 10-15um particle-size fine paper it is time for polishing. We have two grades of polishing-compound. These pics show the coarse type which is polished with a spinning soft disk on a power-drill.


After polishing follows release agents: first Frekote and then wax. It's still possible we will mould a prototype hull this year. Stay tuned.

Pikanto rudder mould

Jari cnc-milled rudder moulds for the Pikanto IOM this weekend. The design is similar to the Sails ETC rudder, but slightly larger and with a NACA 0006 airfoil profile, and a slot for a 4mm rudder stock.


Pikanto moulds


Our three-piece hull/deck-moulds for the Pikanto IOM (designed by Graham Bantock) are now ready. The next step is to sand the surface smooth and polish the moulds. We hope to mould a prototype hull before the new year.


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