IOM sailboat ballast bulb R/C

This is a set of files for making a ballast bulb for an International One Meter (IOM) remote control sailboat.

I have put together a build thread on bulb casting and mold-making using several techniques here: https://www.rcgroups.com/forums/showthread.php?4080263-Learning-to-cast-a-sailboat-bulb-in-7-000-easy-steps-an-epic-tale-and-tutorial

The section on sand casting the IOM bulb starts on page 8.

There are several files:

- A 2D DXF that has a basic side and top view of the bulb. It is oval, not round, so the profiles are different - Full bulb STL and STP files. These are for doing whatever you like. They have a blunted tail for ease of shaping after casting. - Half models with holes for registration pins and a riser. These are for making your mold plug halves. There is a top and bottom half. - There is a riser for molding the pour spout. - There is a clamping jig for holding the bulb while drilling and machining. - There are 2 ballast shoe files. One is a blank .stp file , the other STL version matches my fin design, it may not match yours. There is also a second set of half model files with a relief around the edge for help with sand casting molds to keep the edges from crumbling. it may be useful for other methods as well to ease release of the casting from a metal mold.

7.  2025 UPDATE:  There is a new set of bulb halves called fattailbulbTop and fattailbulbBottom.  These are the newest molds for sand casting.  They are set up to pour through the tail end of the bulb.  There is also a tailPourSpout file for the new hole you need in the mold.  My build thread has been updated with the new plugs in use.

Category: R/C Vehicles