There are several reasons we have not released this designer to the "world". There are no checks to make sure a given cone can even be turned by us. The overall length is limited by the lathe, currently to about 11.7" useful length. The overall diameter limited by balsa, currently 2.84". The most complex check that is not done is whether the tool will hit the balsa on undercuts, knocking the piece out of the lathe.

We use the designer program on all our nose cones, but we wind up trying a questionable piece before releasing it. We don't try it unless we expect to sell enough to cover the loss of balsa and time testing it. This is not feasible for custom cones.

The other part that is missing is a release protocol. Once a design is finalized and is not going to change any more, we lock it and make no further modifications. We have cut several custom parts to find that what we cut was changed after we cut the part, but before it was received by the customer. In other words, we need to add the capability that once a customer designs a cone, "releases" it, and orders it using a particular part number, we can cut that part AND an exact replacement for that part ten years from now or one day from now. There must be an agreement about what a particular part actually looks like.

Another issue is sizing the finished cone. We size each cone with CA reinforced tubes to make sure it is the correct fit. We use the "Series" box to size the cones. So if the box designates BT-70, we expect the shoulder to fit a BT-70 so we know it is correct after we turn it. Several of the nose cones designed do not have matching shoulders and "Series". Some have diameters that do not match standard tubes. We could measure them with calipers, but that is not as good as actually trying them in a tube.

Yet another factor is balsa cost. We used to keep a wide assortment of balsa sizes in inventory, so we could cut any size balsa part on demand. Balsa has gone up 250% since we started back in 2002 (1025% since 1968!), so we do not keep much balsa in stock beyond our immediate needs.

All this said, we do a few custom parts, but on a time available basis. We charge the same for custom and standard parts, so we know we cannot make money doing custom. They are done when and as we can, as a service for our customers, not to make a business of it. BMS and Gordy have much better business models for full custom parts!

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Carl McLawhorn
NAR#4717 L2
semroc.com