Brass Door Knocker Foundry Pattern

Each new brass door knocker starts out with a design or idea of what it should look like.

We draw out our design using a computer drawing program. We make it as detailed as we can trying to find any problems that may exist.

Once the design is finalized a pattern must be made. This is an exact duplicate of the finished product plus a couple details to help the molding and finishing processes.

brass door knocker pattern in vise Our brass door knocker starts out as a block of wood. In this case the wood is pine. The outline is cut to the approximate shape using the band saw. Most of the rest of the work is done by hand.

The pattern must be a replica of the finished product with a few modifications. Some dimensions must be made larger to allow for material shrinkage and some dimensions will be changed to allow for finishing. At this point we are getting everything as close as we can. We will make final adjustments after first trying the pattern with an actual casting.

brass door knocker patterns being madeAll the details are carved into the pattern just as we would like them on the finished product. The only things lacking in this picture are the hinge pins and the mounting lugs. These will be added next.

brass door knocker mold and pattern When the pattern is ready it is taken to the mold shop and tested in a sand mold. The pattern must be made so that it can be removed from the sand mold without taking any of the sand with it. This mold was packed for test purposes only. No sprues or gates are necessary for this test. Now we know that the pattern can be removed from the mold we will add the sprues and gates that will be the path of the molten brass to flow through and fill the cavity area left where the pattern was removed.

Our pattern is far from being done. Next we must make an actual test casting from it. This will reveal many changes that will need to be made. Some areas may still be to thick or thin, a portion may shrink causing a dimple. There are many little things that will need to be addressed prior to an actual production run.

When we have the pattern producing good castings we will add permanent gates and runners to make the mold making process faster and easier. The pattern can be used many times but the mold is only used once.

Getting the pattern right from the start will save much frustration later as we expect to make hundreds of brass door knocker castings from this pattern.

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