Makecise Log – 20170402

By Cressel

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This week I released the column assembly video, finished the ram cap pattern, finished the a ram pattern, cast the ram cap, cast the ram, and attended the Atlanta Woodworking Show.

In case you missed it, I released Part 2 in the shaper series this week. Here is the video.

I finished up the ram cap pattern and ram pattern by using a heated 20mm steel rod to melt a semi-cylinder in the foam where the arbor is mounted. I clamped together a couple pieces of wood with a slight kerf down each half. I drilled down the tunnel created by the aligned kerfs. I separated the two halves and used one side as a jig for holding the heated arbor while melting the foam as well as for fixturing the arbor as it was hot glued to the foam pattern for casting. I first cast the ram cap as a test for the process since the ram pattern was much more complex and involved. After I glued the arbor to the ram cap pattern, I attached a sprue and coated the entire assembly with plaster of Paris.

I put the plaster-coated foam pattern into sand and pour molten metal into the mold. The arbor separated with ease and the cast part turned out great. I was very excited to cast the ram. I let the arbor cool and then used the jig to glue the arbor to the ram pattern. I coated the ram in plaster and got set up to cast. I am running very low when it comes to aluminum ingots. Between the lathe and the column parts for the shaper I have consumed almost all of a 4-cylinder engine block and transmission case. I pulled together every last bit of aluminum in my shop and loaded it up. I had a full #6 crucible and a ram pattern embedded in sand.

In the footage I will release as an extended cut on Patreon this week, you can see that I didn’t quite have enough play sand to completely fill the flask, so I made little “volcano-like mounds” to pour the metal into. Without enough sand however, the hydrostatic pressure of the molten aluminum distorted the top of the mold. The sand cracked and a fair amount of the metal flowed out the side of the pattern. Another good bit of metal was pressed upward and caused a very gradual bulge in the top of the pattern–which would have formed the bottom of the ram. It was really interesting because all the detail and relative geometry was preserved albeit along a bulged out version of the intended flat surface. The top of the ram was very faithful to the geometry of the pattern, and the steel arbor separated readily.
I strongly considered using the table saw to flatten out the bottom. I feel fairly confident I could make it work, but it will likely be more efficient if I just remake the pattern. Its no fun to rework foam patterns, but not exactly the end of the world either.

I attended the Atlanta Woodworking Show this weekend. It was really a lot of fun to spend time with great creators like Jimmy Diresta, Izzy Swan, and a host of others. Let me toot my own horn, I solved a networking problem for Giaco Whatever that helped him get connected to his newest high speed camera. Man! I am looking forward to all the cool stuff coming down the pipe from this community. I feel really privileged to be a content creator and to be able to share my own journey. I was also really intrigued by the number of creators with relatively new channels. If you have a channel or are considered starting one, shoot me an email if you have any questions.

This week I plan to remake the ram pattern out of foam, test lost PLA casting, and cast some brass for the first time.

Cressel Anderson

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