WoodNet Forums: Re: Making a smoother according to the Work Magazine Reprint Project

Pattern Update:

I have been busy with the project, but have been leaving you all somewhat in the dark here. My apologies.

So, to make it up to you, more photos than decency allows (sorry dial-up users!):

Here, I have changed a couple things since the last photo post. I remade this bottom piece to make it thicker, plus added the frog boss with the grain running the same direction as the base. I did this to aid in clean paring of the mouth. The mouth is drilled out with a series of 1/8" holes.

Paring the mouth with a guide block to 47.5*. The front face of the mouth opening is 75*.

Round dogs make great clamping supports for cutting and shaping the top edge of the coffin sides.

Now that the sides are shaped, and the mouth is pared, I am ready to glue it up.

The wagon vise makes and good clamping jig. I could have made matching, fit cauls to squeeze the sides evenly, but the fit was good enough to just assist with small bar clamps where needed. By the way, persimmon makes very durable dogs that don't scar work. These are my favorites.

Now I'm ready to fit the ends.

The line on the right is square to the sole. The left is the internal draft I'm shooting for for the ends. At this point, during glue up, I'm most concerned about draft internal to the body. Ideally, I can get both internal and external with my tapered side pieces, but if not, I can easily re-taper the outside to a consistant angle afterward (not so, inside).

Gluing an oversized end piece to the body, after trimming the ends of the side walls to the draft line referenced above. The second piece inside the larger piece is tapered and fit to establish the inside draft. This piece is waxed so the glue doesn't stick to it. This procedure is repeated for the toe end piece.

I did have to use an, ahem, stationary belt sander set at the angle I needed to give the outside of the body a consistent draft angle. Through this, the sides became thinner than I wanted, so I had to add a layer of 1/42" mahogany veneer to thicken things up a bit. An added bonus of this is giving more strength to the thin walls.

After interior edges are filleted, I am ready for the layout of the pattern on the match board. The flask will be 12" x 12".

The rough layout of the channels and gates. Due to the deep and thin nature of this part, I have decided to cast it vertically. This should allow more consistant filling of the cavity without cold shots (where the molten metal does not fill entirely at a high enough temperature) or shy edges.

Here you can see the tapered channels and gates leading into the part. The idea of a small gate is to regulate the flow and reduce turbulence as the metal fills the part.

Shellac, sand to 400 grit, then a brushable lacquer to seal and produce a slick finish on the pattern. Yes, I know it's a shame to paint over beautiful wood, but this ain't no wall hanging for your momma!

I am at the foundry now, and am in the process of ramming three molds for a test pour today. Cross your fingers--more photos to come!

--------------------
James Uhrich

Sturnella Toolworks

info@sturnella.com

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