Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Tuesday, September 11, 2012

Sanding Parts To Identical Shapes

Yesterday, I started sanding the parts to shape. All of the frames have some duplicate parts that need to be identical shapes when finished. These parts make up the left and right sides of the frame. Especially critical is the outside curve. Some of the parts require the inner edges to be a specific distance from the outer edge.

In order to accomplish this, it's best to sand both parts at the same time. This provides the best means of insuring that the parts are identically shaped. Most of the parts have at least one straight edge from the original board. I am using that as my starting point. However, to be more accurate, a second edge needs to be lined up.

Since all the other edges are rough cut, it is necessary to sand one of the edges on one of the parts to its final shape. This second edge is then lined up with the line on the second part and the parts are clamped together temporarily. It is very important to get the two edges lines up correctly. It is also important to make sure that the remaining edges will be able to be sanded to final shape and no edge will be short.

An alternative to the above approach is to line up the one edge and try and line up one of the other edges using the drawn lines, but this approach is difficult and prone to error. I like the approach I am using because I can get the second edge lined where I want it.

The following photo illustrates the lined up and rough cut edges. It's not real clear in the next photo but the upper part is lined up on the straight edge and the drawn line on the lower part. If you run you fingers lightly over the lined up edge you will feel no bumps or ridges. That's when you know you have it lined up.

After temporarily clamping the parts, make a final check of the lined up edges and then  move on to the next step which is to temporarily fasten the two parts together. For this I used two drywall screws through both pieces of wood. It's very important to drill a pilot hole first for each screw. This is how you can avoid splitting the wood when driving the screw in. The drill should be a bit smaller in diameter than the drywall screw so that the threads on the screw can bite into the wood.

The next two pictures shows the screws in place. You should endeavor to keep the parts lined up while you're screwing them together. You also do not want to drive the screw all the way through the second board since you will be laying that bottom surface on the sanding table afterwards.

Once the parts are screwed together it's okay to remove the spring clamps and begin sanding. Notice though that the screws are spaced fairly far apart. This gives them more leverage to hold the parts together while your sanding. If the parts were very large, you might want to use more screws. Now you begin sanding the parts down to the drawn lines on the parts as the next photo illustrates.

At first you can make fairly heavy cuts with the sander but as you get closer to the line you need to have a lighter touch. Take you time and get this accurate. This picture shows the part at an angle to the sanding belt but in actuality it will normally be up against the belt. Since this is a curved edge on the part, it is important to keep moving and try to keep the curve gradual with no abrupt transitions.

When you have finished sanding the parts and you're satisfied that they are sanded to the correct shape, then remove the screws and admire your handiwork. Depending on the part you might want the screw holes to be in an area where they will not affect the strength of the part or will will be backed up with other wood parts. I plan to fill all the holes with epoxy before final sanding in order to remove any doubt that the hole will be a weak point.

So I have to do this process to approximately 10 pairs of parts as well as a few individual parts that do not have duplicates. I expect this will take several days. Until next time......

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