At this point, there is still a 2mm margin at the heel and a 1mm lower projection height at the neck, all of which are reserved to match the heel bottom and button surface. Although there is an angle at the throat of the neck, it can give the neck a certain projection height. However, the accurate projection height and the tight fit between the heel base and the button surface at this height require further fine matching.

2. The inclination of the new neck fingerboard surface has been completed before sticking the fingerboard. To maintain the correct inclination of the fingerboard surface when inserting the neck, it is necessary to always pay attention to the parallelism between the two ears of the knob and the panel. However, this is quite troublesome, fortunately by the time of precise matching, almost all parts are in place. So, after aligning the inclination and projection height of the fingerboard correctly, place the piano code against the end of the fingerboard, stand on the curvature of the panel, and draw the arc-shaped contour of the fingerboard on the code along the top surface of the fingerboard end. When matching accurately in the future, the contour line on the code can be used to check the projection height and inclination of the fingerboard.

If there is an angle between the bottom of the heel and the surface of the button, it is obviously impossible for the two to stick together smoothly. First, use a shovel or planer to trim the bottom of the heel and minimize the gap. Do not trim the surface of the button, as the surface of the button is consistent with the reference plane of the panel bottom. Then use the method of applying powder and pencil ash on the surface of the button to continue processing the surface of the heel, making the two closely match. At this point, it is also necessary to consider factors such as neck projection height, protrusion height, and inclination. There are two sharp corners at the heel of the mortise and tenon surface, and the junction between the side and bottom of the mortise and tenon hole and the surface of the button is where these two sharp corners are accommodated. When using a flat shovel to trim the side and bottom surfaces, it is necessary to reach the surface of the button and not leave burrs or obtuse angles at the corners.

4. In addition, the two sides of the neck must be aligned with the two sides of the button. If the neck is narrow, the mortise can be widened to lower the neck, and then some wood on the bottom of the heel can be scraped off to make the heel wider. Scrape some wood off either side of the heel to narrow that side and align it with the button. But it should be noted that this is not a good solution, and this issue needs to be considered before the hardcover, otherwise it may be too late when it comes to precise integration, and the result will either be barely making do or all previous efforts will be in vain.

Before sticking the neck to the body of the piano, it is best to have all the details processed, as this makes it easier to operate. Before sticking the neck, it is necessary to thoroughly inspect the dimensions and positions of all parts. Prepare a clip, which can be used as a clip pad at the fingerboard using sandpaper lining during the grinding of the fingerboard curvature, and a wooden block with cork padding at the button as a clip pad. Adjust the spacing of the clips and place the clip pads in an easily accessible location. Apply fresh hot glue to the neck and mortise, slide the neck into the mortise and align it with the geometric center, projection height, and inclination. Put on the clamp and secure the neck clamp firmly. Tighten the clamp with the force of your fingers. Be careful not to press the clip pad at the button against the curvature of the back panel, otherwise there will be pressure marks on the back panel. Shallow indentations can be filled with water to expand and recover, while deep indentations are difficult to handle. Dip a brush in hot water to remove excess glue and check alignment again. The glue should be dried for at least ten hours, and the clip can be removed after overnight.