Hand Tools Archive

Subject:
Non-issue? And an alternative ...

Derek Cohen (in Perth, Australia)
Especially with softer woods like pine and poplar, when chopping in from each side at the base of the recess that receives a tail or pin, the center of the opening will break back towards the other end, a phenomenon I have seen referred to as spelching. This is not a clear description I know, but I do not have a picture to post.

This seems to occur regardless of how hard or softly a sharp chisel is tapped. With pine the breakout can be within 1/16" of the surface of the board. The 2nd practice board this morning is swirling grain in cherry, and the spelching is much less, perhaps because the grain direction is not parallel to the edge of the board. I understand the end grain that breaks out does contribute to the strength of a glued dovetail joint, but spelching in softer woods can be frustrating. Has anyone found ways to reduce it?

Don, if the area of spelch is centred in the middle third of the pin or tail, it is a non-issue. There is no structural help from this section when gluing the boards together, since both are end grain.

With thinnish boards, where the centre third threatens to spread across the width, care needs to be taken how the waste is removed. The method I use would be considered inefficient by Tom, since it involves both sawing and paring, but it leaves sweet, clean joinery. I am not racing the clock, but I also would not call my work slow.

Step 1 - undercut the baseline and create a chisel wall. (15 seconds) ...

An important reason for doing this is that this ensures that the inside and outside baselines are preserved. The end result will be a clean finish inside and outside the drawer.

Step 2 - saw the waste leave 1mm waste (20 seconds) ...

Step 3 - chop out the top half. I work from the inside first. Take 0.5mm slices ....

Flip and do the other side, stopping as close to the centre as possible ... which means that a smidgeon will remain.

Step 4 - Pare the centre with a narrow chisel (less resistance). It is OK to slightly undercut at this stage ...

Outside ...

Inside ...

Regards from Perth

Derek

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