Roubo Is Coming… Part 27

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Marking the final width of the tenon

I find it interesting how a lot of work can result in something very simple. And how simple does not always mean straight forward (or easy). At first blush, the planing stop is incredibly simple – a square mortise and a square loose tenon that fits the mortise. But that simplicity requires a lot of attention, and being prepared to fuss over the fit. The planing stop needs to be friction fit to the mortise – too loose and it will fall out of the mortise. Too tight and it won’t move at all, or worst case, will split the bench top. So, this most simple element takes time and patience. But that’s ok – I work wood because I like spending time at the bench. One day (soon, hopefully) the bench will be complete, and I’ll be using it to work other projects. All of that is a slightly round about way of saying that the planing stop is fitted and functioning as intended.

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Using the No3 smoother to fine tune the fit of the tenon

Before I started fitting the stop itself I checked the mortise, and did a little tuning with a 1″ paring chisel to remove any bumps or stray lumps. With the mortise in good shape, I started to fit the tenon. I had deliberately left the tenon a few mm oversize, pending the final fitting, and so the first task was to take it down to size. At this point, the numbers are not important, what matters is that the stop fits the mortise well enough to move freely when encouraged with a mallet, but tight enough not to move otherwise. I presented the tenon to the mortise and got two perpendicular sides pressed nicely against the mortise walls. I had deliberately struck the layout lines for the mortise longer than necessary, as this helps to fit the stop. With the tenon located firmly against two sides, I marked off the final width on the remaining sides by dropping my marking knife into the mortise layout lines and nicking the side of the workpiece. I used these marks to set a marking gauge, and struck lines on the stop to identify the final width.

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Chamfering the corners

After planing the stop down to the marking gauge lines, I tested the fit in the mortise, and made fine adjustments with a smoothing plane until the stop moved 1/8″ with each mallet tap (thanks to Mark Hicks for his advise on fitting the stop and this tolerance as being a good indicator of appropriate friction). This took several rounds of fitting, and making small localised adjustments with the plane. I also knocked down the corners with the Phillychamfer plane, as these are a weak point and I did not want any stray fibres in the corners spoiting the fit. I had not squared up the top end of the tenon, and once it was fitting in the bench I planed it flush with a low angle block plane.

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Planing the show-end flush and clean

After testing the movement of the stop through its full length, it was time to drill the hole for the toothed planing stop itself, which Peter Ross forged for me a few years ago. The planing stop had a tapered shaft with a square cross-section, and I drilled the holes while the tenon was fitted in the bench top. I bored the narrowest diameter hole needed first, which was the full length of the stop, using an auger in my North Bros brace. After this, I used engineering bits in an egg beater drill to drill the remaining, wider sections. The tip of the engineering bit follows the path of the pilot hole better than a spur and centre wood bit, which makes them very useful for reaming wider holes. Once the pilot holes were drilled, I hammered the stop into position, placing a saw bench underneath the wooden part of the stop to prevent it being driven through the mortise.

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The toothed planing stop fitted in a 15″ long tenon

To prevent the teeth of the stop from sitting on top of the bench (and catching tools or fingers) when not in use, I knocked the stop as close to the benchtop as possible, and traced roung the teeth with a marking knife. After removing the stop from the mortise, I used a chisel to deepen my marking knife lines and a small router plane to remove sufficient material to allow the teeth to rest under the surface of the bench. This is a small detail, but one which did not take too long and which adds a nice point of interest (and functionality) to the bench.

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Fitted and ready for use

5 thoughts on “Roubo Is Coming… Part 27

  1. A very useful stop, but why not recess the toothed stop into the end of the wooden post to allow it to remain level with the bench top, not trapping shavings in the pocket?

  2. Pingback: Roubo Is Coming… Part 28 | Over the Wireless

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