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Another use for my homemade chuck

I have been making a batch of finials using my homemade chuck. They are to be screwed onto some 12 mm threaded steel rod, and for this they need a blind axial hole.

The chuck insert for this job is just a short length of the threaded rod. Ideally, to make sure it runs true in the chuck, the insert would be made by cutting the thread on  a bit of plain rod, leaving one end unthreaded to go in the chuck. The studding works well enough, though with a little run-out.

I start by preparing the blanks, each with a hole drilled in one end, of a diameter that will screw onto the rod fairly easily.

The running lathe draws the blanks onto the chuck. I wax the thread between items and the blanks align themselves as they go on. The variable speed is turned down and I hold the blank tightly to stop it turning. When it nears full depth on the thread I let go. It only takes a second or two. I move the toolrest out of the way to avoid getting my fingers trapped. Then I bring up the tailstock and toolrest. I have been roughing this batch down using my Alan Lacer skew chisel flat on the rest with its handle low to give a sliding and peeling cut. The middle of the curved edge takes off the waste quickly.

The next job is to rough down the narrow part of the finial. I could do this with the skew too (I would have to use the smaller size because there is not enough room for the large), but I normally use a 10 mm scraper. 3 1/2 adjacent cuts give me the right width. I judge the diameter by eye using the chuck body as a reference. Dimensions are not critical.

I then plane the remaining wider part with the skew. This makes sure the widest part of the finial has a good surface without tear out from the roughing stage.

I use the skew to shape the upper part of the finial, which is like a pointed egg in shape. This can be done either with the long point or the edge. I used both on this batch – it all makes practice. Then the skew planes the lower part of the narrow section – one parallel cut to the left then one to the right to make a short taper.

Then I use a small spindle gouge to make a cove beneath the egg section, and a very small homemade gouge to make a tiny cove separating the two planed bits.

Then I use my favourite 10 mm skew chisel to scrape an undercut at the bottom of the finial. This will let it fit closely to a curved surface when finished. I do this very carefully as I want the undercut to finish as close as possible to the metal thread in the chuck. I usually stop short by about half a millimeter and remove the last little bit by hand later. Occasionally I misjudge it and the point of the skew touches the thread. No harm done with a scraping cut, but that means it’s time to resharpen. I also use the edge close to the short point to plane the little fillet next to the cove beneath the egg.

Then I move the tailstock back and use either of the skews to trim off the centre mark. The small one seems to work best. A light cut stops the finial screwing further onto the chuck, which can throw it out of true.

A quick sand, then I grip the finial with a friction mat and switch the lathe on in reverse to let it wind off the finished job, which will be ebonised.

 

 

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