Turning the Screw, Pt. 1

For folks who like a neat and tidy ending to a story, you may not want to read this one (wait ’til pt. 2).  In December, my first vise screw broke.  It was made from a 3″ thick chunk of ash shaped to form the head of the screw, drilled for a handle and drilled on the end to receive a maple dowel with threads cut using a thread box, and glued and pegged with an oak peg across the grain.  The glue held but the maple split around the peg one day when it was over-torqued.

The first screw

 

It Broke

It Broke

The first fix was to re-drill the head (to get out any remnants of the first threaded maple), turn the maple down to make a round tenon, and epoxy the tenon into the drilled hole.  This fix lasted 2 days.  I decided I’d like to turn a screw with a head from a single thick piece, and did so today.

I started by finding a ~2.5″ square piece of ash long enough to make the head and screw, plus enough extra to hold it on the lathe and trim off the center marks at the end.  I located the centers and marked the ends, and the center across it’s width was marked on the side where the handle would be positioned on the head.

Layout for the through hole

Using an 1-1/8″ forstner bit, the hole was bored through the thickness, then the blank was mounted on the lathe.  As you can see, there is a check (crack) that ran the length of the blank along one corner;  I wasn’t worried about it, as it appeared to all be in the area that would be turned away.

Screw blank mounted on lathe

While I was turning, I neglected to take in process images- I had just received my Easy Wood Tools rougher and finisher, and was eagerly putting them through the paces.  My opinion of them, in short: not bad, but not as wonderful as I expected, at least for this dry ash spindle work.  There was a great deal of noise (relative to the cutting action of roughing and spindle gouges) due to the scraping action and resulting vibration in the spindle, the cuts were not any cleaner than traditional tools, and in many cases didn’t cut as quickly as standard tools.  I suspect that these tools will shine on end-grain work (bowls) and I did like not having to concentrate on proper tool position. In fact, I took out a skew to do a final pass at one point, and got a catch which sent me right back to the Easy Finisher.  All in all, pretty good tools (probably excellent, just not for this particular piece) that take alot of the effort out of turning.  More on this in the future as I work more with them on other projects.

Turned Screw blank

After turning the bulk of the screw: the head, the groove for the garter ring, and the screw shaft (to the diameter required for the thread box) and tapering the first 2-3 inches to start the threading, I applied some boiled linseed oil.  I found that applying oil to the wood prior to cutting threads helped the thread box work freely on previous attempts, and the finish for the rest of the ash on the bench is BLO, so I did the head as well.  I had also experimented in the past with using the lathe to assist in cutting the threads:  On the lowest speed with the thread box started on the tapered end, the lathe is turned on while holding the thread box handle firmly.  If all goes well, you have a threaded screw in a few seconds. (note: be prepared to stop the motor at the end of the shaft, or in the case that the cutter catches and the belt starts slipping.  Also, make sure to move the tool rest out of the way.  If there are no obstructions, you can let go of the handle and let the box spin freely to ‘pause’ cutting, though I advise stopping the motor before trying to grab it to start cutting again).

Moment of truth. I turned on the lathe and it cut the first few inches before catching (the spindle stopped, drive belt slipping on the headstock wheel). I backed it off a few turns, and restarted it, but I noticed that the threads were chipping pretty badly.  No going back.  I turned threads for about 12″ of the total length, before quitting.  The ash is just too splintery (I think due to the ring porosity of the species) for decent threads.

"threaded" ash - more like splintered mess

So I re-epoxied the old broken vise shaft back into the head to see how long that will last…or until I can get my hands on a 3″ square blank of something dense and nice to thread, like maple.  Part 2 will, when it happens, be about the same process (with more details of the turning and layout) in maple, and will hopefully have a neat and tidy ending… for those who need one.

 

About Nick

Nick Roulleau is founder, craftsman, designer, joiner, finisher, floor-sweep and all of the other roles at Mansfield Fine Furniture. A woodworker for more than a decade, Nick started the company with the goal of filling the need for heirloom-quality furniture hand-made from premium woods. Every piece is designed to suit the customer's needs and desires, hand-picking each piece of wood, and built one piece at a time, using both modern and centuries-old traditional methods to yield furniture to last for generations.
  • antony sutton

    What a shame! Still, it looks good and looking forward to the next installment.

    Only found your blog today and like what I’ve seen so far.

    One thing I would like to suggest is that you pin right through the epoxied head and thread and I think you’ll find it’ll last ages (I would pin with 6mm steel personally)
    tony