Smaller Wooden Screws, Part 2

At the end of the last post, I had a little success cutting outside threads in a 13/16" poplar dowel, but the thread-box started getting bogged down.  I thought the problem was that shavings were getting caught in the box and messing things up.

I tried running another poplar dowel through the screw-box without the cover plate on so that I could see how shavings were getting caught.  This is using the same screw-box that has some partly damaged inside threads.  Out came beautiful shavings.  No shavings were getting caught inside the box.  Last time I probably just didn't have the escapement oriented properly to expel the shavings.

The open screw-box with cutter clamped in place

Getting nice shavings with nothing getting caught anywhere

Out the other end

Continued for the length of the dowel - some damaged threads, but overall pretty good

Testing with the nut from the plough plane - it a bit tight after first 6-8 threads

Turns out that even though my thread-box has exactly 7 1/2 threads per inch, I'm cutting the outside threads a little narrower, close to 7 3/4 threads per inch.  This is probably due to a little bit of slop.  It would make no difference with a nut that only has 5-6 threads, but with a long nut like the plough plane has, it gets stuck after 6-8 threads.  So I tried deepening the threads by positioning the cutter to cut a bit deeper and running the screw through again, but that just destroyed most of the poplar threads.

Tilted the cutter down by shimming at the pointers

Only succeeded in destroying the existing threads

I don't know what wood was used for my plough plane's screws and nuts.  They might be boxwood.  Of course, I don't have any boxwood, so I tried some cherry, which is a fairly tight grained wood.  No oil was used and the inside threads came out pretty good.  The peaks of the threads were a bit rough in the end grain areas, though.

Threads along the grain looked great

Threads along this end grain had rough peaks ...

... although the other side end grain was pretty good.

So I made a new screw-box using cherry as the rear block.  After creating the inside threads and chopping out the cutter mortise and escapement, I gave it a whirl.  This time I used a maple 13/16" dowel.  As I fed in the dowel, out the other end came nicely formed threads.

New screw-box of cherry (with inside thread) and poplar (with 13/16" guide hole).
13/16" maple dowel getting threaded.

Checking the fit of the plough plane nut - it fits, but it's a little too loose

The maple threads were a bit pointy at their peaks, probably due to cutting a little too deeply.  So I shimmed the cutter to move it up slightly away from the dowel and tried again.  And re-sharpened it, too.

Got nice threads in the maple dowel, but the plough plane nut was tight

Here's a nice feature of this type of screw-box.  When you get to the back end of the dowel being threaded, you can remove the guide plate and keep threading.  I was able to thread this dowel all the way to the square end that I made to fit a handle.

Here's the thread-box with guide plate removed

And just because it's so cool, here's a close-up of the curly
 shavings coming off the V-cutter

This wooden screw stuff has been an interesting journey.  I've learned a lot and have a lot of respect for those who did this without the help of the internet.  I had Roy's book to learn from, as well as some YouTube videos, but there are so many small details that you'll never know about unless you try it for yourself.  I'm glad I did.