A Simple Machine to make large diameter wooden screws – cont’d

So here’s a pic of the lunettes in place:

The “lead” (or master screw) and the workpiece are connected with a socket and stub joint that is locked with a  screw.  The stub should be the same diameter as the socket, close to the shoulder, but should be a little tapered away from the shoulder.  This will allow for some very probable misalignment.  Remember, we’re dealing with wood here and my shop is 90 degrees with a fair amount of humidity.

Set the router to depth (several passes are probably, but experiment), turn ‘er on and start twisting the lead screw.

Forty odd hours later, $50 lighter in your wallet, here’s what you end up with:

Wooden screws, these will be seated into hubs - but blanks with integrated hubs will work just the same

Have fun.  You’ll need to experiment a little.  But I think you’ll find that it’s very worthwhile.

A Simple Machine for making large (2 1/2″) diameter wooden screws

Alright!  I should have been cleaning up this hell hole that I call a shop.  I should’a just bought the damned things.  But wait a minute…

walnut "machine screw"

After forty hours or so of scratching my head and puttering around in the shop, I’ve managed to build two simple machines that will allow me to manufacture all of the big wood screws I want, in short order.  So if I figure my time at $35/hour, I’ll be in the black after I’ve made a dozen or so.  So, guess what everyone’s getting for Christmas this year.

Well okay.  If you only need a couple of big wooden screws, buy ‘em.  However, it seems that a number of wooden screw manufacturers have come and gone in recent times.  So, it might be a valuable skill to have in your “toolkit”.

Here’s what did:

First, I laid out my spiral on the cylinder that would ultimately become the “lead screw”.  Then I sawed down to the root depth.

Note the "depth stop" held in place with a couple of small clamps

Then I built a “box beam” and eight (or so) “stantions” that will be used during the screw making process. 

some stantions are held fast, others are loose so they can moved during the process

Followers of this blog will immediately note that there is a router involved.  I’m sorry!!  But the machine is built in such a way that a manual cutter could be used.  But, you know, I’m getting older, I don’t know how much time I have left, I’m not as strong as I used to be….  So live with it!!  I used a router!!

router simply secured to the stantions by a couple of drywall screws

Then I used one of the stantions to mount two “lunettes”.  The lunettes are actually made from a .025″ x 12″ feeler gauge.  See Roy Underhill’s book, “The Woodwrights Workbook” for an excellent explanation of how this will work and remember that the lunettes must be offset by half of the pitch (you’ll figure it out immediately).  The “ramps” are set at an average angle of the pitch taken from the minor and major diameters.

Well, I’ll finish this up tomorrow.  It’s been a full day and, alas, it’s time to retire.

 

Making Wooden Screws – The Saga Continues

There’s a pretty good chance that if I would have charged myself $10/hour for my time, I could have paid for the two screws from Lake Erie Toolworks by now (maybe more).  But I’m havin’ fun and I do consider myself a bit of a woodworking historian.  So…I’m living history.

nut blank in place – tapping in progress

The nut being made above will replace the right hand support, thereby eliminating the temporary “lunette”.

 

right support replaced with permanent model

Alignment is critical.  At 2 2/2″ diameter, there is no “give”.  Lesson learned this morning; If threads are not filed absolutely evenly, they can be overstressed if there is the slightest misalignment.  The good news is, the screw works well even though two threads have chunks missing equal to about 1/5th of their circumference.

This screw is made from cherry.  It was what I had on hand, but it may not have been a great choice.  Something “tougher” like elm, hickory, apple or even sycamore (with it’s interlocking grain) are probably better choices.  When the threading “machine” is complete, I’ll try a few other species.  Stay tuned…

Making Wooden Screws

Well, I decided that the Little Underhill Bench needed to outfitted with two, not just one, but two wooden screw vises.  I thought about buying a couple of screws and nuts from Lake Erie Toolworks.  That would have cost me $300, give or take a little.  But then I thought, how hard can it be?  Plus I’m a guy who loves the process and the history of woodworking, I’m “semi” retired, so why not make them myself?  That’s how it started…

I went to my bookcase, pulled out the “Woodwright’s Workbook”, in which Mr. Underhill discusses making your own screws at considerable length.  Then I pulled out “Woodturning Techniques”, by Mike Darlow.  His presentation is even more in depth than Roy’s.  Hey, these guys are heavy hitters and between the two I found all of the information I needed to get started.

I decided to make a number of 2 1/2″ diameter, 1/2″ pitch screws.  The first task was to layout and hand carve the master screw which is used in building the “Big Tap”.  I have found out that tapping the nuts is the more difficult of the two tasks (threading the screw, tapping the nuts) and I decided to make a tapping “machine” as shown in the Underhill text (one from the Williamsburg Collection).

Master screw on the lathe, just carved and cleaned up with a triangular file

 The major diameter of the screw is 2 1/2″.  The minor diameter is 1 5/8″.  Note that I’ve stripped the threads from about the first 8″ of the screw.  That section will be inserted through the nut bland, then into the left support.  Also a 60 degree V cutter will be inserted (held in place by an insert and set screw) about 4″ from the left end.

 

Filed and sanded to create slightly truncated threads which will be more durable.

 The major diameter of the screw is 2 1/2″.  The minor or “root” diameter is 1 5/8″.  Note that the threads have been removed from the left section of the screw, approximately 8″ from the end.  This portion will be inserted through the nut blank, then positioned into the left support to maintain position during the tapping process.

 

The parallel surfaces of the right support will be cut and angled at about 5 degrees, the pitch angle of the screw.  My original plan was to use two “lunettes”.  However, I opted for a single 1/4″ brass bar to use as a temporary nut.  The left hand support is temporary and will be replace with the first “nut” made on the “machine”.

 

Right support showing temporary "lunette" and angled surface to match pitch. Note the abundance of paste wax. Trust me, use a lot of wax or oil

Think I’ll make another “simple machine” for threading the screws.  Carving them is great therapy,

but one of these days I’ve gotta get this bench done and on to other projects.

 

I’ll keep you informed…