NUTS! What one can learn from failure

I’m very happy to be in possession of a couple of nuts from Lake Erie Tool Company.  They’re beautifully made.

Nuts from Lake Erie Tool Company

As I mentioned to you in a previous post, I highly recommend that you buy your wooden bench screws and nuts from a vendor who is set up to manufacture them on a production basis.  Okay, the screws are easy enough.  Make them if you want to, but I’m still suggesting that you buy the nuts and save yourself a whole lot of headaches. 

Never being one to take my own good advice, I just had to try to come up with a way I could produce a higher quality nut for my own use with stuff I already had in the shop.  I had produced several screws that were undersized and I didn’t want to waste them.  So why not waste three or four days of my time instead?

 

DON’T TRY WHAT I”M ABOUT TO SHOW YOU AT HOME – IT’S DANGEROUS AND NOT WORTH THE TIME YOU’RE GOING TO WASTE!!!

 

I decided I could use my lathe as a spindle to hold a fly cutter.  I ground down an old spade bit and made a fly cutter with two 60 degree cutting edges.

 

Then I figured that I could use my “lunette box” from the screw making machine.  I could use the same lead screw.  All I had to do was make a hub with a couple of stand-offs to support the nut blank.

Then I’d use a center plug and mount the blank and simply slowly turn the blank into the flycutter and voila, a perfectly formed nut.

Okay, pull the plug, turn on the cutter, turn the leadscrew….

Then it all went awry.  Cumulative clearances, an over-extended leadscrew, a “too thin” cutter all came together to form the perfect storm.  Overwhelming vibration set in.  And, try as I might, I simply was not man enough to restrain the whole thing.  I did succeed in creating several nuts, all of which were over diameter and not nearly concentric. 

Though I lost a couple nice pieces of hard maple, I was reminded of a valuable lesson: failure can be a much better teacher than success, assuming that you can kick your ego out of the room while the class is being held.

So, once again I say unto you, make a screw, buy your nuts.

I think I’m gonna try to repair my old wooden tapscrew.  What the heck?????

Making Wooden Screws – Lessons Learned

Well, just a few minutes ago my big wood tap screw went KABLOOIE!!  It was made out of cherry, so I didn’t expect it to have an extremely long life.  I’ll have to make another one, maybe.

If you’ve been reading the blog over the past few weeks you know that I became completely enchanted by the big wood screw making process.  Now I can share with you the wisdom I have acquired as a result of this process.

Three wooden bench screws in ash (it’s tough and it’s what I had on hand)

If you’re willing to put in the time (and a little money), making the screws is pretty simple stuff.  The nuts, on the other hand, are difficult to make, at best.  They’re not that challenging in a technical sense.  It’s just extraordinarily laborious work.  Using the type of traditional tapping machine that Underhill shows (shown in previous articles in this blog), the nutmaking process requires hours of manufacturing time and a significant amount of elbow grease.  Fitting is required and though serviceable, the internal threads show an appreciable amount of  damage, created when the scraping cutter traverses the “against the grain” quadrant of the “face grain” presented block.

The nuts are the HARD part!

 The long and short of it is this:  I’m glad I did it.  And since I’ve built the fixturing, I may well make more screws in the future, a few for working, a few as gag gifts.  But my STRONG suggestion is this – BUY THEM.  Wooden bench screws are great for any bench application.  For hundreds of years they were the standard.  They’re still great!  But do yourself a favor, buy your bench screws from a reputable supplier; someone like Lake Erie Tool Works .  If you want to make your own screw, so be it.  But save yourself a lot of headaches and buy the nuts.  You’ll be glad you did.

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.

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…