The Largest Screw I Have Ever Made

george wilson

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PICT0024.JPG PICT0025.JPG This is a 12" diameter wooden(Beechwood) screw and nut I made for a giant cider press and mill that my director wanted made. For size comparison,I am 6' 5" in the picture.

I had been trying to figure out how to do this for some time. Especially how to thread the HOLE that the big screw went through.

Finally,I found a country machine shop that would let me use their equipment. Of course they were paid! I used a very old lathe that would not be hurt by the huge number of wet shavings from the beechwood log. You can see in behind me with the finished screw. rotated. The chips literally got 2 feet deep in front of the lathe during the week I was making the screw. I was working on my KNEES before they finally on Friday got a young guy to clear away the shavings.

The first consideration I had was how to keep the wooden screw from splitting wide open. Logs split open because there is no place for the CENTER of the log to go. So,I drilled a 2" hole through the center of the log. I slathered beeswax all over the screw with a large torch tip and a big brush when finished. It was still turning in the lathe. This was to force the screw to dry out via the 2" hole down its axis,and not let the screw tips get all cracked. It worked pretty well. I lost no chunks of screw over the years. This 2" hole would never be seen as the press was 10' tall when finished. I CAN"T FIND A PICTURE OF IT RIGHT NOW.

This worked well,and to this day the screw has never split. It was not possible to find a dry log anywhere as lumber mills do not let them lay around for 30 years!

I had to hand chop the tailstock end 1of this log to be small enough to clear the top of the cross slide. Plenty of back breaking work! After that,I could take a deep enough cut to let the rest of the log clear the cross slide.

The threads are 2" wide. 6 threads per foot. Fortunately,correct wood threads were 90º,not 60º like metal threads. This was to make the more blunted screw tips harder to break off. I was able to rig up a router held at 45º and fed into the wood at a 45º angle to produce a perfect 90º wood thread.

The finished screw was 12" in diameter,with a 18" "bulb" at the end. This bulb was cross drilled with 2 holes 5"in diameter to fit tommy bars into to tighten the press on the apples.

The NUT was the bigger problem. The original was flat on 3 sides,with one side left un cut,from a pretty gnarly looking tree.I found a 32" diameter old,gray log at a lumber mill. Sure enough,it turned out to have barbed wire in it. As a young tree,it served as the corner of some farmer's fence. That is why they hadn't cut this log!

I had to chain saw 1 side down to make it SMALL enough to be run through a circular saw at another country saw mill. This was very painful to me due to ma chronic back pain. But,I got it done,even running through the barbed wire as I had found no other suitable log.

When the log was squared up on 3 sides,we took the cross slide off the lather,and CHAINED it down tight with ratchets.

The hole was bored through the 16" thick nut-to-be. This is where I was lucky: There was JUST room to feed the router,held at 45º through the hole,if I took a big bite on the first pass.

THE LARGEST MACHINE SHOP IN HAMPTON had wanted to make an "Inserted thread". That would have looked very phony,and would soon have fallen out!!!

We made a primitive jig to hold the router at 45º.and let it be adjustable. I let the LOOOONG extension cord wrap around the 4" pipe that the router was mounted on as it was fed through the hole. The hole threaded beautifully!

So,HOW did I keep the nut from shrinking onto the screw? I chose a newly cut log to make the screw. Water ran around and around on it as the log was turned down. The NUT was made of an old,gray log that had been cut many years ago. The bark had even fallen off of it. This nut was SUPPOSED to be oak,but it turned out to be a HICKORY log,which was HARD AS THE DEVIL to chainsaw!! But,the semi dry nut could never shrink more than the screw and bind it up. THIS PLAN WORKED,much to my JOY!!!:)

This project was done 1n 1985. That is me,much younger,in the pictures. Except for the black haired fork lift operator.

The cider mill is used to cut and crush the apples up. Obviously these 2 machines were for a large cider operation. But,my boss saw them in Summerset England,and went cider happy over them! Cider was exceedingly important in the days before soda pop,though.It was available either SOFT,or HARD (fermented into an alcoholic drink). This was so prevalent that every old house in England, Made during the 17th(?) c. or after,can be seen to have had the two large vertical timbers at the bottom of the slanted outside cellar doors,hacked away some. This is because the standard size of cider barrels was increased,and they had to enlarge all these doors to receive the larger barrels. I can't recall the exact century this happened in. Been too many years since I retired.

The apple pulp was shoveled into a horse hair bag and squeezed in the press. This horse hair bag was black,and looked just like those old,cheap woven nylon seat covers you could buy for your old car back in the 1950's,except it was black. I have no idea where they got this cloth! Must have cost a bundle!

It would take pages to go into this in more detail. Enjoy. Just another of the odd ball jobs I was assigned to do,as no one else had both woodworking and machinist skills.

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Ulma and francist: You may have read this thread before I was done with it. Maybe go back and see more of a description of how it was accomplished?
 
PICT0032.JPG The biggest screw up ever!

I am surprised that so many have read this thread this morning. I'll have to be more diligent about posting projects I did. And,thank you all!!:)

BTW: we also had to make some large,very coarse toothed gears for the cider mill. But,only one of the smaller ones can be barely seen in one picture. There were 2 16" in diameter,and 2 more 8" in diameter. Now all hidden inside the wooden body of the mill.

When my director left,interest in the cider program diminished. Now they can't seem to find a place to put the equipment since a cider mill would not be seen in a TOWN (Williamsburg,of course!) , but rather on a farm somewhere. Or a special site where cider was produced.

I think it is too bad. The public would love to see this anyway. It shows a BIT of 18th. C. industry on a larger scale than a blacksmith shop,gunsmith,etc..

There is talk of GIVING the whole shebang to MOUNT VERNON. George Washington was the largest brewer in the colonial period. I forgot to even sign the equipment anywhere.

The screw and nut alone took me a whole Summer to make.

Here are a few more pictures. In one I am chain sawing the length of the semi dry 32" dia, hickory log to make it small enough to get onto a saw mill's carriage. This sideways forcing really killed my BACK. That hickory was VERY tough! I hurt my back as a young man,and have suffered with it all my life.

The other picture is starting to bore out the large hole in the nut. It would eventually JUST clear the router fed through it to cut the 6 threads per FOOT. Note the chains tightly holding it down to the carriage,from which the cross slide had been removed. These chains had ratchets to really get them tight. The rough chainsaw cuts are seen. After I got this nut threaded,I spent many hours hand adzing everything to get rid of the modern cuts,leaving an authentic 18th. C. finish on it.

You have to admire the poor guys who made these and LARGER wooden screws in the 18th. C.,and earlier. They used horses and gangs of men. They had a primitive method of cutting internal threads by means of a single tooth guided scraping cutter to thread the holes.

If you have seen "The Woodwright's Shop,Roy Underhill gives you an idea on a SMALL SCALE of how they did it back then. Those logs are very heavy,and horses or water wheels had to be used to turn them on large wooden lathes. This was a very specialized occupation back then(like most other things were,too!) Must have cost a fortune to get a big press made at that time!

Sorry,I had a picture of the finished press,but it seems to have been eliminated by posting other pictures.

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When I was stationed in Germany back in 1970, I bought a bottle of Sumerset cider. As far as I'm concern, it's the best cider in the world.
 
Wow! what a great accomplishment, thanks for sharing.
 
Some might say you just screwed up, but I think that is very cool. Mike
 
George you are the best, a master machinist and no problem stands in your way! Magnificent!!


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