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Traditional Vise screw, Taken up a notch

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Project by CMDEvans posted 1112 days ago 4871 views 15 times favorited 23 comments Add to Favorites Watch

I was buying Maple stock recently, and saw this beautiful piece of wood next to the stock I was purchasing. It went back to the shop with me, in a rare act of overspending on my part.

Well, acts of spontaneity need to have some justification in my case, so it was the first to go on the lathe. I like the results.

My apologies for the pictures, and I will try to get some up that do the maple justice.

2 TPI, 45 degree thread pitch, 2 1/4 diameter. Hard Curly Maple.





23 comments so far

View PurpLev's profile

PurpLev

8476 posts in 2235 days


#1 posted 1112 days ago

looks great!

what lathe/fixture are you using to get 2TPI?

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#2 posted 1112 days ago

Thanks!

I rough the blank out on the lathe, then use custom tap and die sets to make the screw threads.

View Bertha's profile

Bertha

12951 posts in 1279 days


#3 posted 1112 days ago

I have a lathe. That is the extent of my experience. Can someone explain to me in layman’s terms how to do this? I’m terribly intrigued.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#4 posted 1112 days ago

Bertha,
You CAN chase threads on a lathe, but I have not seen threads this large done on a lathe. I use the lathe to turn the blanks and the handles.

First you have to make a tap. I use a series of three taps that I have made, each taking a successively larger amount of wood out of the nut.

Then, you use the nut to make a thread box, using a cutter or two embedded in the wood around the nut.

I can tell you from experience that the first 7 or 8 setups you make won’t work all that well. (well, that could just be me) Once you get the first few made though, you can use them to improve the subsequent taps and dies.

alternately, you can hand carve a nut first, make the threadbox, then use that to make all your taps.

View Bertha's profile

Bertha

12951 posts in 1279 days


#5 posted 1112 days ago

Thanks, CMD. Can I just buy a tap? This all sounds very scary to me. I’m planning a massive workbench build and it just “feels right” to use wooden Acme’s. Thanks again.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#6 posted 1112 days ago

You can buy a commercially made tap a hair smaller than this. . .but the kicker is the price. nearly $2,000 from DICK in germany.

I can make a tap for someone, but would have to charge a hefty amount for it.

As long as I am not stepping on toes, which, if I am, please let me know, You can buy the finished screws and nuts, as well as handles and garters from me. I have sold many of them. If that is what you are after, let me know.

And if that is a breach in protocol for the forum, let me know please.

View David Kirtley's profile

David Kirtley

1276 posts in 1584 days


#7 posted 1112 days ago

Bertha,

Not up to that size but you can get an appreciable 1-1/2 5 in from Beall Tools. I have the smaller set and will eventually get the two larger sizes. He has a router fixture that you use for threading. It makes nice clean threads. I prefer it to a thread box. I recently gave away all my old thread boxes. (Well, not that nice of a gift. I had lost the taps.)

That said, up in that size, the cost of buying the tooling takes many screws to pay for itself. It is generally just cheaper to buy a screw.

Roy Underhill goes through the main ways to make them in Woodwright’s Apprentice (I believe it was that one.) It is like “Which comes first, the chicken or the egg?” You want to have a screw to make the tap but you need the tap to make something to feed the screw in at the right speed.

For doing it by hand:

You start with a screw. Take a dowel the appropriate size and then take a strip of paper (like cash register tape) and wind it around the screw blank. Saw a kerf following the spiral. Carve the thread following the kerf. Clean up with chisels and scrapers. Now you have the screw.

To tap, you cut a saw shaped blade that has the teeth that match the threads. Slit the screw and put the blade in the screw with the teeth barely out. Turn the screw into the nut and the blade scrapes out threads. Keep advancing the blade until the threads are cut full depth.

There are many variations on doing it by machine. Most include a geared arrangement so the cutter is advanced as the screw is turned. Take a look at Beall’s “Pen Wizard.” It works the same way as one of the older thread cutting tools. That is how it makes spirals.

The old way for doing it on the lathe was to chase the threads. You take a saw toothed cutter with the teeth that match the threads. You lay out the threads and maybe start a kerf to follow as above but you do most of the cutting on the lathe with the work turning and you are feeding the chasing tool at the right speed to match the thread pitch. Not that hard but definitely a real skill.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View SCOTSMAN's profile

SCOTSMAN

5235 posts in 2172 days


#8 posted 1112 days ago

Nice work.I have a metal screwcutting lathe and have cut many metric and some imperial screws on that in metal.
If tried however on wood it gives very poor to terrible results chasing is ok but you can make a woodent tap and die box or buy one quite reasonably they work well in hard woods only. Alistair

-- excuse my typing as I have a form of parkinsons disease

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#9 posted 1112 days ago

Scotsman,

How many TPI does your metal lathe go up to? I haven’t seen one in an affordable range that cuts fewer than 4 TPI around these parts.

David,

The difference in 5-6 TPI with the commercially available wood taps and the 2 TPI screws I make are pretty drastic. Both are threads, both are made in an approximation of the same manner. however, 5-6 TPI is pretty slow for a bench vise. To illustrate the difference, refer to the pictures below.

!https://s3.amazonaws.com/lumberjocks.com/lngu4tm.jpg!

One of the major problems I have with Most wood threading nowadays is that they have the thread pitch wrong. Most have the thread pitch set at the same angle as metal threads (60 degrees) For wood, you should have a 90 degree angle. This does several things.
A. It directs the force into the shaft of the screw rather than laterally, reducing the risk of breaking the threads.
B. it provides a thicker base, and a more robust thread so blunt force is less likely to break or chip the screw.
C. It allows the cutters to cut across the grain in manufacture better, so there is less manufacturer defect.

For smaller screws I don’t consider this to be an issue, but for the large screws, you want longevity and reliability, so I follow that protocol.

View llwynog's profile

llwynog

282 posts in 1165 days


#10 posted 1112 days ago

CMDEvans,
Thanks a lot for this most interesting read.

-- Fabrice - "On est bien bête mais on sent bien quand on se fait mal" - my grandfather

View David Kirtley's profile

David Kirtley

1276 posts in 1584 days


#11 posted 1111 days ago

Most of the lathes with manually changed gears can do it but it is not normally put on the tables as few people are cutting that pitch. My lathe could do the 2 thread per inch. Of course my screw would have to be about 3 inches long because my lathe only has 10 in between centers. The problem is still cutting the internal threads unless you are going to do it on a lathe too.

But unless you are just fascinated by cutting threads on big dowels or want to break into a really small market, it is smarter to buy it from someone like CMDEvans here or one of the other 3 or 4 people that make them. Tooling up to make one is going to be either really expensive or a whole lot of work and you are going to have to cut a lot of screws to make back your investment in work or money.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#12 posted 1111 days ago

David. . .

I called a few lathe manufacturers to find out about that last year. They keep on telling me the same thing. . .It can be done, but you have to make custom gears first. Not sure what lathe you have, but I would be interested to know which manufacturer it is, as that would really come in handy for me.

View David Kirtley's profile

David Kirtley

1276 posts in 1584 days


#13 posted 1111 days ago

I just have a little Harbor Freight 7×10.

Little Machine Shop’s gear calculator shows this for a 2 tpi.

A B C D Thread Pitch Percent Error Error in 1” of Thread
80 20 80 40 2.000 TPI 0.000% 0.0000 in
80 40 80 20 2.000 TPI 0.000% 0.0000 in

Since I have a metric lead screw in mine, I would have to approximate:

A B C D Thread Pitch Percent Error Error in 1” of Thread
60 21 80 27 2.000 TPI 0.012% 0.0001 in
60 27 80 21 2.000 TPI 0.012% 0.0001 in

Varmit Al’s gear calculator program is available as well. (Google)

If you were going to be cutting a lot more of them and get more into the mechanics of it, I recommend the Holtzapffel books on ornamental turning. They go into some pretty good detail on screw cutting. You could also pick up an old Craftsman Router Crafter or whatever it is called and it would be pretty good for cutting the threads with a router but you might have to get some other gears for it. I don’t know what pitches it can handle out of the box, they really mean it for spirals and barleycorn twists. It is like the little PenWizard I posted before but like 36in between centers.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View CMDEvans's profile

CMDEvans

28 posts in 1112 days


#14 posted 1111 days ago

better pictures..If anyone has a suggestion as to how to photograph figured wood, I would appreciate it. The grain really stands out in real life, but the pictures don’t convey that very well. Must be a technique to it that I am missing.

.

View David Kirtley's profile

David Kirtley

1276 posts in 1584 days


#15 posted 1110 days ago

Those sure are pretty. What kind of finish do you put on them?

The figure would probably stand out more under bright daylight for the pictures.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

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