A Fairly Simple Dividing Head
I made a simple indexer some years back. It works well, but I can only divide in numbers that
are already drilled into an indexing plate. I have a number of index plates for mine, but I often
find a division is needed that my premade index plates will not provide. A simple dividing head
will make some of my shop tasks easier, and besides, I want one.
I made this one from a picture I saw in Tony Jeffree's Taig book, (thanks for the ideas, Tony.)
First, a shot of the finished item. It's not fancy, but works quite well.
Here it is shown on my Taig lathe, doing what it does. In this case, I'm making a pinion (gear)
for an old Ingraham clock movement I am repairing.
I didn't make up any prints for this, just thinking it out as I went. The photos here may offer some
ideas for someone interested in making a similar item. I'll just put the photos in a kind of logical
order with comments that may apply.
Squaring up the ends of the main body with a fly cutter.
And squaring up the ends of the blocks for the worm shaft.
The worm shaft blocks mounted to the main body.
The bearing holes for the worm shaft are drilled and reamed for the proper size of the shaft.
In this case, 1/4".
The main body is drilled through and reamed to fit the shaft for the worm gear, then partially
bored to a depth that is suitable for the end arbor of the main shaft. Since the boring opera-
tion here doesn't go all the way through the main body, I circled the side that needed boring
so I wouldn't bore the wrong side.
Here, the main shaft, which is 1/2" CRS, has had a length turned down to take 3/8-24 threads for
a drill chuck. The end closest to the chuck has had a landing turned into it, with a small relief where
the threads will end. This will let a drill chuck or a threaded arbor mount up tight to a true surface,
similar to the way the Taig chuck mounts to the spindle.
The excess has been nearly parted off, and I stopped so I could take this picture, with a mind for
the following;
Many people have trouble parting-off, and if things aren't set up just so, it can be a problem. The piece
shown is full strength CRS, not leaded steel. This parting cut only took about 10-15 seconds with a spindle
speed of about 550 RPM. It will really help when parting-off if you have the parting tool at exactly 90 degrees to
the work piece, (or parallel to the face of the chuck, same difference). Your parting tool needs to be sharp!
Also, some type of lubricant is a real plus. For this cut, I used just two drops of Tap Magic.
It's a fast cut, and that's all it takes.
Now that I have the arbor to the proper length, the end is threaded for 3/8-24. I have a die holder
that mounts to the Taig tail stock, but the only die I have in this size is six sided, which won't fit the
Taig die holder, (it takes round dies). So, I'm doing it the inconvenient way, with a die handle.
I run the tail stock drill chuck, (with it's jaws fully retracted) up against the die to help keep the threads
square while threading. Also, a little Tap Magic helps. CRS is hard, and threading will sometimes
chip it. A good lube will usually help in preventing this problem.
After the threading is done, the work piece is reversed and indicated in on the four jaw chuck.
Then the small end is turned down for a running fit in the main body.
This is the finished main shaft.
And the shaft with a chuck mounted. It can also take threaded arbors for special applications.
The main body complete.
And the first assembly fit up.
Yes, that's a lot of teeth on the gear. I used what I had on hand. I got this worm and gear a while
back for $5. I had to make something to use it. It's 100:1.
30:1 or 60:1 would make better sense, but I can do a lot with this and a 60 hole plate. For
instance, I can make more plates.
This is what will become the brake for the main shaft.
After boring a whole the size of the big end of the main shaft, mounting holes are drilled to match
holes in the main body. Looks kinda like Mr. Bill. Oh Noooo...
Another hole is drilled and tapped for the clamp that will tighten the brake, then a slot is cut
so the brake can flex and close against the main shaft.
The end of a piece of drill rod is turned down and threaded for the brake shaft.
The lock shaft is then turned to the proper length behind the threads so as to fit in the brake. A
shoulder at the end of this cut is left and that diameter continues for the rest of the length of the shaft.
The shoulder will bear against one surface of the brake to close it as the shaft is tightened.
The shaft is of drill rod.
Here you can see how the completed brake assembly fits to the main body.
Next a bushing is turned and threaded for the indexing pin.
Here is a detail shot of the index pin with it's bushing.
Another shot of the index pin assy. Easier to see the indexing arm in this one. The indexing pin
bushing, along with it's pin, can be loosened and moved in the slot in the arm to adjust for plates
of different sizes.
A plate is attached to the back side of the indexer, as seen in this shot, with six mounting holes
matching the Taig slide. Only four of the six hole are used at one time, depending on how high
the divider needs to sit on the milling column.
That's it.
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copyright July 2008 Dean Williams