Sunday, December 27, 2015

Dividing Head for Indexing and Cutting Gears

Building a dividing/indexing head for my lathe

Difficulty Level (Easy, Medium, Hard, Insane):

Similar to Alice tumbling down the rabbit hole, I've been on a journey on a thousand rabbit trails lately. It all started when I bought a Metal Band Saw, didn't notice that the previous owner kludged the gearbox together with some low-quality machine screws which came loose, jammed up the worm and snapped off 3 teeth of the worm gear. So here's the journey along these rabbit trails ending with the dividing head:

1. I need to replace the worm gear used in my metal band saw
2. To do #1, I need to be able to cut a worm with a 2.76 TPI pitch
3. To do #2, I need to have a 96 tooth gear for my metal lathe change gears
4. To do #3, I need to have a dividing head

I decided to not do a full write-up, but instead let the pictures speak for themselves. Please feel free to email me at eigenheerc at hot mail dot com if you have any questions.

A few more notes:

1. I had to make the chuck spindle and the chuck spindle guide plate twice because after I had finished it for the first time I realized that I didn't have enough room to lock the chuck spindle with enough force so I decided to make it pretty much the same size but out of square stock so I had some room for the locking clip in the corner

2. When you hear a tap creak TWICE, STOP and take it out. I learned that the hard way by snapping it right off at the very bottom of a hole. It was very nasty. I did fix it by welding it and re-turning it but in the end it didn't matter anyways because I had to re-do the entire part.

3. I also learned the hard way that it's a lot easier to move holes in AutoCAD than AFTER they are drilled

4. I can see how people would get addicted to making metal chips; the colors are truly beautiful


Parting off a 4" diameter piece of metal for the base
The three parts making up the swivel base
The base assembled and marked for the holes
The underside of the swivel base
The finished swivel base ready for install on the gear reducer
The gear box I bought at an auction among other things for a few bucks
Matching up the center of the gear output shaft with the lathe center
Another view of the bear box on the swivel base attached to the cross slide of my lathe
Another view from further down
Testing the concept of an angled miter gear cutting scenario
After the gear box was taken apart, sand blasted and painted
Milling one of the cover plates perfectly parallel to the gear box
The finish after milling the cover
The cleaned up gear box
Getting ready to cut off a piece of the 4" diameter 10V45 I bought at an auction for $2 bucks
Facing the blank
Done facing and getting ready to turn it down to size
Starting to turn down the chuck spindle support part
Another view, with the colorful chips
Almost done turning down the chuck spindle part to the proper diameter
Colorful chips
Some more chips
The chuck spindle guide plate
Another view
Mounting on an arbor to get both sides of the part concentric
Another view with the diy lathe dog. I don't like it a lot so I'll probably make another (smaller) one
Marking out the holes on the chuck spindle
Getting ready to cut the 8 TPI thread
Cutting a relief groove for the thread
After the scratch pass
Back to the chuck spindle support plate
Clamping it down to the cross slide
Drilling the holes in the chuck spindle support bracket
The front of the chuck spindle support bracket
The back of the chuck spindle support bracket
The finished chuck spindle
The chuck spindle inside of the chuck spindle support bracket
After I broke that bloody tap. It was a 1/4" x 20 HSS tap and should not have snapped as I was being very careful not to put too much pressure on it. This was such a PITA
I was so mad so I took the oxy/acetylene torch and melted the crap out of that stupid tap
Fitting a piece of metal into the hole
The fitted plug
After the plug was welded into the chuck spindle support bracket
After the weld had cooled down
After the chuck spindle support bracket was machined back down to size
The outside actually turned out quite nicely
The two holes drilled and tapped. They ended up not being strong enough to clamp down the chuck spindle so I had to re-do this entire part
Close-up of the welded and machined area where the tap broke off
The chuck spindle support bracket mounted to the gear box
The finished (first version) of the chuck spindle and support bracket
Getting ready to cut another chunk of 4" diameter 10V45
Another chunk I bought at the auction for a few bucks. This one is a 12" by 16" by 1" mild steel
Cleaning up the surface
Marking out the piece for the (second version) chuck spindle support bracket
Milling the other side
Getting ready to drill and then bore the hole
After the front was faced off
Boring the front
The finished bore
Dialing in the back side
Test fitting the (second version) chuck spindle support bracket on the gear box
After the holes were drilled and counter sunk
Starting on the chuck spindle. This had to be perfectly accurate. I ended up turning it to 1 thou oversize and then sanded the rest down to within half a thousands
Starting on the threaded side of the chuck spindle
Almost ready to cut the thread
Bluing the part with Dykem layout fluid
The finished chuck spindle
The chuck spindle (second version) fit into the chuck spindle support bracket. There is less than half a thousands gap between the two parts. This is probably the most accurate part I have ever machined so far
Marking out the position for the chuck spindle locking clip
Milling down a piece of mild steel to make the chuck spindle locking clip
Laying out the two holes for the roll pins to prevent the clip from rotating when tightening it
The finished chuck spindle locking clip
Close-up of the locking clip
Another view
Getting ready for the crank handle extension
After the scratch pass
The threaded end
The crank handle extension installed with a small set screw
Some more beautiful metal chips
Getting ready to bore the indexing plate holder
The finished indexing plate holder
The back of the indexing plate holder
The front of the indexing plate holder
Test fitting the indexing plate holder
After the mounting holes were drilled and counter sunk
Before installing the screws
The indexing plate holder installed on the gear box along with a test crank handle
5/8" melamine pattern for the sector arms
The two sector arms and two of the three indexing plates
Facing off the indexing plate
The finished indexing plate
Another view
Boring out one of the sector arms
Almost finished one of the sector arms
Another view of the sector arm
Test fitting the sector arm
After my neighbor drilled the indexing plates for me on his CNC machine. Thanks Bernie! That saved me countless hours of mind-numbing drilling
Cutting some small grooves to make it easier to follow the correct hole pattern
Drilling the second sector arm
Both sector arms test-fitted on the dividing head
Using the dividing head and the mill to mill the outside of the sector arms
Top view of milling the outside rim of the sector arm
Another view
Milling the slant of the sector arm
Another view
And another one
Close-up of milling the sector arm slant
And yet another view
Installing a  little ball bearing with a spring on the underside of the sector arm to provide a bit of friction to the sector arms
Close-up of the installed ball bearing
The finished crank handle my brother in law and I made on night
The bored out side where the plunger will go
Starting on the plunger
Test fitting the plunger in the crank handle
Close-up of the latch pin of the plunger in the indexing head plate against the sector arm
Knurling a brass knob
Tapping the brass knob to 5/16 x 18
The finished brass knob
Another close up of the latch pin
The modified plunger with the latch pin at the end
The finished plunger
Another close-up of the plunger
The finished brass knob to lock the plunger in the retracted position
Marking out the hole in the crank handle for the brass knob that locks the plunger in the retracted position
The finished dividing head
Close-up of the knob that locks the plunger in the retracted position
Close-up of the knurled brass knob
Close up of indexing plate 2
Indexing plate 3
Close-up of indexing plate 3
Indexing plate 1
Close-up of indexing plate 1
The chuck spindle locking clip
Another view of the locking clip
Another close-up of the latch pin in one of the holes
Another view of the brass knob that locks the plunger in the retracted position
Top-view of the latch pin engaged in the indexing plate against the sector arm
The latch pin engaged and touching the other sector arm
Close-up of the knurled brass knob
Close-up of the locking screws for the sector arms. The silver screw locks the sector arms together, the black screw keeps the sector arms from falling off
A front view of the crank handle, sector arms and the indexing plate
Another front-view
The finished dividing head
Side View A
Side View B
Index Plate Holder
Crank Handle
Index Plate Side View
Sector Arm 1
Sector Arm 2
Crank Handle Extension
Chuck Spindle Guide Plate
Chuck Spindle
Chuck Lock Clip
Chuck Spindle Guide Plate Front View
Chuck Spindle Guide Plate Front View with Chuck Lock Clip
Index Plate 1
Index Plate 2
Index Plate 3

Metal lathe & accessories
Angle grinder
Oxy/Acetylene torch
Measuring tape
Drill press
Tap & die set
Bench top grinder
Aluminum foundry

5lbs cast aluminum
12" of 4" diameter 10V45
6" of 2" diameter 1018
6" of 5/8" stainless steel
1" spring 3/8" diameter
1" of 1" brass
Nuts & bolts

Probably about $50 bucks in materials

40 hrs


It works great. I can't wait to start cutting gears


Unknown said...

It would take me 400+ hours and it still would not be right.
The recovery from the broken tap was impressive!

Ursi said...

You're insane, bro!!! But you certainly take after Dad!!

Gary D said...

I have resisted reading your blogs until now due to not wanting to be jealous, but i had to see how you were going to do the indixing holes.
Good job bro, if you had all this 4 years ago i would have been over to your place a lot more often. Hehe.
Be blessed.

Unknown said...

I would like to attempt this project however my master machineist level is about minus 37 so I have a ways to go.Looking on the optimistic side after looking at the video I can skip all that useless stuff in between,Thanks a million,Dale

Jason Cameron said...


This was very interesting. I am one of the instructors for the Mechanical CAD Technician program at the Nova Scotia Community College in Dartmouth. I was wondering if you minded if I referenced the material on this blog post in a Machine Design / CAD course I am teaching this semester?

Gonsi said...

Well done

Trip said...

Hi, I'm curious to know how he managed to precisely pin the holes with the same space between one and the other.

Chris Eigenheer said...

Trip, I actually cheated on this one. My neighbor had a cnc router table which he used with my autocad drawings of the plates with the holes. An alternative option would have been to do it with a ruler and compass on a piece of paper and then use a regular drill press.

Pablo said...

Chris, podrías pasarme tus archivos autocad, de las placas con los agujeros?
Me ayudaría mucho!!!

Chris Eigenheer said...

What is your email address?

Juan Carlos C said...

Podrías compartir el link donde imprimir los platos con los diversos números de agujeros por favor

Chris Eigenheer said...

@Juan Carlos, the pictures are in the blog at the bottom

Unknown said...

Çok güzel bir proje. Tebrikler.

Unknown said...

Muy buen trabajo me sería de gran utilidad saber el módulo o paso del sinfín y el engrane con la cantidad de dientes

Gas Contractors Kenner said...

Awesome blog yoou have here

Pablo said...

has logrado un trabajo excelente

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