SIMPLE DIVIDING HEAD FROM A CAR STEERING COLUMN

petcnc

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I needed to cut a useable worm gear for a car door (window) mechanism

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The motor and the enclosure of the mechanism are pretty solid but the plastic gear gave up making it useless.

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I intent to use it for a new project and I need a new metal worm gear to replace the plastic one. To machine it I need a simple dividing head which I do not own! To solve the problem I made a simple dividing head that uses gears as the index. Thus, the number of teeth on the back gives you the same number at the front.
To expand the indexing range I intent to use all gears provided by my mini lathe. My minilathe has a wide range of gears (20, 30, 35, 40, 45, 50, 55, 57, 60, 65, 80) so I can cut gears with a variety of teeth: 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 19, 20, 25, 30, 35, 40, 45, 50, 55, 57, 6 0, 65, 80.
First lets see what car industry offers ready made for that job!

Column1.jpg

Yes! That is a motor assisted steering wheel column.
It offers a section that is very convenient for the job.

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After machining the shaft at steering wheel end, I made it support 8mm and 12 mm (mini lathe) indexing gears.

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I also made a 20x1mm large nut to secure the shaft to the indexer body.

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An adaptor to support 8mm hole gears


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A thick washer to secure 12 mm gears


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I machined a 55cm recess at the other end of the shaft to fit a 3” chuck

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And welded 3 steel extensions at the back of the shaft plate to secure the chuck in place

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Dividing head ready!

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All I need now is an index finger stop. Something simple…

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Made using a few angle bars and a spring

P3102122s2.jpg

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Now I can copy this peculiar plastic worm gear to a bronze one.

8deggear.jpg

I secured the indexer to the mill vice at 8deg angle.

8deg inclination.jpg

Chose the appropriate gear cutter 0.5mod, 20 deg. #8 (>135 teeth)

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Prepared the bronze blank on the lathe

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And cut the gear

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It looks nice

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Fits nicely

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And works nicely

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Thanks for reading

Petros
 
Ingenious! What make and model was the steer column off of?
Next trip to Pull-a-Part I'll be looking around... Steering column w/o airbag is $33.
 
Very clever Petros. I always look forward to your posts. Mike
 
Awesome Petros, inspiring indeed, wish I could give you more than one 'like'.
 
Great idea. I have thought about doing something similar to this. With google Sketchup you can divide a circle into as many equal parts as you need for teeth on your gear.

72 circle.jpg
This circle has been divided into 72 parts. You can also divide the circle by an odd number, 39 or 13 or whatever you want.


Print this out and glue it to a flat plate. You would need a some kind of clamp to keep the plate from turning. Using as large of diameter for the circular plate as you can minimizes any error that you may have in lining up the lines with a pointer. I thought of using an 8" diameter plate.

gear fixture 001.jpg
gear fixture 002.jpg
Rough sketches of what I have thought of making. Just a concept and needs refinement and further thought on the details. Another project for another day.
 
Ingenious! What make and model was the steer column off of?
Next trip to Pull-a-Part I'll be looking around... Steering column w/o airbag is $33.

It is a part made by General Motors (GM) The one as in the 3rd picture. The model over here is OPEL ASTRA in UK is VAUXHALL ASTRA
Look for electric motor assisted column as the fault they develop is the breaking of the plastic worm gear connected to the motor! (It usually breaks when you try to steer with the engine OFF as the worm prevents the worm gear from rotating)
 
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