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SIMPLE DIVIDING HEAD FROM A CAR STEERING COLUMN

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petcnc

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

P2232082s.jpg

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

P2232075s.jpg

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.

P3102126s.jpg

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

P3102132s.jpg

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

P3102135s.jpg

An adaptor to support 8mm hole gears


P3102139s1.jpg

P3102140s.jpg


A thick washer to secure 12 mm gears


P3102137s.jpg

P3102138s.jpg

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

P3102128s.jpg

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

P3102133s.jpg

Dividing head ready!

P3102122s1.jpg

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

P3052086s.jpg

Made using a few angle bars and a spring

P3102122s2.jpg

P3052085s.jpg


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)

P3072101s.jpg

Prepared the bronze blank on the lathe

P2232073s.jpg

And cut the gear

P3052089s.jpg

It looks nice

P3072099s.jpg

Fits nicely

P3072096s.jpg

And works nicely

P3072092s.jpg

Thanks for reading

Petros
 

middle.road

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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.
 

RandyM

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I like the part where you are using the old gear to make the new one.
 

FOMOGO

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Very clever Petros. I always look forward to your posts. Mike
 

Tozguy

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Awesome Petros, inspiring indeed, wish I could give you more than one 'like'.
 

mickri

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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.
 

petcnc

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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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petcnc

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petcnc

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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.

View attachment 262838
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.

View attachment 262839
View attachment 262840
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.
Nice idea!
But building it I feel like re-inventing the wheel as I usually have to copy a gear and not make one from scratch!
I intend to make one indexer controlled by a microprocessor so you can set the angle, teeth etc and it will signal a stepper motor for full rotation accuracy.
I found plenty of info on the subject and I started collecting parts!
Stay tuned I will publish it when I will start making it
 

rpmMan

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Nice work!! I am surprised that the index latch is able to hold it securely while machining...

rich
 

petcnc

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[QUOTE="Nice work!! I am surprised that the index latch is able to hold it securely while machining... " QUOTE]

I tested by hand and it needed some force to dissengage from the teeth.
I had no problem in milling it as there are no vertical forces involved (Z is locked). On the other hand the 8 deg. inclination was not enough to create problems due to forcing the gear to rotate and/or jump a tooth.
I might was in luck also and the spring I chose from the scrap box was strong enough...
I dont know!!
 

tjb

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

View attachment 262752

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

View attachment 262753

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!

View attachment 262754

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

View attachment 262755

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

View attachment 262756

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

View attachment 262757

An adaptor to support 8mm hole gears


View attachment 262758

View attachment 262759


A thick washer to secure 12 mm gears


View attachment 262760

View attachment 262761

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

View attachment 262762

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

View attachment 262763

Dividing head ready!

View attachment 262764

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

View attachment 262765

Made using a few angle bars and a spring

View attachment 262766

View attachment 262767


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

View attachment 262768

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

View attachment 262769

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

View attachment 262770

Prepared the bronze blank on the lathe

View attachment 262771

And cut the gear

View attachment 262772

It looks nice

View attachment 262773

Fits nicely

View attachment 262775

And works nicely

View attachment 262776

Thanks for reading

Petros
Beautiful work, Petros. Very creative.

Regards,
Terry
 

PHPaul

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Pure genius!

I've scanned a couple of different threads with titles like "A dividing head anybody can build" and have come to the conclusion that I'm obviously not "anybody" because I wouldn't have a whisker of a chance of building something like that, even if I HAD the tools. I'm the rankest of rank amateurs and at 67, it's not likely I'll be around long enough to develop the necessary skills.

Your device, I think I could build successfully.

As soon as I scrape together the money for a mill that is.

Bookmarked...
 

dbq49

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Very interesting to see your construction process and to see the part in place. I come back to thinking that plastic was used for what reason? As most gearing is suppose to have one material as the sacrificial material to keep something else from being destroyed. If not from another plastic, what about a brass gear? Just wondering what will break next????
DBQ49er
 

mickri

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I need to replace two gears to be able to cut metric threads through the QCGB on my lathe. I could just buy them but what fun would that be. The need to cut metric threads is a ways in the future. So no rush right now to be able to make gears.
 

petcnc

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Very interesting to see your construction process and to see the part in place. I come back to thinking that plastic was used for what reason? As most gearing is suppose to have one material as the sacrificial material to keep something else from being destroyed. If not from another plastic, what about a brass gear? Just wondering what will break next????
DBQ49er
This plastic gear meshes (through some rubber material that works as cushion), to another plastic spool where the steel cables wind up on.
dodge_window_spool0.jpg
This is also a usual failure. Half of the mechanisms I was given were replaced because of this!
I have no intention to use it as it was used! I just need a slow-turning 12v DC mechanism for a different project and the plastic gear was the best candidate for failure!
The funny thing to all these mechanisms is that failures do not happen due to normal wear & tear but there is always a part "designed" to fail prematurely. This was the case with the steering column and with the window opening/closing mechanism used here!
If all sub systems of the mechanisms were solid then in a window blockage situation you would have a blown electric fuse, not the mechanism itself.
A friend of mine that owns a car repair shop, provides me with plenty of failed car devices and when I examine them I feel its a big waste of materials to throw them away/recycle for a part that it was obvious that it will fail VERY soon in normal operation.
I have seen beautiful (and very expensive) air pumps for air suspension cars to be replaced because of an o-ring failure as there is no repair kit available on the market to fix the leak!!!
I'm afraid that we are the last generation that repairs things. The tendency is for the market to develop "fitters" that replace the part for a new one and do not bother in fixing anything!

petros
 

PHPaul

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I'm afraid that we are the last generation that repairs things. The tendency is for the market to develop "fitters" that replace the part for a new one and do not bother in fixing anything!
Indeed. That's been true in the electronics business for a long time. I graduated from the Navy's Electronics Technician Class "A" school in 1970. For the next several years I was stationed at various places as a technician. Vacuum tubes were still in widespread use, discrete transistors were common and becoming more so, and we were hearing rumors about these new fangled "integrated circuits". Everything got troubleshot down to the component(s). One piece of equipment I worked on regularly had "potted modules" which were basically discrete components encased in a block of epoxy with pins out the bottom.

In 1979 I went back to school on a more advanced system. All digital, pretty much everything but the power supplies were high density circuit boards with IC chips. By then, it was "run the diagnostics and replace the boards it tells you to replace." Some thinking required to interpret diagnostics, and maybe peek at a signal here and there with a oscilloscope to confirm it, but the most important thing was a complete and well-stocked spare parts kit.

In fact, one component of it, an early digital computer, didn't even go that far. They used what they called the "handspread" method: Run the diagnostic, put your "social finger" on the board it called out, and replace that board and any on either side of it you could cover with your hand! True story!

I shudder to think what electronic "troubleshooting" has devolved to in this day and age.
 
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