Thread: 127 tooth gear

Have you tried Mick Moyles?

Mick Moyle's Engineer Supplies

Cheers,
Andrew

They made a few models over the years up to a monstrously heavy ~20" model...

If you can't find one ready made, step one is to make up a blank the right size. Off the top of my head a 10DP 127t gear will be something like 270mm diameter, so the steel won't be cheap to start with.
Step two is to find someone with a universal dividing head (because it will need differential indexing) and a 10DP cutter to cut one. (I have the dividing head but not the 10DP cutter). Bear in mind though that cutting that on a mill will take several hours (I'm guessing 4 to 6) so is not a casual favour to ask of someone.
It would be possible to do it on a CNC machine with a 4th axis, but most home workshops would probably have trouble with the size - it will still take time, but can run in a less attended way. Manually you have to index every 3/4 minutes.
Commercial cutting is the 3rd option but will cost hundreds.

Michael

Originally Posted by Michael G

If you can't find one ready made, step one is to make up a blank the right size. Off the top of my head a 10DP 127t gear will be something like 270mm diameter, so the steel won't be cheap to start with.
Michael

Michael,

I make it 327.66mm OD for the gear blank if it is 10DP, so it is indeed a fair lump of steel. A couple of more managable pairs of compound gears, e.g. 63/80 or 37/47 will give very close approximations to the exact result obtained with the 127T gear with much more compact gear diameters if space or material size is a problem. While there will be quite a saving in material, the actual cost of cutting the gear teeth using a dividing head on a milling machine would, as you say, still be very high.

Frank.

Thanks Frank
(Don't know where 270 came from. That will teach me to remember things (incorrectly))

Michael

You could put that in the other thread about what you learnt today.

Her is the 'improvised' method: cut three terrth off your VW ring gear, weld the ends back together and fettle to shape. Then turn down the step of the flywheel to suit the new size and shrink back on to the flywheel.
Tada! 127 tooth wheel.
You could then use that to index the spindle to make a new one-piece one in any size or DPI...
Joe

Originally Posted by jhovel

cut three terrth off your VW ring gear, weld the ends back together ...
Joe

Hey Joe what a great idea.............I honestly don't think the old sloppy gear system would even notice the slight innacurracy!

Thanks.
Bill.

You dont particularly need a Universal Dividing Head with differential indexing,you can just use a Dividing Head or Rotary Table with a 127 plate.

Bill do you have any idea of the gear specs (eg DP) of your current lathe? If compatible, is it possible to modify the bore of a Hercus 9", either by boring the gear out or making a bush? The Hercus/Southbend transposing gears are freely available and not absurdly expensive.

Pete

Originally Posted by jhovel

cut three terrth off your VW ring gear......
Joe

Joe.........
First major obstacle! Yesterday I cut through what I thought was a conventional ring gear but it did not pop off as expected! It is a one piece flywheel/ring gear!!!! Those damn Germans! Why can't they just make things the same way that the rest of us do?

I will now look at other flywheels to see if they are suitable.

The existing gears are 12DP I believe (not 10DP as earlier suggested). I'm not too keen to spend heaps on this project because I rarely cut metric threads but just the other day it cost me $20 at the local engineering shop to have a hyd cyl gland thread refurbished. Yes, cheap I know but I hate having to get other people to do jobs that I could easily do.

If I have to resort to buying a new "Hercus" gear (if suitable) which is the best place to go?
By my calculation a 12DP gear with 127T will be 10.75" OD. Is this the same as the Hercus one?
Rgds.
Bill.

Any 12DP gear with that number of teeth will be the same OD, ID and PCD. The potential differences will be in the hub bore & keyway and the tooth width.

Michael

Originally Posted by Michael G

Any 12DP gear with that number of teeth will be the same OD, ID and PCD. The potential differences will be in the hub bore & keyway and the tooth width.

Michael

Michael....agreed. I merely gave that OD so that a Hercus owner maight quickly check!
The bore, keyway, etc can easily be re-jigged by bushing as I have done with the old VW beetle flywheel. The tooth width is not critical because in my case this gear would rarely be used. Just handy to have.
Bill.

Hercus gear is 7.166".