Ring gear for Edwards radial.

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danallen

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I am working my way through building an Edwards 5 cylinder radial engine and I thought I'd share how I made the ring gear that drives the cam. I couldn't bring myself to spend the 200 plus dollars for the Boston gear specified in the plans. I machined three 120 degree segments and was able to machine the teeth starting in the center working to one end and then flipping the part and repeating. The pictures show a finished segment and a segment in jig with its mating gear to check size. Also a picture in the mill and with all 3 in the cam.
 

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I am working my way through building an Edwards 5 cylinder radial engine and I thought I'd share how I made the ring gear that drives the cam. I couldn't bring myself to spend the 200 plus dollars for the Boston gear specified in the plans. I machined three 120 degree segments and was able to machine the teeth starting in the center working to one end and then flipping the part and repeating. The pictures show a finished segment and a segment in jig with its mating gear to check size. Also a picture in the mill and with all 3 in the cam.
Nicely done indeed. I'm working on an Edwards too and have pondered on the production of that very part. Very interesting procedure.
 
I am working my way through building an Edwards 5 cylinder radial engine and I thought I'd share how I made the ring gear that drives the cam. I couldn't bring myself to spend the 200 plus dollars for the Boston gear specified in the plans. I machined three 120 degree segments and was able to machine the teeth starting in the center working to one end and then flipping the part and repeating. The pictures show a finished segment and a segment in jig with its mating gear to check size. Also a picture in the mill and with all 3 in the cam.
A great way to solve the problem !
Thank you for sharing.
 
What?!? :oops:o_O That is a creative aproach. I made a slotting head a while ago. It would be useless most people said, I start to see why :cool:. But it can do ring gears as well.
One trap I ran into was that the ring gear needs a bigger inside diameter and same cutting depth, because addendum and dedendum are reversed. (can be disappointing to notice after spending lots of time copying your method)
addendum dedendum.jpg
Why did you need to flip the parts? (because the workpiece was not "sticking out from the rotary table enough?"
Makes me wonder if a helical ring gear can be made in a similar fashion. (of course necessary to make a spiral milling arrangement to rotate gear blank)

The single segment looks like a "very important part of some tilting mechanism".
How did you get the segments to fit exactly?
Did you face any problems with tool deflection at the ends? when the cutter is only working on one side.

The big question is: Was it really about the money? Or more a matter of eliminating one "store bought item"? (even if the part sits deep inside the Engine, no one can see it. But you know, who did it.
Should you present the engine in any exhibition; I guess "certain people" will find it very interesting. You should make a 2nd gear like this.

Greetings Timo
 
What?!? :oops:o_O That is a creative aproach.
View attachment 154907
Why did you need to flip the parts? (because the workpiece was not "sticking out from the rotary table enough?"
Makes me wonder if a helical ring gear can be made in a similar fashion. (of course necessary to make a spiral milling arrangement to rotate gear blank)

The single segment looks like a "very important part of some tilting mechanism".
How did you get the segments to fit exactly?
Did you face any problems with tool deflection at the ends? when the cutter is only working on one side.

The big question is: Was it really about the money? Or more a matter of eliminating one "store bought item"? (even if the part sits deep inside the Engine, no one can see it. But you know, who did it.
Should you present the engine in any exhibition; I guess "certain people" will find it very interesting. You should make a 2nd gear like this.

Greetings Timo
I flipped the segment because if I indexed it any further than the center tooth the top would hit the arbor holding the cutter.
I carefully machined the blanks on locating pins so that they just fit the cam ring. See picture.
There was no problem with deflection.
The money part was the satisfaction of not spending that much on something I could make in a few hours.
I have a couple of spare segments that don't fit the test jig but are fine for show and tell.
Thank you and everyone else for your kind words.
 

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I am working my way through building an Edwards 5 cylinder radial engine and I thought I'd share how I made the ring gear that drives the cam. I couldn't bring myself to spend the 200 plus dollars for the Boston gear specified in the plans. I machined three 120 degree segments and was able to machine the teeth starting in the center working to one end and then flipping the part and repeating. The pictures show a finished segment and a segment in jig with its mating gear to check size. Also a picture in the mill and with all 3 in the cam.
I really like this solution. Your showing a purchased cutter, but a DIY cutter would also work.
 
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I really like this solution. Your showing a purchased cutter, but a DIY cutter would also work. It is a single tooth cutter.
 
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I am working my way through building an Edwards 5 cylinder radial engine and I thought I'd share how I made the ring gear that drives the cam. I couldn't bring myself to spend the 200 plus dollars for the Boston gear specified in the plans. I machined three 120 degree segments and was able to machine the teeth starting in the center working to one end and then flipping the part and repeating. The pictures show a finished segment and a segment in jig with its mating gear to check size. Also a picture in the mill and with all 3 in the cam.

OMG, you're a genius, keep posting :) !!!

PS, over in UK there's hpcgears-dot-com that has steel internal ring gears for about 1/4 the price
 
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