Posted by BillS on April 13, 2013 at 04:55:49:
In Reply to: TRILOBE change gears for 4GS gear shaper? posted by Aditya Patel on April 12, 2013 at 11:46:06:
Looks like there are special pull broaches for cutting the Fellows TriLobe shape from a round hole.
One for 3/4" minor diameter and one for 1.095 minor dia.
Ash Gear & Supply's website shows these in their online catalog (look under products/broach and scroll down to "TriLobe bore"). They have a huge inventory of new and used tools which you can buy or rent.
In the good ole' days, I had an earlier model Fellows shaper that had a full range of change gears with round 3/4" bore and 1/8" keyway. Later I bought a 2nd shaper just like it (or so I thought), but it turned out to use trilobe change gears.
After some thought, it was fairly easy to remove the change gear shafts and turn down the ends to 3/4" diameter and mill 1/8" woodruf keys.
The shafts didn't perfectly "clean up" to 3/4" diameter, but my change gears worked very well, so I was able to use the same set of gears on both machines. I suppose you could "build up" the low spots with weld or chrome before turning or ginding, but it hardly seems necessary since they were just a few thousandths low.
You might take a look and see if that would work on your 4GS...and let us know what you find out.
Anyone have TriLobe change gears for sale?
Were all Fellows shapers originally made to use TriLobe change gears?
Anyone have an opinion about which is best - round or TriLobe?
I hope you'll let us know how it works out for you.
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