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General Category => General Shop Discussions => Topic started by: Piggiron on May 01, 2024, 07:32 PM
What methods/tools are available for cutting internal splines inside a smaller diameter bores, say less than 3/4" ?
They are typically cut with a broach that is made specifically for the desired spline.
Given the small dimension I think that may be about the best, and only option. We're the hole size larger I would say that would be a perfect shaper job, but I can't imagine that given the small size.
Sure, could be a shaper job, or even any machine with a carriage or quill.
I've done internal splines several times on the shaper. I have made two different diameter tool heads. One larger diameter shaft with a square hole at the end for a 3/4" hss square shank tool. One smaller with a brazed on tool.
In this caller case you likely need to grind the profile in the tool itself.
I would grind the appropriate cutter from a piece of HSS stock. It would take a boat load of grinding and if you break the tip off, you gotta start over. But could be done.
If it's a through bore. The best way to machine an internal spline would be Wire EDM. I came close twenty years ago to purchase one for my home shop. Needless to say I begged off.. Next choice with be machining a graphite electrode that's easily accomplished on a surface grinder using an indexing head.. Then setting it up in my EDM Machine and burn the spline,, reverse of the electrode... This is 1.000" diameter
Electrode..
(https://hosting.photobucket.com/images/c239/OldCarGuy_1955/7B848C8D-DBE1-417D-AF01-E8A7D86D3B51.jpeg)
EDM Machine
(https://hosting.photobucket.com/images/c239/OldCarGuy_1955/0C3D5062-330B-4743-8BA9-B522BD8CCBC7.jpeg)
Here's a simple electrode to grind.. But near impossible shape to machine in steel
(https://hosting.photobucket.com/images/c239/OldCarGuy_1955/A10E532A-F13C-4D38-8E60-08C7FB55D9B1.jpeg)
Vertical slotter.
I've got one on my Cincy Toolmaster and a much smaller on my Van Norman 6.
Someday I'll finish making the cutter holder for the Cincy. Meanwhile the VN6 and a RT work well enough. Although I haven't made an internal spline.... I have made square holes and square slots.
Should be just a matter of grinding the cutter and managing the RT.
I've no doubt that EDM is much faster. But old school still works.
Daryl
MN