Repairing A Keyway Question.

[savarin]

I am re-visiting some earlier rough work on my telescope in an effort to improve things.
I originally cut a 3mm keyway in a 12mm shaft that skewed slightly so I want to recut it straight.
Also making new tight fitting keys.
What would be the better method?
Using the original 3mm end mill and make two cuts in the old keyway widening it by .5mm each side producing a 4mm keyway
or
using a 4mm end mill and cutting over the original keyway cutting both sides at the same time also producing a 4mm keyway.
Unfortunately without a mill I cant use a woodruff cutter.

 

[David S]

I am not an expert, but I think your first suggestion would be best.

David

 

[Ebel440]

Use the 3mm and 2 cuts. The 4mm could cut oversize.

 

[savarin]

3mm x 2 cuts sounds good to me. Thanks

 

[Ulma Doctor]

i agree, 3mm x 2 ! good luck Sav!

 

[Bob Korves]

If you go to 4 mm you will also have to make the depth deeper in both pieces if you use a standard square key. You can machine a key to a custom dimension (3 x 4mm) to fit instead.

 

[savarin]

If you go to 4 mm you will also have to make the depth deeper in both pieces if you use a standard square key. You can machine a key to a custom dimension (3 x 4mm) to fit instead.

Ha Ha Bob, the accuracy of my machining means I have to make everything to fit what I did before.

 

[12bolts]

Charles,
Could you mount a woodruff cutter in your chuck and use your vertical slide to move the shaft. Might be a bit iffy getting in there that close to the chuck?

Cheers Phil

 

[savarin]

maybe next time Phil.
Its done


way better that the original but still not perfect. Hopefully good enough.

 

[Bob Korves]

Ha Ha Bob, the accuracy of my machining means I have to make everything to fit what I did before.

Oh, yes, I know that story well... Cut to fit, paint to match... 8^)