Oddball motor shaft!

P

Projectnater

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I'm having a little issue, I have the original electric motor on my lathe, 1956 LaBlond that has a 1" diameter shaft but only a 3/16th. keyway. I had to machine a new pulley and am trying to find the correct dimensions for the keyway, I checked my Machinery's Handbook, 11th edition and does not show a dimension for 1" shaft 3/16th key, all the 1" shafts use a 1/4th key. I can get a ballpark measurement from the old one but someone along the way used a hammer on the pulley and the end is pretty mangled.
 
I don't think motor frame and shaft sizes were standardized until the late 60's or early 70's. I have a number of motors built from the 1940's to the early 1960's and the combination of shaft sizes, key sizes and even frame sizes are all over the map. They work fine, but it would be a real nightmare to find replacement parts for many of them.
 
projectnut said:
I don't think motor frame and shaft sizes were standardized until the late 60's or early 70's. I have a number of motors built from the 1940's to the early 1960's and the combination of shaft sizes, key sizes and even frame sizes are all over the map. They work fine, but it would be a real nightmare to find replacement parts for many of them.
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My 1945 Cincinnati horizontal mill parts book lists the different HP motors as pre or post NEMA, Your post got me wondering and googled it, Says NEMA started in 1926! I'm pretty sure not everyone jumped on that train right away, I called Lablond about a replacement pulley, said those motors were built for them and they still have the molds (I'm guessing cast iron) for the pulley, 2.75 dia, 4 groove, 1" shaft. Their price was over $2000.00 for 1! I have now become a pulley maker....

It's a good thing this is just a hobby now, I spend more time making parts and tools just to keep my machines running than actually making anything else.
 
Projectnater said:
It's a good thing this is just a hobby now, I spend more time making parts and tools just to keep my machines running than actually making anything else.
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This is what we all do. It helps build/maintain our skills and our machines. It does the same for our relationships by keeping us out of the house.
 
Rule of thumb was 1/2 key size, 3/16 would be .09375
 
When cutting a keyseat in a shaft, you plunge the cutter until it reaches full diameter, then half the thickenss of the key. Cutting the keyway half the key thickness into the bore leaves the chord height for clearance. I always cut the keyseat in the shaft an additional .005 just to be safe. No one ever complained about a key with a little too much clearance.
 
Do you have a broach and bushing for the 3/16?

You can make one for the larger od and mill the slot same as the smaller one.



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They make stepped key stock, but I just checked McMaster and they don't seem to have 3/16" x ¼", You could make your own if you have a mill.
 
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