Woodruff Key Cutter Question

[chips&more]

One important feature of a woodruff cutter is it does little or no cutting on the sides. It makes a slot the width of the cutter. Milling a slot to a close tolerance for a key to "fit tight" with and end mill is not easy. It is much easier to get repeatable dimensions in width with a woodruff cutter than with an end mill…Good Luck.

 

[schemer]

If the Woodruff key is attached to the pulley, the curved side of the key would be buried inside the pulley, no?

Which would make the key look like just a regular square key to the shaft.


You don't mean that the curved side of the key is sticking out off the pulley, and meant to mate with the shaft, do you?

If so, using a Woodruff cutter to cut a semicircular Woodruff keyseat would be silly, as there would be no way to get the pulley/key onto the shaft....

Actually the pulley has the woodruff key (or what appears to be a woodruff key) with the curved end facing the shaft. The slot in the shaft is cut from the end but the inside end has the radius. So when I put the pulley on the shaft it can only go so far and it cannot go any farther. Then an external snap ring holds it from coming off. I thought maybe that was by design and for a reason.
Thanks,
TS

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No you wouldn't cut a Woodruff key slot. I would use the key cutter to cut the slot the lingth needed to get the pully on. An endmill will leave sharp conners in the bottom of the slot. With a keycutter the corners will have a radius on them. This chart shows the radius for each key size. http://www.transeals.com.au/catalogues/files/Transeals_Keyway chart.pdf . You may be able to get endmills with the radius on them. I have just always used a keyway cutter.

That is what I was thinking and for the reasons I mentioned above in the last reply. But I would have to use the proper radius cutter to duplicate the operation. Thanks for the chart. I will look at it in a few minutes.

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Yeah, but I think the OP is not worried so much about the corners at the bottom of the keyway, but the radius left at the end where the keyway curves up.

Yes, exactly. But knowing about the corners at the bottom of the slot is good info and news to me.

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In theory in high stress app. an endmill leaves a sharp corner in the keyway witch can break under high stress. A keyway cutter has a radius on each touth that makes a lot tougher slot. Has nothing to do with the end of the cut. The larger the key the larger the radius at the bottom of the keyway. Now in the op's app an endmill will probly do just fine.

See other replies here where I mention the stop action of the radius. Do you think that was part of the design plan?

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See; again history reapetes its self, you need a shaper done deal.........

samuel

I don't think you are referring to me but I would like a shaper some day. I used to run one in a machine shop where I worked. Pretty cool machine.

 

[kd4gij]

Actually the pulley has the woodruff key (or what appears to be a woodruff key) with the curved end facing the shaft. The slot in the shaft is cut from the end but the inside end has the radius. So when I put the pulley on the shaft it can only go so far and it cannot go any farther. Then an external snap ring holds it from coming off. I thought maybe that was by design and for a reason.
Thanks,
TS

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See other replies here where I mention the stop action of the radius. Do you think that was part of the design plan?

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Yes it sounds like thet the end of keyseat is the stop for the pully. However I don't thing you have to match the old exactley. The internal key won't pass the end of the keyseat. no mater what it looks like.

 

[schemer]

One important feature of a woodruff cutter is it does little or no cutting on the sides. It makes a slot the width of the cutter. Milling a slot to a close tolerance for a key to "fit tight" with and end mill is not easy. It is much easier to get repeatable dimensions in width with a woodruff cutter than with an end mill…Good Luck.

Good point but I have done some keyways in a mill before and I found that the keystock I buy is slightly oversized and I have some filing/fitting to do and get a very good fit. Now of course that doesn't help me here if the used part doesn't fit right. :whistle: But that is worth mentioning.
Thanks,
schemer

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Actually the pulley has the woodruff key (or what appears to be a woodruff key) with the curved end facing the shaft. The slot in the shaft is cut from the end but the inside end has the radius. So when I put the pulley on the shaft it can only go so far and it cannot go any farther. Then an external snap ring holds it from coming off. I thought maybe that was by design and for a reason.
Thanks,
TS

- - - Updated - - -


See other replies here where I mention the stop action of the radius. Do you think that was part of the design plan?

- - - Updated - - -
Yes it sounds like thet the end of keyseat is the stop for the pully. However I don't thing you have to match the old exactley. The internal key won't pass the end of the keyseat. no mater what it looks like.

Right, I will just cut the slot long eough for the same stop effect and fit. Ok, enough talking and now I need to do my simple little project. I learned a few things I didn't know about woodruff keys and that is whats important. Thanks to all that responded.
schemer

 

[Wreck™Wreck]

Right, I will just cut the slot long eough for the same stop effect and fit. Ok, enough talking and now I need to do my simple little project. I learned a few things I didn't know about woodruff keys and that is whats important. Thanks to all that responded.
schemer

Many external keyways were made (in the past) on a dedicated machine for just this purpose, or a horizontal mill using a tool that is edge cutting much like a Woodruff key tool but mounted through a center hole on an arbor, a small horizontal will have a 1" or larger arbor, the diameter of the cutter is not important since they were not making a Woodruff keyseat. To mill a Woodruff keyseat to within published parameters you need to control the diameter of the tool, don't waste your money on the tool.

If you are worried about having a radius in the corners of the key slot, buy endmills with radiused corners, they work well in every application not requiring sharp corners, they last much longer in general milling as an added bonus.

My employer will often ask me (tell me) to run internal key seats on an old clapped out Morrison Keyseater. I hate that machine very much, every part is a trial, and I am accustomed to old worn out manual machines, go figure.