Thread: Keyway in a tapered bore

Originally Posted by bob ward

I need to put a 3/16" keyway in a nominal 1" dia tapered bore, the taper is 1° per side. I'll use my Alba 1A shaper for this (I'm a shaper novice) and I'm thinking that for setting out purposes its going to be simpler to cut the keyway in the horizontal position.

In all the reading I've done keyways are cut vertically, either downside or upside. Is there any major reason why a keyway can't be cut horizontally, anything to watch out for?

Hello Bob

When you say cut vertically I assume mean cut in a slotter or broached? Many keyways have been cut in a shaper. The only thing you will need to keep an eye on is the clapper box. Generally these will be pinned or bolted up for cutting internal slots. You don't want it to lift on the return in case it hits the top of the hole. Other than that not much to it, just take your time if your not on the clock.

Garry

Ah! Maybe I haven't explained myself very well. The part will be secured to the shaper table with the bore horizontal to the table.

Where I talk about cutting the keyway horizontally, I mean cutting it on the side of the bore. As opposed to the usual practise of cutting it at the top or bottom of the bore.



EDIT Thanks Garry3 3 or 9 o'clock, that's what I meant to say.

Originally Posted by bob ward

Ah! Maybe I haven't explained myself very well. The part will be secured to the shaper table with the bore horizontal to the table.

Where I talk about cutting the keyway horizontally, I mean cutting it on the side of the bore. As opposed to the usual practise of cutting it at the top or bottom of the bore.

Hello Bob

Am I safe to assume you want to cut the keyway at the 3 or 9 o'clock position? In that case you definitely want to lock the clapper box, otherwise no great issue.

Garry

Originally Posted by bob ward

....I'm thinking that for setting out purposes its going to be simpler to cut the keyway in the horizontal position.
....Is there any major reason why a keyway can't be cut horizontally, anything to watch out for?

That is a very interesting question - and I'll be following the discussion on that too.
Since you have to lock the clapper box anyway, I can;t think of any reason you coudn't cut sideways and use the cross-feed to advance the tool. I guess few if any shapers have dials on the cross-feed, so you would have to stop a few times and measure the depth of cut, but then you could check the cross-feed scew pitch and go by the number (or fraction thereof) of turns of the crank....
By the way, I tried to cut an external slot about 3/16" wide with a suitably shaped tool (with 3/16" wide tip). That didn't work! It cut a few shavings with horrible chatter than grabbed and stopped the ram - moving the workpiece in the vice a bit as well....
I'll have to do a bit more reading and you may too, if you plan to cut that keyway in one pass....

I'm not sure of the shaper you have Bob, but i know on the Queen the cross feed would be far to course as a slotting feed. The finest i can go is about .010".
I have cut slots 1/4" wide with a BIG parting tool. BUT (always one of those) even my 2+ton machine had trouble, the tricks in the end were lube and heavy DOC to make sure the tool could not come out of the cut. 24" Queen City shaper parting tool - YouTube

I would take it slow, and maybe cut it in 3 goes, one on each edge and then take out the middle. IIRC i had as little as possible end clearance on the tool and maybe 8-10deg of back rake.
I'll be interested to see how you go.

Cheers,
Ew

Thanks guys. My shaper is an Alba 1A. Re the cross feed I was thinking I would disconnect the auto feed and slowly feed by hand.

Hi Bob,
normally when a keyway is cut on the shaper, the shape is marked out on the face of the hub to give you a line to machine to. Generally this is done at the top for a couple of reasons.
Firstly it is easier to see the line you are cutting to and secondly so the the load on the ram is pushed to the non-movable part of the slide and not towards the gib key (if there is one).
Kinda' like parting off in the lathe in reverse where the load pushes the spindle down into the headstock bearing and not trying to lift it out.
Cutting on the side will try to twist the clapper if there is any play in the clapper pin whereas at 6 o'clock or nine o'clock will push the clapper flat against it's seat.
Definitely lock the clapper while cutting and angle the bore so it's paralell to the ram ways.
Having said all that I haven't tried to cut a key at 3 or 9 o'clock but it should work.

Phil

My only though is that if you are cutting at 6 or 12 o'clock gravity is in the direction of your DOC. If cutting at 3 or 9, it is on the side of the keyway. Any slop or movement may then be reflected in keyway width.

Michael

It dawned on me that I could put the job in a tilting vice (just fits onto the table) and take care of the 1° taper that way, ie cut the keyway conventionally at 12 o'clock. Using the tilting vice is probably not kosher but its only a 3/16" keyway in aluminium so I can get away with it.

Made up some tooling to suit the job and cut 3 practice keyways on a dead casting. That worked out well, I'm very impressed. I reckon me and my shaper will become firm friends.

Anyway way that works is kosher.
One degree taper though?
You couldn't of just cut it square to the axis?

Originally Posted by Clubman7

Anyway way that works is kosher.
One degree taper though?
You couldn't of just cut it square to the axis?

Its a 1.5" long bore, the keyway height difference at the ends would bug me.