Keyway cutting

[Jay-z]

A future project is going to require me to cut a 3/16 keyway inside of a Steel collar with a 1" hole drilled thru it. The keyway needs to be 1.5 in long and is at one end of the piece. The collar is around 6in long with an outside diameter of 2 inches. I don't cut many keyways, so what would be the Simplest way of doing this without the use of a shaper? Jay

 

[itsme_Bernie]

Hate to say it, but hand filing is always an option if you set up some "guards" hear sensitive surfaces.

There is also a square tool set in the tailstock of your lathe and part fixed in the chuck or compound somehow. Then "feed" the tailstock into the part.


Bernie

 

[Jay-z]

Sounds like that there is a file in my future with this project. Jay

 

[Ulma Doctor]

another method would be the use of a broach and broach bushing.
the broach bushing is set into the bore to be keyed.
the broach is lubricated and set into the bushing slot.
the broach is pushed through the bushing that cuts the slot by means of a shop press .
you add a broach bushing shim and push the broach through again.
you will repeat the shim process until the keyway is to depth!

good luck!
mike)

 

[T Bredehoft]

It sounds to me as if the keyway is 1 1/2 inches deep in a 6 inch bore. I'd mount the 'collar' in a three jaw chuck, about flush with the jaws, with one jaw at the 9 o'clock position, mount a boring bar on the compound with a square tool bit (pointing toward you (9:00)) to 'broach' the keyway. manually, with the chuck stationary, hand crank the boring bar in and out, feeding it toward you .001 at a time until you got the keyway to the proper depth. It's work, but it will work. You'll have to go beyond the 1 1/2" depth at first, you can't broach to the bottom of the cut each time, moving back a little with each pass. Use plenty of cutting oil.

 

[Wreck™Wreck]

This may be a bit more work than you would like but it works well, it helps to have a surface grinder. It can be ground freehand with patience.

Buy a 1/2-5/8" HSS reamer blank.

Grind it similar to the attached drawing. Only grind as much of the blank away as needed to clear the work in order to leave the tool a rigid as possible. Add cost of tool to invoice.

Mount in tool post on center. If you have a QC tool block with a V-Groove all the better.

Lock spindle, I put the lathe in back gear and direct drive at the same time, put a block of material on the ways and use a jack against one of the jaws to remove any backlash. (Or find a way that works on your machine) DO NOT TURN SPINDLE ON

Drill a hole through the part where the keyway will end so that the chip breaks off, alternatively, if a hole is not permissible turn a groove in the bore.

Run tool in by hand with the carriage using the cross slide to control the depth, set a carriage stop so that the tool stops at the center of the hole, (or groove). Advance cross slide and repeat as needed, this may take MANY passes. Use a cutting fluid and don't get greedy with the DOC. Depending on the size of the tool blank and rigidity of the machine of course.

This is Lathe as manual Shaper, cut keyway(s), put tool in toolbox most likely never to be used again.

Find tool several years later and wonder why you made it, this is optional but happens to me often, I have hundreds of tools and fixtures that I have no idea what I made them for.

A 1/2" blank is $12.20 from McMaster-Carr http://www.mcmaster.com/#reamer-blanks/=vlv9yj

 

[T Bredehoft]

Wreck, you did a better job than I did explaining. I like the reamer blank idea.

 

[Wreck™Wreck]

Wreck, you did a better job than I did explaining. I like the reamer blank idea.

Thanks, crude but effective, I never thought of using a boring bar and a round or square tool blank, it would make the grinding much faster.

Because I don't have any and haven't used one in 20+ years (-:

I made an aluminum part recently with a blind hole keyway in one end, the other end has a diameter tolerance of +0 -.001", my employer sends that sort of keyway work out to another shop. I finished the whole part but the keyway, when it came back it had workholding marks all over it so it wouldn't hold the .001 tolerance after polishing and was scrap, the part is hard anodized after machining. I made another with a finished bore and oversized OD and finished it after the Goon Squad put the key in.

 

[Jay-z]

Wreck wreck , I am definitely going to give your idea a try. Got to do some digging, but I know I have a half-inch high-speed steel blank around here somewhere. Is there any particular way that you grind the cutter? Or is it a scraper? Jay

 

[Wreck™Wreck]

Wreck wreck , I am definitely going to give your idea a try. Got to do some digging, but I know I have a half-inch high-speed steel blank around here somewhere. Is there any particular way that you grind the cutter? Or is it a scraper? Jay

Have done this several times with excellent results, it is however time consuming so not a viable method if you are trying to turn a profit, I have only done it when the customer was willing to eat the tooling costs in an emergency.

As noted I have only made the tools on a surface grinder using a V-Block and thumb clamp, this allows you to easily get the width grinding parallel so that it remains the same after sharpening the end only.

Just put some mild positive rake on the cutting edges and a very small chamfer on the corners, very sharp corners will break down rapidly, key stock has a very small corner radius as manufactured.

Good Luck