Blind Hole Keyway

[madman]

Had the Job last evening of making a 3 inch long .250 wide keyway in a One Inch Dia Blind Hole with a Milling machine. Man what a frustrating Job. Its a variable speed Mill. I put it in low as slow as possible. Then bungeed the brake lever on the spindle to keep it from moving. The tooling I had was a old piece of HSS someone gave me, The material was stainless steel 306 material. I spent all evening then filing out the last thou or so for a Passable key slot. I started the second piece but by then the night was over (10 hour shift) and I wanted out. Id appreciate any tips anyone has regarding this type of operation. I asked a few guys in the shop but No one had ever done it (Oh ive heard of that they would say) Fairly sore arm and hand from spinning the mill handle for a entire shift . HA hA was fun though. I need to find a better way of doing these Internal Key slots in a mill. NO our edm is out of action., thanx Mike

[Paul Alciatore]

I assume you have more to do.

One possibility that occurs to me would be to buy a keyway broach (better get two if you are like me) and make a bushing to fit your 3" long, blind hole. Use an extra piece of 1/4" square stock to push the broach to the bottom. Use a lot of lube/cutting fluid to make extracting the broach easier.

After doing all the pieces that way, cut off the bottom step on the broach and do them again. Repeat this by cutting one step off the broach at a time until the slots are fully cut to the bottom.

It will cost you one or two sacrificial broaches, but it should work.

[armedandsafe]

This is not a BLIND hole, but it does show how a key broach works. TubalCain, to whom I was introduced recently through this site, has more information than I can absorb easily, but he has solved a couple of problems for me already.

http://www.youtube.com/watch?v=8tAz5YDFtAs

Pops

[Forrest Addy]

I assume you were slotting the keyway with the quill using it as a vertical shaper ram. 1/4" wide cut takes a lot of thrust and the pinion and shaft in a turret mil quill is dinky and ftail. I suggest you start with narrow tools and increment so each cut =takes the same amount off each side.

It goes pretty quick once you get tooled up. You can cut the depth of a 1/4" keyway in about 20 strokes per tool and it saves wear and tear on your quill pinion.

[armedandsafe]

Here is another approach I found.

http://www.youtube.com/watch?v=XcU0LTavzDM&feature=related

Pops

[Tony]

how about one of those "key way mills" that come up every now
and again?

all i can say is "ouch" it hurt just reading.

edit.. maybe that was vague.. i'm referring to the mill tool that has a cutter
on the end (the width of the desired keyseat) and spins in a plane along your
Z axis, effectively "milling" the slot out). would leave a radius at the bottom
I suppose.

[Richard Wilson]

Sounds like a job for a slotting head, but you would need an undercut at the end of the blind bore to let the tool run out into. Could do it in the shaper as well, with the clapper box locked, and cutting on the reverse stroke.


Richard

[wbleeker]

How I would get rid of most of the metal first is to turn a plug to fit the hole with a head on it, then mark out the keyway position on the head, place the plug in the hole and drill a hole through it, which basically gives you nearly a whole keyway that you only have to clean up.
I use this method quite often for a blind keyway I have to do, I also drill a hole in through the side of the shaft for the keyway to end in.
Will

[Rustybolt]

how about one of those "key way mills" that come up every now
and again?

all i can say is "ouch" it hurt just reading.

edit.. maybe that was vague.. i'm referring to the mill tool that has a cutter
on the end (the width of the desired keyseat) and spins in a plane along your
Z axis, effectively "milling" the slot out). would leave a radius at the bottom
I suppose.

LOL.
We used to use one of those to mill the 1/2 inch keyway on Davenport screw machine cams. Each tooth on the cutter is offset a little from the one before.
Ours was mounted on an old Rockford camelback drill press, we called shakey marvin. Once it got to cutting it was pretty good, but the initial approach could shake the change out of your pockets.

[Mcgyver]

Mikey, you still have that shaper right? ergo that horizontal slotting machine? drill a relief hole at end and away you go

guess you're doing this at work.....and they threw out their shaper 30 years ago, right?

homework?

[Black Forest]

What I run into alot over here is say a pulley mounted on a shaft and then a hole drilled and tapped at the junction of the shaft and pulley. Sometimes on opposite sides, meaning there will be two of them.

THen there is a allen screw threaded into the threaded hole to act as a keyway.

[John Stevenson]

Get quite a few converter bushes to make for small motors, these are harderto do than larger ones which can be slotted on the slotting machine [ OK I know he doesn't have one - bear with me ]

The smaller ones are usually 14mm diameter, 5 mm key blind into a 30mm long hole.

I usually make a thru hole bush 30mm long and keyway this using broaches then press this into a piece of material that the final part is made from.

Prior to pressing in I drill 3 equally spaced holes in the larger piece then once pressed in these are plug welded and the OD turned down to suit.

Once done is nearly impossible to tell they are two piece items.

The project can be scaled to any size.

[dian]

what does "plug welded" mean?

[Black Forest]

A plug weld is just a weld in a hole. The weld attaches the inner part to the outer part. The hole is completely filled in with the weld. After that you can finish off the surface how you want. Where you see the blue through the red is where you would weld making a plug weld.

[madman]

Thanx

Tis Job was in Stainless it sucked and i spent some time filing it in. Tool all night to make one work out then started the other one but didnt even finish it. I checked the tram of the head last night it was also way out .perhaps from my 240 pounds ramming a cutter up and down the Hole like a big Monkey, Thought of quitting but .. Jobs are scarce. Also last night hand tapping 2 inch dia taps into holes ,,that sucked also. ha ha Life of the Old machinist .