face groove

Got a tuff little job for tomorrow morning...

I'm making a new end of an air cylinder. Start with a 3.5 by 3.5 block

1.5" thick. Center and turn in the lathe so you now have a 2.5" round protruding 0.25".

Now for the tuff part, turn a groove 0.062" wide on the face right at the 2.5" round. (This holds rubber ring seal). I've turned a groove on a face in the lathe before, but never with the protrusion in the way.

I started grinding a little tit on the end of a cutoff HSS tool. I can see this effort will break right off. I'm thinking to try mangling a two flute endmill in the morning.

Maybe somebody has a better idea.

Karl

Reply to
Karl Townsend
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The groove is right at the base of the cylindrical part ? Can you put the block on a rotary table , mill the round , change to the appropriate end mill to cut the groove ?

Reply to
Snag

That's a thought. I'd like to try in the lathe first though, cause it will hold tight tolerance.

Right now, I'm a dreamin' up some way to hold a 1/16 endmill. Put one in backward ground into a "D". It would stick out 5 diameters if I hold it in a collet. May just snap right off.

Karl

Reply to
Karl Townsend

Here is a tool holder that would do the job. It might be a little more than you want to spend but you could make him an offer.

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Here is the insert for the groove. They are cheap enough.

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John

Reply to
John

The trick here is to grind a tool that looks like a curved parting tool, with radius of 1.25" on the wide part. The curvature is so the supporting material under the cutting edge stays within the groove that the cutting edge makes. The projection would be about .060" thick (groove width minus a skosh), projecting length need only be slightly more than the required groove depth. I'd grind it out of a square HSS tool bit.

Reply to
Don Foreman

That's beyond my ability to freehand grind. But, you gave me an idea. I could CNC machine the perfect cutter out of the soft end of a drill

1/2" bit. Then harden.

OK, I don't remember best procedure to harden drill rod into a cutter. Anybody?

Karl

Reply to
Karl Townsend

If I understand correctly you are cutting an o-ring groove on the face of the block adjacent to the 2.5" round portion you just turned? What is difficult". Just grind a tool bit to do it. I'd probably start out by grinding the end of a new HSS tool bit at about 45 degrees to get clearance for the cylindrical portion. then grind a protruding cutting point the size and shape of your o-ring groove. You now have a tool bit positioned at 45 degrees to the centerline of the lathe with a cutting portion parallel to the centerline and ground to cut the correct size and shape groove. Then do it :-)

Reply to
john B.

I dunno ... maybe. Having it in your hand makes you the better judge. But, it's worth a shot. Being smaller also means less force on it. Try it.

Bob

Reply to
Bob Engelhardt

You want a trepanning bit. Plenty of "how to grind" on Google. I've made a bunch over the years, no biggy.

Reply to
Tom Gardner

Make something like this? The ring is bored to 2.520. The red tit is a piece of 1/16 x 3/16 HSS brazed onto the ring. The outside of the HSS is bevelled for clearance in the groove.

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Reply to
Ned Simmons

This cutter shape is not hard to grind.

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John

Reply to
john

It sounds like that puts a little (.062") end mill, with a shank no larger, into over a quarter inch of trouble. The endmill finish at the bottom of the groove is gonna be bad for sealing, too, unless you have some kind of finishing cut in mind.

I'd think in terms of a boring bar held (near) transverse to the lathe axis, with its tip doing this work. In mass production, make a holesaw for the right radius, and many teeth will make light work of the task.

Reply to
whit3rd

"Drill Rod", i.e., 1095 steel - heat to cherry red, hole at that temperature for a few minutes; quench in salt water; polish and reheat to light straw color and re-quench.

If it cracks try light oil or maybe kerosene.

At least that's how my apprentice-master told us to do it :-)

Reply to
john B.

... and between the round and the endplate, there's no good way to position any common toolholder and tool to do the groove for the O-ring. If you could turn a 2.0" round, then machine the groove, could you knurl the round and press a 2.5" OD ring onto it?

Or, make the groove wider and press a 2.5" plug onto the short inner sidewall (the O-ring will seal on its OD at the groove, on its ID at the plug).

Reply to
whit3rd

whit3rd fired this volley in news:f3541ff9-0847-4915- snipped-for-privacy@glegroupsg2000goo.googlegroups.com:

Doesn't anyone custom-grind tools anymore? (besides me?)

Anyone who does could make such an "off-angle" grooving tool in a few minutes.

LLoyd

Reply to
Lloyd E. Sponenburgh

Somebody else said basically the same thing , and posted a link to a picture of what it would look like . Looked like it was ground from a 1/4" cutter , and it'd work just fine in my lantern toolpost . Karl might not have a way to mount one like that ... because , it seems , lantern toolposts just ain't that common any more .

Reply to
Snag

Take a 1/4" HSS blank, why? Less to grind. Grind a vee relief to clear the radius of the groove. You will be fine.

I wish I could show you a picture of our stacked groovers we use to cut tightly spaced grooves in rotors. Cutting 8 grooves at a time in aluminum will take a 15 hp spindle to the edge and poly microvee belts suck compared to rubber. One will slip and melt, the other will grip and stop the spindle motor.

Wes

Reply to
Wes

We make a lot of special hand ground tools for special jobs including a tool for cutting a 3/4 tpi acme internal thread by thread milling it. I must have a whole shelf of special ground tools. I use an Armstrong tool holder that is cut down to fit an aloris holder. Another way is to braze the tool to another shank that will fit in the holder you have. I sometimes will weld a tool to a longer shank . The tool in the picture was a 5/16 hss blank. It was for a .189 groove which is a standard for an 'O' ring. Grinding tool bits takes a little practice but it is well worth learning. Once learned it will save you a bunch in aggravation and time when doing special jobs.

John

Reply to
John

THANKS The picture was worth a 1000 words. I just ground a real nice cutter.

Karl

Reply to
Karl Townsend

Just make sure you have enough re leaf for the arc of the groove. If the side of the .062 tip rubs the groove will be oversized. Check the cutter for rubbing on the side and if it is grind a little more side clearance,

John

Reply to
John

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