How can one cut out a plug on a lathe? Just a parting tool?

[WobblyHand]

I have a piece of stock that I'd like to use part of. Namely the outer part. Trying to make a collet wrench, using the thread "Operation spanner wrench". It seems almost criminal to bore out the center, turning it into curlicues. I'll do it, if I have to, but it just seems wrong to waste it. So is it possible to cut out the center with a parting like tool, but from the facing direction? Piece in question is a disk of 1144 steel, it's 3.75" in diameter by 1/2" thick. I'd like to cut out a 2.5" plug from the center. Maybe I can use the plug for something. Sure can't use the swarf for anything good.

Any suggestions on how t do this? I have 1/8" and 0.040" parting blades I could use, as well as HSS bits.

 

[Karl_T]

fairly easy with a rotary table on the mill...

For a lathe your parting blade will need two radii with relief on the OD and ID. Bit of a tricky thing to grind.

 

[WobblyHand]

So all I need to do is make sure the non-cutting edges don't rub? No way am I going to grind a curved blade, that's far out of my feeble grinding skills. However, making the tool height shorter so the non-cutting edges don't foul, that's possible. Maybe this belongs in the tool grinding thread.

 

[theperfessor]

I bet a good holesaw run at the proper (slow) RPM would do the trick. Might even get away with not drilling a center hole if you run it out of the tailstock. I wouldn't get in any hurry! And use lots of lube and peck drill.

 

[royesses]

I think you are talking about trepanning. It is like a plug cutter. It cuts a ring out leaving a plug in the center. A parting tool that is only about 1/8" high from top to bottom would be able to do it from the front I think. Or grind the bottom of the tool to clear it from rubbing.

Roy

 

[ThinWoodsman]

Trepanning/parting tools can't go all that deep - half inch might be pushing it. Hole saw requires drilling through the center, so you are left with something more like a bushing or washer than a slug. Annular cutters do pretty good, up to I think 1 1/2" or 2" deep. Pretty pricey though, and probably require an HP or two.

 

[theperfessor]

If you're setup is rigid enough you don't always need a center hole for a hole saw. A necessity tho if you're using one in a portable hand tool.

 

[Lo-Fi]

As a point of interest, this guy does trepanning ops on an epic scale:

93" deep!

You'll get away with a good hole saw. Chip clearance is always the biggest issue with deeper holes, but you'll be fine with 1/2 thick.

 

[NortonDommi]

As a point of interest, this guy does trepanning ops on an epic scale:

93" deep!

You'll get away with a good hole saw. Chip clearance is always the biggest issue with deeper holes, but you'll be fine with 1/2 thick.

userwl2850 -Trepanning YouTube - YouTube shows how to make his trepanning tools as well.
I use a parting /grooving tool with the bottom of the tool below the blade ground for more clearance, can go about 6 mm deep. thicker stuff I turn around and cut from both sides. Need to make something better though. Deep cuts can be made with a hole saw and starting the cut by trepanning stops that unpiloted wander at the start of the cut. Bore to final size . At least you will have a usable slug.

You could make a tube type cutter but they are only good for one size.

 

[Bi11Hudson]

This sounds almost childish, but on the mill (out in the field) you do what you got to do to get done. If it was me, I would spin the blank up and cut enough for a mark. Then, on the bench drill a circle of holes. The smaller the drill, the less waste. Face it, the blank is only a half inch or so thick. When cut inside the finished ID of the project, wallowing the drill will remove most of the span between drills. It then falls to a big hammer. . .

Grinding a specialty tool for one time use would be a waste of time to me. And in the time spent grinding the tool, you can have drilled all 137 holes and be done, , , at least that part. Simpler isn't always better, but time is a factor as well.

I'm partial to hole saws myself. And they will work in the tailstock without a center drill. But you gotta work slow, real slow. And having one near the right size does count. The cost of a couple of HF drills VS a decent hole saw makes it worthwhile to use the simplist solution.

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