School me on using annular cutters in my milling machine

[brian Rupnow]

I have just purchased three sizes of annular cutters for my manual milling machine. They have 3/4" Weldon shanks. I bought 1" diameter, 15/16" diameter, and 7/8" diameter. I also bought three R8 collets with 3/4" capacity to make dedicated holders for the three annular cutters. Here is what I know---they require much less torque to drive them than a drill of the same diameter. they should be ran at a fairly low rpm. They require lots of lubrication (squirt on cutting oil) while working. What I don't know is this---Do they require a center "pin" to extend out past the cutting edge to pick up a center punch mark in the piece being cut. Do I have to buy appropriate center pins from a manufacturer, or can I make my own. If I have to make my own, there is a great YouTube video on how to make your own with a compression spring to automatically eject the center plug that is left inside the annular cutter. I have never used annular cutters before, so any help is appreciated.---Brian

[Toolguy]

Hi Brian-

You don't need a center pin, but can use one if you want to, in the mill. A center pin is a really good idea in a drill press. If you do use a center pin, you will need to drill a guide hole for it first (usually 1/4").
You want to run in low gear if you have it, around 200 RPM. You should be able to stick a pin punch or similar to poke out the slug, but it will likely just fall out.
Use enough down force to keep it cutting, too much may make it dig in. Once you do a couple of holes, you will have it down. These are one of the very best ways to make big holes. If you need a different size, it's a simple matter to follow up with a boring head.

[LKeithR]

Annular cutters are awesome on lower powered machines--we've used them in our shop for over
thirty years. The pins are only necessary if you want to pick up an existing hole or a centre punch
mark--they have nothing to do with locating the cutter while it's working.

You can make your own. I make them without the shoulder on one end so you can locate the hole
and then raise the quill enough to remove them while you finish the cut. Even with a spring the slug
will sometimes hang up in the cutter but it's your choice whether you use one or not.

Why three holders? Annular cutters have a weldon shank so you can easily change them out. We've
got one holder we use for all sizes. In fact, for smaller cutters like you have you can get away with just
running them in a collet without using the setscrew at all.

Annular cutters really come into their own when you start going above 1-1/2" in size. A 2" cutter will
work just as well as a 1" in a decent sized drill press or mill where a 2" twist drill would require some
serious power...

[tom_d]

The center pin is not an absolute, carved in stone necessity, but it does help in tool rigidity, hole size control, and surface finish, so is highly recommended. They also help in preventing the center slug from getting fowled up in the work and potentially causing problems. I usually start with drilling a 1/4 inch hole on location and use a hard straight shank, like a dowel pin, for the center pin. I prefer to use the hardened dowel pins as they last longer, but anything off the stock rack will do (made of steel is preferred). It's not rocket science, these annular cutters are basically plunge cutting end mills. As for speed, yes, they do work better at slower RPMs. I usually start at about half the normal cutting speed and adjust from there. Lots of coolant-lube too. Paint it on with a brush or use a squirt bottle.

[metalfixer]

Hi Brian,
I have the Hougen drill, came with a set of cutters, Ejector pin goes in from the back, no spring. The cutter is hollow, so you can just use about a 1/8 diameter pin
to knock the slug out.
I use them in the mill, but as Toolguy said, the slugs usually just fall out.
Drill came with an oil squirt bottle, and they also have a type of wax lube to use on the cutters when drilling overhead, I try to avoid doing that.
The finished hole is almost as good as a reamed hole finish.
Larry

[LKeithR]

...If you do use a center pin, you will need to drill a guide hole for it first (usually 1/4")...

There's no need for a starter hole--the pins have a point on them so you can locate from a
centre punch mark. The pins are a little sloppy in the hole so if you want a really accurately
located hole your best bet is to use a DRO to locate your position--depends entirely on what
you're trying to accomplish. Over the years we've made hundreds of holes with annular
cutters using either method for locating a start point...

[Mark Rand]

My Rotabroach mag drill actually runs at 600rpm fixed speed. But when using annular currers on the milling machine, I use 90-100fpm the same as most other HSS cutters. They really are good for knocking out close to size holes in plate.

A spring loaded ejector pin can be useful if making multiple holes, but you don't need a pilot in a rigid machine like a mill.

[nickel-city-fab]

Congratulations! Annular cutters are wonderful.
The center pin is usually only needed to knock the slug out in a drill press setup, usually a magnetic drill.
It also helps with locating on a center punch mark. With a mill, you don't really need it.
I usually run them around 200 RPM with a flood of sulfurized pipe-cutting oil.
Keep a steady feed, you'll "feel" when its biting into the steel just right.
Make sure your setup and clamping is absolutely rock solid and tightly torqued! The cutters can easily yank your work out and break themselves off in the process. Ask me how I know... ($$$)
A needle-nose pliers is handy for clearing the chips and digging the slugs out.
Annular cutters can do "partial" half-moon holes, on the edges of things, or overlapping each other
making certain difficult shapes 'possible"

[CalM]

A 1/8 " hold drilled at the radius (kerf) of the hole helps break and clear chips.
Really helpful in thicker stock. '

If this chip breaker hole is drilled almost, but not all the way through it can be filled with cutting lube that holds lube for a lot longer than just brushing it on.

[boslab]

I have a few to drill so I’m going to use your chip break tip, I hate the giants birds nests, dangerous whippy, slashy whips of doom.
I have an ammeter on the drill it’s really low with a rotobroach
mark

[Video Man]

The cutter holders are for a 3/4 inch shank; I found that making a center pointer (turned a 3/4" piece of crs to a sharp point) is a help in getting close to the punch mark, and usually all I need to center the cutter. Obviously, I use the pointer then replace it with the cutter.

[JoeLee]

Let me know if it squeals and chatters.

JL................

[CalM]

IF you get squeals and chatters..........

take up a small bit of scrap cotton fabric about the square size of the annular cutter. Soak this waste material in the cutting juice of your choice, and place it between the cutter and the work before bring the cut to bare.

Cut right through the saturated cloth.

See if that doesn't help.

[JoeLee]

IF you get squeals and chatters..........

take up a small bit of scrap cotton fabric about the square size of the annular cutter. Soak this waste material in the cutting juice of your choice, and place it between the cutter and the work before bring the cut to bare.

Cut right through the saturated cloth.

See if that doesn't help.

I never heard of that trick before but I'll give it a try. I don't think squeal is about lubrication, it's more about rigidity.



JL.......

[CalM]

I never heard of that trick before but I'll give it a try. I don't think squeal is about lubrication, it's more about rigidity.



JL.......

the cloth adds a dampening effect, the added lube is just a bonus. The lube gets thrown out of the kerf fast enough.

Works for c'sinks and c'bores too.