School me on using annular cutters in my milling machine

[J Tiers]

Thanks for mentioning feed pressure. That has been a question for me.

I have a number of annular cutters which I am told (here) are for relatively thin metal, like heavier sheet metal. I found the feed pressure to be quite high, even on 7075 aluminum, which was the last thing I tried to use them for (and abandoned the effort).

Never tried them on steel, but I would anticipate they would need very high feed pressure. Enough to be impractical.

So the feed pressure for the true annular cutters is an important point, especially since they are "not cheap". It seems that as the drills are magnetic, the pressure cannot be v ery much, or the drill would shift.

[nickel-city-fab]

You might be surprised. Of all the mag drills I've ever used, the cheapest, crappiest magnet was rated at 800 lbs force. "Standard" is around 1100 lbs, and the high-quality name brand drills can do 2,000 lbs. (and cost in the single-digit thousands). The better or best brand names include Jancy and Hougen. The higher-end models often have variable speed, auto coolant flood, etc. I have used them on up to 2-1/2" holes on 1-1/2" plate, and it takes the same amount of time and pressure as the smaller diameters -- for some weird reason, the feed rate seems to be constant regardless of dia.

In use, they drills feel as solid as the part they are stuck to. On a relatively good surface, its very difficult to dislodge them. It all depends on the condition and surface area of the contact with the magnet. Rust and scale is your enemy. For example, a full-house sledge hammer blow will only move a good drill a few sixteenths off center on clean structural plate that has been oiled.

Thanks for mentioning feed pressure. That has been a question for me.
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So the feed pressure for the true annular cutters is an important point, especially since they are "not cheap". It seems that as the drills are magnetic, the pressure cannot be v ery much, or the drill would shift.

[J Tiers]

Hmmm. So is the feed pressure pretty high? I was cranking on the T/S handle pretty hard, and the cutter I had, which felt sharp and had the correct relief, was just not cutting worth a hoot. I'd hope the real annular cutters are a lot less than that.

I have not used one, but I have FIXED a Hougen, and on the thinnish plate I had to test it on, I was not overly impressed. But thinner plate affects holding power.

[nickel-city-fab]

Hmmm. So is the feed pressure pretty high? I was cranking on the T/S handle pretty hard, and the cutter I had, which felt sharp and had the correct relief, was just not cutting worth a hoot. I'd hope the real annular cutters are a lot less than that.

I have not used one, but I have FIXED a Hougen, and on the thinnish plate I had to test it on, I was not overly impressed. But thinner plate affects holding power.

Yep, thin plate is a PITA, I won't use a mag drill on anything thinner than 1/4". The feed pressure that I "feel" with a good mag drill, is less than what I would use on a conventional drill press and bit. Because more pressure simply isn't required on a good setup, and instead it is risky for the cutter.

I think the feed rate tends to be constant because of the multiple cutting edges on the cutters -- as they go up in diameter the number of cutting edges does too. So, once you feel the edges bite in smoothly, you hold the pressure constant and let the bit do the work --

[JRouche]

Center Pin? You guys are clueless. No big,

I have some boxes of new core bits. I dont play with them like some. They are not in-expensive, just saying. You tend to protect your cutting bits I would hope. Costley or not, I would think. Give me a dull drill bit and I can make it cut again.

Thats what I do. Take the trash and make it better. JR

[Beazld]

Using a mag press on thin stuff a thicker piece of steel under the magnet helps with the holding power if you can use it depending on the application.

[brian Rupnow]

I couldn't figure out why the correct R8 holder for these annular cutters cost $75, while a standard R8 holder for a 3/4" drill was only $31. Now that I have the parts here, I see that there is a spring and a snap ring inside the correct R8 holder that lets a centering-pin retract into the body of the holder as the annular cutter passes thru the plate you are cutting. The centering pin then becomes spring loaded and pushes the "slug" out of the annular cutter after your cut so you don't have to fish for it with a pair of pliers. You can see the end of the centering pin sticking out past the face of the cutter. You can also see a centering pin setting beside the cutter---I made that one .001" undersize, which normally wouldn't matter, but in this case the pointy end is cantilevered out so far from where it is held that with 0.001" undersize it wobbled all over the place---Not what you want for centering.

[Tundra Twin Track]

Brian is that a Accusize Holder,I believe their Warehouse is in Ont.

These are some the different Brands of cutters that Flats are slightly different in size and depth,in a the Holder in Brian’s pic they all fit fine.If using a modified Endmill Holder with Nose Machined off in pic the large Set Screw may need to be beveled to allow Cutter to fit correctly.

[brian Rupnow]

Yes, they are from Accusize, but I purchased them thru Amazon.

[Tundra Twin Track]

I have 2 of the Accusize holders MT 2&3 and a 4” Extension been very pleased with them,bought direct from Accusize.