Anyone know of one?

[wms]

Andrew,

I have to agree with the guys here. I don't think you will be able to plunge a 16MM end mill at 10,000 rpm in to your part and end up with very good results as far as a bearing bore goes.

My guess would be that it would squeal like a mashed cat at that speed. Not to mention chatter.

Even under the best conditions with a rigid spindle and machine it is difficult to get a 16MM end mill to make a precision 16MM hole by plunging into the work. Pre drilling would almost be a necessity. Leaving only a couple of thousands to clean up.

At 10,000 rpm even with a good spindle and holder there is some run out. And to plunge with that, then there is the deflection that will inevitably occur as the tool fights it's way in.

But I have an Idea that might work. How about using circular interpolation as suggested. Making sure you a little over sized, for a nice slip fit.

Then as in the picture below drill and tap a set screw hole into the bearing area. And lock the bearing race from turning. That way you don't have to be as picky about your hole size.

Looks like you may be able to use one of the existing hole in your bulkhead from your picture. Just drill all the way to the bearing bore. Tap it thru and then install the set screw. Then the regular screw could go in on top of the set screw.

Looks like the assembly is captive from the design. So all you need to worry about is rotation. Just snugging up the set screw should take care of that.

Also Criterion Machine works just came out with a sub miniature boring head, about the size of a dime. I can't find it on their web site but here is a link. You could e-mail them as to info. Maybe ask if it will handle 10,000 RPM.

http://www.criterionmachineworks.com/

[HuFlungDung]

Squeal like a mashed cat

The hole might be perfectly okay if you invent a new name for the finish: "vibra-bored bearing housings" Sounds like something you'd have to pay extra to get

[ESjaavik]

Why not plunge with a smaller bit to establish the position, then drill in a drill press. Clamp your piece to a piece of plywood or similar so the drill does not break violently through. If it's not a through hole, the bearing won't matter if the bottom of the hole slants away. It will seat against the edge.

[ger21]

Squeal like a mashed cat

I've actually heard a mashed cat squeal (broken overhead door at our old shop). Terrifying.

[ger21]

Why not use a 1/2" endmill, do a vertical plunge to clean out most of it, then go back and do the circular interpolation? Maybe add a clean up pass if you need it.

[RotarySMP]

A 1/2 end mill at 10 000 rpm in a router based CNC? Sounds like a bad idea.

[IJ.]

I agree with the guys as I did 4>500 precision 17 mm holes for bearing pockets last year using the method you're thinking of!

I was using my manual Mill and the best results I could get were using a slow by comparison speed of around the 700 Rpm mark.

I first cut to within .25 from the finished depth with a 16 mm End mill then a finish cut with the 17 mm slot drill this gave me an exact pocket as long as I stopped the spindle BEFORE withdrawing from the workpiece.

I also agree with Hu's suggestion to try a smallish end mill around the 6 mm size with circular interpolation.

Draw your self 6 holes starting at 15.5 mm and increasing .1 each time then drill a through hole to say 12 mm in each and then run your program to cut each to size with the 6 mm end mill!

You may need to experiment with DOC and spindle speeds to get the finish you need. (I do mine with 2 mm DOC x2 for a 4 mm wide bearing leaving .25 for a full 4mm finishing pass)

Once this is done run your vernier over each hole and pick the one that's closet to the required fit and this will be YOUR 16 mm hole! (This is how I'd do it in your place and how I've done it here.)

[Cold Fusion]

Just got back from machining some bearing mounts. I'm getting a tight press fit on the recessed 16mm hole with a brand new 1/4 carbide.

[DSL PWR]

Just had to think inside the box.