Bearing Reamer?
 

Has anyone experimented with using a carbide 1.125 inch bowl and tray router bit as a final pass on your bearing holes when using a CNC router? Like the one below, thoughts? Any idea on the tolerances on a bit like this one?

http://www.amanatool.com/products/ro...nch-shank.html

Re: Bearing Reamer?
 

A combination of the motor not having enough torque, a low enough rpm, and the router not being rigid enough means the reamer would chatter alot. We have had success making our holes around .015 inch undersized and reaming them out on a drillpress.

Re: Bearing Reamer?
 

Ditto

We had some custom reamers made a while back. We go .015 to .01 undersize and then ream (press fit thanks to custom sizing )

Re: Bearing Reamer?
 

For anyone curious, this is the reamer we bought off ebay. We got two of em and they've been great. We are lucky that our Drill Press spindle and Clausing Lathe tailstock both have Morse Taper #3, so we can use the reamer on both machines effortlessly.

-Mike

Re: Bearing Reamer?
 

As a machinist, I would recommend an offset boring tool. You could put it in the drill press and then bore any sized hole you would like.

Re: Bearing Reamer?
 

I used to use an offset boring head, but after a couple years I got (extremely) lazy, especially because switching to the boring head required me to drop the knee of the mill 3" or so. Now we use positive bearing retention everywhere and 1.125" holes.
My method is to drill with a 1/2" drill first (largest one we have), then go in with a 3/4" then 1" endmill. After that I finish up the hole with a 1.125" endmill. This gets some tight slip fits and a very round hole.
My dream is to own a 1.124" reamer, but the $200 cost for a custom one doesn't suit me too well. :P Given that we use a manual mill anyway, it doesn't hurt to use the 1.125" endmill we already own.

Re: Bearing Reamer?
 

Im not sure if this is the exact model we have but this is what my team uses. We spent some time last offsetting setting it to exactly 1.124 and we never change it. The CNC router gets us to 1.12 ish and we manually clean it up with this:

http://www.mscdirect.com/product/details/02239093

Re: Bearing Reamer?
 

I got my 1.124" reamer for $52 shipped on eBay. Brand new. Keep an eye out for them!

Re: Bearing Reamer?
 

That bit is NOT a reamer, and don't count on the tolerance to be down to 0.001".

As others have said: make the hole several thousandths undersize and use a hand reamer to make it half a thousandth (or so) undersize.

EXPERIMENT in the off season!

Re: Bearing Reamer?
 

Boring heads are great when used on a mill, but there is no good way to use one on a drill press. There isn't really a good (safe) way to hold your work or locate the center of a hole. The spindles in drill presses are not designed to take the unbalance load from a boring head.

Re: Bearing Reamer?
 

Another option is to ream it to 1.125 and then use locite designed for beating retention.

Re: Bearing Reamer?
 

You could also polish a 1.125 drill or mill slightly under sized on a lathe with Emory paper. (Run the lathe in reverse). Taking off 0.0005 should be easy with HSS.

Lapping compound is another option.

Re: Bearing Reamer?
 

If you can chuck it in a lathe, you can bore it to half a thousandth with some care.

Re: Bearing Reamer?
 

An experienced mentor machinist with a Starrett micrometer can achieve half a thousand on a nice big lathe that well is adjusted.

An above average student machinist on a mini-lathe using $15 digital calipers would be good to hold 0.002".

My point was either end of the machinist spectrum could take a 1.125 mill or drill and undersized it enough to achieve a snug R8 bearing fit.

Re: Bearing Reamer?
 

I don't think that this is what you're looking for, but we used this step drill bit to clean up bearing holes in our waterjetted pieces this past season. It can put a 7/8" OD hole into 1/8" thick material, or run through thicker material with a 1.125" OD hole. Just the right size for the 3/8" and 1/2" bearings we all use.

http://www.mcmaster.com/#8841a35

Step drills are cheaper than reamers, but they can wander if you are taking off a lot of material. Our gearboxes worked great, but we had padded in an extra .003" between adjacent bearing holes to prevent gears from binding if things were off. If you want tighter tolerances, you probably don't want a step drill.