Bearing Reamer?

[Fusion_Clint]

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

[AnthonyDV]

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.

[R.C.]

Originally Posted by AnthonyDV

A combination of the motor not having enough torque, a low enough rpm, and 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.

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 )

[Michael Corsetto]

Originally Posted by AnthonyDV

We have had success making our holes around .015 inch undersized and reaming them out on a drillpress.

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

[teslalab2]

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.

[asid61]

Originally Posted by teslalab2

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.

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. Given that we use a manual mill anyway, it doesn't hurt to use the 1.125" endmill we already own.

[Owen Busler]

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

[protoserge]

Originally Posted by asid61

My dream is to own a 1.124" reamer, but the $200 cost for a custom one doesn't suit me too well. Given that we use a manual mill anyway, it doesn't hurt to use the 1.125" endmill we already own.

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

[DonRotolo]

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!

[AnthonyDV]

Originally Posted by teslalab2

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.

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.

[Munchskull]

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

[InFlight]

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.

[DonRotolo]

Originally Posted by InFlight

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.

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

[InFlight]

Originally Posted by DonRotolo

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

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.

[asid61]

Originally Posted by InFlight

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.

I can get to half a thousandth without too much care on the small Taig that the woodshop teacher owns. If one is using a good pair of Brown and Sharpe calipers or Mitutoyo, those hold to 0.0005" easily. Of course, maintaining a "good pair" of quality calipers is difficult in a student's hands. Ironically, I find that using a telescoping gauge and micrometer is harder for me than just trusting the calipers, although either method isn't impossible.
Back when we used to use the boring head, all measurements would be taken on the B&S calipers, well before I was on the team. They were able to get reasonably good presses on bearings, although I don't know what the skill level of the people were before I was there.
That being said if I tried to get that tolerance on steel, I wouldn't have much luck.

Drilling a 1.125" hole with a drill bit I would try to avoid. Using an endmill will get those tolerances but a drill bit won't hold the tolerances easily unless you drill undersized by 1/64" or something first, and even then I'm not sure. The largest hole I have drilled in metal was with a 7/8" drill bit, and that did not go as well as just using an endmill of the same size. What is your method to make sure it works correctly?