How drill/bore larger pockets in aluminum???

[jeffo2001]

Hi all,
I need to bore a few larger dia holes in aluminum on my mill. (1.024" dia and
0.828" dia.) These will be pockets for bearings so they will need to be
fairly accurate.

I am planning on making a couple "counterbores" with
these diameters to use to cut these holes. Does anyone have
any other ideas how I can drill or bore these holes using a small
benchtop mill? The holes only need to be about 1/4" deep or so.

I really don't want to spend the time making special counterbores
for only two holes.

Any advice would be greatly appreciated....

Thanks !!!!

Jeff

[jc_eng]

You should get the tolerance from your bearing manufacturer before making the holes. How are you getting your dimension?

[wildcat]

Do you not want to use a boring head because of the time needed to enlarge the hole?

[jeffo2001]

Thanks for the replies guys. To answer your questions:

The dimensions for the holes are for a slip fit for the bearings I have.

I don't have a boring head available. I've never even used one on my
mill. I looked at a few on ebay but they were too large and too expensive.
Any reccommendations on where I might can look for a small boring head?

McMaster has a neat little adjustable counterbore but it's like $400.00.

Thanks again fellas,
Jeff

[wildcat]

Originally Posted by jeffo2001 I don't have a boring head available. I've never even used one on my mill. I looked at a few on ebay but they were too large and too expensive. Any reccommendations on where I might can look for a small boring head?

Just for example...

http://www.littlemachineshop.com/pro...1266&category=

[The_Roadrunner]

Originally Posted by wildcat Just for example... http://www.littlemachineshop.com/pro...1266&category=

That's a mighty low price. I'm not very fond of boring heads with only .001 graduations, but if that head is balanced it seems like a good deal.

[Delcamfan]

a cheap way to do this is just to snag up a piece of high speed......hand grind your cut edge and go to town.....for only two holes i think that this would be the most inexpensive way to do it

[jeffo2001]

Thanks guys!!!!! I love this site......

[The_Roadrunner]

Originally Posted by Delcamfan a cheap way to do this is just to snag up a piece of high speed......hand grind your cut edge and go to town.....for only two holes i think that this would be the most inexpensive way to do it

I agree, that would be the most cost effective, and you should be able to hold the slip fit tolerance.

It would also be pretty easy to whip up those 2 tools on a surface grinder with a whirlygig and an endmill face sharpening fixture.

[alexccmeister]

I am doing a 38mm diameter pocket on a fairly small work piece. around 3" by 2" by 10mm thick aluminium. Here is the thread I just started on how to make a temporary rotary table.

http://www.cnczone.com/forums/showthread.php?t=39316

[mhtom]

Why buy or make tools for special jobs. Doesn't your mill have circle-interpulating capabilities? If it does use it. Very accurately.

[tobyaxis]

Originally Posted by mhtom Why buy or make tools for special jobs. Doesn't your mill have circle-interpulating capabilities? If it does use it. Very accurately.

I believe this is a Manual Bench Top Mill.

Anyway you would be better off with the Boring Head because then you could Bore both large and small bores when ever you wanted. The investment is small when you compare it to buying different tools for different sized bores. This is of coarse if you plan on doing other projects.