Tooling for bore with 0.0005" diameter tolerance at bottom of 5.5" deep blind hole

[wobblers]

Tooling for bore with 0.0005" diameter tolerance at bottom of 5.5" deep blind hole

Hello,

I have a job that requires boring out a stainless steel sleeve of sorts, then replacing with same sleeve, then boring out the ID to be concentric within 0.001" to the axis of cylindrical datum, and to have finished diameter be 1.1 +/-0.0005". Wall thickness is about 1/10"

The sleeve is 0.5" tall, so the final bore in the sleeve is 0.5"x1.1"

There is a surrounding 5.5" deep and 2.5" blind hole around the bore.

My spindle is cat 40. I think I need a new boring head and boring bar. The longer the better, to provide access to adjust the boring head on the machine while approaching the final diameter.

Any suggestions or pointers for tooling?

Thanks, and please forgive any ignorant oversights.

 

[Milland]

What year/condition of machine and spindle? Are the bearing, spindle taper, and drawbar force good? What boring head do you have, condition? It sounds likely you'll need a new bar, question will be solid carbide or inserts.

What actual ss alloy are you cutting, and what hardness?

How are you installing the new bushing/sleeve? A little cocking over of the sleeve during install will give you headaches, good fixturing here (like a piloted close tolerance arbor) will save you problems.

How is the part being help to the machine?

 

[slowmotion]

A solid carbide shank with a Big Kaiser boring head should do it. I am an automotive machine shop but have a CAT40 CNC mill for block work and that tooling is what we use for lifter bores in that diameter. I've had it extended out quite far with no chatter issues. Granted we bore cast and bronze so I'm not sure the same insert would work for stainless.

 

[hvnlymachining]

I'm sure you're well aware longer with boring bars is never better, since you lose rigidity with length you also increase the likelihood of chatter. Considering the depth challenge I would recommend using a larger diameter boring head and an extension to make the distance,then a short boring bar just a bit longer than required to give you a little clearance and length to work with while retaining higher rigidity. Another possible option may be a reamer and guide bushings to maintain alignment.

Good luck with it.

 

[AARONT]

I would use a Criterion Cri-Bore bore head with an extension on a threaded cat40 holder. This will keep you as a rigid as possible. https://alliedmachine.cld.bz/Criterion-r/30/

 

[QualityMan3185]

I know this might not be completely related, but I have a very specific type of material that is .260 bar-stock that I'm trying to get turned into .150OD and .123ID, but due to the type of material it is, I haven't been able to find a machinist that will touch it. A machinist that we work with recommended asking around in this forum to see why it is so difficult to machine. The Material is 80% Nickel 5% Molybdenum .5% Silicon .02% Copper and the remainder balance is Iron.

 

[upthebikes]

^ Start a new thread.

Sounds like hymu 80 alloy, or something similar, for magnetic shielding. Search on here, or I’m sure the Carpenter book has machining data.