Boring a 3" diameter hold in titanium with .0005 tolerance with 2' long...

[neurosis]

Apparently we can't find a shop to hone these things. 

We have a bore head that is extended a little over 2' out of the spindle to bore a 3" hole with a .0005 tolerance. 

What are the odds of this working out?   

[gcode]

Apparently we can't find a shop to hone these things

at a price the bean counters are willing to pay

So

You'll spend twice that turning them into scrap

[JParis]

They rarely want want to spend the time & $$$ to do it right but they'll spend the $$$ to do it again.

[neurosis]

at a price the bean counters are willing to pay

So

You'll spend twice that turning them into scrap

The parts are $25000 each. We've tried to convince the boss to find someone to hone them but he's not having it. 

The guy running the job is about as stressed out as I've ever seen someone.   

[gcode]

Apparently we can't find a shop to hone these things. 

We have a bore head that is extended a little over 2' out of the spindle to bore a 3" hole with a .0005 tolerance. 

What are the odds of this working out?   

Actually, with a tight machine, a good setup and a Sandvik DeVibe boring bar assembly, you might pull it off
but the Sandvik Devibe assembly will set you back $10K +  $15k+
(edited for accuracy)

[Here's Johnny!]

Is it too late to No-Bid that bitch?? LOL

[gcode]

Is it too late to No-Bid that bitch?? LOL

We just had a part in for quote, an aluminum hogout 80" x 12" x 12"
Complete it probably weighs 20 pounds at most
.003 tru-po holes with .0002 diametral tolerance in line across 10" of flimsy .125" thick walls
The part looked like the devil sat down to design the impossible part.
It's actually an F-35 production part and they want them fast and cheap.
Our sales department had it all quoted and approved to blast them out on a 10 year old
beat to shit Haas VF-8 in an non temperature controlled building.
Thankfully my new boss spotted the problems and took their crack pipe away.

[JParis]

It's actually an F-35 production part and they want them fast and cheap.

"Good", "Fast", or "Cheap" You can only pick 2


So I guess the "good" part was left out of that equation 

[neurosis]

Is it too late to No-Bid that bitch?? LOL

We've already made 3 other deliveries on these parts.  They dropped the tolerance from .002 on the hole diameter down to .0005 because they were having issues with the bearings after swage. We already had the job so there was no getting out of making them.

We ended up finding the best holders available and helical interpolated the holes.  They ended up about .001 undersize with some taper and out of round.  He used a make shift cylinder hone to bring them up to size.

We won't be making these again if they keep the tolerance that tight.

[RobertELee]

We just had a part in for quote, an aluminum hogout 80" x 12" x 12"
Complete it probably weighs 20 pounds at most
.003 tru-po holes with .0002 diametral tolerance in line across 10" of flimsy .125" thick walls
The part looked like the devil sat down to design the impossible part.
It's actually an F-35 production part and they want them fast and cheap.
Our sales department had it all quoted and approved to blast them out on a 10 year old
beat to shit Haas VF-8 in an non temperature controlled building.
Thankfully my new boss spotted the problems and took their crack pipe away.

And based on how those enginerds think, I'm assuming those pieces were structural beams where the holes were just pass thru for wiring and such and actual location/diameter didn't precisely matter.

[gcode]

I'm assuming those pieces were structural beams where the holes were just pass thru for wiring and such and actual location/diameter didn't precisely matter.

actually, I think they are consumable parts, one time use,  something the do with weapons delivery.. which is why they want them fast and cheap.

[Jeff]

They dropped the tolerance from .002 on the hole diameter down to .0005 because they were having issues with the bearings after swage.

I've seen customers try that trick before. They change the tolerance to some near impossible tolerance only after someone accepts the job.

[neurosis]

I've seen customers try that trick before. They change the tolerance to some near impossible tolerance only after someone accepts the job.

It wasn't a trick in this case but I've seen that happen as well.

The first order of the parts were prototype. We worked closely with the customer and the bearing company while they were trying to do the bearing install.  The bearings were also prototype.

They had initially set the tolerance at .004 but we held them within .002 because we suspected that was going to be a problem. They changed the drawing to .002 and then when they *still* had issues withe the bearings, changed it to .0005

[mkd]

Heidenhain has a grind option if you can find a machine equipped. I know of a couple makers.
 Interpolating that tolerance is easy peasy in aluminum. Fighting tool wear and taper on Ti would be the challenge. How many do you want to scrap to find the perfect recipe?
 interpolation-turning seems like it would work, in theory.🤣

[CNCAppsJames]

MAM72-100H with the Synchro-Tip option (Spindle Turn plus rotary axis)... that machine can handle the OAL for that length IIRC. I'd have to double check. There's at least 5 or 6 of those machines in the Northwest. Not sure if any have the option.