Technique For Drilling Small .043 Inch Holes in Invar

[Milland]

Sorry it didn't work out, but thanks for the update.

If nothing else, you got a renewed appreciation for the usefulness of good machinists...

 

[implmex]

Hi again morsetaper2:
As others have remarked, there's no harm in trying and we live in hope the experience wasn't too awful.

But I do have to smile at everyone who remarked that an 0.043" drill is TINY.
In my world, that's like a telephone pole, and I'll betcha many others on this forum are nodding agreement and chuckling quietly too.

Of course as I recently remarked on another thread, I've got a buddy who thinks a 1/2" drill is too small to use so I guess it all depends on your perspective.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

BTW: with regard to your spindle speed...you were NOT running it too fast for the material and the drill, you were running it too fast to be able to keep up with the necessary feedrate to keep the drill cutting.
The nominal RPM for your drilling operation in Invar is 40 FPM with HSS drills, so about 3500 RPM, and at a 0.001" chipload (recommended for a 1/16" drill) you'd be feeding around 3.5 IPM which is way faster than you can control.

Your machinist is both correct and not correct (if that's even possible).
I neglected to mention that on a manual machine, you want to run the drill about as he recommended and never ever EVER follow the CNC chart recommendations...you just don't have the reflexes and the control to get away with it.

 

[Conrad Hoffman]

I haven't done invar in decades but the FM or FC is pretty easy. As above, 0.043 is anything but small, if not a telephone pole, at least a stout log. We used to use Castrol Moly-D. People here may laugh because it's been offered as the cure for just about anything, but it did work well with invar. I think we used HSS back then and I'd be afraid of snapping carbide on a manual setup. Far worse than invar 36FC is Super Invar. That's even lower expansion, but a real nightmare to machine. What is Super Invar? - Eagle Alloys Corporation A blend of nickel and cobalt from hell.

 

[mnl]

Yes I did. I was advised by everyone to peck drill it. But I peck drilled by hand, hadn't read your note about using the stop. By that time I had given up.

Called machinist on phone asking for advise, he said lots of lube, but I was running way too fast at 2800 rpm. Said I needed to be down around 500 rpm for HSS and a bit higher w/ carbide drill. Still broke carbide drills and/or dulled HSS drills. I just don't have the speeds and quill pressure right and am hesitant of ruining those $800 optical mounts. So just backed off, I just don't have experience w/ invar to have a good feel for it. And the drills are just tiny.

But thanks all, for your contributing advice.

Good on you for trying. Better on you for knowing when to stop.

 

[mnl]

Dumore not. Boley, mayhap?

Or P&W's Sigourney, Or a Muehlmatt/Hamilton.

Unless used with an add-on rising-table, the E-M is actually clumsy by comparison what with the extra mass of that stone-age variable speed rig - same physics - AFAIK - as the one on my old-but-good Hobart heavy-lifter kitchen mixer. Which does have a crank operated rising BOWL on Z-axis dovetail ways!

More HP than the Burke #4 mill as well. Then again, talk about "earning your crust"?

My ex could crank out round loaves of bread on that machine as if feeding a Roman Legion!

I wish I could remember what it was, but ‘‘twas almost four decades ago. Not a large machine, it fit into something like an oversized microscope case. Fixed head, movable stage like a microscope stage with big micrometer knobs to move it. On the stage was a nifty little raising platform that actuated by pressing down on a thumb lever on either side of the stage. I used to to drill a grid of 0.020” holes in a silver heat exchanger.

 

[Terry Keeley]

Haven't read through all this to see where you're at but these will get the job done for you:

Precision Twist Drill 018357 R18CO #57 Cobalt Jobber Drill 135deg | Kaufman Company Inc.

I just drilled some 3/64" 15D in 6Al4V with them, they have split points down to #60.

Not sure about your material but for Ti lots of pecking with fine feed and flood coolant.

 

[LKeithR]

...I'm a RapidTap fan, but you may pick from a wide offering that's out there....

I'll bet some of the old, "nasty" Rapid Tap would work good on this stuff. It's been years but I remember
drilling holes in 316 SS using the stuff and the material cut like butter (well, maybe not quite that nice,
but it worked pretty damn good).

 

[CITIZEN F16]

Hi again morsetaper2:
As others have remarked, there's no harm in trying and we live in hope the experience wasn't too awful.

But I do have to smile at everyone who remarked that an 0.043" drill is TINY.
In my world, that's like a telephone pole, and I'll betcha many others on this forum are nodding agreement and chuckling quietly too.

Of course as I recently remarked on another thread, I've got a buddy who thinks a 1/2" drill is too small to use so I guess it all depends on your perspective.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

BTW: with regard to your spindle speed...you were NOT running it too fast for the material and the drill, you were running it too fast to be able to keep up with the necessary feedrate to keep the drill cutting.
The nominal RPM for your drilling operation in Invar is 40 FPM with HSS drills, so about 3500 RPM, and at a 0.001" chipload (recommended for a 1/16" drill) you'd be feeding around 3.5 IPM which is way faster than you can control.

Your machinist is both correct and not correct (if that's even possible).
I neglected to mention that on a manual machine, you want to run the drill about as he recommended and never ever EVER follow the CNC chart recommendations...you just don't have the reflexes and the control to get away with it.

I would not call a .043 drill tiny in a machine with CNC control, make it out of carbide and drill manually it is real easy to break one that size. That being said I think the smallest hole I have drilled was .012".

 

[Milland]

I would not call a .043 drill tiny in a machine with CNC control, make it out of carbide and drill manually it is real easy to break one that size. That being said I think the smallest hole I have drilled was .012".

.004" was my smallest. Now watch for the "Yeah, well I drilled a hole through the shank of one of those" guys...

 

[rogertoolmaker]

Invar: Drilling Small .043 Inch Holes

Machinist at work is out for an extended period. I'm a mechanical engineer, but when odd-ball fixes need to be done I get tapped to do them when its an emergency and machinist is out. I'm no journeyman machinist by any means. Competent in alum, steel, brass, some stainless, various plastics, etc.

I have zero experience working with invar.

I believe the material is invar 36 FM. And the parts are nickel plated. I need to drill 3 small .043 diameter holes in five parts (15 holes). These are expensive optical mounts so I don't want to ruin them.

I'll be using .043 carbide drills. Exact hole size and position is not critical. I read some posts about drilling invar. But none were for drilling small drill holes. Read that it work hardens. I'll be drilling into a tube that is hexagonal on the outside with a round ID. Where the hole needs to go wall thickness is about .100 thick.

Any advice so I don't screw this up? Work will be done on a Bridgeport clone.

Drill RPM for .043 carbide drill?

Drill RPM for .043 HSS drill?

Coolant: oil or water based?

Will it act unusual when drill breaks through to ID?

Thanks.

 

[wesg]

Bridgeport should be fine. At least less leverage than a typical drill press, but more than you may want. Hold the handle down near the pivot, 1/4 to a 1/3 out. And as already noted, keep it wet, with oil, and split point drills. Peck a bunch. It ain't hard, it's gummy, keep the chips out.

 

[Winterfalke]

Plugging the main bore is dangerous...you may never get the plug back out once the burs lock it in.

We've had luck with this using a 2 piece plug, a third on top under the hole, the rest tapered for easier removal. We even managed to waste more time screwing around trying NOT to make a plug than we did making the plug before we gave up and made the plug anyways. Twice, because the engineer said we didn't need it and threw it away...