Drilling stainless a bunch of times. 2

[itsmoked]

I have to modify an industrial humidifier, really just a electro-mechanical atomizer.

It's made of some-sort of stainless steel. I have to drill twenty 6mm holes and twenty 13mm holes.

This is 0.042in sheetmetal. I was thinking of getting a piece lasered out with all those holes then realized I'd then have to cut a long narrow slot out of the same sheetmetal, probably an even worse task!

Does anyone have a favorite SS drilling recipe they can share? Technique? Drill bits? Psychiatrist?

If this mod works I'll have to do it all a second time...

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mfgenggear]

thanks tugboat I missed that, to flimsy unless supported. unsupported will be like wet noodle

 

[Sparweb]

If the holes aren't in the middle of a very large sheet, I try to use a sheet metal hand punch:

The distortion you see in the photo is from using it on paper-thin aluminum. IME this tool won't distort your 0.04" sheet of Cres.

Drilling CRES by hand isn't that bad. Mind a few additional rules: The Cres will work-harden if you allow it to. Support the sheet as already mentioned, and while drilling DON'T STOP. The work-hardening happens as the cutting force is released (so I was told) so keep the bit cutting and feeding at a constant rate. Fluid won't help on thin sheet.

Since it sounds like you're modifying the humidifier, account for the time wasted to disassemble everything to make it suitable for the laser, water, CNC, whatever fancy process, and then put it back together again. I would rather find a convenient way to drill the holes in-situ, provided I can do it cleanly.

For accuracy, yet allowing for hand-drilling, consider a CNC/Laser drill-guide template. Cut pilot holes in a piece of steel plate first, with whatever accurate process is cheap and handy. Clamp that in place on the humidifier enclosure, thus guiding your drill bit. The rest is elbow-grease.

You didn't specify if these holes are close-tolerance safety-critical structural holes (on a humidifier, yeah right) or bracket mounting holes that can have 3mm slop (on a humidifier, more likely). Or the positional tolerance... suggesting completely different approaches. Best odds are that hand-drilling will be fine.

 

[mfgenggear]

drilled holes is done a lot on sheet metals parts on aircraft structures. but with it it's all about edge distance and match drilling multiple components. and is not close true position.
the question also is what true position is required. if more 1/8 tolerance than hand drilling is an option.

 

[berkshire]

It smoked
If you have the capacity to cut holes with a laser then you can cut the slot in the same way.

You are judged not by what you know, but by what you can do.

 

[itsmoked]

Here's a shot of the problem child:

The holes will run along the bottom edge about 1/2" from the bottom. Sooo no cool hand punches WindWright.

You guys have given me a ton of possibilities that now are swamping me with selection.

It's been suggested:

Drilling - but using the sandwich method top and bottom to prevent horrid burrs and a triangular hole.
Stepped drills - "The Best!"
Punch die sets - Then need the appropriate press to put them in.
Lasering - None around here and tends to need flat sheet starting point.
Water Jetting - Several around here and purportedly they don't care about the preexisting shape. Next town over.
Rotary Sheet Metal Cutters - Seems excellent but needs a buying cycle.
Two point endmills - Had them handed to me.


I have a mill/drill press. I have a fist full of TiN drill bits in 6 and 13mm I can walk out back and try these. I think I will.

Depending on how hard this is I may forgo 13mm holes for 20 fuse holders and just drop them in the bottom of the pan. Then do only the 6mm holes for the blown fuse indicator lights. I'll start with those easier 6mm holes and see how things might feel for the 13mm.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

The main problem with drills isn't just triangular holes and burrs but the when one flute catches and either tries to jerk the drill on the steep spiral out of the drill, the drill out of the user's hands, or - on small pieces - to both wind it up the drill and then whip it like a razor blade right where the hand that was holding still is. I've got at least one small scar from not using a block on top and a clamp to prevent that climb "to save some time." On a bigger piece the scarring won't happen, but I can see it making a dent on a drill press or mill.

The nice thing about the step drill is it doesn't have a helix, so it cannot spiral into the sheet metal.

 

[JohnRBaker]

Someone commented on using a Step-Drill if you could find one in Metric. Well, they're readily available, just not 13mm. The ones I found has steps for 12mm and 14mm but not 13mm:

https://www.amazon.com/High-Speed-L...ven_browse-bin:3622111011&s=industrial&sr=1-4

But 13mm is close to 1/2 inch so you might be able to use an Imperial Step-Drill.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[3DDave]

Go half a step?

 

[TugboatEng]

Then you end up with a hole with a very sharp inside edge on one side.

A word of warning about step drills, they do leave a nasty bur on the opposite edge. I usually flip the part over and kiss the back side with the same drill if I can.

Sorry, I have been holding out on simply linking a vendor. Your local welding supply has the rotary broaches. Don't forget the arbor.

https://www.airgas.com/product/Tool...YaFYOx4N3TX2gFX8kyspOKUoxNNcgpggaAum2EALw_wcB

 

[3DDave]

The metal is thin - most everything leaves a sharp edge. Half-was was half-joking, but if one can reach the other side then the sharp edge can be right in the middle, the location where someone might say, is that sharp? And then mumble a lot with a bleeding finger in their mouth on the way to a bandaid box.

 

[itsmoked]

Yeah, yeah, Microstepping! No, wait, wrong field.

John;

McMaster-Carr:
High-Speed Steel Multidiameter Drill Bits

Titanium-Nitride (TiN) Coated High-Speed Steel

5.0 mm, 7.5 mm, 10.0 mm, 13.0 mm, 16.0 mm, 19.0 mm, 21.0 mm, 23.0 mm, 26.0 mm, 29.0 mm, 31.0 mm, 33.0 mm, 35.0 mm 0.1968", 0.2953", 0.3937", 0.5118", 0.6299", 0.748", 0.8268", 0.9055", 1.0236", 1.1417", 1.2205", 1.2992", 1.378"

No of sizes: 13
Length: 79mm
Max material thickness: 4mm
Shank: Hex 11.1mm Standard
Materials: Steel, Hardened Steel, Tool Steel, Iron, Stainless Steel, Nickel, Aluminum, Brass, Bronze, Plastic

89275A35
$117.42

Keith Cress
kcress -

http://www.flaminsystems.com

 

[TugboatEng]

I made an edit but see there was some activity during the edit. The RotaCut bits are available through your local welding supply. Don't forget the arbor.

https://www.airgas.com/product/Tool...YaFYOx4N3TX2gFX8kyspOKUoxNNcgpggaAum2EALw_wcB

 

[itsmoked]

Well, out into the rainy dark I stalked with my cache of drills and the stainless pile seen above.

Opening one of the big 13mm Cobalts I love the jewelry like look and finish and the dangerous potential it implies.

I planned to use my little mill but quickly discovered this box on it's side used up all but about 3" of my Z travel leaving nothing for a collet mounted drill chuck or the drill bit.

So I chucked up the 6mm TiN coated "sheetmetal drill" in my Milwaukee Brushless drill with a fully charged 5Ahr battery.

I was able to blast out 40 holes. It took a while since I used three clamps for my 3 inch wide aluminum backing plate I had to move numerous times. That picture is after the 40 holes. I pushed HARD and each hole took about 5 seconds.

Then I chucked up the 13mm and tried the first hole. ARGH!!!!!

No dice! It left that nasty result.

I'll use my buddy's offered step-bit tomorrow and see if that's any better.

I still had some burrs on the 6mm holes so I used the 13mm to deburr them on both sides and it worked a charm on those. Took maybe 2 seconds a hole side. Used one bar of the battery.

Stay tuned for the saga of the 13!





Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Finally got it done.

Christmas Tree bit to the rescue. Or Unibit. Or Stepped drill.

https://www.youtube.com/watch?v=SCf37uZlbWE

Thanks for all the help folks. Helped me know I'd somehow get it done.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[JohnRBaker]

Looks good A job well done is the best reward.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[berkshire]

It smoked,
Very good Keith, now what about the slot?
B.E.

You are judged not by what you know, but by what you can do.

 

[3DDave]

No sweat - they make a stepped slotting tool. Look between the hole shrinker shelf and the hole-repositioner shelf.

 

[itsmoked]

LOL

Berky; The slot was a contemplation of having all the above holes laser'd out of some flat-stock that then was screwed onto this box instead of trying to drill the holes in the box manually. The slot presented an even worse problem so I gave drills and stepped drills a shot. And it worked. (Drilled 40 6mm holes with a Titainium Nitrided "sheet metal" drill then chased 20 of them with a stepped drill that maxed out at 1/2" which was apparently enough to fix 20 "13mm" fuseholders.)

Keith Cress
kcress -

http://www.flaminsystems.com