Thin wall tube drilling

Looking for concepts and machine and cutter suggestions to "drill" a 1.00" dia. hole at 90 degrees to a 2.00" dia .05" wall T-304 SS tube.

Also, same question as to how to "cope" the end of a 1.00" dia x .05" wall T-304 SS tube with a .50" radius, in about 1/4".

Thanks in advance.....Mike

How many? How precisely?
If its more than a few, I would have it done by laser.

If it must be done at home, as cheap as possible, a carbide hole saw, like the ones used in mag drills, will work. Slow, steady downfeed, lots of lube, dont stop in the middle and let it work harden.
I do this in my milling machine, for rigidity.

Same process works for the coping- the carbide hole saw in a mill will handle interuppted cuts like that.

Like these-http://www.jancy.com/index.cfm?fuseaction=products.showProduct&productid=76

That is about 18 ga tube- which is no fun, but certainly do-able. If you have a problem with the coping crushing the tube, you could put in a sacrificial plug of wood dowel or cerrobond (low temp fixturing alloy, that is re-usuable).

But it would be a lot easier to just send it out to somebody with a multi-axis cnc laser.

If you are only doing one, drill in steps starting with a small drill; and finish with an offset boring head. (I'm assuming crushing/bending is your problem?)

If _many_ , subject to how far down the tube the hole is located, I believe you could make a simple die & punch that would give acceptable results. Or sub it out and mark it up is the foolproof method.

smt

.05" is roughly 16 ga., a 2" tube is going to present a work-holding problem.

After typing a nice paragraph, I noticed that Ries already mentioned a plug. I'd suggest that wood isn't hard enough for 16-ga. The wood will crush and you'll put flat spots in your tube. Slugs of aluminum on either side of the hole are better for this purpose.

Please tell us what equipment you have at your disposal, and we'll be better able to make practical suggestions.

Sounds like exhaust work.

Let me try to cover all Q's....say 1000 holes and copes per yr, but maybe 50 of each at one setup.

+/- .02 on the hole, +/- .04 on the cope.

Working in an industrial shop with access to a Bridgeport and several floor drill presses. We would make appropriate fixtures and buy the "right" tools, and consider purchasing the "correct" machine at auction.

Outside costs for cutting are too high but we haven't looked yet at lasering.

when doing fishmouth on tubing I like to use the hole saw on the milling machine, set up to do both fishmouth and cut to length in the same operation, avoid the interupted cut.

if you have trouble with crushing make some soft jaws machined to o.d. of tube (plastic, aluminum or mdf work well) kee the inside of the tube clear if you can so chips can clear themselves and heat can disipate.

pm

Does the 1.00" hole go through one or both walls? How about the R.500"?

We have done many operations like this on our waterjets.

The sacrificial wood trick works well here, but it's to protect the ID of your tube, not support it. A piece of hardwood kills an abrasive waterjet stream faster than you'd think.

Round bar still works better. Don't use a piece too close to the ID of your tube or the swarf may wedge it.

In those quantities, you'll not be wanting to use a hole saw, no matter how nice a hole saw it might be. And, think carbide, as HSS dulls quickly in SS.

I think you can hit your desired tolerances using a carbide step drill for the 1" hole, if you can find one that goes to that size. Mine quits at 7/8". They do leave quite a burr on the back side, so be prepared to budget time to deburr. An ordinary twist drill will grab the sheet metal.

For the fishmouth, I've been using both roughing cutters and a single-point brazed carbide boring bar. The roughing cutter is vastly faster, but might be a bit too brutal on the thin sheet. Both rough and finish cutters are available in shell-mill form using an R8 arbor, which is pretty much ideal for your B'port.

those quantities I would definitely be looking to send it out,
laser would be my first choice although I expect waterjet would also do a respectable job.

I'm learning a lot from the replies. Some more answers....Most cases, we drill thru only one wall of the tube, 3 to 4 holes per tube, so any mandrell will be trapped by the burrs. We cut both side walls of the cope...should we drill downward with the quill or inward with the table feed?

The Jancy annular cutter is the type of suggestion I'm looking for. But how do you eject the slug? Any other choices....MSC PN's will help.

Ejecting the slug should not be a big problem- I had a project a while ago where we drilled a thousand or so holes like this in 1/2" 316, and I would say 95% of the time the slug falls right out.
In thin material, it is more likely to fall out than in thick.

I think the jancy style annular cutters will work fine with no backing plug or mandrel for the holes. Not sure about the copes, but it should work there too.

Since they are only 30 bucks or so, I would buy one and try it.

For the copes, the other possiblity is abrasive coping- I think Jancy makes machines for this too, but if not, try these guys- basically, a belt sander, with different sized nose pieces, and good fixturing, so it will cope the ends with alumina zirconia sandpaper.
http://www.vansantent.com/coping_machine.htm

There is also some machinery out there that uses end mills in a dedicated machine to cope-
http://www.mittlerbros.com/
They call them "tubing notchers" but really, they are copers.