PDA

View Full Version : Drilling SS tube without burrs



beanbag
06-04-2010, 03:33 PM
I need to drill a bunch of .04 holes in 1/4" SS tube, but I don't want burrs on the inside. I'll be doing this on the CNC

Option 1: Drill undersize and then finish with a little circular loop using a little 1/32 end mill.

Option 2: Drill to size, and put an aluminum plug on the inside

Option 3: Drill to size, and try to clean up the burrs on the inside somehow.

Option 4: ????

doctor demo
06-05-2010, 01:08 AM
Drill it under size and then use a boring bar to finish it from the inside out, or drill normal and run a 1/4''reamer down the tube. I didn't say it would be fast or easy though:( .

Steve

Fasttrack
06-05-2010, 03:23 AM
They have these nifty de-burring tools for CNC machines. I see them advertised in the banners all the time. If you have a tool changer, you might look at investing in one of these tools. It has a carbide insert and plunges in to the freshly drilled hole. As it is withdrawn, it is supposed to deburr. No idea if they actually work worth a darn ... but it's a thought.

beanbag
06-15-2010, 05:49 AM
After I posted this, I realized that .04 holes are really small. Anyway, this is what I did:

1) drill the holes
2) find a rod with an OD slightly less than the ID of the tube I drilled, and jammed it thru. Some of the burrs popped off, and some up them got pushed back up into the holes
3) push the burrs out of the drilled holes with the back end of the drill bit
4) repeat step 2, but from the other end
5) wrap some sandpaper around the rod, and jam it thru the tube to sand off the remaining burrs.

BobWarfield
06-15-2010, 12:38 PM
The burr forms for lack of support underneath. On some materials, it helps to slow the feed just before it pops through. On stainless, I'd worry that could work harden it, especially with these small holes.

A small piece like this could be a candidate for the ice frozen inside approach.

Cheers,

BW

SGW
06-15-2010, 03:14 PM
You might try filling the tubes with some of that low-temperature fixturing alloy (Cerrosafe, or similar).

winchman
06-15-2010, 05:13 PM
How would having ice in the tube (bringing the temperature of the material much lower than normal) affect the work hardening characteristics?

RKW
06-15-2010, 05:22 PM
I'm not sure it would. In this case, it would be used to support the backside of the work during the drilling operation. Although I have to say, I'm not sure how long it would stay frozen. One of the low temp alloys might be better.


How would having ice in the tube (bringing the temperature of the material much lower than normal) affect the work hardening characteristics?

Scishopguy
06-16-2010, 02:43 PM
I need to drill a bunch of .04 holes in 1/4" SS tube, but I don't want burrs on the inside. I'll be doing this on the CNC



Option 2: Drill to size, and put an aluminum plug on the inside





I'd vote for option #2. You could even use hardwood dowel stock and it should work. ;)

beanbag
06-16-2010, 05:23 PM
The tube I was drilling was about .2 ID and 12" long, with a row of about 30 holes. I didn't use the dowel approach because I was worried that if any burrs formed at all, it would cause the dowel to get stuck inside the rod.