drilling in ss...untill it stopped part 2...WTF

R

rsmithsr

Well-known member
so here I am again.
back ground..i am 71, been in the mechanical field most of my life.
have a lathe and a drill press air compressor bla bla bla
I bought a 1" dia ss bar that is suppose to be 304, and as was noted in the first thread
I could not drill a hole in the center/bore. simple wind flag counter weights.
got those holes done.
I have tried 6 times to drill and tap set screw holes at 90 degrees to the bore.
(one hole in each..3 pcs)
best is about 3/16 deep with another broken drill.
this is not a production shop, just me at home
WTF
I have never had such frustration
chamber a bbl, no issue,
drill a hole no way
drill press will do 300 to 1500 rpm
have some new ti coated bits coming
shop class is now in session...
 
I have found hardware store (Metal Supermarkets) 304 to be sticky like bubble gum. THEN work-harden like a Mother.....

I have found this brand of drill bit https://smile.amazon.com/gp/product/B000OV9I8A/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 to be remarkable. Cut slowly enough that you're ALWAYS taking a sliver, never let 'er burn even the slightest bit...... and peck at it using Do-Drill, VV, Ridgid or other cutting oil to cool the bit.

I say PECK at it, like come in firmly but lightly so she grabs a bite, let 'er eat for a few revs, maybe until you see a curl coming out the hole and POP 'er out breaking off the chip and leaving the fresh-cut edge for the next bite. Peck and Pop, Peck and Pop..... but when I say "peck" that doesn't mean slam into the work, just come in firm and get 'er eatin'....

304 will work-harden on one turn if you're not biting.

304 will break your pecker off if you bite too deep.

I've also found the Champion taps to be Champion..... https://smile.amazon.com/gp/product/B004OG05JM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ......

I STILL hate 304, but IME these drills and taps will get you thru the jobs, and when you get back into 416R you'll think you've died and woked up in 12L14 "Leadloy" heaven
 
BTW...... BLOW YER HOLE OUT!!! ...... or just as you get a nice rhythm you'll land on a chip and !@#$%^!!!!!

You will blow lube all over your face and shop and splatter chunks all up in y'er all that........ for this reason I'll often use tapwater instead of cutting oil (not recommending it, just sayin' WHAT I DO...sometimes)

but blow yer hole out so the clean cutting edge meets clean metal each bite.
 
Throw that stuff into the woods as far you can muster. Buy a short length of 303 from MacMaster.com. 304 is the most hated SS in a machine shop.(actually some types are worst, but they are specialty metals) Great for welding shops though.
Charlie
 
they make a lot of food processing stuff from 304- cause it's cheap in the realm of things- what a royal pia to deal with. Least little bit of heat at cutting edge and it goes glass hard for several thousands deep & around. Snap a carbide edge off and dull a hss instantly. For me slow is best to the point where I will hand crank a bit through it. Saw plates act the same way when I have to rebore them, but I do not have to deal with a production schedule.
 
304 can be drilled all day long with HSS drills. Depends on size... I will start with a small split point drill and flood hole with coolant. Make sure the point stays cool. Once you got a hole, step up in diameter. Speeds and feed is important. Most guys run way too fast and toast a bit in minutes. I drill alot of stainless and inconel on a regular basis. Keep er cool.
 
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