mopowers
Well-Known Member
Which stainless steel is easier to drill and tap, 316 or 18-8?
Thanks!
Thanks!
Drilling Stainless Steel
- Thread starter mopowers
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69_340_GTS
Well-Known Member
18-8 (same as 304) is going to machine easier than 316. So unless you need the better corrosion resistance of 316, use the 18-8.
mopowers
Well-Known Member
Awesome. Thank you. I'm just opening the hole in a thumb nut and threading it for an air cleaner/carb stud. Similar to what's pictured:
I'm going to try this without breaking a tap, hopefully. Is hand tapping something like possible, or is it just a pipe dream? I've never worked with stainless before and the particular nut I need only comes in 18-8 and 316.
I'm going to try this without breaking a tap, hopefully. Is hand tapping something like possible, or is it just a pipe dream? I've never worked with stainless before and the particular nut I need only comes in 18-8 and 316.
Treblig
Well-Known Member
Awesome. Thank you. I'm just opening the hole in a thumb nut and threading it for an air cleaner/carb stud. Similar to what's pictured:
I'm going to try this without breaking a tap, hopefully. Is hand tapping something like possible, or is it just a pipe dream? I've never worked with stainless before and the particular nut I need only comes in 18-8 and 316.
If you use Tap Magic when you're tapping the hole in the stainless it will decrease the chances of breaking the tap. Tap Magic decreases the friction between the tap and the metal.
Treblig
ir3333
Well-Known Member
stainless steel is just any steel with nickel added.Nickel is not overly hard so it will be as hard as the parent steel.
1/4 turn clockwise followed by 1/2 turn back to clean your threads
1/4 turn clockwise followed by 1/2 turn back to clean your threads
Treblig
Well-Known Member
Stainless tends to be a little "gummy" (machine shop term). As such it will tend to bind against the tap. Tap Magic will keep the stainless from sticking to the tap and reduces friction. It's much easier to break a tap in stainless than it is in regular cold rolled steel. With practice stainless can me tapped just as easy as regular steel but it does take practice. Stainless will dull a cutting surface faster than regular steel because it is a little "tougher" to cut. Just ask any machinist!!
"1/4 turn clockwise followed by 1/2 turn back to clean your threads", totally agree!!
treblig
mopowers
Well-Known Member
If I can't find Tap Magic at any of the local hardware stores, if there a good substitute? I kinda want to get this done this weekend.
Oh yeah, thanks a lot for the advice guys. I appreciate it!
Oh yeah, thanks a lot for the advice guys. I appreciate it!
Treblig
Well-Known Member
You can use cutting oil but it's not as efficient as Tap magic. I think Lowes carries cutting oil and usually hardware stores carry it as well. Cutting oil will also decrease the friction you get when tapping stainless but Tap Magic is "KING". Just be careful and don't rush and "back" the tap out of the hole frequently to clean out the tap threads.
PS - Cutting oil is not the same as regular oils, it's designed for cutting metal.
treblig
mopowers
Well-Known Member
Thanks treblig. Hopefully between the handful of hardware stores within a few miles of me, someone will carry Tap Magic. Up until now, I've always use WD40 or PB blaster. lol
ValiantOne
Well-Known Member
Treblig nailed it. Tap Magic is your friend in this instance. Works pretty well in aluminum too. Go online to use-enco.com and you can get a 4 oz bottle pretty cheap. I use it every day in the machine shop. Rapid Tap is my other favorite. I use it on tough steels.
303 series Stainless is much more, drill, tap machine friendly than most other common series Stainless..........drilling 304, use a slower spindle speed than you might usually use, keep pressure on the bit, stainless will work harden, keep it cool, set up an air line to blow air on it . Use a GOOD drill bit and tap......better quality here makes a huge difference.
I work with Stainless all the time and I hate it.
I work with Stainless all the time and I hate it.
mopowers
Well-Known Member
How would you compare the machining properties of 18-8 and 316? Those two are my choices.
Treblig
Well-Known Member
WD40 and PB blaster do lubricate the cutting surface and it does help a little bit but it doesn't have the friction reducing properties of Tap Magic or cutting oil. Once you use Tap magic you'll never want to be without it. You can actually hear the metal shearing off as you cut when you apply Tap Magic to any cutting surface. When you're cutting/tapping stainless it makes a BIG difference because most times Stainless is much more gummy or sticky.
Treblig
ValiantOne
Well-Known Member
Lol. I hate it every time too. Gummy crap.......
When people asked me what stainless was made of, I used to tell 'em it was an alloy of steel with a percentage of F-U and a little bit of SOB mixed in.
Yes, good quality taps make a huge difference. I prefer OSG electra lube taps in this instance.
CE
ValiantOne
Well-Known Member
69_340_GTS
Well-Known Member
There are lots of charts around comparing various alloys, so depending on who you believe, results will vary. This is because “machinability” is not an exact term. I did a little research, and it averages out like this: 18-8(304) is rated at 40% machinability. 316 is rated at 25% machinability. For comparison, mild steel, such as B-1112, C-1212, is rated at 100% machinability, while brass/bronze is usually around 250%-300%. (all of the above are in the annealed form).
In a pinch, plain old motor oil will work as a lubricant for tapping. Make sure you use high speed steel taps, at a minimum. Preferably titanium coated. Don't even try using carbon steel taps!
mopowers
Well-Known Member
Well, It turns out the Grainger near my house sells Tap Magic cutting oil. I'm going to pick some up today after work.
I've got a couple 1/4-20 taps. I'm not quite sure if they're HSS, but they're older American made taps. I'll look at them closer and see if they say HSS. Is there another way to find out?
I've got a couple 1/4-20 taps. I'm not quite sure if they're HSS, but they're older American made taps. I'll look at them closer and see if they say HSS. Is there another way to find out?
Treblig
Well-Known Member
It might be stamped (etched) on the tap but I don't think I've ever seen a tap (designed to tap threads in metal) that was not HSS. There are even stronger more higher quality taps but HSS should work just fine if you use Tap Magic and you go slow. Remember that the material a tap is made out of is brittle (very, very hard). If you accidentally dropped the tap onto concrete it could break. So be sure to keep the pressure directly along the axis of the tap (no side to side stress) or it will snap off!! If you try and tap too deep without backing up it will snap.
Good Luck
Gil
69_340_GTS
Well-Known Member
You can find carbon steel taps in hardware stores. They are typically all black or dark grey, because normally they are not ground after heat treating.
jos51700
Green Bearing thread connoisseur
You can over drill the hole on something that doesn't need high strength or high precision heads. That will make your life easier when tapping threads.
Use an arbor or a tap stand to keep from side loading the tap. That will make the biggest difference in keeping a tap from breaking.
Stainless ain't so bad. Titanium is a *****.
Use an arbor or a tap stand to keep from side loading the tap. That will make the biggest difference in keeping a tap from breaking.
Stainless ain't so bad. Titanium is a *****.
Phreakish
Well-Known Member
You mean chromium. Nickel is often present, but stainless is defined by chromium content.
It's not the heat, it's the deformation or 'cold work' done to it. Stainless gets harder when it's bent, formed, or basically deformed. This is what 1/2 and full hard stainless materials are: a description of the total surface area reduction done to work harden the material.
Hate cutting stainless? Try Inconel (718 spefically), you'll love 300 series after that!
303 is much nicer to turn parts with, but try plating that stuff... I'm convinced 303 is just an amalgam of whatever garbage the mill had laying around plus a bit of chromium.
mopowers
Well-Known Member
Got it done guys. Thanks for the pointers. It actually wasn't as bad as I thought. No broken taps or drill bits, so I'm a happy dude.
Treblig
Well-Known Member
Got it done guys. Thanks for the pointers. It actually wasn't as bad as I thought. No broken taps or drill bits, so I'm a happy dude.
Well that came out very nice. If I had known you had a drill press a would have told you to drill the hole then put a chamfer on top edge of the hole with a larger drill bit to give the tap a easy way to start the first thread. Then before you move anything you stick a pointed 1/4" rod in the chuck and (using hand pressure) you can use the point on the rod to insert in the backside of the tap. Just about every tap I've seen has a counter sink on the back end so you can support the tail end of the tap as you start the first thread. By pressing down on the drill press handle as you turn the tap you'll ALWAYS get a straight start on the hole. When you "back the tap up" you relieve the pressure so it can come up out of the hole. After you break the binding you apply hand pressure again and keep tapping until you finish the thread.
Good Job!! Sometimes it's EASY and sometimes it's a BEAR, it depends what alloy of stainless you're tapping. It also depends on well prepared you are when you start!! You were prepared!!
treblig
mopowers
Well-Known Member
Damn, those are a couple great tips! I could've used them this time yesterday. Lol Oh well, live and learn... Next time I hand tap something, I'll be sure to stash those tips in the ol memory bank. Thanks again.
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