We have a customer who is asking us to tap an M8 x 1.25-6H thread, 1.05" Deep in 304 Stainless, on a lathe. We are having a hell of a time with it being able to run in production. Our guys are stopping before each tap cycle to ad Emuge Lube to help. We are using an Emuge tap, but will take any suggestions you can offer. I don't know the exact grade on the tap, but could find out.
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Tapping in 304 Stainless Help
- Thread starter wjohn13
- Start date
- Replies 24
- Views 10,736
Mr. PishPosh
Aluminum
- Joined
- Dec 6, 2008
- Location
- Jewell, IA USA
It may be worth it to invest in a thread mill. I used to always think they were too slow, but then I tried a full form npt and was blown away with how quick it was. Plus I got a way nicer finish on the threads than I could ever get with a tap.
You'd probably even be time ahead since you wouldn't have to stop to put oil on the tap every time.
Hope this helps.
Josh
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You'd probably even be time ahead since you wouldn't have to stop to put oil on the tap every time.
Hope this helps.
Josh
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I could see that if we were milling the hole, but this is on a lathe. I forgot to mention that in the post and have edited it for future responses. Can you use a thread mill on a lathe though? I have never thought of that. The hole is too deep to try and single point cut the threads, since the bar size would have to be so small. Any other options would be greatly appreciated.
Bobw
Diamond
- Joined
- Feb 8, 2005
- Location
- Hatch, NM Chile capital of the WORLD
I don't think an M8 threadmill is going to be long enough, those damn things are
always too short. Might not be the worst idea to threadmill and then finish the
bottom with a tap, less wear and tear, less heat build up, probably need a floating
holder.
As for tap recommendations.. Something that is made for shitty stainless?? I don't know
Its 304, so its going to suck, can you change suppliers and get something that is a
little more consistant than the normal garbage I get?
always too short. Might not be the worst idea to threadmill and then finish the
bottom with a tap, less wear and tear, less heat build up, probably need a floating
holder.
As for tap recommendations.. Something that is made for shitty stainless?? I don't know
Its 304, so its going to suck, can you change suppliers and get something that is a
little more consistant than the normal garbage I get?
I'm buying good material already from Schmolz-Bickenbach. Our next step is to have a rep from OSG or Emuge come out here and see if there is something we can do better. We want to put it on our L32 Citizen and run it in oil, but the hole depth is the concern still.
Mr. PishPosh
Aluminum
- Joined
- Dec 6, 2008
- Location
- Jewell, IA USA
If you can run it in oil on a different machine, then I'd say a form tap would be your best bet. Depth shouldn't be much of a problem with one of those, since it's not creating a chip that could cause issues.
Otherwise, see what your reps say, I guess.
Josh
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Otherwise, see what your reps say, I guess.
Josh
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DMF_TomB
Diamond
- Joined
- Dec 13, 2008
- Location
- Rochester, NY, USA
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304 in work hardened or cold rolled is like 200% harder to machine. annealed is easier to machine.
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tap drill size often many just use bigger tap drill for SS
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starter tap, plug tap, bottom tap by hand tapping. repeat if needed. often people tap shallow on the machine and hand tap to final depth
Larry Dickman
Titanium
- Joined
- Jan 30, 2014
- Location
- Temecula, Ca
just roll tap it and all your problems will go away
J
Johnny Larue
Guest
I single point them all the time....and yes there are threading bars like this....on page 48...Z STYLE CRITERION THREADING BORING BARS....for that one you could do a Z63C and turn diameter A back aboot 3/8 to reach 1 inch...easy peasy...I also use 100 RPMs on that stuff....LMAO
DirectIndustry - The online Industrial Exhibition
AARONT
Stainless
- Joined
- Feb 19, 2013
- Location
- Madison, WI
I'm on the thread form train. Also if you're able to, go with a 60% thread engagement. OSG has a nice tap drill calculator OSG | Taps | End Mills | Drills | Indexable | Composite Tooling | Diamond Coating | Die Products
J
Johnny Larue
Guest
just checked me notes....it aint so easy peasy so I take that back otay....LOL....it is for like 1 or a couple....but for a lot I either single pointed it not to finish X depth and then ran a tap in it by hand rest of way...or I single pointed em to the 1 inch depth not to finish X and then ran a tap by hand...its a PITB.....so forming might be quicker like the guys say above...I never tried it as I only get small piece numbers and no extra stock so I gotta do it that way or else
countryboy1966
Hot Rolled
- Joined
- Jan 10, 2009
- Location
- Thompson, Ohio
Rule out work hardening first.
http://www.practicalmachinist.com/v...id-work-hardening-304-while-machining-152729/
What material is the drill made out of? What are your speeds and feeds?
I tap 8-32 UNC in 304 stainless and unfortunately hand tap the threads. During hand tapping, I can tell when my HSS drill is getting dull as well as if I was off on my speeds and feeds.
http://www.practicalmachinist.com/v...id-work-hardening-304-while-machining-152729/
What material is the drill made out of? What are your speeds and feeds?
I tap 8-32 UNC in 304 stainless and unfortunately hand tap the threads. During hand tapping, I can tell when my HSS drill is getting dull as well as if I was off on my speeds and feeds.
I know that feeling, you get the same thing if a drill burns up and you come back and finish the hole with another drill, the material will tap fine but will suddenly feel like you've hit bottom as soon as you hit the work-hardened layer
Bobw
Diamond
- Joined
- Feb 8, 2005
- Location
- Hatch, NM Chile capital of the WORLD
Years ago I was making some some small clevises out of 304, and there was a 10-32
tapped at the bottom of the clevis, and it was pretty deep.
I form tapped as deep as I could go on the machine (the clevis got in the way), and then
I finished hand tapping them with a cut tap, cut really easy with the large minor..
tapped at the bottom of the clevis, and it was pretty deep.
I form tapped as deep as I could go on the machine (the clevis got in the way), and then
I finished hand tapping them with a cut tap, cut really easy with the large minor..
I secound the drilling issue, my experieance with 304 is it taps easy, if the holes been drilled well. If the holes been rubbed in and has a hardened skin, yeah your hosed already, drilled with a HSS cobalt bit and i never have a issue. Let the drill get even slightly blunt and you will eat taps all day long.
+2 to form tap. Any nasty gummy materials like SS 304, 316, mild steel 1005~1020 series, Aluminium....Form tap is the way to go. We use them all the day without issues. We use through coolant ones, coolant concentration >7%.
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