Started my 30 cal can - fun with stainless steel

[John_TX]

Finally got started on my 30 caliber build with cones and spacers with the tube/spacers in 316 stainless steel and the cones out of 304 stainless. This is my first experience working with any material this hard and boy, it's a bunch different than the softer metals (as expected.)

I bought four tool insert kits from Grizzly for stainless steel and they work fairly well, but the parting/cutoff tool is a whole 'nother can of worms. As you can see in my first cone, I had some severe chattering on the inside of the lip and I'm not quite sure what was the cause of that. I've been experimenting with spindle and feed speed, cutting fluid or dry, etc. Usually I don't have this much trouble with the parting tool but I was working at the end of the stock and maybe the chuck wasn't tight enough. I'll work on cone #2 tomorrow and see what happens.

When I made my .22 can (aluminum) I was able to make three K's in a day when I got on a roll, but I think I'll be making only one stainless cone a day due to the time it takes me to work the harder material.

Learned a valuable lesson today about how sharp the thin strands of stainless chips are when I tried to pull a couple of chips out of the way. See the picture of my finger, I sliced it pretty good.

Ugly spacer shelf<sigh>


One set, cone and spacer


Together, forever...


Dummy me, I knew better

[Capt. Link.]

Finally got started on my 30 caliber build with cones and spacers with the tube/spacers in 316 stainless steel and the cones out of 304 stainless. This is my first experience working with any material this hard and boy, it's a bunch different than the softer metals (as expected.)

I bought four tool insert kits from Grizzly for stainless steel and they work fairly well, but the parting/cutoff tool is a whole 'nother can of worms. As you can see in my first cone, I had some severe chattering on the inside of the lip and I'm not quite sure what was the cause of that. I've been experimenting with spindle and feed speed, cutting fluid or dry, etc. Usually I don't have this much trouble with the parting tool but I was working at the end of the stock and maybe the chuck wasn't tight enough. I'll work on cone #2 tomorrow and see what happens.

When I made my .22 can (aluminum) I was able to make three K's in a day when I got on a roll, but I think I'll be making only one stainless cone a day due to the time it takes me to work the harder material.

Learned a valuable lesson today about how sharp the thin strands of stainless chips are when I tried to pull a couple of chips out of the way. See the picture of my finger, I sliced it pretty good.
Ugly spacer shelf<sigh>
One set, cone and spacer
Together, forever...
Dummy me, I knew better

I never thought I would write a dear John letter but here goes.
John first welcome!
I'm glad you did not loose a finger.Stainless can be very dangerous because of the long strands it makes.You should use whats called a chip breaker on your tools.Most of the chatter is the material work hardening from the previous cut.You need to get under this cut and avoid the skim cut so it takes a bit of practice. Make yourself a swarf removal tool and never remove swarf when the chuck is in motion.Next time if not now change to 416 SS it cuts like butter and dose not work/self harden.You may need to stiffen your setup as well.Sharp tools or small radius carbide tips will help too.Ask questions or PM me if you have questions you don't wish to post.Looking forward to the build.
PS: a little blood makes them quieter ask anyone who works in stainless.
-CL

[CMV]

I would swear that someone on here warned you about that......

Use a fish & make sure you're perfectly on centerline with your parting blade. When I first started I kinda jumped right in with harder to machine materials. Sometimes parting got really frustrating for me. Problem ended up being I just didn't have a parting tool/tool holder that was worth a nickel. My lathe came with one for a lantern style but I couldn't get a blade to sit in it correctly. Then the one that came with my faux-loris QCTP would let blades slip. I finally got one that I like and it works really well. But it took me a long time to get there as I figured it out.

http://www.ebay.com/itm/3-8-SELF-LOCK-C ... 43d2e78258 from this seller & pretty much like this, but 1/2" size which I don't see listed. I did have to fins some better inserts for it as the ones it came with were poor, but after that I love it.

Also dial in your tool to make sure it's cutting perfectly square. Trusting the hash marks on my compound was an early mistake. Fine for grooving, but parting something thick was disastrous being off a little.

My hands do a whole lot better since I started wearing the 9mil black nitrile gloves from HF. Lowes sells some similar ones called Venom Steel that that are also good, but the HF ones seem to last longer and are cheaper. Cheap, disposable, & thick enough to keep from getting minor splinters & cuts. A SS bird's nest will still chew them (and your fingers) all up, but for run of the mill stuff, they help a lot. Anyway, I now view the gloves like I do the safety glasses. If I think I should wear one, I should wear the other. I don't like the mechanic's gloves though. The sides actually hold chips and lead to more metal splinters although the would be good for grabbing bird's nests. They also feel too 'squishy' when they get soaked with coolant.

[partsguy22]

Higher feeds and lower speed seem to do best on stainless for me. Like Capt. Link. said stainless will work harden 3xx stainless work hardens pretty easily and all stainless is stringy (without the proper chip breaker) I keep a pair of needle nose pliers on hand to remove stringy Stainless and Ti bits

as far as cutting fluid I've found heavy dark cutting oil (Mobil 760)works best on stainless for me

[daviscustom]

Your chuck and tool holder has to hold everything rock solid......if ANYTHING shifts position slightly during part-off you are going to have big trouble. A good part off tool such as the style CMV suggested works very well as long as you don't let the insert get too bad, that blade type insert holder can self-destruct in a heartbeat.

[curtistactical]

I've been machining around 23 years and I just pulled a chip and sliced my finger, you would think one would learn to use the pliers laying there but I guess I needed to show my wife why I tell her not to grab chips. I almost had a real good one last week, I was facing some baffles in the engine lathe as a second op so I was putting a plug in the inside to keep from crushing the baffles. I had to hold the plug in by sticking a finger between the jaws and holding the plug as I tightened the chuck, I dropped the chuck wrench on the spindle lever turning the lathe on, luckily it knocked it down kicking it in reverse so it knocked my finger out of the chuck, if it would have went forward I wouldn't have a trigger finger any longer. Even after all these years you can still get careless, just too many 16 hour days lately, time to slow down some. Take Capt. Link up on the offer of his help, he is full of useful information and a nice guy too.
Joe

[John_TX]

I would swear that someone on here warned you about that......

Uh, yes - I do remember. Lesson learned the hard way, I was amazed at how sharp those little thin chips were. I was getting really, really annoyed at the bird nest I was having to clear almost every pass when machining the cone faces. I was using a screwdriver, pliers, side cutters and my hand once or twice.

Use a fish & make sure you're perfectly on centerline with your parting blade. When I first started I kinda jumped right in with harder to machine materials. Sometimes parting got really frustrating for me. Problem ended up being I just didn't have a parting tool/tool holder that was worth a nickel. My lathe came with one for a lantern style but I couldn't get a blade to sit in it correctly. Then the one that came with my faux-loris QCTP would let blades slip. I finally got one that I like and it works really well. But it took me a long time to get there as I figured it out.

I was careful to set the height of the parting blade, and I established square of the compound rest - learned that lesson early on. I've spent a small fortune on tools, etc. for the lathe so I suppose a few bucks more to find a better parting tool would be the ticket

http://www.ebay.com/itm/3-8-SELF-LOCK-C ... 43d2e78258 from this seller & pretty much like this, but 1/2" size which I don't see listed. I did have to fins some better inserts for it as the ones it came with were poor, but after that I love it.

That one doesn't look like it will part very deep. I was using my parting tool to turn a neck from 1.75 to 0.543 on these cones.

Also dial in your tool to make sure it's cutting perfectly square. Trusting the hash marks on my compound was an early mistake. Fine for grooving, but parting something thick was disastrous being off a little.

I'll double check before getting started tomorrow

My hands do a whole lot better since I started wearing the 9mil black nitrile gloves from HF. Lowes sells some similar ones called Venom Steel that that are also good, but the HF ones seem to last longer and are cheaper. Cheap, disposable, & thick enough to keep from getting minor splinters & cuts. A SS bird's nest will still chew them (and your fingers) all up, but for run of the mill stuff, they help a lot.

I was looking on Amazon at Kevlar gloves like a meat cutter might use - that might be just the ticket

Thank you all for the advice and the "don't do this" experiences. I'm having a blast with the project and I have come such a long way since I chucked that first piece of metal and started the lathe. I'll keep this thread updated as I move along.

John

[Handloader]

Just me, but I would not use any type of glove that would not tear away free and fast. The nitrile gloves will rip away fast. You do not want a Kevlar glove getting caught on anything spinning and suck your hand into the lathe.....

[a_canadian]

Yeah, I had an absent minded moment with a grinder many moons ago while wearing Kevlar gloves, something Lee Valley tools was pushing for just such power tool usage. Index finger of the glove just barely touched the wheel which YANKED it off my hand as I felt the pull and whipped my hand towards myself. First two fingertips were torn right apart. Would have ruined my fingers. And that was just a 1/4 horse motor with a 6" grindstone. Imagining what a bigger tool might do, faster, made me toss what was left of the gloves and swear off ever buying such a stupid thing again. Reminds me of the story of the death of Isadora Duncan. Scarf caught in a sports car wheel... Or the advice of that clothing designer in The Incredibles - no capes. Bits of cloth can get you killed.

[T-Rex]

Good for you, learning the hard way. It sucks, but it's a necessary evil and the only real way danger imprints to our brain.

Gloves do not belong ANYWHERE near rotational machinery. The same goes for loose articles and a distracted operator.

2yrs ago, one of our mechanics was using a run of the mill, 1/2hp, hand drill. He was wearing a pair of the flexible, rubber gripped gloves. He took his hand off the drill's side handle to guide a 4' long bit into a pipe. Gone are 2/3's of his ring and pinky fingers! It happens that quick.

I use a pair of extra long, needle nosed pliers, to remove any swarf and stringy bits.

[John_TX]

Ah, okay - Kevlar/mechanic's gloves crossed off the list.

[Samson1044]

are you using a live center , that will often help with chatter when you have a long piece of stock sticking out of the chuck.

While an aggressive chipbreaker on the insert is very useful it doesn't always work like you want when making lighter cuts so getting the strings is just a pain you have to deal with. Chatter could come from several things , improper tool alignment , tool geometry , feed rate , lathe speed. Generally the more difficult metal that work harden require higher feed rates as opposed to the chuck speed , run the chuck around 300 RPM and play with the feed rate till you get it figured out. As for tool geometry , if you are making light cuts under .015" you are you to want the tool to be really sharp , a lot of inserts don't come this way. A radius isn't bad so long as its not real big. If you are making you final light cuts a piece of sharp Rex-95 works great with the RPM around 100.

The chatter you are getting on the parting tool will get you in trouble QUICK , if you are to aggressive with the feed the stock will try to "climb" over the tool. When i have to use HHS for parting I grind a very aggressive breaker in it to allow for a sharper cutting edge , get your tool square to your part then lower the tool about 1/4 turn on the tool holder , this will let it cut a little easier and not rub at all. Run your chuck and feed rate as slow as possible and have you hand on the cross slide handle ready to back it out if it starts to bind , when a parting blade binds and snaps off it can shoot pieces of blade everywhere and shoot it into your face.

[Samson1044]

If you don't have any Rex shoot me a message with your address and i'll send you a couple pieces.

[John_TX]

are you using a live center , that will often help with chatter when you have a long piece of stock sticking out of the chuck.

I do have a live center but I only have 4 to 5 inches of 1.75" bar sticking out from the chuck.

While an aggressive chipbreaker on the insert is very useful it doesn't always work like you want when making lighter cuts so getting the strings is just a pain you have to deal with. Chatter could come from several things , improper tool alignment , tool geometry , feed rate , lathe speed. Generally the more difficult metal that work harden require higher feed rates as opposed to the chuck speed , run the chuck around 300 RPM and play with the feed rate till you get it figured out. As for tool geometry , if you are making light cuts under .015" you are you to want the tool to be really sharp , a lot of inserts don't come this way.

I did find my compound slide was not square to the work piece - it was off maybe a degree. I used a machinist's square against the stock and along the parting tool and discovered the cutting edge of the insert was touching the work head-on and not at a slight rake, no wonder it was chattering . Got that squared away, slowed the chuck speed down to 360, used a little cutting oil and we were going to town. I was playing with different feed rates along with chuck speed so I think I have things figured out much, much better now. An increased feed rate with a sharp insert made some smooth cuts.

The chatter you are getting on the parting tool will get you in trouble QUICK , if you are to aggressive with the feed the stock will try to "climb" over the tool.

You should have seen the show when I had the cross slide feed on with the parting tool. Note to self, something else not to repeat.

[propeine]

are you using a live center , that will often help with chatter when you have a long piece of stock sticking out of the chuck.

While an aggressive chipbreaker on the insert is very useful it doesn't always work like you want when making lighter cuts so getting the strings is just a pain you have to deal with. Chatter could come from several things , improper tool alignment , tool geometry , feed rate , lathe speed. Generally the more difficult metal that work harden require higher feed rates as opposed to the chuck speed , run the chuck around 300 RPM and play with the feed rate till you get it figured out. As for tool geometry , if you are making light cuts under .015" you are you to want the tool to be really sharp , a lot of inserts don't come this way. A radius isn't bad so long as its not real big. If you are making you final light cuts a piece of sharp Rex-95 works great with the RPM around 100.

The chatter you are getting on the parting tool will get you in trouble QUICK , if you are to aggressive with the feed the stock will try to "climb" over the tool. When i have to use HHS for parting I grind a very aggressive breaker in it to allow for a sharper cutting edge , get your tool square to your part then lower the tool about 1/4 turn on the tool holder , this will let it cut a little easier and not rub at all. Run your chuck and feed rate as slow as possible and have you hand on the cross slide handle ready to back it out if it starts to bind , when a parting blade binds and snaps off it can shoot pieces of blade everywhere and shoot it into your face.

This is going to sound counter intuitive but I always parted in back gear until I started cutting 17-4. For whatever reason with an 0.060 parting blade it cuts significantly better at ~300 rpm even with a parting blade. I blew up one blade completely cutting @80 rpm. At 80 it would climb and chatter, then climb and cut until the thin little blade would blow up. Slower feed rates and it work hardened too much, faster rates would skip and then cut. Little bugger was razor sharp too. A little kerosene helps too if you're careful with it.

[curtistactical]

When I started out years ago with a small Atlas lathe I would just stick the bar in the cut off saw and cut the baffle off that way instead of using a parting blade. With a cut off blade it all comes down to rigidity of the machine, there is a lot of force involved there. Just food for thought but I never liked using a cut off tool on a small lathe, you can pick up a small cut off saw at Harbor freight for around $200.
Joe

[John_TX]

Actually when it's time to part the cone off, that's no problem, there's only half an inch or so left. I have a horizontal bandsaw that I've been using to cut off my blanks to chuck up. Thanks for the idea though!

John

[Hard_ware]

Sliced my thumb starting to pull stainless steel wire made when turning down the stainless.
Very thin wire, went to pull it and zip right thru the skin and blood on the lathe, a little black tape and back to work.
Then I used some piers to pull it loose it was pretty stout, no way I could have pulled it off.
Another lesson of what not to do

[John_TX]

Good grief - I started this can in February . Well, it is finished as of this afternoon, I thought I was only working on this project for five or six weeks. It was a challenge and I learned so many things about machining, my hat is off to those who can precisely follow a diagram and have a lathe that is as good or better than the operator and get it right the first time. Even with my digital read out on my Griz gunsmith lathe I was floundering around at times.

Bottom line is I think I did fairly well for a newbie lathe operator and I have an operational finished product . It wasn't an easy process but the result makes it all worthwhile and I learned so much.

Performance is quite good, I can shoot 200 grain subsonic ammo (this rifle is chambered for 300 Blackout) with no hearing protection, it's not much louder than my .22 can but has a little sharper report. Supersonic ammo will be probably need hearing protection.

This guy is no lightweight 2 pounds 15 oz (or 1.331 kg) but at least the gun balances very well.

I tried to embed a couple of pictures of the can but the forum software says It was not possible to determine the dimensions of the image. Please verify that the URL you entered is correct. Sorry forum software, the URL is correct, it's my website. Here's the links:

http://gallery.janeandjohn.org/Gun-stuff/300Blackout_a
http://gallery.janeandjohn.org/Gun-stuff/300Blackout_b

[curtistactical]

Congratulations on your first completed can. Just keep doing lathe work and it will all become second nature to you eventually. I still enjoy machining even after making a living at it for most of my life.

[John_TX]

Thanks Joseph! This is actually my second can, the first one was the usual .22 version most everybody starts with. I liked working with a larger can compared to the .22, but stainless was a bit of a challenge over the .22 can.

One real problem with my Griz lathe I discovered was the steady rest wasn't large enough for this barrel. I had to pull out the bearing arms to where the thumb adjustment was inoperative, really complicated my setup job.

[T-Rex]

John,
Glad to see you made it out alive

I'm not sure of your final dimensions, but:
A 1.5"x10" rod of 416 weighs 4.95lbs
If your can weighs 2.94lbs, then you've only removed 40%.

You should be able to remove material, gain volume, and increase suppression.

[a_canadian]

Looking at his picture above showing cone and spacer I doubt only 40% of the material was removed. Looks closer to 75% ballpark. My guess would be a faulty scale weighing the finished can. Probably not giving accurate numbers at low weight. A decent digital kitchen scale can often deliver good numbers, as they're calibrated for lower weights.

[John_TX]

John,
Glad to see you made it out alive

It was a close call a couple of times, I discovered you cannot successfully thread at 200 rpm (don't ask!) That was a big oops that ruined a blank and hurt what little pride I had left in my craftsmanship but I kept plodding along......

I'm not sure of your final dimensions, but:
A 1.5"x10" rod of 416 weighs 4.95lbs
If your can weighs 2.94lbs, then you've only removed 40%.

You should be able to remove material, gain volume, and increase suppression.

I weighed it using a digital scale that will measure down to the gram. My can is larger that that, it's 11" long overall (the tube itself is 10.50") and stepped down in diameter. I started with 1.751 diameter and 0.12" wall stock and turned it down to 1.710, then 1.690, and finally 1.670. The spacers are very light, the cones are probably nominal size and weight. I thought the tube was 316 stainless but it's 304. I'm looking at my invoice for the 1.750 round bar for the cones and my 11" piece weighed 7.59 pounds (and $35.)

The design criteria was to be able to use it on my 300 blackout and my .308 Bushy (I can make a steel plate move and ring at 500 yards with the .308.) The can is really designed for the higher pressures of the .308. Come to think of it I need to try it on my Bushy.

No doubt an experienced machinist with a great can design could produce a state of the art can, but that ain't me. I'm just thrilled to have a finished product. I want to give everybody here a big thank you for helping this newbie, it's really appreciated. -> John <-

[vaeevictiss]

since were on the topic of cutting yourself while machining ill tell ya an end mill not even in motion has cut me far worse than any swarf has. I was holding on to the end mill holder as i was unscrewing it from from the machine. So i was simultaneously lightly pulling down. Well, my hand slipped and instinctively i tightened up my grip...bad idea. It was nearly painless.

I looked at my finger and saw a little blood...ok thats not bad...then it started flowing. I ran from the machine to the sink leaving a trail of blood the whole way. put it under cold water to try and slow it down and the sink just filled with red water faster than it could drain. I was freaking out pretty bad lol. Once it slowed down i curiously wanted to see how deep it was so i gently pulled the cut open and it was REALLY deep. Probably needed stitches but i ended up using my usual method of cut repair. wrap a paper towel around it and electrical tape over that.

Over the next couple days it hurt bad...like it was throbbing to the point where every throb felt like hitting it with a hammer.

so yea, now i just hold the holder and dont pull down with it.