materials for baffles..need some feedback

[cjacobs58190]

working on my baffles since my stamps just came back. I have machined my blast baffles out of 17-4 stainless in a 60 degree cone pattern with a 3/4in skirt/integrated spacer and it has been a total pain to turn. Im using a minilathe 8x16 1hp lathe and it just does not have the rigidity to turn that hard of an alloy. I would like to stick with stainless for the rest of my baffles but want some longer term durability to them as well. I went with the 17-4 blast baffles for the erosion resistance and strength.
Would a 304 stainless work for the remaining baffles or would another metal work for the following baffles. Have two cans i will be doing both for semi-auto rifles. both 30 cal cans one 8in oal and the other 10in oal. 8in will be used on a 16in ar in .223 and 300 blackout. the 10in is 30cal. used on ar 16in barrel in .223, 8in 300 blackout shooting supersonics and sub and also on 20in 308 boltaction shooting supers and subs.
Trying to find something easier to machine that wont chatter so much when doing boring operations on cutting the inside cones as well as having to take shallow passes. running indexable carbide inserts and koolmist. I dont have flood coolant capability, have been running the coolmist heavier keeping close to material and tool head.

[propeine]

working on my baffles since my stamps just came back. I have machined my blast baffles out of 17-4 stainless in a 60 degree cone pattern with a 3/4in skirt/integrated spacer and it has been a total pain to turn. Im using a minilathe 8x16 1hp lathe and it just does not have the rigidity to turn that hard of an alloy. I would like to stick with stainless for the rest of my baffles but want some longer term durability to them as well. I went with the 17-4 blast baffles for the erosion resistance and strength.
Would a 304 stainless work for the remaining baffles or would another metal work for the following baffles. Have two cans i will be doing both for semi-auto rifles. both 30 cal cans one 8in oal and the other 10in oal. 8in will be used on a 16in ar in .223 and 300 blackout. the 10in is 30cal. used on ar 16in barrel in .223, 8in 300 blackout shooting supersonics and sub and also on 20in 308 boltaction shooting supers and subs.
Trying to find something easier to machine that wont chatter so much when doing boring operations on cutting the inside cones as well as having to take shallow passes. running indexable carbide inserts and koolmist. I dont have flood coolant capability, have been running the coolmist heavier keeping close to material and tool head.

303 would be much easier to turn than 304. The 400 series possible as well. Good sharp HSS might would better than carbide on that small of a machine as well.

[T-Rex]

I turn 17-4, on an Atlas 6x18, all the time.
While I can't take large bites, it cuts.
I turn it in the annealed state with HSS and some coolant.

Find a glass blower or someone with a pottery kiln. Both usually have digital temp controls and can heat treat the finished pieces in no time. The type of people who have these hobbies are generally very friendly.

[Capt. Link.]

Good sharp HSS might would better than carbide on that small of a machine as well.

+1 Propeine I been preaching that since day one.

I have tool-bits that I first made as a apprentice machinist plus three decades ago.Most people who use carbide with a under 14" lathe will never see long tool life or a good finish.Carbide death is caused by vibration,interrupted cuts,and less than ideal load and cooling.These are the exact conditions the hobbyist faces every day.

By some S7 or M35 cobalt HSS tool bits and a slow speed 1X8 inch grinder.Make the classic tool bits seen in a older machinery bible or the Adel series of books and switch to 416 stainless.A cutting oil dipped brush is all that's needed.

PS:Please grind a chip breaker if you like fingers attached!

Good luck

-CL

[cjacobs58190]

I had some smaller HSS blanks in my box at home. I made some LH cutting tools and a inside boring bar last night and made some test cuts with them. They cut pretty nice. still having some chattering with the inside boring bar but not the same I was getting with the brazed carbide cutter. i figure its the size of the blanks i used with a larger blank i can grind the tool head so it sits a bit higher with the tooling sitting lower in the tool post put less of an angle on the tool post.
Thanks for all the input.

[T-Rex]

As the Capt hinted to:
If you have a small grinding wheel for a Dremel, you can sculpt a nice chip breaker on the tip.

[BinaryAndy]

304 certainly wouldn't be any easier. I'd rather work with 17-4. 303 is a lot nicer, and as Capt. Link mentioned, 416 is pretty easy. Neither is going to hold up as well as 17-4 though.

Sharp HSS is a good idea, but for some reason I've always had better luck with the ridiculously sharp carbide inserts like some of the ccgt inserts intended for finish cuts on titanium and super alloys.

[partsguy22]

Sharp HSS is a good idea, but for some reason I've always had better luck with the ridiculously sharp carbide inserts like some of the ccgt inserts intended for finish cuts on titanium and super alloys.

Ive done this as well however be warned you will get ridiculously sharp long stringy chips

[Samson104]

if you do not intend on welding them then 416 , 410 would be alot easier to cut than any of the 300 series stainless.

In all honestly unless you are running a full auto , do a lot of mag dumps or shooting on a really short barrel , after the first 3 baffles you can use 7075 series aluminum for baffles , even if you make then twice as thick as the SS ones they will be lighter and WAY easier to machine.

[Capt. Link.]

if you do not intend on welding them then 416 , 410 would be alot easier to cut than any of the 300 series stainless.

In all honestly unless you are running a full auto , do a lot of mag dumps or shooting on a really short barrel , after the first 3 baffles you can use 7075 series aluminum for baffles , even if you make then twice as thick as the SS ones they will be lighter and WAY easier to machine.

I think using aluminum is a poor choice for economic reasons.You really need all surfaces hardcoat anodized as the home done stuff is not nearly as good.The use of a high temp paint over that is a good idea as well.I know only one place that can do type 1 hardcoat on a weapon and its not cheap.The coatings are important because of the nitric and sulfuric acids present in burned powder residue.Its important to re-coat surfaces from wear as well which is not difficult but takes time.You can turn very thin 400 series baffles and heat-treat them for lightness and strength saving much time and money in the long run.You need to evaluate what resources you have as part of the material selection.
-CL

[BinaryAndy]

Sharp HSS is a good idea, but for some reason I've always had better luck with the ridiculously sharp carbide inserts like some of the ccgt inserts intended for finish cuts on titanium and super alloys.

Ive done this as well however be warned you will get ridiculously sharp long stringy chips

That all depends on the material, and the inserts. I use Mitsubishi CCGT inserts, I think the grade is VP10rt, on the small lathe. They have a sharp corner and a much better chip breaker than I could grind myself, so they generally make tiny chips, even on 316.

Most of the insert grades meant for stuff like inconel and titanium are quite sharp and do a decent job breaking chips.

[alordnapa]

I know it's slightly off-topic, but it sounds like a lot of you have strong feelings about Carbide vs HSS tools. My anemic little Mini-Lathe has real trouble using a cutoff tool on most materials, but I use mostly aluminum: Steel goes to the chop-saw. Is HSS a "better" cutting tool for aluminum than a carbide too? Cut off accuracy and finish are usually not a major consideration, but having the tool stall my lathe is an irritation and usually totally FUBAR'S the part. One guy on Youtube shows his cut-off technique by running his lathe backwards and installing the cutting bit upside down, to avoid chip loading. Is this a solid idea?

[cal50]

304 is "gummy" and clings to cutting tools, carbide anyway.
The non-magnetic 300 series SS is great if you are making parts for food processing or rust free applications but 17-4 is the better pick for baffles IMHO.

17-4 is not that bad to machine with the right tooling.

[cjacobs58190]

little bit of an update. i picked up some 1/2 hss blanks and ground some cutting tools out of them. was able to make a nice turning and facing tool as well as getting an inside boring bar made. took a bit of playing around getting the rake and relief cut right on the boring bar, im still getting the hang of grinding my own tools. used my bench grinder then my dremel with a good stone to finish up the the edges. polished the edges on a diamond stone to put a finished edge on them. Probably overkill but they cut nice. Have to use a lot more cutting lubricant. I turned down my speeds and feeds from running carbide inserts and it has made a huge difference when cutting the 17-4. i was surprised how much easier the hss cutters are cutting than the carbide. much smoother cuts and less chatter, not sure if its due to the more rigid tool or the edge. im running rustslick coolant using a slow drip gravity feed using some old small copper pipe and a quarter turn valve from an old metal wd40 can. i tried some pieces of 304 stock and it was terrible to turn, chattered like crazy was gumming the cutting edge up chip didnt want to break. much happier with the 17-4. Thanks for all the input. I cant wait to get these baffles all done and get these cans out on the range.

[T-Rex]

You definitely did not go overboard with your sharpening method. You want that HSS to be SHARP!
There will be a very noticeable margin for rake angles. Keep messing around and take notes.
Coolant makes a mess, but has many benefits for the little lathes.
Going off the top of my head, I believe I would have the rpm's set in the 200 range, for a 1.5" OD blank of 17-4, with HSS.
Your speeds and feeds will be much lower than if you were using Carbide, especially if you're on a small machine.


alordnapa:
At home, I run an Atlas 6x18. I have no issues using carbide on Al. Although, I'm not taking 50thou passes.
I have HSS and a carbide parting tool. Both seem to work about the same, on a small machine.
I, too, will use the band saw and make manageable pieces, before chucking in the lathe.

Once you've learned the machines limits, stay within and make them work for you. Sure, it may take a bit longer, but it's less time than having to start over.

[L1A1Rocker]

Sharp HSS is a good idea, but for some reason I've always had better luck with the ridiculously sharp carbide inserts like some of the ccgt inserts intended for finish cuts on titanium and super alloys.

Ive done this as well however be warned you will get ridiculously sharp long stringy chips

I have read, though I have not done it myself, that you can use a dremel with a cut-off blade to carve a chip braker notch.