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View Full Version : Wow, I'm getting into HSS.



383 240z
08-03-2011, 09:46 PM
Buddy of mine (the guy who convinced me to buy a mill and lathe) showed up yesterday with a present for me a handfull of HSS cutting bits. I spent some time grinding them up on my cheap ass Delta grinder, after watching the tublicain how to videos. I can tell you that you guys who were pushing me towards HSS cutters and to leave my carbides on the shelf. Thank You! they grind easy, I can set them to what ever radius I want and DAMN they are cheap!! I dont know if the Enco ones are any better or worse than the name brand ones, but they are working for me. I'll be grinding up some for the 2 projects I have on my plate now, the floating tailstock die holder and the brake master adapter I have posted about a few days ago. Keith

Carld
08-03-2011, 09:57 PM
Congratulations, you have discovered how useful HSS is. I will suggest you buy an American made brand and I prefer HSS Cobalt because of it's wear resistance. In fact it makes an ideal threading cutter because it resists wear and chipping.

The only time carbide is really good is for production work or for hard to machine material. For machine work at home HSS is just fine and most the time best.

You can grind form cutters in HSS much easier than you can carbide. HSS don't chip easy while carbide does and when the carbide chips you have to grind a lot of it to get the sharp edge back. With HSS you seldom have to grind much off to get the edge back.

Black_Moons
08-03-2011, 10:12 PM
Hey, Id never say leave the carbide on the shelf. But DEFINATELY try the HSS :) Learn when HSS is better, because it really is for a lot of jobs!

Some jobs still do better with carbide. Like roughing through nasty rusty, scaley steel, Or just roughing lots of steel period.

For finishing, HSS can be just whats needed. As well as for custom forms tools, threading tools, And just tools you need to make for the job at hand. Who needs a $100 speciality carbide tool when your only making 5 of these things and may never use the tool again?

You can allways regrind a (no longer used) HSS tool into a diffrent HSS tool too. Even if its totaly diffrent shape, all you lose is maybe 1/2" of length if you have to cut it off and start fresh.

gwilson
08-03-2011, 10:24 PM
The truth is,MOST home shop lathes aren't even able to use carbide to its full potential. Don't be seduced into thinking you have to buy a $200.00 holder and inserts. I do just about everything with HSS. It will get much sharper than your carbide inserts,and will stand up to interrupted cuts better. Stop the steel while threading with a carbide bit,and it will usually break the tip off the bit. By usually,I mean MOST of the time. If you get in a jam,and need time to think,don't be threading with carbide.

The time I use carbide is when I am doing something like taking a truing up cut on a large cast iron face plate. C.I. will really wear the edge off your HSS tool. PARTLY because hardly any lathes are now made to turn SLOW enough.In the old days,they made do with plain CARBON steel tools,because they had very slow speeds available. They used to drill holes in armor plate with plain carbon drills and soapy water.

I have my 16" lathe geared down to go 30 RPM. It will swing 24" in the gap. I wish it would do 10 RPM or less for big work. It would only go down to 60 RPM when I got it. That's ridiculous for a lathe that big.

I have found Chinese HSS to be a little harder than USA HSS. Also,a little more BRITTLE from either the hardness,or the chemistry. It will work fine for home shop use. I use it,along with the old USA made HSS I have found.

HWooldridge
08-03-2011, 10:30 PM
I work in a production machine shop; we have about 55 lathes in all sizes and types with lots of high spindle speeds, multi-axis machining and holes drilled down to .006". Over the entire shop, we use about half carbide and half HSS. HSS is very good on aluminum, brass and leaded steels - especially when a good finish is needed. I have a home shop and do short run machining for a variety of customers; I also use HSS regularly because it is easier to sharpen or grind to a particular form.

Forrest Addy
08-04-2011, 01:34 AM
Thank you lord!! I've been preaching the use of the appropiate tool for the appropiate work since I discovered machnist's message boards. I've been frustrated by the carbide mind set (it's gotta be good, it's what the big dogs run) where expensive tooling is selected and under-utilized on inadequate equipment even when the right HSS tool is in the drawer.

My years of urgings have centered around using carbide when carbide works best, HSS when it works best, and the wisdom to know which and when.

Willy
08-04-2011, 01:57 AM
...............

My years of urgings have centered around using carbide when carbide works best, HSS when it works best, and the wisdom to know which and when.

Well said Forest.
I too have always wondered what the infatuation was with carbide, especially for those just getting started.
That, and the desire to use the biggest dang tool bit that can conceivably be made to fit in the tool post, usually so darn huge it gets in the way.

Mom always used to say..... knowledge is knowing that a tomato is a fruit...wisdom is not using them in a fruit salad.;)

DATo
08-04-2011, 04:15 AM
TOLD YA !!!!! *LOL*

"Empirical evidence is the final arbiter of all argument." - DATo

I almost never use carbide unless it is absolutely essential for exactly the reasons you describe. When you've ground the HSS bits down to nubs you can still braze them to boring bars and get even more use out of them and a 5/16 C-L HSS bit only costs about $3 from MSC. The next thing I need to do is ween people off of inserts and insert holders.

EDIT: Stick with quality HSS though. They don't cost that much to begin with. As stated above a Chicago-Latrobe 5/16 bit is only $3 and should last you a very long time. We bought some cheapies from China for our summer shop classes and they worked well enough for the class but when I attempted to use them in the main shop under normal shop conditions they were a disaster. (In the class the students only cut CRS and aluminum and even the CRS required touching up the bits from time to time.)

PixMan
08-04-2011, 06:59 AM
TOLD YA !!!!! *LOL*

"Empirical evidence is the final arbiter of all argument." - DATo

The next thing I need to do is ween people off of inserts and insert holders.



LOL. You won't get me to do it, I'm still nursing. ;)

Why all the carbide hate? Like others have said, both HSS and carbide insert tooling have their place, and it is the wisdom to know how to choose and apply the appropriate tool that is so elusive yet so valuable.

Some people simply will not ever bother to learn how to grind a HSS tool and use it at a proper speed. Those people will never understand the joy of creating a specific geometry to control a chip, get a great finish, or turn a cool feature on a part. Those who think carbide insert tooling is the path to nirvana never get to learn how a slight change in grind can transform a tool from chatter and galling to controlled chips and mirror finishes at lower, safer speeds. Then the carbide insert fanboy tries to run a Rex AA tool on 3" 304SS at 400rpm & .012" per rev and decides that HSS tooling just sucks. Blame the tool instead of the fool!

Others will never educate themselves about what modern carbide insert tooling is and what it can do for you. The Luddites will never understand how it feels to get done in 12 minutes that which took an entire afternoon with HSS. No question, it is a very daunting task to know what carbide tooling is out there, how to select it, apply it, and rationalize it's acquisition. More often, the wrong tool and application is employed and epic failure ensues. They use a large negative rake tooling on a 1" 9" flat belt lathe at 150 RPM on a 1/4" round and wonder why they got a horrible finish on a tapered part and a chipped insert. Blame the tool instead of the fool!

For me, it's 80% carbide, 19% HSS, and 1% carbon steel files, but I earned my stripes to be able roll this way. :D

Black Forest
08-04-2011, 07:01 AM
Maybe Mr. Addy should write a machinist's prayer along the lines of the Serenity Prayer.

Dear God,

Give me the courage to change the things that need to be changed.
The serenity to accept the things that cannot be changed.
And above all else the wisdom to know the difference.

Amen


Forrest's prayer could go something like this.

Dear God,

Give me the courage to use Carbide when its right.
The serenity to use HSS for the easy cuts.

And above all else the wisdom to know which is which.

Amen!

loply
08-04-2011, 07:28 AM
Hi folks,

If I can give my input as a relative newbie.

I bought a mini lathe about 6 months ago and initially purchased brazed on carbide tools.

I had immense trouble getting them to do anything - on reflection I believe this is because they are ground badly (very cheap) and in the early days the lathe was set up badly.

I tuned the lathe up a bit and reground/sharpened these cheap tools and they worked a lot better but were totally unpredictable, sometimes not working at all other times cutting like butter.

I then bought some 1/2" HSS blanks and ground a few tools. I found them much less 'dramatic', they seem to cut quietly and easily, and were a breath of fresh air.

However, in time I started to get annoyed because I spent ages grinding and sharpening them and they started to blunt quicker than I was happy with. Also, I eventually started to feel they too were unpredictable - sometimes cutting properly, sometimes not. Nothing more frustrating than being halfway through a 30 minute job and then you notice the tool is cutting funny because the edge has come off... Get the the oil stone again...

I then blew some cash on expensive carbide tooling and have not had any problems since - just simple, consistent, repeatable work. The boring bars in particular made life a lot easier (I bought 12mm and 5mm boring bars, which can fit into a 7mm or 13mm starting hole).

Having said that! I have now started looking again at my HSS bits, because I have chipped a few CCGT carbide inserts (never chipped a CCMT one), and when I finish building my new belt grinder it will make sharpening the HSS bits a lot quicker. Changing a carbide tip takes 60 seconds and doesn't involve removing the tool from the post, a lot easier than resharpening HSS.

All things considered, as a newbie, cardbide tooling makes life a lot easier in terms of reducing the human-error factor and making things 'just work'.

In time, with experience, I will hopefully reintroduce my HSS blanks when appropriate.

3jaw
08-04-2011, 10:14 AM
I'll throw my $.02 worth in this discussion.
I always start my students out on HSS. It takes a little longer to teach them how to grind a proper tool, but they learn what works and what doesn't and what it takes to create a good cutting edge. I only introduce carbide once the students have been in my class for a couple of school years or more. Also, I only have 2 lathes that can use carbide to its potential. The rest of them are belt driven South Bends which are great for learning but lousy for carbide.

I sometimes use a comparator when I show a student how to grind a threading tool. A half a degree isn't easy to see when using a thread center gauge but is is pretty obvious with a comparator.

Grinding a good cutting tool isn't a skill you're born with. It takes practice.

firbikrhd1
08-04-2011, 10:44 AM
About 20 years ago, when I had zero machine shop experience and first got a lathe and started learning, I bought some cheap Chinese carbide bits to get started. I didn't yet know how to grind HSS so the carbide bits were supposed to get me started. Fortunately for me they got me nothing but failure and I was forced to learn how to grind HSS. I started with a Diamond Tool holder which is probably the easiest to grind a HSS bit for, studied how the angles of that tool worked as they cut and learned to grind other bits from that. I've never been back to carbide. HSS has served my home shop needs so well that I have little reason to even consider giving carbide a try again. Those cheap bits were a blessing!

J S Machine
08-04-2011, 12:17 PM
Grinding a good cutting tool isn't a skill you're born with. It takes practice.

Correct.

I can make just about any tool cut. Don't discount carbide tools and toss them if you chip or break them. Some of my best carbide cutters are ones that were previously broken and the resharpened with a green wheel (silicon carbide).

gary350
08-04-2011, 12:31 PM
I have both HSS and Carbine cutters. They both have their place. There are certain jobs that work best with certain cutters.

quasi
08-04-2011, 01:04 PM
I prefer using H.S.S. with Cobalt in it, like M42. It stays sharp longer than regular H.S.S. Of course there is a downside to it, it is harder to sharpen.

My favorite H.S.S. is a bunch I bought from Princess Auto, it is marked "Tantung". It is really tough and hard to sharpen, but the edge really lasts. Proper grinding wheels really help for grinding H.S.S., I find a belt sander is fastest for rouging in the cutter.