Learning to sharpen HSS lathe bits......A lesson in futility.....

[TheOldHokie]

Thanks to everyone for helping me out.

After some "intensive research" I have decided to "try" HSS inserts.

A few things that I have noticed/realized/learned.

My machine is pretty small as compared to many of yours which puts me in a "weird category" that is somewhere between "mini hobby lathe" and "Big 'Ole Industrial lathe"

One thing that struck me as odd, just this weekend, was that all of the tooling that came with the machine, some 10+ years ago, was HSS.....I literally have "hundreds" of HSS blanks, but the Old Man did not have even one "carbide" bit.

Hmmmmmm.........So maybe/probably the Old Man that used it before me "knew something"??????.....He did have a massive work shop.

Long story short.....I found a company that makes HSS inserts, and so I ordered a LH and RH tool, and a few inserts.

At 10+ bucks per insert, they are not cheap, but I am hoping that they are a good choice for my machines size, capability and my experience level.

They get great reviews on the "machinist sites" that I have been perusing, and apparently they are "easily" and quickly sharpened on flat stone, so they last a long time.

I have also decided to "not give up" on my "lathe bit grinding", but just "takees my time" and practice, but am keeping my "options open" for carbide tooling as well.

I will post my results when I get a chance to try them out.

The size of your lathe is not the issue
There are a gadzillion small lathes using solid, brazed, and/or indexable carbide. You simply have a learning curve to climb.

Dan

 

[Lil Foot]

Another thing to keep in mind with carbide tooling; they resist wear far better than HSS, but they don't like interrupted cuts.
Carbide is brittle.
Use light cuts in interrupted situations.

Worst scenario I have found is turning a flame cut disc of steel round.
It is interrupted, uneven, out of round, has slag & hard spots; none of which are conducive to long insert life.
Once you are below the bad stuff, you are golden.

 

[TheOldHokie]

Another thing to keep in mind with carbide tooling; they resist wear far better than HSS, but they don't like interrupted cuts.
Carbide is brittle.
Use light cuts in interrupted situations.

Worst scenario I have found is turning a flame cut disc of steel round.
It is interrupted, uneven, out of round, has slag & hard spots; none of which are conducive to long insert life.
Once you are below the bad stuff, you are golden.

All true. And like most things understanding the process helps to maximize results.

Interrupted Turning

Turning is a game of fundamentals more so than other machining operations such as milling, drilling, or grooving. There is really nothing fancy about turning.

www.canadianmetalworking.com

Dan

 

[Yooper]

Thanks to everyone for helping me out.

After some "intensive research" I have decided to "try" HSS inserts.

A few things that I have noticed/realized/learned.

My machine is pretty small as compared to many of yours which puts me in a "weird category" that is somewhere between "mini hobby lathe" and "Big 'Ole Industrial lathe"

One thing that struck me as odd, just this weekend, was that all of the tooling that came with the machine, some 10+ years ago, was HSS.....I literally have "hundreds" of HSS blanks, but the Old Man did not have even one "carbide" bit.

Hmmmmmm.........So maybe/probably the Old Man that used it before me "knew something"??????.....He did have a massive work shop.

Long story short.....I found a company that makes HSS inserts, and so I ordered a LH and RH tool, and a few inserts.

At 10+ bucks per insert, they are not cheap, but I am hoping that they are a good choice for my machines size, capability and my experience level.

They get great reviews on the "machinist sites" that I have been perusing, and apparently they are "easily" and quickly sharpened on flat stone, so they last a long time.

I have also decided to "not give up" on my "lathe bit grinding", but just "take my time" and practice, but am keeping my "options open" for carbide tooling as well.

I will post my results when I get a chance to try them out.

After reading this a bell started ringing in my head. Some years ago I purchased a set of HSS lathe bits and inserts. So I opened up the the drawer and there they were. Forgot that I even had them!

 

[Yooper]

So everybody understands what we are dealing with, the images are the speeds, hp and feeds that our lathes have. Yup, a whopping 1/4 hp on the original motor! If you want to put on a larger motor you will run the risk of wiping out the aluminum (Zamack) gears that drive everything except the quick change gears.

As an example of what I use on my 15 x 50 lathe with a 7-1/2 hp motor turning a 2" x 1045 round, I'll take between a .050 to .100 depth of cut at 500 rpm with a .010 feed rate to get a beautiful finish. Might drop the feed rate to about .005 on the final cut and up the rpm to 750 to even get a better finish. For 1" steel I'll be up at 1000 rpm. Might be able to take a .005 depth of cut with the Crafstman lathe but I don't think it will even handle this. And carbide does not like that depth of cut.

 

[TheOldHokie]

So everybody understands what we are dealing with, the images are the speeds, hp and feeds that our lathes have. Yup, a whopping 1/4 hp on the original motor! If you want to put on a larger motor you will run the risk of wiping out the aluminum (Zamack) gears that drive everything except the quick change gears.

As an example of what I use on my 15 x 50 lathe with a 7-1/2 hp motor turning a 2" x 1045 round, I'll take between a .050 to .100 depth of cut at 500 rpm with a .010 feed rate to get a beautiful finish. Might drop the feed rate to about .005 on the final cut and up the rpm to 750 to even get a better finish. For 1" steel I'll be up at 1000 rpm. Might be able to take a .005 depth of cut with the Crafstman lathe but I don't think it will even handle this. And carbide does not like that depth of cut.

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Yikes!!!

Dan

 

[Lil Foot]

After reading this a bell started ringing in my head. Some years ago I purchased a set of HSS lathe bits and inserts. So I opened up the the drawer and there they were. Forgot that I even had them!

View attachment 135661 View attachment 135662
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Been there, done that!
There have been a couple times when I thought "Boy, XYZ tool would really come in handy".
Then I think, "that sounds familiar", and I dig in a drawer somewhere, and there is my XYZ tool.
It is hell getting old.

 

[Runs With Scissors]

After reading this a bell started ringing in my head. Some years ago I purchased a set of HSS lathe bits and inserts. So I opened up the the drawer and there they were. Forgot that I even had them!

View attachment 135661 View attachment 135662
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Hahahah....well look what just showed up in the mailbox yesterday.

 

[Runs With Scissors]

Been there, done that!
There have been a couple times when I thought "Boy, XYZ tool would really come in handy".
Then I think, "that sounds familiar", and I dig in a drawer somewhere, and there is my XYZ tool.
It is hell getting old.

Its even worse, when I go buy the tool, then find the original when I go to put the duplicate away....



Very analogous as to why I have 77 rolls of teflon tape ( all of which have 4 inches used), but I can never find one when I need it.

 

[DustyRusty]

Its even worse, when I go buy the tool, then find the original when I go to put the duplicate away....



Very analogous as to why I have 77 rolls of teflon tape ( all of which have 4 inches used), but I can never find one when I need it.

You need to be better organized. Just leave things where you last used them, don't do any cleaning, and when someone says "what a cluttered mess" you can reply, "yes, but I know where everything is". I only have to ask the wife where she moved it when I can't find it. Today I get even. I left a new to me implement in the space where she parks. That should get her going for at least an hour or two.

 

[TheOldHokie]

Its even worse, when I go buy the tool, then find the original when I go to put the duplicate away....



Very analogous as to why I have 77 rolls of teflon tape ( all of which have 4 inches used), but I can never find one when I need it.

Pair of VT cloth work gloves. Nothing special but I wore them snd then could not find them.

Several days later found the right one on the ground. Figured the dog had carried it off. Picked it up and put it away for "safe keeping*.

Several days later found the left one on the ground just like the other but now could not find the right one.

Today I was folding laundry and found the right one under some towels my wife had placed on the dryer. The two have been reunited and I am once again ambidextrous but who knows how long that will last....

Dan the Forgetful

 

[Yooper]

Hahahah....well look what just showed up in the mailbox yesterday.






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Excellent choice! The tool on the top will quickly be your favorite. Will both face and turn.

 

[John T]

I would rather be spending my time making shit, rather than burning my fingers and swearing......

I remember going through the same thing when I had my lathe...
I finally got the hang of it... but I did buy some cheap carbides and they worked good also...

but every once in a while you need a weird shape and HSS is the ticket..

Heres a pro tip....

If you start to burn your fingers, Pour some beer on them.

 

[torch]

Another thing to keep in mind with carbide tooling; they resist wear far better than HSS, but they don't like interrupted cuts.
Carbide is brittle.
Use light cuts in interrupted situations.

A real nice alternative is M42 -- 8% cobalt. Takes the heat almost as well as carbide, handles interrupted cuts like HSS. Since it's sharpened to the same angles as HSS, it's a great option for smaller, less powerful and less rigid machines. Carbide is so brittle it can't handle much (if any) rake; consequently the cutting tip pressures are very high. But M42 is tough and has no problem with positive rake so tip pressures are much lower.

 

[PoTreeBoy]

I remember going through the same thing when I had my lathe...
I finally got the hang of it... but I did buy some cheap carbides and they worked good also...

but every once in a while you need a weird shape and HSS is the ticket..

Heres a pro tip....

If you start to burn your fingers, Pour some beer on them.

Finally, a use for Lone Star. Just don't lick your fingers.

 

[Lil Foot]

Finally, a use for Lone Star. Just don't lick your fingers.

I was thinking Corona...

 

[lugbolt]

I use, and have used, HSS on almost everything (particularly when turning aluminum and magnesium). It's cheap, and I can grind it to whatever shape I want, depending on the desired surface finish. Grinding it is easy, once you know what angles (and radii) to use.

My machine is an older Atlas 12x36 (rebranded as "Craftsman"), 3996 I believe. They are not known for "production quality", rather a "homeowner" lathe. That being said, the compound is about as rigid as a wet noodle and when turning some steels, it tends to chatter-which WILL break carbide tooling.

also most of the tasks I've been asked to do with the lathe don't require but .001 tolerance, which is fine for this machine. If someone wants it better, they'd be wise to carry it elsewhere-as the little atlas just isn't "that" accurate.

I find using the lathe sort of mildly therapeutic, relaxing in a way. It's work but at least it's easier work than physically crawling around under dirty customer's tractors and lawn mowers. Also kind of brings back memories of a lot of things. I went to school to become a machinest and never followed through with it-against my dad's wishes. Dad was a journeyman at the railroad, his last years prior to retirement machining turbocharger parts for the EMD's.