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How long due lathe tools last?

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mickri

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#1
I was under the belief that tool bits were short lived and needed to be constantly replaced. That the constant resharpening of tools just wore then away. When reading through the thread on models for grinding HSS lathe tools I came across references where posters had said they had been using some tools for years. If that is the case I think that I have a lifetime supply of tool stock. I am sure that the answer to this question is it all depends. Looking for some feedback on the life span of HSS tooling.
 

JimDawson

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#2
I am sure that the answer to this question is it all depends.
Yup :grin:

I have burned up tools in seconds, and some special shapes I have been using for years without resharpening. Material, feed speed, and surface speed are the critical factors. I tend to be more careful with the special shapes and don't push them as hard.
 

Technical Ted

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#3
With reasonable use, common shaped tool bits for turning, boring, facing, etc. will last a hobbyist a very long time. Typically, resharpening only takes a very minor touch up. I use HSS 99% of the time and have been using the same bits for years.

To get this kind of life span you need to be aware of the proper feeds and speeds (most important is speed) for HSS. Keep your chips silver colored and if they start to turn blue you should back things down. With a good grade HSS you can even shoot for straw colored chips and get decent life.

Also, remember there are a lot of different grades of HSS. If they contain a nice amount of cobalt they are going to typically last longer. I've got some Chinese end mills I have to run much slower than some of my nice ones made in the good ole USA... there is night and day difference between them.

Ted
 

P. Waller

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#4
An insert carbide lathe tool used in commonly available aluminum alloys such as 6061 T6, 360 free machining brass and 12L14/1215 free machining steels will last for thousands of parts if not pushed to their limits of speed.
The same is true of HSS tooling, push it and it will fail quickly, if you baby it along a single tool may last for years, if you push it it may last for minutes as JD mentioned above.

ALL tooling decisions are a trade off between cycle time and tool life, if you have to make time on a job and the money is there for it just throw tools at it as needed, if a hobby then slow it down and the tooling may last for years.

As a side note turning slowly may not produce the desired finishes, this is another trade off, often turning a part as fast as possible will achieve an excellent finish at the cost of more frequent tooling changes.

To answer your question, how long tooling lasts is mostly your decision.
 

projectnut

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#5
Over the last 30+ years I have accumulated several hundred if not more HSS lathe tools. The 3/16" and 1/4" were inherited from my wife's grandfather. the 5/16", 3/8" 1/2" and 5/8" were purchased new. At the time I was buying them it was far cheaper to buy them by the box than on an individual basis. Thinking I would go through them in short order I purchased several boxes of each size. Depending on size there were between 50 and 75 pieces per box. In those days a box of 75, 5/16" tools was going for around $35.00. A box of 70, 3/8" tools was about $55.00. Prices today are nearly triple that.

To this day I've discarded very few. Some of the smaller sizes have been sharpened so many times they're getting close, but so far they still fit in the appropriate tool holders and still do the job. By in large they are ground in the standard AL, AR BL, BR, C, D, and E cutting profiles.
They seem to need only minor touchups from time to time. I would guess the vast majority are close to their original lengths. To minimize the amount of material being removed, and the time it takes at each sharpening I made a machine similar to the Accu-Finish II tool sharpener.

https://accu-finish.com/product/series-ii

The average tool can be sharpened in less than 2 minutes, and requires only a few thousandths of material to be removed.

There are also quite a pile of specialty profiles that have been made as one offs or get minimal use. Given the fact that I was able to purchase large quantities of the same size tooling for minimal prices I keep them in their original configuration rather than regrinding them to a new profile. Should I have to change profiles I'm sure the tools would be consumed quite quickly
 

P. Waller

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#6
Much like you I have worked non stop in machine shops for the last 30 years, haven't used a HSS lathe tool in the last 20 of them aside from the occasional end mill, what industry do you cater to that requires that much high speed steel lathe tooling?
 

mickri

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The accu-finish sharpener is interesting. I have thought of making a similar table for one end of my bench grinder. Thanks for the link.
 

Dabbler

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#8
|I've used up 2 or 3 HSS tool blanks in 40 years. Only in the last 2 years I've been using carbide insert tooling as a primary cutting option.

For roughing, I did buy one insert tool holder 37 years ago, and used up 6 corners since. I always reuse the corner, diamond honing it until I can fix it no more. I'm stingy. I hate to throw out things. Oh and the triangle used up inserts are saved for making brazed boring bars....
 

P. Waller

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|I've used up 2 or 3 HSS tool blanks in 40 years. Only in the last 2 years I've been using carbide insert tooling as a primary cutting option.

For roughing, I did buy one insert tool holder 37 years ago, and used up 6 corners since. I always reuse the corner, diamond honing it until I can fix it no more. I'm stingy. I hate to throw out things. Oh and the triangle used up inserts are saved for making brazed boring bars....
Fascinating, I scagged 3 different inserts in the last 3 days making these very small parts (110 of them), OD turning, threading, drilling then parting.
It was however about 2 minutes of spindle time per part, the tool changes took far longer then the actual machining.
A NC lathe that lacks a turret or gang tool capability is pretty much useless on a production job.

I can not even count the ways that I hate quick change tool posts, 5 tools per part, 500 manual tool changes in 3 days, this grows very old very quickly.
 

Dabbler

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#10
I never do more than one part... I take it you have a turret lathe! Well done! Nice work by the way...
 

mickri

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#11
I want to thank everybody. In the future I am going to strive for perfection in grinding my HSS tooling. Being just a hobbyist what I have now will last me a long time.
 

mikey

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#12
If you grind them well the first time and hone your tools lightly after every use they will last a decade or more and be sharp every time you use them.
 

projectnut

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#13
Much like you I have worked non stop in machine shops for the last 30 years, haven't used a HSS lathe tool in the last 20 of them aside from the occasional end mill, what industry do you cater to that requires that much high speed steel lathe tooling?
I have been retired for a little over 10 years. Most work now is repairing older machinery and hobby work. When I was working in a shop it was for a food company that designed and made it's own proprietary processing and packaging machinery. The most common materials we used were 316 stainless and 6061 aluminum. Our shop didn't do production work, but rather prototyping and modifying existing parts for better longevity and easier maintenance.

In those days HSS was the choice for almost all tooling. I learned to use and sharpen it and got good results so I tend to stick with it for most things. I do have some carbide tooling with most of it being the cheaper brazed tip style. I also have a few tools that use inserts, but since I already have more than enough HSS tooling that's what I use the most.

Most of my HSS tooling was purchased when the production shops were changing to carbide. The vendors saw HSS as dead stock and were all but giving it away just to get it off the shelves to make room for more saleable items. Since I was comfortable using it, I didn't need the additional speed and feed rates carbide is designed for, and the prices were right I stocked up.

As for mill tooling it's the same story. I have a few assorted carbide end mills and a few tools that use inserts, but 90+% of the tooling is HSS. It's what I learned to use and since I could buy it for pennies on the dollar that's primarily what I use. It's all sort of old school, but I'm not trying to meet production demands and it's easier on the pocket book.
 

P. Waller

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#15
I never do more than one part... I take it you have a turret lathe! Well done! Nice work by the way...
The last operation was done in a turret lathe, .478" ream through.
Everything else was done in an old Bridgeport NC lathe, this is where the manual tool changes were required. We do not have a turret lathe that will make the finished part.
 
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