Lathe Inserts

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rexcsmith
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Joined: Wed Aug 26, 2015 8:24 pm
Location: Portland, Or.

Lathe Inserts

Post by rexcsmith » Wed Apr 20, 2016 2:37 pm

I need to stock up on lathe inserts. I typically buy tools from MSC Direct, but my problem here is that they have so many choices of coatings, etc, for inserts, that I have no idea which way to go. Can someone point me to a simple tutorial that helps me understand what coatings are suitable for what materials. Most of my machining is done on aluminum and mild steel. thanks, rex

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SteveM
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Location: Connecticut

Re: Lathe Inserts

Post by SteveM » Wed Apr 20, 2016 8:19 pm

Simple tutorial? I doubt one exists.

carbidedepot.com has a lot of information, but like a lot of other sites, you look up an insert and it tells you what it's for, so you have to dig.

Kennametal has a product selector:
http://www.kennametal.com/en/resources/ ... ector.html

A lot of the manufacturer's grade descriptions are so vague as to be useless. They almost read like the horoscopes - they could mean anything to anyone.

Steve

mikeehlert
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Location: Los Alamitos, CA

Re: Lathe Inserts

Post by mikeehlert » Thu Apr 21, 2016 9:00 am

Rex:
I second Steve's comment, this is far from simple.

First though:
Why carbide at all? A "good" properly sharpened HSS tool will do most things in aluminum and mild steel. Do you have the spindle speed and rigidity to take advantage of carbide? There are some speed and feed guides around, Google is your friend.

Aluminum is soft enough to machine easily with HSS and for all except the high silicon alloys gives little tool wear. Coating can prevent welding though.

Mild steel (1010?) almost requires a very sharp HSS tool to get a good finish. You'll get better results with a bit higher alloy. If your going after heavy metal removal in steel your looking at negative rake, heavy depth and feed with a lot of speed. Glowing red / dark blue chips maybe. Hear coating may help especially in a production situation.

I'm just an amateur at machining. I do have a light industrial machining operation going on PVDF (a Teflon like plastic) where I have chosen to use un-coated positive rake inserts (TT321) and a brazed zero rake radius tool as it allows me to use production operators who don't need to learn tool sharpening and such. One edge lasts me months and they are running the Grizzly 4000 about 33% of the time.

Hope this helps. There are others on this board who are real machinests who will chime in if needed.

all the best

mike

hanermo
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Re: Lathe Inserts

Post by hanermo » Thu Apr 21, 2016 4:36 pm

Whats the goal ?
How many ? How good ?

Machine ?
CCMT size 21.51 is a great all around choice.
Works fine on small machines.
Cheap.
Some industrial stuff may outdo 10-100x on production stuff.

If you want high xxx, specific data is needed, and you will need specific inserts.

I had customers who do 250.000 large pieces per year (alu)/machine (20+ machines).
One tool.
30 secs machining time (they thought long).
Zero insert changes.
Zero tool changes.
Auto stuff.
Diamond tooling.
3k each, dirt cheap.

Magicniner
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Joined: Thu May 30, 2013 4:40 am

Re: Lathe Inserts

Post by Magicniner » Sat Apr 23, 2016 6:23 pm

rexcsmith wrote:I need to stock up on lathe inserts.
Buy boxes of 10 at the best prices you can find, I'd venture that if you haven't tested any you can't know what you need and for anyone else to know they'd need far more information about your lathe, it's power and speed ranges, your job sizes, etc.

- Nick

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Gary Armitstead
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Re: Lathe Inserts

Post by Gary Armitstead » Sat Apr 23, 2016 10:05 pm

Rex,

I have to agree with Mike on his assessment of using carbide. I was in the die sinking trade for forty years plus and we went through thousands of dollars a month of various carbide inserts cutting die blocks, mostly roughing steel to prepare for impression locks. We always finished the lock with HHS cutters. Some days, we would rough away enough steel that the chip bin at the end of the day probably weighed a 1000-2000 pounds or more. In these cases we needed carbide because we were battling heat issues. I never used carbide on aluminum fixture work or even mild steel. Too costly and it's overkill.

To machine aluminum, your best tool would be a well made and sharpened HHS cutter. Same for mild steels 1010-1020.
Gary Armitstead
Burbank, CA
Member LALS since 1980
Member Goleta Valley Railroad Club 1980-1993

Harold_V
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Re: Lathe Inserts

Post by Harold_V » Sun Apr 24, 2016 1:07 am

I'm assuming our good friend Gary is making reference to high speed steel (HSS) when mentioning HHS.

I fully agree. All too many are using carbide inserts when they aren't justified, nor offer any real benefits. I can't help but think that some do so as a dodge, an effort to avoid the learning curve for grinding cutting tools. What a disservice they are doing to themselves, if so.

I've said it before, and I'll say it again. Nothing will set a guy free like having the ability to hand grind proper tools. If you have a few pieces of HSS stock on hand, any configuration you can imagine can be ground and put to work faster than you can find a similar insert----and it can all be done in the same day, very unlike ordering inserts.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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SteveM
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Re: Lathe Inserts

Post by SteveM » Sun Apr 24, 2016 11:13 am

Harold_V wrote:If you have a few pieces of HSS stock on hand, any configuration you can imagine can be ground and put to work faster than you can find a similar insert
And if you pick up HSS inserts at estate sales and flea markets, you can get them with shapes already ground into them, so you may only have to sharpen them or tweak them to get useful tools.

Steve

Magicniner
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Re: Lathe Inserts

Post by Magicniner » Wed May 04, 2016 3:29 am

Harold_V wrote: I can't help but think that some do so as a dodge, an effort to avoid the learning curve for grinding cutting tools.
Some of us who can grind HSS and braze our own custom carbide tipped tools, but for whom time is at a major premium, use indexable tooling as a "dodge" to increase workshop productivity.
If you have to re-grind a tool partway through a job then you've lost not just the time to re-grind but also your DRO (or dial) settings and possibly tool centre height too, this is not an issue with indexable tooling,
Regards,
- Nick

Harold_V
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Re: Lathe Inserts

Post by Harold_V » Wed May 04, 2016 3:47 am

Magicniner wrote:If you have to re-grind a tool partway through a job then you've lost not just the time to re-grind but also your DRO (or dial) settings and possibly tool centre height too, this is not an issue with indexable tooling,
Regards,
- Nick
All too true, but it's not a big deal unless you're running a CNC. I used a mixture of HSS, brazed carbide and carbide inserts for years, doing exactly that--sharpening as required---and this in commercial shops, where time was money. That includes sharpening threading tools, often in the middle of a thread. While it took a few minutes to re-establish the reference points, it wasn't fatal---all part of doing the work. It was expected of those of us who were considered to be machinists.

I still maintain that unless a guy is involved in large production, using a CNC, there's no real need for insert tooling---especially if there's a limited number of choices of grades, although for those who can justify the cost and have the machines that benefit, sure, they're real nice. They're just not the answer to everything, but knowing how to grind proper tools can be, which is my point

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

Patio
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Re: Lathe Inserts

Post by Patio » Thu May 05, 2016 12:27 am

I am in the process of learning a bit about insert tooling also. It seems pretty confusing, with all the different holder and different inserts.

I have learned how to grind most of my tooling and I am in the process of improving grinding of chip breakers. It was required with my other lathe a SB10L but the Cazeneuve can take advantage of some of the benefits with carbide tooling.

I have found that the Shars tool company catalog has a easy to understand what goes with what kind of layout and has been helpful for me figuring out the formats. As to what kind of insert is good for what kind of work, I have very little to add. Other may help with that if you were to provide more specific of the job you wish to do and the equipment you have to do it.

Good luck
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rexcsmith
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Re: Lathe Inserts

Post by rexcsmith » Wed May 11, 2016 12:42 pm

Sorry, I was off on vacation when all these responses came in. I'll take time to study them. thanks much for the input; it looks very valuable. rex

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