Lathe Tools

[Damaged]

Hi all,

Does anybody have a link to or a suggestion of a book regarding the selection of lathe tools for various tasks?

Although I've been given an old school Colchester I haven't used one since my apprentice days, I've figured out most of the controls (ignoring screw cutting for now) but surface finish always leaves something to be desired!

I'm clueless regarding the sharpening of lathe tools so want to go indexable tools but the vast array is baffling me.

Thanks,

Mick.

 

[Pete.]

I would set an evening aside and read up here: http://bbs.homeshopmachinist.net/

This is one good thread (sic) and links to another good source of info too:
http://bbs.homeshopmachinist.net/showthread.php?t=35818

 

[Angusdog]

HSS (high speed steel) tools are versatile, easy enough to grind and customisable to what you need to do. Avoid carbide tips tools (you see a lot of them on Ebay etc, HSS is much better). Although indexable inserts are great, I think you should start with HSS tool blanks. It's easy to grind them, although you just need to be aware of what you're cutting and the angles required. Here's all you need to get going (links to a PDF with diagrams).

Grinding tools is a bit of an art, but easy enough to get started and get good results from. The advantage with HSS tools is you can grind one for cutting metric threads, regrind it for imperial threads, cutting a thread right up tight to a shoulder, cutting aluminium and so on. They're cheap and you can always put a particular profile in a drawer for say cutting internal threads. Inserts do a nice job, they're long lasting but you do need a range of them and you can't for example customise them to do a certain job.

I found the most important thing about grinding HSS is the nose - it can be hard to see, but you need a little curve there, and that's what affects the finish the most. If it's sharp, you'll end up putting a very fine groove into the work, a bit like a victorian wax cylinder, but just give the tool a wee dress on a sharpening stone and you'll get a lovely shiny finish.

 

[Archie]

I have to say that in all the lathe work I did at school I have never once had need for anything more than a bog standard turning tool, a boring bar, a parting off tool and a knurling tool. I've never cut a thread either so, while I realise that may just be a result of what I've used the lathe for, that's why I've always preferred indexable tooling. If I were to have a lathe (which would be a Colchester you sod! ) I'd buy indexable tooling straight away.

 

[HasBean]

As above,

But I tend to use indexable tips these days and HSS for specials.

The tips you tend to receive with the tools from the usual suppliers are dubious, I don't like Tungsten Carbide and tend to use Titanium Carbide (Cermets)

For good quality tools try HERE

Also they can supply Mitsubishi NX2525 cermet inserts in 0.2, 0.4, 0.8mm tip radius' (0.2, 0.4mm most usefull)


If you want any pics just PM me.

Paul

 

[Angusdog]

I forgot to mention that I did a machining evening class (1 night/week for 12 weeks) and it was superb value for money. And screwcutting is very easy once someone talks you through it, although for most uses, taps and dies are much quicker. It's not often you need a thread larger than most sets provide. One project I did make was a die holder for my lathe which fits in the headstock - makes the threads perfectly aligned and easy to cut.

 

[HasBean]

I forgot to mention that I did a machining evening class (1 night/week for 12 weeks) and it was superb value for money. And screwcutting is very easy once someone talks you through it, although for most uses, taps and dies are much quicker. It's not often you need a thread larger than most sets provide. One project I did make was a die holder for my lathe which fits in the headstock - makes the threads perfectly aligned and easy to cut.

Best way too.

I cut the threads in the lathe to ensure they're correct and then just clean them up with the tailstock die holder.

Paul

 

[R Kraft]

I like to use cobalt bits with the lathe, they take a nice edge and hold it better than HSS.
Here's a link to basic tool sharpening:
http://www.sherline.com/grinding.htm
Robert

 

[HasBean]

There's a definate knack to using tipped tooling so I'd recommend using HSS first (also gives you an understanding about rake/clearance angles etc)

Cobalt HSS is great but a bu**er to grind to shape. I use it on my flycutters with quite a large radius as it can take far higher speeds and gives a lovely finish (I know it's not recommended to run them at high speeds but it works for me )

Paul

 

[Damaged]

Wow!

Cheers for all the replys Gents

Will have a read.

 

[hareng]

Something no one mentioned is avoid the ****** tooling, its false economy.
Very expensive the tipped tooling but again dont skimp on quality stick to decent brand names as Kennametal and Sandvik.
Agree with the flycutter HSS or HSS/Cobalt bits spinning up to 2000rpm, no radius leaves a finish you can see the grain.

 

[shenion]

Yes, those "10/20-piece carbide" sets are junk. I wasted money on them. They chattered or did a poor finish. Seem to dull quickly.

The issue is not that they are carbide, it is that they have no rake or relief angles (near square front.) Needs a lot of force to work and small lathes are too weak for them. Many say "these older lathes were not designed for carbide tooling". That is not true, they were not designed for 0-degree rake tooling. The manuals all describe how to add the correct rake and relief angles for HSS bits. Carbide works the same if you get the same angles.

I use indexed carbide tooling. Creates a real smooth finish and cuts easily.

WHen they get worn, i keep an eye on ebay for name-brand inserts. I picked up 10 for $10 of Mitsubishi inserts recently. They work great but don't have a chip breaker.

Most of the inserts on ebay seem to be the 'N' type for no relief angle, I look for 7 or 8 degrees. Makes a big difference. Also, I usually get 1/32" radius for a smoother finish than the sharp pointed ones.

I use HSS for threading or custom profiles. I have various sizes.

I recently picked up a cobalt T-type cutoff tool. Works much better than the HSS cutters.

On hard metals (recently did some tool steel), the carbide work real well over HSS and last longer. HSS will tend to have a smoother finish on grainy materials. I find that due to the bit dulling quickly.

 

[Pete.]

I use THESE inserts. I made a simple holder with 5 degrees of negative rake which gives me 60 cutting edges at 5 degrees of positive rake (given by the 10 degree chip-breaker) for just 8 quid delivered. You can't beat that for value! I use them for roughing stuff out and if I need a beter finish I grind-up a finishing tool from HSS.

These work great on stainless BTW, which is a devil to cut with HSS unless you really like stopping to re-sharpen every few minutes.

 

[hareng]

We use those at work Pete for spring steel and tool steel, different grade though Kennametal holder.

Best tooling i have ever known is the Kennametal Top Notch stuff, last ages and cut very well in soft to hard steels.
Normally use the ones meant for cast iron because they were free, work ok on aluminium.

JLS are very expensive, i only buy whats on offer or whats being sold off.
Ebay is a good source but you need to know what you are buying with part numbers etc.

 

[MrFluffy]

I use indexable carbide tooling in the mill, and in the lathe, brands kennametal, korolloy and sandvik and a few other well knowns though , no bulk purchases to save a bit.
Where most people mess up with carbide tooling is they require a much higher cutting speed and depth of cut. Sometimes older lathes have a bit too much slop in bearings/slides and insufficient top speed to deliver this, in which case hss is the better option.
Inserts win over normal tooling in that their cutting angles etc are preset by the toolholder manufacturer to present the optimum rake/clearance for their inserts, and means you have to use a sandvik insert with a sandvik toolholder...
Also where hss wins over carbide is on interrupted cuts. Say you have to turn across a hole in a shaft, the hole interrupts the steady cut of the tool and upsets it, the carbide tends to chip its cutting edge in these circumstances, whereas the hss will carry on like a trooper.

One last advantage of indexable tooling, if the tool goes off half way through the job, you can index the insert and present a new sharp cutting edge, which should already be on centre and roughly set up near enough to carry on without having to re-set up...
Hss tool grinding is a knack worth learning, but the best of both worlds is to be able to use the hss and grind them sharp, and use the carbide inserts when you need to save time/bulk material removal and other cases. Best of both worlds...

 

[Pete.]

We use those at work Pete for spring steel and tool steel, different grade though Kennametal holder.

Best tooling i have ever known is the Kennametal Top Notch stuff, last ages and cut very well in soft to hard steels.
Normally use the ones meant for cast iron because they were free, work ok on aluminium.

JLS are very expensive, i only buy whats on offer or whats being sold off.
Ebay is a good source but you need to know what you are buying with part numbers etc.

The ones I linked are meant for cast iron & stainless, but are great for aluminium too and for some reason the ally doesn't weld to the edge of the tip no matter how hard I drive it. Hogging material off with those on alloy is a revelation after HSS. I ahve also managed to turn the casing off some induction-hardened excaator pins with these inserts which had defied all previous attempts. I had blue & purple curls flying everyhere and had to roll my sleeves down, hid behind the guard and still made sure I had my safety specs on.

As far as checking for the grade/useage of eBay inserts, I followed this advice from Glenn Wegman in the link above and it worked out great for me so long as it's one of the manufacturers listed:

As far as your question about a grade chart:

Each manufacturer has their own grade designation for inserts so you would need to go to a specific manufacturer to research what grade they recomment for your purpose.

Another method, if you plan on browsing eBay for inserts, is to look it up according to it's listed grade. Find an interresting looking insert and then go here. http://www.carbidedepot.com/. As long as the manufacturer's Icon is shown on this page, just click on the icon and that will take you to a support page for that manufacturer. Then click on the link next to "Online application support" and that page will have lots of links to different sorts of info. I use the "Grade look up" link and type in the grade listed on the insert on eBay and it will tell you what it's primary use is.

Sounds complicated, but it isn't bad once you do it a few times.

Glenn