Carbide tooling

[TakeawayParticipant @takeaway]

I have a set of carbide tipped lathe tools like these:

**LINK**

which I use on my mini lathe/mill. At the moment I am using the left hand tool in the set for fly cutting some MS. Trouble is the cutting edge blunts so quickly I am struggling to get the work done and my diamond tool grinder is working overtime. Others in the set also blunt quickly. I am beginning to think that these tools are not of sufficient quality to do what I want them to.

I had thought about ordering some of these:

**LINK**

but they are near the same price as the others and may be of similar (poor?) quality.

The alternatives are very expensive but I suspect that I am going to have to cough up and buy quality but before I do I'd welcome your opinion.

Stuart (hope these links work, they look a bit wierd to me)

[TakeawayParticipant @takeaway]

Tips about tips

[JasonBModerator @jasonb]

Those e-bay ones look a bit bargain basement, you would pay more than that for five mid range replacement tips.

I tend to use HSS when I flycut, only a quick touch on the grinder and its sharp again.

[Roderick JenkinsParticipant @roderickjenkins93242]

Stuart,

Links are fine. I have 2 comments really. The sort of braised tips in your first link do not have any top rake and so are not really suitable for cutting steel, especially on a mini lathe where you do not have much power. Great for cast iron though. The second point is that if you are fly cutting then presumably the cut is interrupted. Carbide really does not like the impact that happens every revolution – the tip is brittle and is liable to chip. I think you would be far better off using a high speed steel tool.

cheers,

Rod

[JasonBModerator @jasonb]

I've never found the top rake as supplied to give problems in steel and I used those type of tools quite a bit in the past before Indexable cutters became more common, I still tend to reach for them when I want a radius on an internal corner though and a tip does not have one big enough.

Again your problems may just be down to quality of teh carbide, a single 10mm tool from say J&L will set you back half the price of that set of 11.

Again I have not had problems with carbide and intermittant cuts, lets face it there are many carbide face mills and indexable endmills about and all the tips on those are getting intermittant loading. There was an interesting post about it on Madmodder the other week which relates to flycutting with carbide.

And here is a brazed tipped tool cutting rectangular steel bar on my lathe with the supplied top rake

Edited By JasonB on 06/02/2013 16:39:03

[AESParticipant @aes]

Hullo Stuart,

That 1st picture you show looks EXACTLY like the set of lathe tools I ordered from Einhell as an option to go with my then new Einhell MTB 300 lathe a few years ago. The Einhell is a re-badged Chinese Minillathe from Real Bull (similar to Sieg).

At that time I didn't know any better, and exactly as others have posted above, those tipped tools are/were a PITA to cut steel with, and ali too (but were pretty good on the little bit of cast iron I've done so far).

I can't say anything about the tipped tools you show in your 2nd pic but after the above troubles I went in a completely different direction – based on the ads here and elsewhere, plus their video, I bought the Eccentric Engineering "angled" tool holder which has a simple HSS tool bit (plus sharpeneing jig). I must say that since then I haven't looked back. I still have the above tipped tools but use the Eccentric Engineering tool for 99% of my jobs.

Marvellous tool, highly recommended, usual disclaimers.

Hope this helps, even though it's pointing you in a different direction.

Best of luck

Krgds

AES

[Clive HartlandParticipant @clivehartland94829]

This business of carbide tooling comes up all the time, one thing is that carbide tooling needs a 150% speed increase to cut properly and it must be a good cut. No fine cuts as it will give a poor finish so adjust the tool and work diameter to be very near finished diameter and leave slightly raised steps for bearings and finish those parts with HSS tooling. carbide tooling will remove metal very quickly and save time but only if the lathe/mill is rigid.

Cutting steel with carbide, will if cutting correctly, give blue swarf and its very hot as I have lots of burns on the backs of my hands to show for it.

Also bear in mind that there are different grades of Carbide tips, like P and K which seem suitable for normal work. Unfortunately people see, 'Carbide' and jump straight in thinking its magic and it is not as it requires some knowledge of the types available.

In general, 'Cobalt' tooling is quite adequate for model engineers and Carbide will only be needed occasionally for very hard applications like turning down a milling cutter shank.

Drill shanks are sometimes turned down to fit collets or chucks when you want a large drill but no holder to fit it in. In this case carbide will give a very smooth finish and aid the grip of the drill and chuck.

Clive

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by JasonB on 06/02/2013 16:36:35:

And here is a brazed tipped tool cutting rectangular steel bar on my lathe with the supplied top rake

Can't argue with that – lovely finish. However, it's clearly not working for Stuart. Possibly due to the quality of the carbide.

I don't really think that flycutting is analagous to milling, when I flycut the the tooth loading is much more than on any mill I use.

Rod

[Anonymous]

Rod,

I though that the analogy between flycutting and milling was a good one, but may be not? I'm curious as to what conditions you're using for flycutting in terms of speeds, feeds and depth of cut. I assume that by 'tooth loading' you mean chip load, ie, feed per tooth?

Regards,

Andrew

[TakeawayParticipant @takeaway]

Thanks to you all who have replied. Tried to reduce the thickness of a piece of MS about the size of a box of Swan Vesta by about 3mm this afternoon on this mini machines milling head. The head can be angled from side to side but despite the caphead screws retaining it in position being well tightened, the sideways cutting forces (and I was being careful) pushed the milling head sideways. The cuts were accompanied by chattering and vibration and the whole machine was jumping up and down. On my old Bridport years ago I would have done the job in five minutes, I have not even finished yet but I bet I have been at it for five hours! Turning a bit of say, 1/2" diameter MS produces the same nasty vibrations and chatter marks on the material.

I think maybe that the lack of rigidity may be enhancing the shock to the carbide tipped tools previously referred to when fly cutting thus causing the edge to dull/chip.

I have had this little machine for 3 years now and have decided that its lack of solidity/rigidity is spoiling my enjoyment of the hobby. Till now I have regarded the machines limitations as a challenge but "b—-r" challenges – I want to get the job done! Some would remark that I have been pushing the little darling to hard – I won't argue. Although I had hoped to make it do me for my retirement years I think I might have to get shot and find something with a little more welly.

Thanks again chaps -Stuart

[Sub MandrelParticipant @submandrel]

I recall Tubal Cain did a lengthy comparison of flycutting and milling. In short he reckoned that to get comparable results flycutting was slower due to lower rpm and feedrates, despite the much larger sweep. He did point out that fklycut surfaces generally LOOK better even if they are technically the same roughness average.

Neil

[magpieParticipant @magpie]

Hi Stuart, If you look at "workshop tools and tooling" in the forum section, go to page 6 and click on "indexable fly cutter" you will find what i have found to be the best little fly cutting tool i have tried yet. I dont know how to put a link to the thread, perhaps someone who knows could oblige for the benifit of any new members.

Cheers Derek.

[MadMikeParticipant @madmike]

Stuart at the risk of sounding stupid, and that's not difficult for me, why are you bothering to fly cut such a small piece? I wouldn't bother with flycutting except on a large flat piece. I think that your description of a mini-lathe mill may actually say it all, particularly after reading your comments about using a Bridgeport in another life. All the talk about HSS v Crbide tools is OK but probably will not solve your problem, particularly as your milling head "tilts"during a light load cutting process. Other opinions are available of course. HTH.

[TakeawayParticipant @takeaway]

Hello MadMike – thanks for your comments but fly cutting this small piece imposes less side strain on the milling head. Also. bear in mind that for this tiddly little machine this Swan Vesta sized piece of MS is HUGE!!! – Regards – Stuart

[JasonBModerator @jasonb]

Can you not do it in the 4-jaw on the lathe?

 

Click for Magpie's Flycutter

 

J

Edited By JasonB on 06/02/2013 21:13:07

[TakeawayParticipant @takeaway]

Could do Jason but chatter and vibration would be as bad – I've tried it.

[JasonBModerator @jasonb]

Just out of interest how much are you trying to take off per pass?

J

[TakeawayParticipant @takeaway]

Lo Jason – 0.2mm per pass absolute max to prevent vibration – for good finish I have to sharpen tool and take a VERY fine cut (but I do end up with a superior finish)! But don't waste to much of your time over me (although it is much appreciated) because I've already decided to ditch this kit and find something else. – Best regards – Stuart

[Roderick JenkinsParticipant @roderickjenkins93242]

Andrew,

Most of my flycutting experience is on cast iron and I have not done any for some time, I would always choose to end mill these days. When I was young and impatient I guess I would have been taking a 10 or 20 thou depth of cut to get below the skin at about 3 inch radius and probably increasing the feed by 10 thou at each revolution in back gear. Brutal stuff that would not quite stall the Super 7. Each revolution would certainly start with quite a bang that would eventually lead to complaints from the household authorities. I can feel my ears ringing just thinking about it.

Clearly modern carbide inserts are much better at dealing with these sorts of conditions than the cheap brazed tools I tried and I'm sure a big rigid mill can give these sorts of feeds per tooth on a face mill but not in the amateur workshop.

cheers,

Rod

[Michael GilliganParticipant @michaelgilligan61133]

Posted by magpie on 06/02/2013 20:28:01:

Hi Stuart, If you look at "workshop tools and tooling" in the forum section, go to page 6 and click on "indexable fly cutter" you will find what i have found to be the best little fly cutting tool i have tried yet. I dont know how to put a link to the thread, perhaps someone who knows could oblige for the benifit of any new members.

Cheers Derek.

 

Nice reference Derek … here is a link

All you need to do is go to the thread in question, then copy the URL

… then use the insert hyperlink button … 6th icon on the lower row

[easier if you have two instances of the forum open at the same time]

MichaelG.

Edited By Michael Gilligan on 06/02/2013 22:27:31

[magpieParticipant @magpie]

Thanks for that Michael, ( and Jason ) but i do'nt even know what a URL is !!!!!!!

Cheers Derek.

[Ady1Participant @ady1]

You need good alround stiffness and setup, this stops them blunting/chipping

You need to grind a slight concave just behind the tip

(use a green grit wheel for carbide)

You need to grind a tiny amount of clearance from the tip to the base of the tool, giving it internal strength because it's almost vertical

Give it a slight rounding, sharp pointy tips are too weak, but keep the top flat, so it goes straight into the concave depression

The bottom line is:

Practice practice and…. practice

In the case of carbide tooling, it's well worth the effort

 

This is an oval concrete reinforcing bar done with a single resharpening

Loads of intermittent cutting and only just fitting into the lathe centres

 

——

I have a set of carbide tipped lathe tools like these:

**LINK**

etc

——-

 

edit:

Sometimes negative rake is better for cast iron, worth bearing in mind if you get a tough job

(It's pretty weird to see how well it cuts if you do run into this situation)

Edited By Ady1 on 06/02/2013 23:57:09

[Ady1Participant @ady1]

When you get it just right with carbide, even an intermittent cut whispers

Amazing amounts of material are effortlessly removed with a straight cut, it hisses

Watch that swarf though, it can be hot stuff

 

It's well worth the effort to learn, carbide is now always my first choice for those bigger basic jobs

 

Edited By Ady1 on 07/02/2013 00:08:48

[Anonymous]

Rod,

Thanks for the information. In my limited experience of flycutting it didn't live up to expectations, probably due to vibration and tool resonance arising from the initial impact of the tool. I'll agree that 10 thou per rev is a respectable feedrate. I'll use a value like that milling plastics, but for milling metal the values tend to be lower, albeit with much bigger DOC.

I have recently bought an 80mm diameter insert milling cutter, which I hope will speed up the milling of the cylinder blocks and other castings for my traction engines. It will be interesting to see what feeds and speeds it will cope with. Substantial I hope, as it'll have 5hp behind it.

Regards,

Andrew

[Michael GilliganParticipant @michaelgilligan61133]

Posted by magpie on 06/02/2013 22:32:12:

Thanks for that Michael, ( and Jason ) but i do'nt even know what a URL is !!!!!!!

Cheers Derek.

 

Sorry Derek … I shouldn't have assumed TLA-awareness

<TLA = Three Letter Acronym>

<URL= Uniform Resource Locator>

… which is the "proper" name for the web-address that you should see at the top of your Browser window.

If you need to know more, please send me a personal message

[click on "Message member" at the bottom of this post]

Hope that helps

MichaelG.

 

 

Edited By Michael Gilligan on 07/02/2013 20:46:30

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